Scrutiny of the mechanism of small molecule inhibitor preventing conformational transition of amyloid-β42 monomer: insights from molecular dynamics simulations.

PubMed

Shuaib, Suniba; Goyal, Bhupesh

2018-02-01

Alzheimer's disease (AD) is a progressive neurodegenerative disorder that is characterized by loss of intellectual functioning of brain and memory loss. According to amyloid cascade hypothesis, aggregation of amyloid-β 42 (Aβ 42 ) peptide can generate toxic oligomers and their accumulation in the brain is responsible for the onset of AD. In spite of carrying out a large number of experimental studies on inhibition of Aβ 42 aggregation by small molecules, the detailed inhibitory mechanism remains elusive. In the present study, comparable molecular dynamics (MD) simulations were performed to elucidate the inhibitory mechanism of a sulfonamide inhibitor C1 (2,5-dichloro-N-(4-piperidinophenyl)-3-thiophenesulfonamide), reported for its in vitro and in vivo anti-aggregation activity against Aβ 42 . MD simulations reveal that C1 stabilizes native α-helix conformation of Aβ 42 by interacting with key residues in the central helix region (13-26) with hydrogen bonds and π-π interactions. C1 lowers the solvent-accessible surface area of the central hydrophobic core (CHC), KLVFF (16-20), that confirms burial of hydrophobic residues leading to the dominance of helical conformation in the CHC region. The binding free energy analysis with MM-PBSA demonstrates that Ala2, Phe4, Tyr10, Gln15, Lys16, Leu17, Val18, Phe19, Phe20, Glu22, and Met35 contribute maximum to binding free energy (-43.1 kcal/mol) between C1 and Aβ 42 monomer. Overall, MD simulations reveal that C1 inhibits Aβ 42 aggregation by stabilizing native helical conformation and inhibiting the formation of aggregation-prone β-sheet conformation. The present results will shed light on the underlying inhibitory mechanism of small molecules that show potential in vitro anti-aggregation activity against Aβ 42 .

Platelet-derived growth factor inhibits platelet activation in heparinized whole blood.

PubMed

Selheim, F; Holmsen, H; Vassbotn, F S

1999-08-15

We previously have demonstrated that human platelets have functionally active platelet-derived growth factor alpha-receptors. Studies with gel-filtered platelets showed that an autocrine inhibition pathway is transduced through this tyrosine kinase receptor during platelet activation. The physiological significance of this inhibitory effect of platelet-derived growth factor on gel-filtered platelets activation is, however, not known. In the present study, we investigated whether platelet-derived growth factor inhibits platelet activation under more physiological conditions in heparinized whole blood, which represents a more physiological condition than gel-filtered platelets. Using flow cytometric assays, we demonstrate here that platelet-derived growth factor inhibits thrombin-, thrombin receptor agonist peptide SFLLRN-, and collagen-induced platelet aggregation and shedding of platelet-derived microparticles from the platelet plasma membrane during platelet aggregation in stirred heparinized whole blood. The inhibitory effect of platelet-derived growth factor was dose dependent. However, under nonaggregating conditions (no stirring), we could not demonstrate any significant effect of platelet-derived growth factor on thrombin- and thrombin receptor agonist peptide-induced platelet surface expression of P-selectin. Our results demonstrate that platelet-derived growth factor appears to be a true antithrombotic agent only under aggregating conditions in heparinized whole blood.

Native-like aggregates of Factor VIII (FVIII) are immunogenic von Willebrand Factor deficient and hemophilia A mice

PubMed Central

Pisal, Dipak S.; Kosloski, Matthew P.; Middaugh, C. Russell; Bankert, Richard B.; Balu-Iyer, Sathy V.

2013-01-01

The administration of recombinant Factor VIII (FVIII) is the first line therapy for Hemophilia A (HA), but 25–35% of patients develop an inhibitory antibody response. In general, the presence of aggregates contributes to unwanted immunogenic responses against therapeutic proteins. FVIII has been shown to form both native-like and non-native aggregates. Previously, we showed that non-native aggregates of FVIII are less immunogenic compared to the native protein. Here we investigated the effect of native-like aggregates of FVIII on immunogenicity in HA and von Willebrand Factor knockout (vWF−/−) mice. Mice immunized with native-like aggregates showed significantly higher inhibitory antibody titers compared to animals that received native FVIII. Following re-stimulation in vitro with native FVIII, the activation of CD4+ T cells isolated from mice immunized with native-like aggregates is ~4 fold higher than mice immunized with the native protein. Furthermore, this is associated with increases in the secretion of pro-inflammatory cytokines IL-6 and IL-17 in the native-like aggregate treatment group. The results indicate that the native-like aggregates of FVIII are more immunogenic than native FVIII for both the B cell and T cell responses. PMID:22388918

Study of anti-fibrillogenic activity of iron(II) clathrochelates.

PubMed

Kovalska, Vladyslava B; Losytskyy, Mykhaylo Yu; Varzatskii, Oleg A; Cherepanov, Vsevolod V; Voloshin, Yan Z; Mokhir, Andriy A; Yarmoluk, Sergiy M; Volkov, Sergiy V

2014-03-15

The macrocyclic compounds mono- and bis-iron(II) clathrochelates were firstly studied as potential anti-fibrillogenic agents using fluorescent inhibitory assay, atomic force microscopy and flow cytometry. It is shown that presence of the clathrochelates leads to the change in kinetics of insulin fibrillization reaction and reduces the amount of formed fibrils (up to 70%). The nature of ribbed substituent could determine the activity of clathrochelates-the higher inhibitory effect is observed for compounds containing carboxybenzenesulfide groups, while the inhibitory properties only slightly depend on the size of complex species. The mono- and bis-clathrochelate derivatives of meta-mercaptobenzoic acid have close values of IC₅₀ namely 16 ± 2 and 24 ± 5 μM, respectively. The presence of clathrochelates decreases the fibril diameter from 5-12 nm for free insulin fibrils to 3-8 nm for these formed in the clathrochelate presence, it also prevents the lateral aggregation of mature fibrils and formation of superfibrillar clusters. However the addition of clathrochelate results in more heterogeneous (both by size and structure) insulin aggregates population as compared to the free insulin. This way, cage complexes-iron(II) clathrochelates are proposed as efficient agents able to suppress the protein aggregation processes. Copyright © 2014 Elsevier Ltd. All rights reserved.

Mapuche herbal medicine inhibits blood platelet aggregation.

PubMed

Falkenberg, Susan Skanderup; Tarnow, Inge; Guzman, Alfonso; Mølgaard, Per; Simonsen, Henrik Toft

2012-01-01

12 plant species traditionally used by the Mapuche people in Chile to treat wounds and inflammations have been evaluated for their direct blood platelet inhibition. Seven of the 12 tested plant species showed platelet inhibitory effect in sheep blood, and four of these were also able to inhibit the ADP- (5.0 μM) and collagen- (2.0 μg/mL) induced aggregations in human blood. These four species in respective extracts (in brackets) were Blechnum chilense (MeOH), Luma apiculata (H(2)O), Amomyrtus luma (DCM : MeOH 1 : 1) and Cestrum parqui (DCM : MeOH 1 : 1). The platelet aggregating inhibitory effects of A. luma (DCM : MeOH 1 : 1), and L. apiculata (H(2)O) were substantial and confirmed by inhibition of platelet surface activation markers.

Mapuche Herbal Medicine Inhibits Blood Platelet Aggregation

PubMed Central

Falkenberg, Susan Skanderup; Tarnow, Inge; Guzman, Alfonso; Mølgaard, Per; Simonsen, Henrik Toft

2012-01-01

12 plant species traditionally used by the Mapuche people in Chile to treat wounds and inflammations have been evaluated for their direct blood platelet inhibition. Seven of the 12 tested plant species showed platelet inhibitory effect in sheep blood, and four of these were also able to inhibit the ADP- (5.0 μM) and collagen- (2.0 μg/mL) induced aggregations in human blood. These four species in respective extracts (in brackets) were Blechnum chilense (MeOH), Luma apiculata (H2O), Amomyrtus luma (DCM : MeOH 1 : 1) and Cestrum parqui (DCM : MeOH 1 : 1). The platelet aggregating inhibitory effects of A. luma (DCM : MeOH 1 : 1), and L. apiculata (H2O) were substantial and confirmed by inhibition of platelet surface activation markers. PMID:22028732

Inhibitory Effects of Flavonoids from Spatholobus suberectus on Sortase A and Sortase A-Mediated Aggregation of Streptococcus mutans.

PubMed

Park, Wanki; Ahn, Chan-Hong; Cho, Hyunjoo; Kim, Chang-Kwon; Shin, Jongheon; Oh, Ki-Bong

2017-08-28

Seven flavonoids were isolated from Spatholobus suberectus via repetitive column chromatography and high-performance liquid chromatography. The chemical structures of these compounds were identified by spectroscopic analysis and comparison with values reported in the literature. Among the flavonoids tested, 7-hydroxy-6-methoxyflavanone ( 1 ) and formononetin ( 4 ) exhibited strong inhibitory activity against Streptococcus mutans SrtA, with IC 50 values of 46.1 and 41.8 µM, respectively, but did not affect cell viability. The onset and magnitude of inhibition of saliva-induced aggregation in S. mutans treated with compounds 1 and 4 were comparable to the behavior of a srtA -deletion mutant without treatment.

Secreted Immunomodulatory Proteins of Staphylococcus aureus Activate Platelets and Induce Platelet Aggregation.

PubMed

Binsker, Ulrike; Palankar, Raghavendra; Wesche, Jan; Kohler, Thomas P; Prucha, Josephine; Burchhardt, Gerhard; Rohde, Manfred; Schmidt, Frank; Bröker, Barbara M; Mamat, Uwe; Pané-Farré, Jan; Graf, Anica; Ebner, Patrick; Greinacher, Andreas; Hammerschmidt, Sven

2018-04-01

Staphylococcus aureus can cause bloodstream infections associated with infective endocarditis (IE) and disseminated intravascular coagulopathy (DIC). Both complications involve platelets. In view of an increasing number of antibiotic-resistant strains, new approaches to control systemic S. aureus infection are gaining importance. Using a repertoire of 52 recombinant S. aureus proteins in flow cytometry-based platelet activation and aggregation assays, we identified, in addition to the extracellular adherence protein Eap, three secreted staphylococcal proteins as novel platelet activating proteins. Eap and the chemotaxis inhibitory protein of S. aureus (CHIPS), the formyl peptide receptor-like 1 inhibitory protein (FLIPr) and the major autolysin Atl induced P-selectin expression in washed platelets and platelet-rich plasma. Similarly, AtlA, CHIPS and Eap induced platelet aggregation in whole blood. Fluorescence microscopy illustrated that P-selectin expression is associated with calcium mobilization and re-organization of the platelet actin cytoskeleton. Characterization of the functionally active domains of the major autolysin AtlA and Eap indicates that the amidase domain of Atl and the tandem repeats 3 and 4 of Eap are crucial for platelet activation. These results provide new insights in S. aureus protein interactions with platelets and identify secreted proteins as potential treatment targets in case of antibiotic-resistant S. aureus infection. Schattauer GmbH Stuttgart.

Inhibitory Effect of Waste Glass Powder on ASR Expansion Induced by Waste Glass Aggregate

PubMed Central

Liu, Shuhua; Wang, Shu; Tang, Wan; Hu, Ningning; Wei, Jianpeng

2015-01-01

Detailed research is carried out to ascertain the inhibitory effect of waste glass powder (WGP) on alkali-silica reaction (ASR) expansion induced by waste glass aggregate in this paper. The alkali reactivity of waste glass aggregate is examined by two methods in accordance with the China Test Code SL352-2006. The potential of WGP to control the ASR expansion is determined in terms of mean diameter, specific surface area, content of WGP and curing temperature. Two mathematical models are developed to estimate the inhibitory efficiency of WGP. These studies show that there is ASR risk with an ASR expansion rate over 0.2% when the sand contains more than 30% glass aggregate. However, WGP can effectively control the ASR expansion and inhibit the expansion rate induced by the glass aggregate to be under 0.1%. The two mathematical models have good simulation results, which can be used to evaluate the inhibitory effect of WGP on ASR risk. PMID:28793603

Probing the inhibitory potency of epigallocatechin gallate against human γB-crystallin aggregation: Spectroscopic, microscopic and simulation studies

NASA Astrophysics Data System (ADS)

Chaudhury, Susmitnarayan; Dutta, Anirudha; Bag, Sudipta; Biswas, Pranandita; Das, Amit Kumar; Dasgupta, Swagata

2018-03-01

Aggregation of human ocular lens proteins, the crystallins is believed to be one of the key reasons for age-onset cataract. Previous studies have shown that human γD-crystallin forms amyloid like fibres under conditions of low pH and elevated temperature. In this article, we have investigated the aggregation propensity of human γB-crystallin in absence and presence of epigallocatechin gallate (EGCG), in vitro, when exposed to stressful conditions. We have used different spectroscopic and microscopic techniques to elucidate the inhibitory effect of EGCG towards aggregation. The experimental results have been substantiated by molecular dynamics simulation studies. We have shown that EGCG possesses inhibitory potency against the aggregation of human γB-crystallin at low pH and elevated temperature.

Phenolic chemical composition of Petroselinum crispum extract and its effect on haemostasis.

PubMed

Chaves, Douglas S A; Frattani, Flávia S; Assafim, Mariane; de Almeida, Ana Paula; de Zingali, Russolina B; Costa, Sônia S

2011-07-01

From the aqueous extract (Pc) of Petroselinum crispum (Mill) flat leaves specimens were isolated and identified the flavonoids apigenin (1), apigenin-7-O-glucoside or cosmosiin (2), apigenin-7-O-apiosyl-(1 --> 2)-O-glucoside or apiin (3) and the coumarin 2",3"-dihydroxyfuranocoumarin or oxypeucedanin hydrate (4). The inhibitory activity toward clotting formation and platelet aggregation was assessed for Pc flavonoids (1) and (2), and the coumarin (4). Pc showed no inhibition on clotting activity when compared with the control. On the other hand, a strong antiplatelet aggregation activity was observed for Pc (IC50 = 1.81 mg/mL), apigenin (IC50 = 0.036 mg/mL) and cosmosiin (IC50 = 0.18 mg/mL). In all cases ADP was used as inductor of platelet aggregation. Our results showed that Pc, apigenin and cosmosiin interfere on haemostasis inhibiting platelet aggregation. To the best of our knowledge this is the first report for the cosmosiin antiplatelet aggregation in vitro activity.

ROCK and PRK-2 Mediate the Inhibitory Effect of Y-27632 on Polyglutamine Aggregation

PubMed Central

Shao, Jieya; Welch, William J.; Diamond, Marc I.

2009-01-01

Polyglutamine expansion in huntingtin (Htt) and the androgen receptor (AR) causes untreatable neurodegenerative diseases. Y-27632, a therapeutic lead, reduces Htt and AR aggregation in cultured cells, and Htt-induced neurodegeneration in Drosophila. Y-27632 inhibits both Rho-associated kinases ROCK and PRK-2, making its precise intracellular target uncertain. Over-expression of either kinase increases Htt and AR aggregation. Three ROCK inhibitors (Y-27632, H-1077, HA-1152), and a specific ROCK inhibitory peptide reduce polyglutamine protein aggregation, as does knockdown of ROCK or PRK-2 by RNAi. RNAi also indicates that each kinase is required for the inhibitory effects of Y-27632 to manifest fully. These two actin regulatory kinases are thus involved in polyglutamine aggregation, and their simultaneous inhibition may be an important therapeutic goal. PMID:18423405

The potent inhibition of vapiprost, a novel thromboxane A2 receptor antagonist, on the secondary aggregation and ATP release of human platelets.

PubMed

Horie, S; Yamada, M; Satoh, M; Noritake, S; Hiraishi, S; Kizaki, K; Kurusu, O; Nakahara, T; Ishii, H; Kazama, M

1997-06-01

The inhibitory effects of vapiprost hydrochloride (vapiprost), a novel thromboxane A2 receptor antagonist, on platelet aggregation and ATP release were studied using platelet rich plasma (PRP) of humans, guinea pigs, rabbits and rats. In in vitro experiments with human platelet, vapiprost inhibited the aggregation and ATP release stimulated with U-46619, collagen or arachidonic acid (AA) at an IC50 of less than 2.1 x 10(-8) M. Vapiprost did not inhibit the primary aggregation or ATP release of human platelets stimulated with adenosine 5'-diphosphate (ADP), epinephrine (Epi) or platelet activating factor (PAF), but inhibited the secondary aggregation stimulated with those agonists at an IC50 of less than 1.3 x 10(-7) M. The sensitivity of platelets in various species of animals to vapiprost was in the following order: human > or = guinea pigs > rats > rabbits. In ex vivo experiments with guinea pigs which received a single oral dose of vapiprost, the agent demonstrated strong inhibition of ATP release from platelets stimulated with U-46619, collagen or AA at an ID50 of less than 25.8 micrograms/kg. These inhibitory effects were observed within 30 min and sustained for 24 h at a single dosage of 5 mg/kg of vapiprost. In AA-induced pulmonary infarction models of mice, the sudden death rates decreased significantly with the oral administration of 10 mg/kg or more of vapiprost. These results indicate that vapiprost effectively inhibits the secondary aggregation and ATP release of human platelets stimulated with various agonists, and that guinea pig and human platelets are similar in response to vapiprost. Furthermore, it was demonstrated in ex vivo experiments with guinea pigs that the inhibitory action of vapiprost appears rapidly and lasts for long periods.

Verotoxin and neuraminidase induced platelet aggregating activity in plasma: their possible role in the pathogenesis of the haemolytic uraemic syndrome.

PubMed Central

Rose, P E; Armour, J A; Williams, C E; Hill, F G

1985-01-01

Certain strains of Escherichia coli producing verotoxin have been isolated in the stools of patients with the haemolytic uraemic syndrome. A platelet aggregating activity has been found in normal plasma after incubation with verotoxin at 37 degrees C for 24 h. This activity, unlike neuraminidase, has an effect that is independent of changing factor VIII related antigen, but requires the IIA and IIIB platelet surface glycoprotein (deficient in thrombasthenia) to mediate its effect. Prostacyclin totally inhibited this effect, but other antiplatelet drugs and heparin were without inhibitory effects. PMID:2859303

Lignans and aromatic glycosides from Piper wallichii and their antithrombotic activities.

PubMed

Shi, Yan-Ni; Shi, Yi-Ming; Yang, Lian; Li, Xing-Cong; Zhao, Jin-Hua; Qu, Yan; Zhu, Hong-Tao; Wang, Dong; Cheng, Rong-Rong; Yang, Chong-Ren; Xu, Min; Zhang, Ying-Jun

2015-03-13

Piper wallichii (Miq.) Hand.-Mazz. is a medicinal plant used widely for the treatment of rheumatoid arthritis, inflammatory diseases, cerebral infarction and angina in China. Previous study showed that lignans and neolignans from Piper spp. had potential inhibitory activities on platelet aggregation. In the present study, we investigated the chemical constituents of Piper wallichii and their antithrombotic activities, to support its traditional uses. The methanolic extract of the air-dried stems of Piper wallichii was separated and purified using various chromatographic methods, including semi-preparative HPLC. The chemical structures of the isolates were determined by detailed spectroscopic analysis, and acidic hydrolysis in case of the new glycoside 2. Determination of absolute configurations of the new compound 1 was facilitated by calculated electronic circular dichroism using time-dependent density-functional theory. All compounds were tested for their inhibitory effects on platelet aggregation induced by platelet activating factor (PAF) in rabbits׳ blood model, from which the active ones were further evaluated the in vivo antithrombotic activity in zebrafish model. A new neolignan, piperwalliol A (1), and four new aromatic glycosides, piperwalliosides A-D (2-5) were isolated from the stems of Piper wallichii, along with 25 known compounds, including 13 lignans, six aromatic glycosides, two phenylpropyl aldehydes, and four biphenyls. Five known compounds (6-10) showed in vitro antiplatelet aggregation activities. Among them, (-)-syringaresinol (6) was the most active compound with an IC50 value of 0.52 mM. It is noted that in zebrafish model, the known lignan 6 showed good in vivo antithrombotic effect with a value of 37% at a concentration of 30 μM, compared with the positive control aspirin with the inhibitory value of 74% at a concentration of 125μM. This study demonstrated that lignans, phenylpropanoid and biphenyl found in Piper wallichii may be responsible for antithrombotic effect of the titled plant. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Inhibitory effects of Oenothera biennis (evening primrose) seed extract on Streptococcus mutans and S. mutans-induced dental caries in rats.

PubMed

Matsumoto-Nakano, M; Nagayama, K; Kitagori, H; Fujita, K; Inagaki, S; Takashima, Y; Tamesada, M; Kawabata, S; Ooshima, T

2011-01-01

Oenothera biennis (evening primrose) seed extract (OBSE) is known to contain polyphenols, which may possess antioxidant activities. Polyphenols extracted from several plants are reported to exhibit cariostatic activities by inhibiting mutans streptococcus growth and glucosyltransferase activities. The purpose of the present study was to examine the inhibitory effects of OBSE on the development of dental caries, both in vitro and in vivo. OBSE was investigated for its inhibitory effects on cellular aggregation, hydrophobicity, sucrose-dependent adherence and insoluble glucan synthesis. Furthermore, biofilm formation was examined in the presence of OBSE, using confocal microscopic imaging. An animal experiment was also performed to examine the in vivo effects. OBSE induced a strong aggregation of Streptococcus mutans MT8148 cells, while cell surface hydrophobicity was decreased by approximately 90% at a concentration of 0.25 mg/ml. The sucrose-dependent adherence of the MT8148 cells was also reduced by addition of OBSE, with a reduction rate of 73% seen at a concentration of 1.00 mg/ml. Additionally, confocal microscopic observations revealed the biofilm development phase to be remarkably changed in the presence of OBSE. Furthermore, insoluble glucan synthesis was significantly reduced when OBSE was present at concentrations greater than 0.03 mg/ml. In an animal experiment, the caries scores in rats given OBSE (0.05 mg/ml in drinking water) were significantly lower than those in rats given water without OBSE. Our results indicate that OBSE has inhibitory activity on dental caries. 2011 S. Karger AG, Basel.

Inhibitory effect of carotenoids on the degranulation of mast cells via suppression of antigen-induced aggregation of high affinity IgE receptors.

PubMed

Sakai, Shota; Sugawara, Tatsuya; Matsubara, Kiminori; Hirata, Takashi

2009-10-09

Carotenoids have been demonstrated to possess antioxidative and anti-inflammatory effects. However, there is no report that the effects of carotenoids on degranulation of mast cell is critical for type I allergy. In this study, we focused on the effect of carotenoids on antigen-induced degranulation of mast cells. Fucoxanthin, astaxanthin, zeaxanthin, and beta-carotene significantly inhibited the antigen-induced release of beta-hexosaminidase in rat basophilic leukemia 2H3 cells and mouse bone marrow-derived mast cells. Those carotenoids also inhibited antigen-induced aggregation of the high affinity IgE receptor (Fc epsilonRI), which is the most upstream of the degranulating signals of mast cells. Furthermore, carotenoids inhibited Fc epsilonRI-mediated intracellular signaling, such as phosphorylation of Lyn kinase and Fyn kinase. It suggests that the inhibitory effect of carotenoids on the degranulation of mast cells were mainly due to suppressing the aggregation of Fc epsilonRI followed by intracellular signaling. In addition, those carotenoids inhibited antigen-induced translocation of Fc epsilonRI to lipid rafts, which are known as platforms of the aggregation of Fc epsilonRI. We assume that carotenoids may modulate the function of lipid rafts and inhibit the translocation of Fc epsilonRI to lipid rafts. This is the first report that focused on the aggregation of Fc epsilonRI to investigate the mechanism of the inhibitory effects on the degranulation of mast cells and evaluated the functional activity of carotenoids associated with lipid rafts.

Inhibitory Effect of Carotenoids on the Degranulation of Mast Cells via Suppression of Antigen-induced Aggregation of High Affinity IgE Receptors*

PubMed Central

Sakai, Shota; Sugawara, Tatsuya; Matsubara, Kiminori; Hirata, Takashi

2009-01-01

Carotenoids have been demonstrated to possess antioxidative and anti-inflammatory effects. However, there is no report that the effects of carotenoids on degranulation of mast cell is critical for type I allergy. In this study, we focused on the effect of carotenoids on antigen-induced degranulation of mast cells. Fucoxanthin, astaxanthin, zeaxanthin, and β-carotene significantly inhibited the antigen-induced release of β-hexosaminidase in rat basophilic leukemia 2H3 cells and mouse bone marrow-derived mast cells. Those carotenoids also inhibited antigen-induced aggregation of the high affinity IgE receptor (FcϵRI), which is the most upstream of the degranulating signals of mast cells. Furthermore, carotenoids inhibited FcϵRI-mediated intracellular signaling, such as phosphorylation of Lyn kinase and Fyn kinase. It suggests that the inhibitory effect of carotenoids on the degranulation of mast cells were mainly due to suppressing the aggregation of FcϵRI followed by intracellular signaling. In addition, those carotenoids inhibited antigen-induced translocation of FcϵRI to lipid rafts, which are known as platforms of the aggregation of FcϵRI. We assume that carotenoids may modulate the function of lipid rafts and inhibit the translocation of FcϵRI to lipid rafts. This is the first report that focused on the aggregation of FcϵRI to investigate the mechanism of the inhibitory effects on the degranulation of mast cells and evaluated the functional activity of carotenoids associated with lipid rafts. PMID:19700409

Time-dependent inhibitory effects of cGMP-analogues on thrombin-induced platelet-derived microparticles formation, platelet aggregation, and P-selectin expression

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nygaard, Gyrid; Department of Biomedicine, University of Bergen, Bergen; Herfindal, Lars

Highlights: • We investigated the impact of cyclic nucleotide analogues on platelet activation. • Different time dependence were found for inhibition of platelet activation. • Additive effect was found using PKA- and PKG-activating analogues. • Our results may explain some of the discrepancies reported for cNMP signalling. - Abstract: In platelets, nitric oxide (NO) activates cGMP/PKG signalling, whereas prostaglandins and adenosine signal through cAMP/PKA. Cyclic nucleotide signalling has been considered to play an inhibitory role in platelets. However, an early stimulatory effect of NO and cGMP-PKG signalling in low dose agonist-induced platelet activation have recently been suggested. Here, we investigatedmore » whether different experimental conditions could explain some of the discrepancy reported for platelet cGMP-PKG-signalling. We treated gel-filtered human platelets with cGMP and cAMP analogues, and used flow cytometric assays to detect low dose thrombin-induced formation of small platelet aggregates, single platelet disappearance (SPD), platelet-derived microparticles (PMP) and thrombin receptor agonist peptide (TRAP)-induced P-selectin expression. All four agonist-induced platelet activation phases were blocked when platelets were costimulated with the PKG activators 8-Br-PET-cGMP or 8-pCPT-cGMP and low-doses of thrombin or TRAP. However, extended incubation with 8-Br-PET-cGMP decreased its inhibition of TRAP-induced P-selectin expression in a time-dependent manner. This effect did not involve desensitisation of PKG or PKA activity, measured as site-specific VASP phosphorylation. Moreover, PKG activators in combination with the PKA activator Sp-5,6-DCL-cBIMPS revealed additive inhibitory effect on TRAP-induced P-selectin expression. Taken together, we found no evidence for a stimulatory role of cGMP/PKG in platelets activation and conclude rather that cGMP/PKG signalling has an important inhibitory function in human platelet activation.« less

Examining the inhibitory potency of food additive fast green FCF against amyloid fibrillogenesis under acidic conditions.

PubMed

How, Su-Chun; Yang, Szu-Ming; Hsin, Ai; Tseng, Chia-Ping; Hsueh, Shu-Shun; Lin, Ming-Shen; Chen, Rita P-Y; Chou, Wei-Lung; Wang, Steven S-S

2016-12-07

More than thirty human proteins and/or peptides can fold incorrectly to form amyloid deposits associated with several protein aggregation diseases. No cure is currently available for treating these diseases. This work is aimed at examining the inhibitory potency of fast green FCF, a biocompatible dye, toward the fibrillogenesis/aggregation of lysozyme. As verified by ThT binding assay along with transmission electron microscopy, fast green FCF was observed to suppress the generation of lysozyme fibrils in a concentration-dependent manner. We next used circular dichroism absorption spectroscopy, ANS fluorescence spectroscopy, and SDS-PAGE to characterize the structural alterations in lysozyme samples upon the addition of fast green FCF. Furthermore, experiments with the addition of fast green FCF at different time points of incubation showed that fast green FCF also exhibited disaggregating activity against the preformed/existing lysozyme fibrils. We believe that the results from this study suggest a potential therapeutic role of biocompatible molecules in treating or preventing protein aggregation diseases.

Lipopolysaccharide treatment reduces rat platelet aggregation independent of intracellular reactive-oxygen species generation.

PubMed

Lopes-Pires, M Elisa; Casarin, André L; Pereira-Cunha, Fernanda G; Lorand-Metze, Irene; Antunes, Edson; Marcondes, Sisi

2012-01-01

High production of reactive-oxygen species (ROS) by blood cells is involved in damage of the vascular endothelium and multiple organ dysfunction in sepsis. However, little is known about the intraplatelet ROS production in sepsis and its consequences on platelet reactivity. In this study, we evaluated whether the treatment of rats with lipopolysaccharide (LPS) affects platelet aggregation through intraplatelet ROS generation. Rats were injected with LPS (1 mg/kg, i.p.), and at 2 to 72 h thereafter, adenosine diphosphate (ADP) (3-10 µM) induced platelet aggregation was evaluated. Production of ROS in platelets was measured by flow cytometry using 2',7'-dichlorofluorescein diacetate (DCFH-DA). Treatment of rats with LPS time-dependently inhibited ADP-induced platelet aggregation within 72 h. The inhibitory effect of LPS on platelet aggregation was further increased when the platelets were incubated with polyethylene glycol-superoxide dismutase (PEG-SOD; 30 U/mL), polyethylene glycol-catalase (PEG-CAT; 1000 U/mL) or the NADPH oxidase inhibitor diphenyleneiodonium (DPI; 10 µM). The ROS production in non-stimulated platelets did not differ between control and LPS-treated rats. However, in ADP-activated platelets, generation of ROS was increased by 3.0- and 7.0-fold, as evaluated at 8 and 48 h after LPS injection, respectively. This increased ROS production was significantly reduced when platelets were incubated in vitro with DPI, PEG-SOD or PEG-CAT. In contrast, treatment of rats with N-acetylcysteine (150 mg/kg, i.p.) significantly reduced the inhibitory effect of LPS on platelet aggregation, and prevented the increased ROS production by in vivo LPS. Our results indicate that the increased intraplatelet ROS production does not contribute to the inhibitory effect of LPS on platelet aggregation; however, the maintenance of redox balance in LPS-treated rats is fundamental to restore the normal platelet response in these animals.

Inhibition of cholinesterase activity and amyloid aggregation by berberine-phenyl-benzoheterocyclic and tacrine-phenyl-benzoheterocyclic hybrids.

PubMed

Huang, Ling; Su, Tao; Shan, Wenjun; Luo, Zonghua; Sun, Yang; He, Feng; Li, Xingshu

2012-05-01

A series of berberine-phenyl-benzoheterocyclic (26-29) and tacrine-phenyl-benzoheterocyclic hybrids (44-46) were synthesised and evaluated as multifunctional anti-Alzheimer's disease agents. Compound 44b, tacrine linked with phenyl-benzothiazole by 3-carbon spacers, was the most potent AChE inhibitor with an IC(50) value of 0.017 μM. This compound demonstrated similar Aβ aggregation inhibitory activity with cucurmin (51.8% vs 52.1% at 20 μM, respectively), indicating that this hybrid is an excellent multifunctional drug candidate for AD. Copyright © 2012 Elsevier Ltd. All rights reserved.

Coconut (Cocos nucifera) Ethanolic Leaf Extract Reduces Amyloid-β (1-42) Aggregation and Paralysis Prevalence in Transgenic Caenorhabditis elegans Independently of Free Radical Scavenging and Acetylcholinesterase Inhibition.

PubMed

Manalo, Rafael Vincent; Silvestre, Maries Ann; Barbosa, Aza Lea Anne; Medina, Paul Mark

2017-04-21

Virgin coconut oil (VCO) has been the subject of several studies which have aimed to alleviate Alzheimer's disease (AD) pathology, focusing on in vitro antioxidant and acetylcholinesterase (AChE) inhibitory activities. Here, we studied an underutilized and lesser-valued part of the coconut tree, specifically the leaves, using in vitro and in vivo approaches. Coconut leaf extract (CLE) was screened for antioxidant and AChE inhibitory properties in vitro and therapeutic effects in two strains of transgenic Caenorhabditis elegans expressing amyloid-β 1-42 (Aβ 1-42 ) in muscle cells. CLE demonstrated free radical scavenging activity with an EC 50 that is 79-fold less compared to ascorbic acid, and an AChE inhibitory activity that is 131-fold less compared to Rivastigmine. Surprisingly, in spite of its low antioxidant activity and AChE inhibition, CLE reduced Aβ deposits by 30.31% in CL2006 in a dose-independent manner, and reduced the percentage of paralyzed nematodes at the lowest concentration of CLE (159.38 μg/mL), compared to dH₂O/vehicle (control). Phytochemical analysis detected glycosides, anthocyanins, and hydrolyzable tannins in CLE, some of which are known to be anti-amyloidogenic. Taken together, these findings suggest that CLE metabolites alternatively decrease AB 1-42 aggregation and paralysis prevalence independently of free radical scavenging and AChE inhibition, and this warrants further investigation on the bioactive compounds of CLE.

Semisynthesis and Structure-Activity Studies of Uncarinic Acid C Isolated from Uncaria rhynchophylla as a Specific Inhibitor of the Nucleation Phase in Amyloid β42 Aggregation.

PubMed

Yoshioka, Takuya; Murakami, Kazuma; Ido, Kyohei; Hanaki, Mizuho; Yamaguchi, Kanoko; Midorikawa, Satohiro; Taniwaki, Shinji; Gunji, Hiroki; Irie, Kazuhiro

2016-10-28

Oligomers of the 42-mer amyloid-β protein (Aβ42), rather than fibrils, cause synaptic dysfunction in the pathology of Alzheimer's disease (AD). The nucleation phase in a nucleation-dependent aggregation model of Aβ42 is related to the formation of oligomers. Uncaria rhynchophylla is one component of "Yokukansan", a Kampo medicine, which is widely used for treating AD symptoms. Previously, an extract of U. rhynchophylla was found to reduce the aggregation of Aβ42, but its active principles have yet to be identified. In the present work, uncarinic acid C (3) was identified as an inhibitor of Aβ42 aggregation that is present in U. rhynchophylla. Moreover, compound 3 acted as a specific inhibitor of the nucleation phase of Aβ42 aggregation. Compound 3 was synthesized from saponin A (10), an abundant byproduct of rutin purified from Uncaria elliptica. Comprehensive structure-activity studies on 3 suggest that both a C-27 ferulate and a C-28 carboxylic acid group are required for its inhibitory activity. These findings may aid the development of oligomer-specific inhibitors for AD therapy.

The antigen-binding fragment of human gamma immunoglobulin prevents amyloid β-peptide folding into β-sheet to form oligomers

PubMed Central

Valls-Comamala, Victòria; Guivernau, Biuse; Bonet, Jaume; Puig, Marta; Perálvarez-Marín, Alex; Palomer, Ernest; Fernàndez-Busquets, Xavier; Altafaj, Xavier; Tajes, Marta; Puig-Pijoan, Albert; Vicente, Rubén; Oliva, Baldomero; Muñoz, Francisco J.

2017-01-01

The amyloid beta-peptide (Aβ) plays a leading role in Alzheimer's disease (AD) physiopathology. Even though monomeric forms of Aβ are harmless to cells, Aβ can aggregate into β-sheet oligomers and fibrils, which are both neurotoxic. Therefore, one of the main therapeutic approaches to cure or delay AD onset and progression is targeting Aβ aggregation. In the present study, we show that a pool of human gamma immunoglobulins (IgG) protected cortical neurons from the challenge with Aβ oligomers, as assayed by MTT reduction, caspase-3 activation and cytoskeleton integrity. In addition, we report the inhibitory effect of IgG on Aβ aggregation, as shown by Thioflavin T assay, size exclusion chromatography and atomic force microscopy. Similar results were obtained with Palivizumab, a human anti-sincitial virus antibody. In order to dissect the important domains, we cleaved the pool of human IgG with papain to obtain Fab and Fc fragments. Using these cleaved fragments, we functionally identified Fab as the immunoglobulin fragment inhibiting Aβ aggregation, a result that was further confirmed by an in silico structural model. Interestingly, bioinformatic tools show a highly conserved structure able to bind amyloid in the Fab region. Overall, our data strongly support the inhibitory effect of human IgG on Aβ aggregation and its neuroprotective role. PMID:28467807

The Antithrombotic and Fibrinolytic Effect of Natto in Hypercholesterolemia Rats

PubMed Central

Park, Kum-Ju; Kang, Jung Il; Kim, Tae-Seok; Yeo, Ik-Hyun

2012-01-01

Antithrombotic and fibrinolytic activity of natto was evaluated on platelet aggregation in vitro and in vivo. Natto showed inhibitory effects on platelet aggregation induced by adenosine 5′diphosphate (ADP) and collagen. Orally administered natto also showed fibrinolytic activity in hypercholesterolemia rats. Normal levels of natto, when administered for four weeks, shortened euglobulin clot lysis time (ECLT) and prolonged partial thromboplastin time (PATT) significantly compared to non-treated group. In addition, the natto treatment decreased total cholesterol in serum. These results showed that intake of normal levels of natto can elicit antithrombotic and fibrinolytic effects, suggesting its consumption may improve blood circulation. PMID:24471066

Inhibitory effects of ethyl pyruvate on platelet aggregation and phosphatidylserine exposure.

PubMed

Li, Wenjin; Yang, Xinyu; Peng, Minyuan; Li, Can; Mu, Guangfu; Chen, Fangping

2017-06-03

Ethyl pyruvate (EP) is a stable lipophilic pyruvate derivative. Studies demonstrated that EP shows potent anti-oxidation, anti-inflammatory and anti-coagulant effects. Inflammation and coagulation are closely interacted with platelet activation. However, it is unclear whether EP has anti-platelet effects. Therefore, we investigated the anti-platelet effect of EP in this study in vitro. We found that EP inhibited agonists induced platelets aggregation, ATP release and adhesion to collagen. Flow cytometric analysis revealed that EP inhibited agonist induced platelets PAC-1 binding, as well as P-selectin and CD40L expression. The underlying mechanism of action may involve the inhibition of platelet PI3K/Akt and Protein Kinase C (PKC) signaling pathways. Additionally, EP dose dependently inhibited platelet PS exposure induced by high concentration thrombin. Lactate dehydrogenase (LDH) activity assay and mice platelet count implied that EP may have no toxic effect on platelets. Therefore, we are the first to report that EP has potent anti-platelet activity and attenuates platelet PS exposure in vitro, suggesting that the inhibitory effects of EP on platelets may also play important roles in improvement of inflammation and coagulation disorder in related animal models. Copyright © 2017 Elsevier Inc. All rights reserved.

Coconut (Cocos nucifera) Ethanolic Leaf Extract Reduces Amyloid-β (1-42) Aggregation and Paralysis Prevalence in Transgenic Caenorhabditis elegans Independently of Free Radical Scavenging and Acetylcholinesterase Inhibition

PubMed Central

Manalo, Rafael Vincent; Silvestre, Maries Ann; Barbosa, Aza Lea Anne; Medina, Paul Mark

2017-01-01

Virgin coconut oil (VCO) has been the subject of several studies which have aimed to alleviate Alzheimer’s disease (AD) pathology, focusing on in vitro antioxidant and acetylcholinesterase (AChE) inhibitory activities. Here, we studied an underutilized and lesser-valued part of the coconut tree, specifically the leaves, using in vitro and in vivo approaches. Coconut leaf extract (CLE) was screened for antioxidant and AChE inhibitory properties in vitro and therapeutic effects in two strains of transgenic Caenorhabditis elegans expressing amyloid-β1–42 (Aβ1-42) in muscle cells. CLE demonstrated free radical scavenging activity with an EC50 that is 79-fold less compared to ascorbic acid, and an AChE inhibitory activity that is 131-fold less compared to Rivastigmine. Surprisingly, in spite of its low antioxidant activity and AChE inhibition, CLE reduced Aβ deposits by 30.31% in CL2006 in a dose-independent manner, and reduced the percentage of paralyzed nematodes at the lowest concentration of CLE (159.38 μg/mL), compared to dH2O/vehicle (control). Phytochemical analysis detected glycosides, anthocyanins, and hydrolyzable tannins in CLE, some of which are known to be anti-amyloidogenic. Taken together, these findings suggest that CLE metabolites alternatively decrease AB1–42 aggregation and paralysis prevalence independently of free radical scavenging and AChE inhibition, and this warrants further investigation on the bioactive compounds of CLE. PMID:28536360

4-allylanisole as an inhibitor of bark beetle (Coleoptera: Scolytidae) aggregation

Treesearch

Jane L. Hayes; Brian L. Strom

1994-01-01

To assess the extent of inhibitory activity of the host compound 4-allylanisole, we conducted field studies with three scolytid species.These species are geographically widespread and economically important.Trials were completed with Dendroctonus brevicomis LeConte (California), D. ponderosae Hopkins (Oregon), and Ips pini (Say) (Wisconsin) by using multiple-funnel...

Quantitative analysis of the flavonoid glycosides and terpene trilactones in the extract of Ginkgo biloba and evaluation of their inhibitory activity towards fibril formation of β-amyloid peptide.

PubMed

Xie, Haiyan; Wang, Jing-Rong; Yau, Lee-Fong; Liu, Yong; Liu, Liang; Han, Quan-Bin; Zhao, Zhongzhen; Jiang, Zhi-Hong

2014-04-10

The standard extract of Ginkgo biloba leaves (EGb761) is used clinically in Europe for the symptomatic treatment of impaired cerebral function in primary degenerative dementia syndromes, and the results of numerous in vivo and in vitro studies have supported such clinical use. The abnormal production and aggregation of amyloid β peptide (Aβ) and the deposition of fibrils in the brain are regarded as key steps in the onset of Alzheimer's Disease (AD), and the inhibition of Aβ aggregation and destabilization of the preformed fibrils represent viable approaches for the prevention and treatment of AD. Flavonoid glycosides and terpene trilactones (TTLs) are the two main components of EGb761 which represent 24 and 6% of the overall content, respectively. In our research, seven abundant flavonoid glycosides 1-7 were isolated from the extract of Ginkgo biloba leaves and characterized by spectroscopic analysis. Furthermore, an ultra-high performance liquid chromatography method was established for the simultaneous quantification of these seven flavonoids. The inhibitory activities of these flavonoids, as well as four TTLs, i.e., ginkgolides A, B, and C and bilobalide (compounds 8-11), were evaluated towards Aβ42 fibril formation using a thioflavin T fluorescence assay. It was found that three flavonoids 1, 3 and 4 exhibited moderate inhibitory activities, whereas the other four flavonoids 2, 5, 6 and 7, as well as the four terpene trilactones, showed poor activity. This is the first report of the inhibition of Aβ fibril formation of two characteristic acylated flavonoid glycosides 6, 7 in Ginkgo leaves, on the basis of which the structure-activity relationship of these flavonoids 1-7 was discussed.

Inhibition of copper-mediated aggregation of human γD-crystallin by Schiff bases.

PubMed

Chauhan, Priyanka; Muralidharan, Sai Brinda; Velappan, Anand Babu; Datta, Dhrubajyoti; Pratihar, Sanjay; Debnath, Joy; Ghosh, Kalyan Sundar

2017-06-01

Protein aggregation, due to the imbalance in the concentration of Cu 2+ and Zn 2+ ions is found to be allied with various physiological disorders. Copper is known to promote the oxidative damage of β/γ-crystallins in aged eye lens and causes their aggregation leading to cataract. Therefore, synthesis of a small-molecule 'chelator' for Cu 2+ with complementary antioxidant effect will find potential applications against aggregation of β/γ-crystallins. In this paper, we have reported the synthesis of different Schiff bases and studied their Cu 2+ complexation ability (using UV-Vis, FT-IR and ESI-MS) and antioxidant activity. Further based on their copper complexation efficiency, Schiff bases were used to inhibit Cu 2+ -mediated aggregation of recombinant human γD-crystallin (HGD) and β/γ-crystallins (isolated from cataractous human eye lens). Among these synthesized molecules, compound 8 at a concentration of 100 μM had shown ~95% inhibition of copper (100 μM)-induced aggregation. Compound 8 also showed a positive cooperative effect at a concentration of 5-15 μM on the inhibitory activity of human αA-crystallin (HAA) during Cu 2+ -induced aggregation of HGD. It eventually inhibited the aggregation process by additional ~20%. However, ~50% inhibition of copper-mediated aggregation of β/γ-crystallins (isolated from cataractous human eye lens) was recorded by compound 8 (100 μM). Although the reductive aminated products of the imines showed better antioxidant activity due to their lower copper complexing ability, they were found to be non-effective against Cu 2+ -mediated aggregation of HGD.

Peptide Inhibitors of the Amyloidogenesis of IAPP: Verification of the Hairpin Binding Geometry Hypothesis

PubMed Central

Sivanesam, Kalkena; Shu, Irene; Huggins, Kelly N. L.; Tatarek-Nossol, Marianna; Kapurniotu, Aphrodite; Andersen, Niels H.

2016-01-01

Versions of a previously discovered β-hairpin peptide inhibitor of IAPP aggregation that are stabilized in that conformation, or even forced to remain in the hairpin conformation by a backbone cyclization constraint, display superior activity as inhibitors. The cyclized hairpin, cyclo-WW2, displays inhibitory activity at sub-stoichiometric concentrations relative to this amyloidogenic peptide. The hairpin binding hypothesis stands confirmed. PMID:27317951

Design, synthesis and evaluation of rivastigmine and curcumin hybrids as site-activated multitarget-directed ligands for Alzheimer's disease therapy.

PubMed

Li, Yujie; Peng, Peng; Tang, Li; Hu, Yunzhen; Hu, Yongzhou; Sheng, Rong

2014-09-01

A series of novel 2-methoxy-phenyl dimethyl-carbamate derivatives were designed, synthesized and evaluated as site-activated MTDLs based on rivastigmine and curcumin. Most of them exhibited good to excellent AChE and BuChE inhibitory activities with sub-micromolar IC50 values. Among all the compounds, 6a demonstrated the most potent AChE inhibition with IC50 value of 0.097μM, which is about 20-fold than that of rivastigmine. In addition, the three selected compounds 5a, 6a and 6e demonstrated inhibitory activity against Aβ self-aggregation similar to cucurmin in TEM assay, which is obviously different from the weak activity of rivastigmine. Moreover, the hydrolysate of 6a (compound 7) also showed potent ABTS(+) scavenging and moderate copper ion chelating activity in vitro. Copyright © 2014 Elsevier Ltd. All rights reserved.

Mango ginger (Curcuma amada Roxb.)--a promising spice for phytochemicals and biological activities.

PubMed

Policegoudra, R S; Aradhya, S M; Singh, L

2011-09-01

Mango ginger (Curcuma amada Roxb.) is a unique spice having morphological resemblance with ginger but imparts a raw mango flavour. The main use of mango ginger rhizome is in the manufacture of pickles and culinary preparations. Ayurveda and Unani medicinal systems have given much importance to mango ginger as an appetizer, alexteric, antipyretic, aphrodisiac, diuretic, emollient, expectorant and laxative and to cure biliousness, itching, skin diseases, bronchitis, asthma, hiccough and inflammation due to injuries. The biological activities of mango ginger include antioxidant activity, antibacterial activity, antifungal activity, anti-inflammatory activity, platelet aggregation inhibitory activity, cytotoxicity, antiallergic activity, hypotriglyceridemic activity, brine-shrimp lethal activity, enterokinase inhibitory activity, CNS depressant and analgesic activity. The major chemical components include starch, phenolic acids, volatile oils, curcuminoids and terpenoids like difurocumenonol, amadannulen and amadaldehyde. This article brings to light the major active components present in C. amada along with their biological activities that may be important from the pharmacological point of view.

Preparation, characterization, nanostructures and bio functional analysis of sonicated protein co-precipitates from brewers' spent grain and soybean flour.

PubMed

Alu'datt, Muhammad H; Gammoh, Sana; Rababah, Taha; Almomani, Mohammed; Alhamad, Mohammad N; Ereifej, Khalil; Almajwal, Ali; Tahat, Asma; Hussein, Neveen M; Nasser, Sura Abou

2018-02-01

This investigation was performed to assess the effects of sonication on the structure of protein, extractability of phenolics, and biological properties of isolated proteins and protein co-precipitates prepared from brewers' spent grain and soybean flour. Scanning electron micrographs revealed that the sonicated protein isolates and co-precipitates had different microstructures with fewer aggregates and smaller particles down to the nanometer scale compared to non-sonicated samples. However, the levels of free and bound phenolics extracted from non-sonicated protein isolates and protein co-precipitates increased compared to sonicated samples. The bound phenolics extracted after acid hydrolysis of sonicated protein co-precipitates showed improved ACE inhibitory activity and diminished antioxidant potency compared to non-sonicated samples. However, the free phenolics extracted from sonicated protein co-precipitates showed decreased ACE inhibitory activity and increased antioxidant activities compared to non-sonicated samples. The free and bound phenolics extracted from sonicated protein co-precipitates showed increased alpha-amylase inhibitory activity compared to non-sonicated samples. Copyright © 2017 Elsevier Ltd. All rights reserved.

Gallic Acid Attenuates Platelet Activation and Platelet-Leukocyte Aggregation: Involving Pathways of Akt and GSK3β

PubMed Central

Chang, Shih-Sheng; Lee, Viola S. Y.; Tseng, Yu-Lun; Chang, Kuan-Cheng; Chen, Kuen-Bao; Chen, Yuh-Lien; Li, Chi-Yuan

2012-01-01

Platelet activation and its interaction with leukocytes play an important role in atherothrombosis. Cardiovascular diseases resulted from atherothrombosis remain the major causes of death worldwide. Gallic acid, a major constituent of red wine and tea, has been believed to have properties of cardiovascular protection, which is likely to be related to its antioxidant effects. Nonetheless, there were few and inconsistent data regarding the effects of gallic acid on platelet function. Therefore, we designed this in vitro study to determine whether gallic acid could inhibit platelet activation and the possible mechanisms. From our results, gallic acid could concentration-dependently inhibit platelet aggregation, P-selectin expression, and platelet-leukocyte aggregation. Gallic acid prevented the elevation of intracellular calcium and attenuated phosphorylation of PKCα/p38 MAPK and Akt/GSK3β on platelets stimulated by the stimulants ADP or U46619. This is the first mechanistic explanation for the inhibitory effects on platelets from gallic acid. PMID:22811749

Peptide Inhibitors of the amyloidogenesis of IAPP: verification of the hairpin-binding geometry hypothesis.

PubMed

Sivanesam, Kalkena; Shu, Irene; Huggins, Kelly N L; Tatarek-Nossol, Marianna; Kapurniotu, Aphrodite; Andersen, Niels H

2016-08-01

Versions of a previously discovered β-hairpin peptide inhibitor of IAPP aggregation that are stabilized in that conformation, or even forced to remain in the hairpin conformation by a backbone cyclization constraint, display superior activity as inhibitors. The cyclized hairpin, cyclo-WW2, displays inhibitory activity at substoichiometric concentrations relative to this amyloidogenic peptide. The hairpin-binding hypothesis stands confirmed. © 2016 Federation of European Biochemical Societies.

An inhibitor of collagen-stimulated platelet activation from the salivary glands of the Haementeria officinalis leech. I. Identification, isolation, and characterization.

PubMed

Connolly, T M; Jacobs, J W; Condra, C

1992-04-05

A protein that blocks collagen-stimulated platelet aggregation has been identified and isolated from the soluble fraction of salivary glands from Haementeria officinalis leeches. We have named this protein leech antiplatelet protein (LAPP). LAPP was isolated from soluble crude salivary gland extract by heparin-agarose, size exclusion, and C18 reverse phase high-performance chromatography. Its molecular weight is approximately 16,000 on sodium dodecyl sulfate-polyacrylamide gel electrophoresis under both reduced and nonreduced conditions. The sequences of peptides generated by V8 digestion of LAPP as well as its amino acid composition suggested no homology to other known proteins. The IC50 for LAPP to inhibit platelet aggregation was approximately 60 nM. This inhibitory activity is specific for collagen-induced aggregation. Platelet aggregation in response to ADP, arachidonic acid, U46619, thrombin, and ionophore A23187 was not inhibited by LAPP at a concentration that blocked platelet aggregation to collagen by 100%. In contrast, crude salivary gland-soluble extract contained activity(ies) which inhibited aggregation to all these agonists except thrombin at 1 unit/ml and 2 microM A23187. Thus, the H. officinalis leech has evolved multiple mechanisms to prevent hemostasis, including an inhibitor of collagen-stimulated platelet aggregation. The identification and isolation of LAPP demonstrates the existence of a new type of platelet inhibitor that should be useful to better understand the mechanism of collagen stimulation of platelets.

Design, synthesis and evaluation of 4-dimethylamine flavonoid derivatives as potential multifunctional anti-Alzheimer agents.

PubMed

Luo, Wen; Wang, Ting; Hong, Chen; Yang, Ya-Chen; Chen, Ying; Cen, Juan; Xie, Song-Qiang; Wang, Chao-Jie

2016-10-21

A new series of 4-dimethylamine flavonoid derivatives were designed and synthesized as potential multifunctional anti-Alzheimer agents. The inhibition of cholinesterase activity, self-induced β-amyloid (Aβ) aggregation, and antioxidant activity by these derivatives was investigated. Most of the compounds exhibited potent acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitory activity. A Lineweaver-Burk plot and molecular modeling study showed that these compounds targeted both the catalytic active site (CAS) and peripheral anionic site (PAS) of AChE. The derivatives showed potent self-induced Aβ aggregation inhibition and peroxyl radical absorbance activity. Moreover, compound 6d significantly protected PC12 neurons against H2O2-induced cell death at low concentrations. Thus, these compounds could become multifunctional agents for further development for the treatment of AD. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Isoform-specific PKA dynamics revealed by dye-triggered aggregation and DAKAP1alpha-mediated localization in living cells.

PubMed

Martin, Brent R; Deerinck, Thomas J; Ellisman, Mark H; Taylor, Susan S; Tsien, Roger Y

2007-09-01

The tetracysteine sequence YRECCPGCCMWR fused to the N terminus of green fluorescent protein (GFP) self-aggregates upon biarsenical labeling in living cells or in vitro. Such dye-triggered aggregates form temperature-dependent morphologies and are dispersed by photobleaching. Fusion of the biarsenical aggregating GFP to the regulatory (R) or catalytic (C) subunit of PKA traps intact holoenzyme in compact fluorescent puncta upon biarsenical labeling. Contrary to the classical model of PKA activation, elevated cAMP does not allow RIalpha and Calpha to diffuse far apart unless the pseudosubstrate inhibitor PKI or locally concentrated substrate is coexpressed. However, RIIalpha releases Calpha upon elevated cAMP alone, dependent on autophosphorylation of the RIIalpha inhibitory domain. DAKAP1alpha overexpression induced R and C outer mitochondrial colocalization and showed similar regulation. Overall, effective separation of type I PKA is substrate dependent, whereas type II PKA dissociation relies on autophosphorylation.

Inhibitory Effects of Cytosolic Ca(2+) Concentration by Ginsenoside Ro Are Dependent on Phosphorylation of IP3RI and Dephosphorylation of ERK in Human Platelets.

PubMed

Kwon, Hyuk-Woo; Shin, Jung-Hae; Lee, Dong-Ha; Park, Hwa-Jin

2015-01-01

Intracellular Ca(2+) ([Ca(2+)] i ) is platelet aggregation-inducing molecule and is involved in activation of aggregation associated molecules. This study was carried out to understand the Ca(2+)-antagonistic effect of ginsenoside Ro (G-Ro), an oleanane-type saponin in Panax ginseng. G-Ro, without affecting leakage of lactate dehydrogenase, dose-dependently inhibited thrombin-induced platelet aggregation, and the half maximal inhibitory concentration was approximately 155 μM. G-Ro inhibited strongly thrombin-elevated [Ca(2+)] i , which was strongly increased by A-kinase inhibitor Rp-8-Br-cAMPS compared to G-kinase inhibitor Rp-8-Br-cGMPS. G-Ro increased the level of cAMP and subsequently elevated the phosphorylation of inositol 1, 4, 5-triphosphate receptor I (IP3RI) (Ser(1756)) to inhibit [Ca(2+)] i mobilization in thrombin-induced platelet aggregation. Phosphorylation of IP3RI (Ser(1756)) by G-Ro was decreased by PKA inhibitor Rp-8-Br-cAMPS. In addition, G-Ro inhibited thrombin-induced phosphorylation of ERK 2 (42 kDa), indicating inhibition of Ca(2+) influx across plasma membrane. We demonstrate that G-Ro upregulates cAMP-dependent IP3RI (Ser(1756)) phosphorylation and downregulates phosphorylation of ERK 2 (42 kDa) to decrease thrombin-elevated [Ca(2+)] i , which contributes to inhibition of ATP and serotonin release, and p-selectin expression. These results indicate that G-Ro in Panax ginseng is a beneficial novel Ca(2+)-antagonistic compound and may prevent platelet aggregation-mediated thrombotic disease.

Evaluation of the effects of amyloid β aggregation from seaweed extracts by a microliter-scale high-throughput screening system with a quantum dot nanoprobe.

PubMed

Ogara, Toshiki; Takahashi, Tomohito; Yasui, Hajime; Uwai, Koji; Tokuraku, Kiyotaka

2015-07-01

Inhibitors of amyloid β (Aβ) aggregation have the potential to serve as lead compounds for anti-Alzheimer's disease (AD) agents because Aβ aggregation is a key step in AD pathogenesis. Recently, we developed a novel microliter-scale high-throughput screening (MSHTS) system for Aβ aggregation inhibitors that applied fluorescence microscopic analysis with quantum dot nanoprobes, and attempted to comprehensively screen the inhibitors from spices using this system (Ishigaki et al., PLoS One, 8, e72992, 2013). In this study, we tried to evaluate the inhibitory activities of 11 seaweed extracts on Aβ aggregation using the MSHTS system. The half-maximal effective concentration (EC50) of the ethanolic extracts from all seaweeds exceeded 4.9 mg/ml, indicating that the extracts inhibit Aβ aggregation although this activity was significantly lower than that displayed by members of the Lamiaceae, a family of herbal spices that showed highest activity among 52 spices tested in our 2013 study. On the other hand, the EC50 of boiling water extracts was 0.013-0.42 mg/ml which was comparable with the EC50 of the extracts from the Lamiaceae family. These results suggest that the extraction efficiency of the inhibitors by boiling water extraction was higher than that by ethanolic extraction. Moreover, analysis of fluorescence micrographs, which were obtained from the MSHTS system, revealed that the morphology of the Aβ aggregates coincubated with boiling water extracts differed from control aggregates, suggesting that the MSHTS system is also useful for screening substances that affect the morphology of aggregates. Copyright © 2014 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

A Novel Direct Factor Xa Inhibitory Peptide with Anti-Platelet Aggregation Activity from Agkistrodon acutus Venom Hydrolysates.

PubMed

Chen, Meimei; Ye, Xiaohui; Ming, Xin; Chen, Yahui; Wang, Ying; Su, Xingli; Su, Wen; Kong, Yi

2015-06-02

Snake venom is a natural substance that contains numerous bioactive proteins and peptides, nearly all of which have been identified over the last several decades. In this study, we subjected snake venom to enzymatic hydrolysis to identify previously unreported bioactive peptides. The novel peptide ACH-11 with the sequence LTFPRIVFVLG was identified with both FXa inhibition and anti-platelet aggregation activities. ACH-11 inhibited the catalytic function of FXa towards its substrate S-2222 via a mixed model with a Ki value of 9.02 μM and inhibited platelet aggregation induced by ADP and U46619 in a dose-dependent manner. Furthermore, ACH-11 exhibited potent antithrombotic activity in vivo. It reduced paralysis and death in an acute pulmonary thrombosis model by 90% and attenuated thrombosis weight in an arterio-venous shunt thrombosis model by 57.91%, both at a dose of 3 mg/kg. Additionally, a tail cutting bleeding time assay revealed that ACH-11 did not prolong bleeding time in mice at a dose of 3 mg/kg. Together, our results reveal that ACH-11 is a novel antithrombotic peptide exhibiting both FXa inhibition and anti-platelet aggregation activities, with a low bleeding risk. We believe that it could be a candidate or lead compound for new antithrombotic drug development.

Cholinesterase inhibitory, anti-amyloidogenic and neuroprotective effect of the medicinal plant Grewia tiliaefolia - An in vitro and in silico study.

PubMed

Sheeja Malar, Dicson; Beema Shafreen, Rajamohamed; Karutha Pandian, Shunmugiah; Pandima Devi, Kasi

2017-12-01

Grewia tiliaefolia Vahl. (Tiliaceae) is a sub-tropical plant used as an indigenous medicine in India. However, its efficacy has not been evaluated against Alzheimer's disease. The objective of this study is to evaluate cholinesterase inhibitory, anti-aggregation and neuroprotective activity of G. tiliaefolia. Grewia tiliaefolia leaves were collected from Eastern Ghats region, India, and subjected to successive extraction (petroleum ether, chloroform, ethyl acetate, methanol and water). The extracts were subjected to in vitro antioxidant, anticholinesterase and anti-aggregation assays. The active methanol extract (MEGT) was separated using column chromatography. LC-MS analysis was done and the obtained compounds were docked against acetylcholinesterase (AChE) enzyme to identify the active component. Antioxidant assays demonstrated that the MEGT showed significant free radical scavenging activity at the IC 50 value of 71.5 ± 1.12 μg/mL. MEGT also exhibited significant dual cholinesterase inhibition with IC 50 value of 64.26 ± 2.56 and 54 ± 0.7 μg/mL for acetyl and butyrylcholinesterase (BChE), respectively. Also, MEGT showed significant anti-aggregation activity by preventing the oligomerization of Aβ 25-35 . Further, MEGT increased the viability of Neuro2a cells up to 95% against Aβ 25-35 neurotoxicity. LC-MS analysis revealed the presence of 16 compounds including vitexin, ellagic acid, isovitexin, etc. In silico analysis revealed that vitexin binds effectively with AChE through strong hydrogen bonding. These results were further confirmed by evaluating the activity of vitexin in vitro, which showed dual cholinesterase inhibition with IC 50 value of 15.21 ± 0.41 and 19.75 ± 0.16 μM for acetyl and butyrlcholinesterase, respectively. Grewia tiliaefolia can be considered as a promising therapeutic agent for the treatment of AD.

New biofunctional effects of the flower buds of Camellia sinensis and its bioactive acylated oleanane-type triterpene oligoglycosides.

PubMed

Matsuda, Hisashi; Nakamura, Seikou; Morikawa, Toshio; Muraoka, Osamu; Yoshikawa, Masayuki

2016-10-01

We review the biofunctional effects of the flower buds of Camellia sinensis and C. sinensis var. assamica, such as antihyperlipidemic, antihyperglycemic, antiobesity, and gastroprotective effects in vivo, and antiallergic, pancreatic lipase inhibitory, and amyloid β (Aβ) aggregation inhibitory activities in vitro. Although the biofunctional effects of tea leaves have been extensively studied, less attention has been given to those of the flowers and seeds of the tea plant. Our studies focused on the saponin constituents of the extracts of the flower buds of C. sinensis cultivated in Japan and China, and C. sinensis var. assamica cultivated in India, and we review their beneficial biofunctions for health promotion.

Multitarget drug design strategy against Alzheimer's disease: Homoisoflavonoid Mannich base derivatives serve as acetylcholinesterase and monoamine oxidase B dual inhibitors with multifunctional properties.

PubMed

Li, Yan; Qiang, Xiaoming; Luo, Li; Yang, Xia; Xiao, Ganyuan; Zheng, Yunxiaozhu; Cao, Zhongcheng; Sang, Zhipei; Su, Fu; Deng, Yong

2017-01-15

A series of homoisoflavonoid Mannich base derivatives were designed, synthesized and evaluated as multifunctional agents against Alzheimer's disease. It demonstrated that most of the derivatives were selective AChE and MAO-B dual inhibitors with good multifunctional properties. Among them, compound 10d displayed the comprehensive advantages, with excellent AChE and MAO-B inhibitory activities (IC 50 =2.49±0.08nM and 1.74±0.0581μM, respectively), good self- and Cu 2+ -induced Aβ 1-42 aggregation inhibitory potency, antioxidant activity, biometal chelating ability and high BBB permeability. These multifunctional properties make 10d as an excellent candidate for the development of efficient drugs against AD. Copyright © 2016 Elsevier Ltd. All rights reserved.

Substitution-inert trinuclear platinum complexes efficiently condense/aggregate nucleic acids and inhibit enzymatic activity.

PubMed

Malina, Jaroslav; Farrell, Nicholas P; Brabec, Viktor

2014-11-17

The trinuclear platinum complexes (TriplatinNC-A [{Pt(NH3 )3 }2 -μ-{trans-Pt(NH3 )2 (NH2 (CH2 )6 NH2 )2 }](6+) , and TriplatinNC [{trans-Pt(NH3 )2 (NH2 (CH2 )6 NH3 (+) )}2 -μ-{trans-Pt(NH3 )2 (NH2 (CH2 )6 NH2 )2 }](8+) ) are biologically active agents that bind to DNA through noncovalent (hydrogen bonding, electrostatic) interactions. Herein, we show that TriplatinNC condenses DNA with a much higher potency than conventional DNA condensing agents. Both complexes induce aggregation of small transfer RNA molecules, and TriplatinNC in particular completely inhibits DNA transcription at lower concentrations than naturally occurring spermine. Topoisomerase I-mediated relaxation of supercoiled DNA was inhibited by TriplatinNC-A and TriplatinNC at concentrations which were 60 times and 250 times lower than that of spermine. The mechanisms for the biological activity of TriplatinNC-A and TriplatinNC may be associated with their ability to condense/aggregate nucleic acids with consequent inhibitory effects on crucial enzymatic activities. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

CD147 and CD98 complex-mediated homotypic aggregation attenuates the CypA-induced chemotactic effect on Jurkat T cells.

PubMed

Guo, Na; Zhang, Kui; Lv, Minghua; Miao, Jinlin; Chen, Zhinan; Zhu, Ping

2015-02-01

Homotypic cell aggregation plays important roles in physiological and pathological processes, including embryogenesis, immune responses, angiogenesis, tumor cell invasion and metastasis. CD147 has been implicated in most of these phenomena, and it was identified as a T cell activation-associated antigen due to its obvious up-regulation in activated T cells. However, the explicit function and mechanism of CD147 in T cells have not been fully elucidated. In this study, large and compact aggregates were observed in Jurkat T cells after treatment with the specific CD147 monoclonal antibody HAb18 or after the expression of CD147 was silenced by RNA interference, which indicated an inhibitory effect of CD147 in T cell homotypic aggregation. Knocking down CD147 expression resulted in a significant decrease in CD98, along with prominent cell aggregation, similar to that treated by CD98 and CD147 monoclonal antibodies. Furthermore, decreased cell chemotactic activity was observed following CD147- and CD98-mediated cell aggregation, and increased aggregation was correlated with a decrease in the chemotactic ability of the Jurkat T cells, suggesting that CD147- and CD98-mediated homotypic cell aggregation plays a negative role in T cell chemotaxis. Our data also showed that p-ERK, p-ZAP70, p-CD3ζ and p-LCK were significantly decreased in the CD147- and CD98-knocked down Jurkat T cells, which suggested that decreased CD147- and/or CD98-induced homotypic T cell aggregation and aggregation-inhibited chemotaxis might be associated with these signaling pathways. A role for CD147 in cell aggregation and chemotaxis was further indicated in primary CD4(+) T cells. Similarly, low expression of CD147 in primary T cells induced prominent cell aggregation and this aggregation attenuated primary T cell chemotactic ability in response to CypA. Our results have demonstrated the correlation between homotypic cell aggregation and the chemotactic response of T cells to CypA, and these data indicate that CD147 and CD98 might play important roles in cyclophilin-induced cell migration. Copyright © 2014 Elsevier Ltd. All rights reserved.

Hydrolysis of short-chain phosphatidylcholines by bee venom phospholipase A2.

PubMed

Raykova, D; Blagoev, B

1986-01-01

In order to find out the aggregation state of the substrate, preferred by bee venom phospholipase A2 (EC 3.1.1.4), its action on short-chain phosphatidylcholines with two identical (C6-C10) fatty acids has been tested. The rate of hydrolysis as a function of acyl chain length showed a maximum at dioctanoylphosphatidylcholine. The effects of alcohols, NaCl and Triton X-100, which affect the aggregation state of phospholipids in water, were also studied. The addition of n-alcohol led to a significant inhibition of the hydrolysis of the substrates present in micellar form and activated the hydrolysis of substrates which form liposomes. The inhibitory effect increased with increasing length of the aliphatic carbon chain of the alcohol. Triton X-100 at low Triton/phospholipid molar ratios enhanced enzyme activity. These results do not agree with the accepted idea that bee venom phospholipase A2 hydrolyzes short-chain lecithins in their molecularly dispersed form and that micelles cannot act as substrates. The data indicate that short-chain lecithins in the aggregated state are hydrolyzed and that the requirements of bee venom phospholipase A2 for the aggregation state of the substrate are not strict.

Vitamin k3 inhibits protein aggregation: Implication in the treatment of amyloid diseases

PubMed Central

Alam, Parvez; Chaturvedi, Sumit Kumar; Siddiqi, Mohammad Khursheed; Rajpoot, Ravi Kant; Ajmal, Mohd Rehan; Zaman, Masihuz; Khan, Rizwan Hasan

2016-01-01

Protein misfolding and aggregation have been associated with several human diseases such as Alzheimer’s, Parkinson’s and familial amyloid polyneuropathy etc. In this study, anti-fibrillation activity of vitamin k3 and its effect on the kinetics of amyloid formation of hen egg white lysozyme (HEWL) and Aβ-42 peptide were investigated. Here, in combination with Thioflavin T (ThT) fluorescence assay, circular dichroism (CD), transmission electron microscopy and cell cytotoxicity assay, we demonstrated that vitamin k3 significantly inhibits fibril formation as well as the inhibitory effect is dose dependent manner. Our experimental studies inferred that vitamin k3 exert its neuro protective effect against amyloid induced cytotoxicity through concerted pathway, modifying the aggregation formation towards formation of nontoxic aggregates. Molecular docking demonstrated that vitamin k3 mediated inhibition of HEWL and Aβ-42 fibrillogenesis may be initiated by interacting with proteolytic resistant and aggregation prone regions respectively. This work would provide an insight into the mechanism of protein aggregation inhibition by vitamin k3; pave the way for discovery of other small molecules that may exert similar effect against amyloid formation and its associated neurodegenerative diseases. PMID:27230476

Vitamin k3 inhibits protein aggregation: Implication in the treatment of amyloid diseases.

PubMed

Alam, Parvez; Chaturvedi, Sumit Kumar; Siddiqi, Mohammad Khursheed; Rajpoot, Ravi Kant; Ajmal, Mohd Rehan; Zaman, Masihuz; Khan, Rizwan Hasan

2016-05-27

Protein misfolding and aggregation have been associated with several human diseases such as Alzheimer's, Parkinson's and familial amyloid polyneuropathy etc. In this study, anti-fibrillation activity of vitamin k3 and its effect on the kinetics of amyloid formation of hen egg white lysozyme (HEWL) and Aβ-42 peptide were investigated. Here, in combination with Thioflavin T (ThT) fluorescence assay, circular dichroism (CD), transmission electron microscopy and cell cytotoxicity assay, we demonstrated that vitamin k3 significantly inhibits fibril formation as well as the inhibitory effect is dose dependent manner. Our experimental studies inferred that vitamin k3 exert its neuro protective effect against amyloid induced cytotoxicity through concerted pathway, modifying the aggregation formation towards formation of nontoxic aggregates. Molecular docking demonstrated that vitamin k3 mediated inhibition of HEWL and Aβ-42 fibrillogenesis may be initiated by interacting with proteolytic resistant and aggregation prone regions respectively. This work would provide an insight into the mechanism of protein aggregation inhibition by vitamin k3; pave the way for discovery of other small molecules that may exert similar effect against amyloid formation and its associated neurodegenerative diseases.

Inhibitory Effect of Flavonolignans on the P2Y12 Pathway in Blood Platelets.

PubMed

Bijak, Michal; Szelenberger, Rafal; Dziedzic, Angela; Saluk-Bijak, Joanna

2018-02-10

Adenosine diphosphate (ADP) is the major platelet agonist, which is important in the shape changes, stability, and growth of the thrombus. Platelet activation by ADP is associated with the G protein-coupled receptors P2Y1 and P2Y12. The pharmacologic blockade of the P2Y12 receptor significantly reduces the risk of peripheral artery disease, myocardial infarction, ischemic stroke, and vascular death. Recent studies demonstrated the inhibition of ADP-induced blood platelet activation by three major compounds of the flavonolignans group: silybin, silychristin, and silydianin. For this reason, the aim of the current work was to verify the effects of silybin, silychristin, and silydianin on ADP-induced physiological platelets responses, as well as mechanisms of P2Y12-dependent intracellular signal transduction. We evaluated the effect of tested flavonolignans on ADP-induced blood platelets' aggregation in platelet-rich plasma (PRP) (using light transmission aggregometry), adhesion to fibrinogen (using the static method), and the secretion of PF-4 (using the ELISA method). Additionally, using the double labeled flow cytometry method, we estimated platelet vasodilator-stimulated phosphoprotein (VASP) phosphorylation. We demonstrated a dose-dependent reduction of blood platelets' ability to perform ADP-induced aggregation, adhere to fibrinogen, and secrete PF-4 in samples treated with flavonolignans. Additionally, we observed that all of the tested flavonolignans were able to increase VASP phosphorylation in blood platelets samples, which is correlated with P2Y12 receptor inhibition. All of these analyses show that silychristin and silybin have the strongest inhibitory effect on blood platelet activation by ADP, while silydianin also inhibits the ADP pathway, but to a lesser extent. The results obtained in this study clearly demonstrate that silybin, silychristin, and silydianin have inhibitory properties against the P2Y12 receptor and block ADP-induced blood platelet activation.

Study on antithrombotic and antiplatelet activities of low molecular weight fucoidan from Laminaria japonica

NASA Astrophysics Data System (ADS)

Chen, Anjin; Zhang, Fang; Shi, Jie; Zhao, Xue

2012-06-01

The antithrombotic and antiplatelet effects of two fucoidan fractions with low molecular weight and different sulfate content from Laminaria japonica were compared in order to examine the influence of chemical character on their antithrombotic activity and the possible mechanism. Both LMW fucoidan fractions exhibited favorable antithrombotic activity in an Fecl3-induced arterial thrombosis. The antithrombotic activity of LMW fucoidan was related with decrease of TXB2 and whole blood viscosity and hematocrit. LMW fucoidan showed a correlation between anticoagulant, antiaggregant and antithrombotic effects in vivo. For LMW fucoidan, antithrombotic activity required high dose of 5-10 nmol kg-1, concomitantly with increase in anticoagulant activity and inhibition of platelet aggregation. Administration of LMW fucoidan significantly promoted the 6-keto-PGF1α content and decreased the TXB2 content, indicating its inhibition of tissue factor pathway and regulation of metabolism of arachidonic acid. By comparison, highly sulfated fucoidan LF2 with Mw 3900 seemed to be a more suitable choice for antithrombotic drug for its antithrombotic activity accompanied with specific inhibitory activity on platelet aggregation, low anticoagulant activity and low hemorrhagic risk in vivo.

Refolding of soluble leukemia inhibitory factor receptor fusion protein (gp 190 sol DAF) from urea.

PubMed

Liu, H; Moreau, J F; Gualde, N; Fu, J

1997-04-01

The insoluble inclusion bodies of soluble leukemia inhibitory factor receptor fusion protein (gp 190 sol DAF) was solubilized in 8 M urea on the unfolding transitions, and several factors on the aggregate formation were indirectly analyzed for the refolding of gp 190 sol DAF. Results indicate that the refolding yield can be considerably increased at lowering concentration of the unfolding protein, a little soluble protein with the slow refolding appears in the process of the aggregate formation and the concentration of the denaturant must be down to a minimum level for its refolding.

Comparison of the effects of omeprazole and rabeprazole on ticlopidine metabolism in vitro.

PubMed

Kinoshita, Yuichi; Matsumoto, Naoki; Watanabe, Minoru; Takeba, Yuko; Yoshida, Yutoku; Ohba, Keiichiro; Suzuki, Satoshi; Itoh, Fumio; Kumai, Toshio; Kobayashi, Shinichi

2011-01-01

The thienopyridine derivative ticlopidine (TCL) is an inhibitor of adenosine diphosphate-induced platelet aggregation. Combination therapy with a thienopyridine derivative and aspirin is standard after coronary stenting, although more hemorrhagic complications occur with the combination therapy than with aspirin alone. A proton pump inhibitor (PPI) is required for prevention or treatment of upper gastrointestinal bleeding in such cases. We examined the effects of PPIs [omeprazole (OPZ) and rabeprazole (RPZ)] on TCL metabolism using pooled human liver microsomes prepared from various human liver blocks and 12 individual human liver microsomes. We calculated the K(i) values of each PPI for TCL metabolic activity and compared the inhibitory effect of each PPI on TCL metabolism. The K(i) values of OPZ and RPZ were 1.4 and 12.7 µM, respectively. The inhibitory effect of OPZ (78.6 ± 0.05%) was significantly greater than that of RPZ (24.2 ± 0.05%) (P < 0.001). Interestingly, a negative correlation existed between the inhibitory effect of OPZ and CYP2C19 activity (r = -0.909, P < 0.001). These results suggest that the inhibitory effect of OPZ is more potent than that of RPZ in vitro. In conclusion, RPZ appears preferable when administering TCL, aspirin, and a PPI in combination.

Isolation and chemical identification of lipid derivatives from avocado (Persea americana) pulp with antiplatelet and antithrombotic activities.

PubMed

Rodriguez-Sanchez, Dariana Graciela; Flores-García, Mirthala; Silva-Platas, Christian; Rizzo, Sheryl; Torre-Amione, Guillermo; De la Peña-Diaz, Aurora; Hernández-Brenes, Carmen; García-Rivas, Gerardo

2015-01-01

Platelets play a pivotal role in physiological hemostasis. However, in coronary arteries damaged by atherosclerosis, enhanced platelet aggregation, with subsequent thrombus formation, is a precipitating factor in acute ischemic events. Avocado pulp (Persea americana) is a good source of bioactive compounds, and its inclusion in the diet as a source of fatty acid has been related to reduced platelet aggregability. Nevertheless, constituents of avocado pulp with antiplatelet activity remain unknown. The present study aims to characterize the chemical nature of avocado constituents with inhibitory effects on platelet aggregation. Centrifugal partition chromatography (CPC) was used as a fractionation and purification tool, guided by an in vitro adenosine diphosphate (ADP), arachidonic acid or collagen-platelet aggregation assay. Antiplatelet activity was initially linked to seven acetogenins that were further purified, and their dose-dependent effects in the presence of various agonists were contrasted. This process led to the identification of Persenone-C (3) as the most potent antiplatelet acetogenin (IC₅₀=3.4 mM) among the evaluated compounds. In vivo evaluations with Persenone A (4) demonstrated potential protective effects against arterial thrombosis (25 mg kg⁻¹ of body weight), as coagulation times increased (2-fold with respect to the vehicle) and thrombus formation was attenuated (71% versus vehicle). From these results, avocado may be referred to as a functional food containing acetogenin compounds that inhibit platelet aggregation with a potential preventive effect on thrombus formation, such as those that occur in ischaemic diseases.

Diarylheptanoids from Rhizomes of Alpinia officinarum Inhibit Aggregation of α-Synuclein.

PubMed

Fu, Guangmiao; Zhang, Wei; Du, Dongsheng; Ng, Yu Pong; Ip, Fanny C F; Tong, Rongbiao; Ip, Nancy Y

2017-08-09

Two new diarylheptanoids, alpinin A (1) and alpinin B (2), together with 18 known diarylheptanoids (3-20), were isolated from the rhizomes of Alpinia officinarum. Their structures were elucidated by comprehensive spectroscopic analysis, including high-resolution mass spectrometry, infrared spectroscopy, and one- and two-dimensional nuclear magnetic resonance spectroscopy. Structurally, alpinin A is a new member of the small family of oxa-bridged diarylheptanoids and contains the characteristic 2,6-cis-configured tetrahydropyran motif (C 1 -C 5 oxa bridge). The absolute configuration of alpinin A was confirmed by asymmetric total synthesis of the enantiomer (ent-1), corroborating the assignment of the molecular structure. The absolute configuration of alpinin B was determined on the basis of the analysis of the circular dichroism exciton chirality spectrum. We evaluated the inhibitory activity of all isolated diarylheptanoids against α-synuclein aggregation at 10 μM. Alpinins A and B significantly inhibited α-synuclein aggregation by 66 and 67%, respectively.

A Cdk5 inhibitory peptide reduces tau hyperphosphorylation and apoptosis in neurons

PubMed Central

Zheng, Ya-Li; Kesavapany, Sashi; Gravell, Maneth; Hamilton, Rebecca S; Schubert, Manfred; Amin, Niranjana; Albers, Wayne; Grant, Philip; Pant, Harish C

2005-01-01

The extracellular aggregation of amyloid β (Aβ) peptides and the intracellular hyperphosphorylation of tau at specific epitopes are pathological hallmarks of neurodegenerative diseases such as Alzheimer's disease (AD). Cdk5 phosphorylates tau at AD-specific phospho-epitopes when it associates with p25. p25 is a truncated activator, which is produced from the physiological Cdk5 activator p35 upon exposure to Aβ peptides. We show that neuronal infections with Cdk5 inhibitory peptide (CIP) selectively inhibit p25/Cdk5 activity and suppress the aberrant tau phosphorylation in cortical neurons. Furthermore, Aβ1−42-induced apoptosis of these cortical neurons was also reduced by coinfection with CIP. Of particular importance is our finding that CIP did not inhibit endogenous or transfected p35/Cdk5 activity, nor did it inhibit the other cyclin-dependent kinases such as Cdc2, Cdk2, Cdk4 and Cdk6. These results, therefore, provide a strategy to address, and possibly ameliorate, the pathology of neurodegenerative diseases that may be a consequence of aberrant p25 activation of Cdk5, without affecting ‘normal' Cdk5 activity. PMID:15592431

Cyclic guanidines: synthesis and antiplatelet activity of 4,6,7,8-tetrahydro-1H-imidazo[1,2-a]pyrazolo[3,4-d]pyrimidin-7-ones and 1,4,6,7,8,9-hexahydropyrazolo [3',4':4,5]pyrimido[2,1-c] [1,2,4]triazin-7-ones.

PubMed

Ferroni, R; Simoni, D; Orlandini, P; Bardi, A; Franze, G P; Guarneri, M

1990-12-01

A series of 4,6,7,8-tetrahydro-1H-imidazo[1,2-a]pyrazolo [3,4-d]pyrimidin-7-ones (1b-n) and 1,4,6,7,8,9-hexahydropyrazolo [3',4':4,5]pyrimido [2,1-c][1,2,4]triazin-7-ones (2a-d) has been synthesized. In view of their potential anti-aggregating activity the compounds were tested in vitro for inhibitory activity towards ADP- and collagen-induced aggregation of human platelets. Among the compounds studied, 8-benzyl-1-(2,5-dichlorophenyl)-4,6,7,8-tetrahydro-1H-imidazo [1,2-a]pyrazolo[3,4-d]pyrimidin-7-one (1n) exhibited the most favorable activity. The 2,5-dichlorophenyl side chain is an important lipophilic and/or steric pharmacophore.

Antiplatelet mechanism of an herbal mixture prepared from the extracts of Phyllostachys pubescens leaves and Prunus mume fruits.

PubMed

Son, Eunjung; Kim, Seung-Hyung; Yang, Won-Kyung; Kim, Dong-Seon; Cha, Jimin

2017-12-19

Bamboo (Phyllostachys pubescens) leaves and Japanese apricot (Mume fructus) fruit are traditionally recognized to be safe herbs broadly used for food and medicinal purposes in Southeast Asia. Our group previously explored their antiplatelet effects. This study was designed to confirm inhibition effects of PM21 (a 2:1 mixture of bamboo leaf extract and Japanese apricot fruit extract) on platelet aggregation and evaluate its potency to use as an herbal remedy to prevent and/or treat the diseases caused by platelet aggregation and thrombus formation. Washed platelets were prepared and platelet aggregation was induced by adding 5 μg/mL collagen. Anti-platelet effects of PM21 (75 mg/kg, 150 mg/kg, and 300 mg/kg for ex vivo and in vivo assays, and 50, 100, 200 μg/mL for in vitro assays) were evaluated. In ex vivo assays, PM21 was orally administered to rats daily after overnight fasting for 3 days and blood was collected 1 h after the final treatment. In vivo antithrombotic effect of PM21 was observed from a carrageenan induced mouse tail thrombosis model. In ex vivo assay, PM21 inhibited platelet aggregation significantly. PM21 showed a strong antithrombotic effect by reducing significantly the length of mouse tail thrombus. PM21 increased intracellular cAMP level and reduced the release of ATP, TXA 2 , and serotonin. PM21 also reduced intracellular concentration of calcium ion, fibrinogen binding to integrin α IIb β 3 , and phosphorylation of ERK2, p38, PLCγ2, and PI3 K. PM21 showed remarkable inhibitory effects on platelet aggregation and thrombus formation. Its inhibitory function seems to influence on GPVI binding to its ligand and subsequent initiation of a signaling cascade that involves activation of effector proteins and secretion of effector molecules, such as ATP, TXA 2 , serotonin, and Ca 2+ . PM21 also appears to exert its anti-platelet effect by deactivation of ERKs activation pathway as well as inhibition of fibrinogen binding to integrin α IIb β 3 .

Label-free fluorescent detection of protein kinase activity based on the aggregation behavior of unmodified quantum dots.

PubMed

Xu, Xiahong; Liu, Xin; Nie, Zhou; Pan, Yuliang; Guo, Manli; Yao, Shouzhuo

2011-01-01

Herein, we present a novel label-free fluorescent assay for monitoring the activity and inhibition of protein kinases based on the aggregation behavior of unmodified CdTe quantum dots (QDs). In this assay, cationic substrate peptides induce the selective aggregation of unmodified QDs with anionic surface charge, whereas phosphorylated peptides do not. Phosphorylation by kinase alters the net charge of peptides and subsequently inhibits the aggregation of unmodified QDs, causing an enhanced fluorescence with a 45 nm blue-shift in emission and a yellow-to-green emission color change. Hence the fluorescence response allows this QD-based method to easily probe kinase activity by a spectrometer or even by the naked eye. The feasibility of the method has been demonstrated by sensitive measurement of the activity of cAMP-dependent protein kinase (PKA) with a low detection limit (0.47 mU μL(-1)). On the basis of the fluorescence response of QDs on the concentration of PKA inhibitor H-89, the IC(50) value, the half maximal inhibitory concentration, was estimated, which was in agreement with the literature value. Moreover, the system can be applicable to detect the Forskolin/3-isobutyl-1-methylxantine (IBMX)-stimulated activation of PKA in cell lysate. Unlike the existing QD-based enzyme activity assays in which the modification process of QDs is essential, this method relies on unmodified QDs without the requirement of peptide labeling and QDs' modification, presenting a promising candidate for cost-effective kinase activity and inhibitor screening assays.

Combined aspirin and cilostazol treatment is associated with reduced platelet aggregation and prevention of exercise-induced platelet activation.

PubMed

Cleanthis, M; Bhattacharya, V; Smout, J; Ashour, H; Stansby, G

2009-05-01

Cilostazol has proven efficacy in increasing walking distance in claudicants, but it has not been demonstrated to be more effective than placebo in secondary cardiovascular prevention. The direct effect of exercise on platelet function remains less well defined. We have investigated the effect of combination treatment with aspirin and cilostazol on platelet activity in claudicants subjected to repeated treadmill exercise. Nineteen claudicants completed a double-blind, randomised, controlled, cross-over trial. Each subject received a 2-week course of aspirin (75mg) and placebo and aspirin and cilostazol (100mg twice daily). Following each 2-week treatment period, patients participated in a standardised treadmill test (3.2kmh(-1), 10 degrees incline) walking to maximal claudication distance. The exercise was repeated thrice in total, and blood was sampled before and after exercise. Platelet activation was measured using free platelet counting aggregation, flow cytometry for surface markers of platelet activation and soluble P-selectin assay. Compared to aspirin and placebo, combination treatment with aspirin and cilostazol was associated with reduced arachidonic-acid-induced platelet aggregation (p<0.01, Wilcoxon signed-rank test). Aspirin and placebo treatment were associated with elevated P-selectin expression, platelet-monocyte aggregation and reduced CD42b expression (p<0.05, Wilcoxon signed-rank test) post-exercise. No difference was seen in spontaneous platelet aggregation whilst soluble P-selectin was reduced post-exercise with combination treatment with aspirin and cilostazol (p<0.05, Wilcoxon signed-rank test). Combination treatment with aspirin and cilostazol results in suppression of platelet activation and reduces the effect of exercise on platelets. The benefit seen may be a result of cilostazol enhancing the inhibitory effect of aspirin on the cyclo-oxygenase pathway.

Pigment Translocation in Caridean Shrimp Chromatophores: Receptor Type, Signal Transduction, Second Messengers, and Cross Talk Among Multiple Signaling Cascades.

PubMed

Milograna, Sarah Ribeiro; Ribeiro, Márcia Regina; Bell, Fernanda Tinti; McNamara, John Campbell

2016-11-01

Pigment aggregation in shrimp chromatophores is triggered by red pigment concentrating hormone (RPCH), a neurosecretory peptide whose plasma membrane receptor may be a G-protein coupled receptor (GPCR). While RPCH binding activates the Ca 2+ /cGMP signaling cascades, a role for cyclic AMP (cAMP) in pigment aggregation is obscure, as are the steps governing Ca 2+ release from the smooth endoplasmic reticulum (SER). A role for the antagonistic neuropeptide, pigment dispersing homone (α-PDH) is also unclear. In red, ovarian chromatophores from the freshwater shrimp Macrobrachium olfersi, we show that a G-protein antagonist (AntPG) strongly inhibits RPCH-triggered pigment aggregation, suggesting that RPCH binds to a GPCR, activating an inhibitory G-protein. Decreasing cAMP levels may cue pigment aggregation, since cytosolic cAMP titers, when augmented by cholera toxin, forskolin or vinpocentine, completely or partially impair pigment aggregation. Triggering opposing Ca 2+ /cGMP and cAMP cascades by simultaneous perfusion with lipid-soluble cyclic nucleotide analogs induces a "tug-of-war" response, pigments aggregating in some chromatosomes with unpredictable, oscillatory movements in others. Inhibition of cAMP-dependent protein kinase accelerates aggregation and reduces dispersion velocities, suggesting a role in phosphorylation events, possibly regulating SER Ca 2+ release and pigment aggregation. The second messengers IP 3 and cADPR do not stimulate SER Ca 2+ release. α-PDH does not sustain pigment dispersion, suggesting that pigment translocation in caridean chromatophores may be regulated solely by RPCH, since PDH is not required. We propose a working hypothesis to further unravel key steps in the mechanisms of pigment translocation within crustacean chromatophores that have remained obscure for nearly a century. © 2016 Wiley Periodicals, Inc.

Inhibitory effects of magnolol and honokiol on human calcitonin aggregation

PubMed Central

Guo, Caiao; Ma, Liang; Zhao, Yudan; Peng, Anlin; Cheng, Biao; Zhou, Qiaoqiao; Zheng, Ling; Huang, Kun

2015-01-01

Amyloid formation is associated with multiple amyloidosis diseases. Human calcitonin (hCT) is a typical amyloidogenic peptide, its aggregation is associated with medullary carcinoma of the thyroid (MTC), and also limits its clinical application. Magnolia officinalis is a traditional Chinese herbal medicine; its two major polyphenol components, magnolol (Mag) and honokiol (Hon), have displayed multiple functions. Polyphenols like flavonoids and their derivatives have been extensively studied as amyloid inhibitors. However, the anti-amyloidogenic property of a biphenyl backbone containing polyphenols such as Mag and Hon has not been reported. In this study, these two compounds were tested for their effects on hCT aggregation. We found that Mag and Hon both inhibited the amyloid formation of hCT, whereas Mag showed a stronger inhibitory effect; moreover, they both dose-dependently disassembled preformed hCT aggregates. Further immuno-dot blot and dynamic light scattering studies suggested Mag and Hon suppressed the aggregation of hCT both at the oligomerization and the fibrillation stages, while MTT-based and dye-leakage assays demonstrated that Mag and Hon effectively reduced cytotoxicity caused by hCT aggregates. Furthermore, isothermal titration calorimetry indicated Mag and Hon both interact with hCT. Together, our study suggested a potential anti-amyloidogenic property of these two compounds and their structure related derivatives. PMID:26324190

Orally given gastroprotective capsaicin does not modify aspirin-induced platelet aggregation in healthy male volunteers (human phase I examination).

PubMed

Sandor, B; Papp, J; Mozsik, Gy; Szolcsanyi, J; Keszthelyi, Zs; Juricskay, I; Toth, K; Habon, Tamas

2014-12-01

Capsaicin is a well-known component of red pepper. Recent studies have shown that capsaicin could prevent gastric ulcer provoked by various NSAID-s like acetylsalicylic acid (ASA). Primary objective of this human clinical phase I trial was to investigate whether two different doses of capsaicin co-administered with ASA could alter the inhibitory effect of ASA on platelet aggregation. 15 healthy male subjects were involved in the study and treated orally with 400 μg capsaicin, 800 μg capsaicin, 500 mg ASA, 400 μg capsaicin+500 mg ASA and 800 μg capsaicin+500 mg ASA. Blood was drawn before and 1, 2, 6 and 24 hours after the drug administration. After that epinephrine induced platelet aggregation was measured by optical aggregometry. Between treatments, volunteers had a 6-day wash-out period. Our results showed that capsaicin had no effect on platelet aggregation, while as expected, ASA monotherapy resulted in a significant and clinically effective platelet aggregation inhibition (p ≤ 0.001). The combined ASA-capsaicin therapies reached equivalent effectiveness in platelet aggregation inhibition as ASA monotherapy. Our investigation proved that capsaicin did not influence the inhibitory effect of ASA on platelet aggregation, thus the capsaicin-ASA treatment would combine the antiplatelet effect of ASA with the possible gastroprotection of capsaicin.

Effects of unripe Citrus hassaku fruits extract and its flavanone glycosides on blood fluidity.

PubMed

Itoh, Kimihisa; Masuda, Megumi; Naruto, Shunsuke; Murata, Kazuya; Matsuda, Hideaki

2010-01-01

The enhancement of blood fluidity may lead to improvements in skin problems resulting from unsmooth circulation or blood stagnation. Since a 50% ethanolic extract (CH-ext) obtained from unripe Citrus hassaku fruits may be a useful ingredient in skin-whitening cosmetics, the present study was designed to examine the effect of CH-ext on blood fluidity. CH-ext concentration-dependently inhibited in vitro collagen-induced rabbit platelet aggregation and in vitro polybrene-induced rat erythrocyte aggregation. The CH-ext showed in vitro fibrinolysis activity in fibrin plate assay. Activity-guided fractionation of the CH-ext using antiplatelet activity, inhibitory activity of erythrocyte aggregation, and fibrinolysis activity revealed that these activities of CH-ext were attributable to naringenin-7-glycoside (prunin). Successive oral administration of CH-ext to rats inhibited the lipopolysaccharide (LPS)-induced decrease of blood platelets and fibrinogen, and LPS-induced increase of fibrin degradation products (FDP) in LPS-induced disseminated intravascular coagulation (DIC) model rats. Effects of CH-ext on blood fluidity were analyzed by a micro channel array flow analyzer (MC-FAN). Preventive oral administration of CH-ext to rats showed dose-dependent reduction of the passage time of whole blood flow of the DIC model rats in comparison with that of the vehicle control rats. These results imply that CH-ext may have effects which improve effects on blood fluidity.

Comparison of the inhibitory effects of cilostazol, acetylsalicylic acid and ticlopidine on platelet functions ex vivo. Randomized, double-blind cross-over study.

PubMed

Ikeda, Y; Kikuchi, M; Murakami, H; Satoh, K; Murata, M; Watanabe, K; Ando, Y

1987-05-01

A randomized double-blind cross-over study was conducted to determine the inhibitory effects of acetylsalicylic acid (ASA), ticlopidine (TP) and cilostazol (OPC-13013; in the following briefly called CS), a new antithrombotic agent on platelet functions ex vivo. Nine patients with cerebral thrombosis were enrolled in this study. Patients were given each of the three drugs for one week in a complete cross-over design according to a randomization schedule, followed by a wash-out period with a placebo for one week. It was found that CS and TP significantly inhibited platelet aggregation induced by ADP. Collagen- and arachidonic acid-induced platelet aggregation was all inhibited by CS, TP and ASA. Duncan's multiple range test to compare the anti-platelet effects of the three drugs revealed that: CS greater than ASA and TP greater than ASA in inhibiting ADP-induced platelet aggregation and CS greater than TP and ASA greater than TP in inhibiting arachidonic acid-induced platelet aggregation. These results may suggest that CS is superior to ASA and TP in inhibiting platelet aggregation ex vivo.

Mechanism of platelet activation induced by endocannabinoids in blood and plasma.

PubMed

Brantl, S Annette; Khandoga, Anna L; Siess, Wolfgang

2014-01-01

Platelets play a central role in atherosclerosis and atherothrombosis, and circulating endocannabinoids might modulate platelet function. Previous studies concerning effects of anandamide (N-arachidonylethanolamide) and 2-arachidonoylglycerol (2-AG) on platelets, mainly performed on isolated cells, provided conflicting results. We therefore investigated the action of three main endocannabinoids [anandamide, 2-AG and virodhamine (arachidonoylethanolamine)] on human platelets in blood and platelet-rich plasma (PRP). 2-AG and virodhamine induced platelet aggregation in blood, and shape change, aggregation and adenosine triphosphate (ATP) secretion in PRP. The EC50 of 2-AG and virodhamine for platelet aggregation in blood was 97 and 160 µM, respectively. Lower concentrations of 2-AG (20 µM) and virodhamine (50 µM) synergistically induced aggregation with other platelet stimuli. Platelet activation induced by 2-AG and virodhamine resembled arachidonic acid (AA)-induced aggregation: shape change, the first platelet response, ATP secretion and aggregation induced by 2-AG and virodhamine were all blocked by acetylsalicylic acid (ASA) or the specific thromboxane A2 (TXA2) antagonist daltroban. In addition, platelet activation induced by 2-AG and virodhamine in blood and PRP were inhibited by JZL184, a selective inhibitor of monoacylglycerol lipase (MAGL). In contrast to 2-AG and virodhamine, anandamide, a substrate of fatty acid amidohydrolase, was inactive. Synthetic cannabinoid receptor subtype 1 (CB1) and 2 (CB2) agonists lacked stimulatory as well as inhibitory platelet activity. We conclude that 2-AG and virodhamine stimulate platelets in blood and PRP by a MAGL-triggered mechanism leading to free AA and its metabolism by platelet cyclooxygenase-1/thromboxane synthase to TXA2. CB1, CB2 or non-CB1/CB2 receptors are not involved. Our results imply that ASA and MAGL inhibitors will protect platelets from activation by high endocannabinoid levels, and that pharmacological CB1- and CB2-receptor ligands will not affect platelets and platelet-dependent progression and complications of cardiovascular diseases.

Oil Palm Phenolics Inhibit the In Vitro Aggregation of β-Amyloid Peptide into Oligomeric Complexes

PubMed Central

Koledova, Vera V.; Shin, Hyeari; Park, Jennifer H.; Tan, Yew Ai; Sambanthamurthi, Ravigadevi

2018-01-01

Alzheimer's disease is a severe neurodegenerative disease characterized by the aggregation of amyloid-β peptide (Aβ) into toxic oligomers which activate microglia and astrocytes causing acute neuroinflammation. Multiple studies show that the soluble oligomers of Aβ42 are neurotoxic and proinflammatory, whereas the monomers and insoluble fibrils are relatively nontoxic. We show that Aβ42 aggregation is inhibited in vitro by oil palm phenolics (OPP), an aqueous extract from the oil palm tree (Elaeis guineensis). The data shows that OPP inhibits stacking of β-pleated sheets, which is essential for oligomerization. We demonstrate the inhibition of Aβ42 aggregation by (1) mass spectrometry; (2) Congo Red dye binding; (3) 2D-IR spectroscopy; (4) dynamic light scattering; (5) transmission electron microscopy; and (6) transgenic yeast rescue assay. In the yeast rescue assay, OPP significantly reduces the cytotoxicity of aggregating neuropeptides in yeast genetically engineered to overexpress these peptides. The data shows that OPP inhibits (1) the aggregation of Aβ into oligomers; (2) stacking of β-pleated sheets; and (3) fibrillar growth and coalescence. These inhibitory effects prevent the formation of neurotoxic oligomers and hold potential as a means to reduce neuroinflammation and neuronal death and thereby may play some role in the prevention or treatment of Alzheimer's disease. PMID:29666700

Curcumin Pyrazole and its derivative (N-(3-Nitrophenylpyrazole) Curcumin inhibit aggregation, disrupt fibrils and modulate toxicity of Wild type and Mutant α-Synuclein

PubMed Central

Ahsan, Nuzhat; Mishra, Satyendra; Jain, Manish Kumar; Surolia, Avadhesha; Gupta, Sarika

2015-01-01

Accumulating evidence suggests that deposition of neurotoxic α-synuclein aggregates in the brain during the development of neurodegenerative diseases like Parkinson’s disease can be curbed by anti-aggregation strategies that either disrupt or eliminate toxic aggregates. Curcumin, a dietary polyphenol exhibits anti-amyloid activity but the use of this polyphenol is limited owing to its instability. As chemical modifications in curcumin confiscate this limitation, such efforts are intensively performed to discover molecules with similar but enhanced stability and superior properties. This study focuses on the inhibitory effect of two stable analogs of curcumin viz. curcumin pyrazole and curcumin isoxazole and their derivatives against α-synuclein aggregation, fibrillization and toxicity. Employing biochemical, biophysical and cell based assays we discovered that curcumin pyrazole (3) and its derivative N-(3-Nitrophenylpyrazole) curcumin (15) exhibit remarkable potency in not only arresting fibrillization and disrupting preformed fibrils but also preventing formation of A11 conformation in the protein that imparts toxic effects. Compounds 3 and 15 also decreased neurotoxicity associated with fast aggregating A53T mutant form of α-synuclein. These two analogues of curcumin described here may therefore be useful therapeutic inhibitors for the treatment of α-synuclein amyloidosis and toxicity in Parkinson’s disease and other synucleinopathies. PMID:25985292

Functional neuroanatomy of the central noradrenergic system.

PubMed

Szabadi, Elemer

2013-08-01

The central noradrenergic neurone, like the peripheral sympathetic neurone, is characterized by a diffusely arborizing terminal axonal network. The central neurones aggregate in distinct brainstem nuclei, of which the locus coeruleus (LC) is the most prominent. LC neurones project widely to most areas of the neuraxis, where they mediate dual effects: neuronal excitation by α₁-adrenoceptors and inhibition by α₂-adrenoceptors. The LC plays an important role in physiological regulatory networks. In the sleep/arousal network the LC promotes wakefulness, via excitatory projections to the cerebral cortex and other wakefulness-promoting nuclei, and inhibitory projections to sleep-promoting nuclei. The LC, together with other pontine noradrenergic nuclei, modulates autonomic functions by excitatory projections to preganglionic sympathetic, and inhibitory projections to preganglionic parasympathetic neurones. The LC also modulates the acute effects of light on physiological functions ('photomodulation'): stimulation of arousal and sympathetic activity by light via the LC opposes the inhibitory effects of light mediated by the ventrolateral preoptic nucleus on arousal and by the paraventricular nucleus on sympathetic activity. Photostimulation of arousal by light via the LC may enable diurnal animals to function during daytime. LC neurones degenerate early and progressively in Parkinson's disease and Alzheimer's disease, leading to cognitive impairment, depression and sleep disturbance.

Abnormal response to methylphenidate across multiple fMRI procedures in cocaine use disorder: feasibility study.

PubMed

Moeller, Scott J; Konova, Anna B; Tomasi, Dardo; Parvaz, Muhammad A; Goldstein, Rita Z

2016-07-01

The indirect dopamine agonist methylphenidate remediates cognitive deficits in psychopathology, but the individual characteristics that determine its effects on the brain are not known. We aimed to determine whether targeted dopaminergically modulated traits and individual differences could predict neural response to methylphenidate across multiple functional magnetic resonance imaging (fMRI) procedures. We combined neural measures from three separate procedures (two inhibitory control tasks differing in their degree of emotional salience and resting-state functional connectivity) during methylphenidate (20 mg oral, versus randomized and counterbalanced placebo) and correlated these aggregated responses with cocaine use disorder diagnosis (22 cocaine abusers, 21 controls), symptoms of attention deficit hyperactivity disorder, and working memory capacity. Cocaine abusers, relative to controls, had a lower response in the dorsolateral prefrontal cortex to methylphenidate across all three procedures, driven by responses to the two inhibitory control tasks; reduced methylphenidate fMRI response in this region further correlated with more frequent cocaine use. Cocaine abuse (and its frequency), associated with lower tonic dopamine levels, correlated with a reduction in activation to methylphenidate (versus placebo). These initial results provide feasibility to the idea that multimodal fMRI tasks can be meaningfully aggregated, and that these aggregated procedures show a common disruption in addiction in a highly anticipated region relevant to cognitive control. Results also suggest that drug use frequency may represent an important modulatory variable in interpreting the efficacy of pharmacologically enhanced cognitive interventions in addiction.

Design and synthesis of some new carboxamide and propanamide derivatives bearing phenylpyridazine as a core ring and the investigation of their inhibitory potential on in-vitro acetylcholinesterase and butyrylcholinesterase.

PubMed

Kilic, Burcu; Gulcan, Hayrettin O; Aksakal, Fatma; Ercetin, Tugba; Oruklu, Nihan; Umit Bagriacik, E; Dogruer, Deniz S

2018-05-08

A series of new carboxamide and propanamide derivatives bearing phenylpyridazine as a core ring were designed, synthesized and evaluated for their ability to inhibit both cholinesterase enzymes. In addition, a series of carboxamide and propanamide derivatives bearing biphenyl instead of phenylpyridazine were also synthesized to examine the inhibitory effect of pyridazine moiety on both cholinesterase enzymes. The inhibitory activity results revealed that compounds 5b, 5f, 5h, 5j, 5l pyridazine-3-carboxamide derivative, exhibited selective acetylcholinesterase (AChE) inhibition with IC 50 values ranging from 0.11 to 2.69 µM. Among them, compound 5h was the most active one (IC 50  = 0.11 µM) without cytotoxic effect at its effective concentration against AChE. Additionally, pyridazine-3-carboxamide derivative 5d (IC 50 for AChE = 0.16 µM and IC 50 for BChE = 9.80 µM) and biphenyl-4-carboxamide derivative 6d (IC 50 for AChE = 0.59 µM and IC 50 for BChE = 1.48 µM) displayed dual cholinesterase inhibitory activity. Besides, active compounds were also tested for their ability to inhibit Aβ aggregation. Theoretical physicochemical properties of the compounds were calculated by using Molinspiration Program as well. The Lineweaver-Burk plot and docking study showed that compound 5 h targeted both the catalytic active site (CAS) and the peripheral anionic site (PAS) of AChE. Copyright © 2018 Elsevier Inc. All rights reserved.

Zn(II)- and Cu(II)-induced non-fibrillar aggregates of amyloid-beta (1-42) peptide are transformed to amyloid fibrils, both spontaneously and under the influence of metal chelators.

PubMed

Tõugu, Vello; Karafin, Ann; Zovo, Kairit; Chung, Roger S; Howells, Claire; West, Adrian K; Palumaa, Peep

2009-09-01

Aggregation of amyloid-beta (Abeta) peptides is a central phenomenon in Alzheimer's disease. Zn(II) and Cu(II) have profound effects on Abeta aggregation; however, their impact on amyloidogenesis is unclear. Here we show that Zn(II) and Cu(II) inhibit Abeta(42) fibrillization and initiate formation of non-fibrillar Abeta(42) aggregates, and that the inhibitory effect of Zn(II) (IC(50) = 1.8 micromol/L) is three times stronger than that of Cu(II). Medium and high-affinity metal chelators including metallothioneins prevented metal-induced Abeta(42) aggregation. Moreover, their addition to preformed aggregates initiated fast Abeta(42) fibrillization. Upon prolonged incubation the metal-induced aggregates also transformed spontaneously into fibrils, that appear to represent the most stable state of Abeta(42). H13A and H14A mutations in Abeta(42) reduced the inhibitory effect of metal ions, whereas an H6A mutation had no significant impact. We suggest that metal binding by H13 and H14 prevents the formation of a cross-beta core structure within region 10-23 of the amyloid fibril. Cu(II)-Abeta(42) aggregates were neurotoxic to neurons in vitro only in the presence of ascorbate, whereas monomers and Zn(II)-Abeta(42) aggregates were non-toxic. Disturbed metal homeostasis in the vicinity of zinc-enriched neurons might pre-dispose formation of metal-induced Abeta aggregates, subsequent fibrillization of which can lead to amyloid formation. The molecular background underlying metal-chelating therapies for Alzheimer's disease is discussed in this light.

Inhibitory effects of Atractylodis lanceae rhizoma and Poria on collagen- or thromboxane A2-induced aggregation in rabbit platelets.

PubMed

Nasu, Yuiko; Iwashita, Masaya; Saito, Masaki; Fushiya, Shinji; Nakahata, Norimichi

2009-05-01

Kami-shoyo-san (Jia-Wei-Xiao-Yao-San), Toki-shakuyaku-san (Dang-Gui-Shao-Yao-San) and Toki-shigyaku-ka-goshuyu-shokyo-to (Dang-Gui-Si-Ni-Jia-Wu-Zhu-Yu-Sheng-Jiang-Tang) are Kampo (traditional Chinese) medicines which are traditionally and effectively used for the treatment of chilly sensation (Hiesho) in Japan, but the active components and their detailed mechanisms have not yet been clarified. Etiologies of Hiesho include poor peripheral blood circulation and platelet aggregability contributes to peripheral blood circulation; therefore, we investigated the effect of Kampo medicines on platelet aggregation using rabbit platelets in vitro. Collagen and U46619, a thromboxane A(2) receptor agonist, caused rabbit platelet aggregation, which was potently inhibited by pretreatment of platelets with Kami-shoyo-san and Toki-shakuyaku-san in vitro. Toki-shigyaku-ka-goshuyu-shokyo-to, however, did not significantly inhibit collagen- or U46619-induced platelet aggregation. Therefore, we examined the effect on platelet aggregation of two herbal medicines, Atractylodis Lanceae Rhizoma and Poria, both of which are contained in Kami-shoyo-san and Toki-shakuyaku-san but not in Toki-shigyaku-ka-goshuyu-shokyo-to. As the results indicate, Atractylodis Lanceae Rhizoma inhibited platelet aggregation induced by collagen but not by U46619. Poria effectively inhibited U46619-induced platelet aggregation and it partially inhibited collagen-induced platelet aggregation. On the other hand, Atractylodis Lanceae Rhizoma and Poria did not inhibit adrenaline/adenosine diphosphate- or adrenaline/serotonin-induced platelet aggregation. These results suggest the possibility that the inhibition of platelet aggregation by two Kampo medicines, Kami-shoyo-san and Toki-shakuyaku-san, is one of the mechanisms underlying the improvement of Hiesho. Furthermore, Atractylodis Lanceae Rhizoma and Poria are possible herbal medicines for the inhibition of platelet aggregation.

Colloidal and antibacterial properties of novel triple-headed, double-tailed amphiphiles: exploring structure-activity relationships and synergistic mixtures.

PubMed

Marafino, John N; Gallagher, Tara M; Barragan, Jhosdyn; Volkers, Brandi L; LaDow, Jade E; Bonifer, Kyle; Fitzgerald, Gabriel; Floyd, Jason L; McKenna, Kristin; Minahan, Nicholas T; Walsh, Brenna; Seifert, Kyle; Caran, Kevin L

2015-07-01

Two novel series of tris-cationic, tripled-headed, double-tailed amphiphiles were synthesized and the effects of tail length and head group composition on the critical aggregation concentration (CAC), thermodynamic parameters, and minimum inhibitory concentration (MIC) against six bacterial strains were investigated. Synergistic antibacterial combinations of these amphiphiles were also identified. Amphiphiles in this study are composed of a benzene core with three benzylic ammonium bromide groups, two of which have alkyl chains, each 8-16 carbons in length. The third head group is a trimethylammonium or pyridinium. Log of critical aggregation concentration (log[CAC]) and heat of aggregation (ΔHagg) were both inversely proportional to the length of the linear hydrocarbon chains. Antibacterial activity increases with tail length until an optimal tail length of 12 carbons per chain, above which, activity decreased. The derivatives with two 12 carbon chains had the best antibacterial activity, killing all tested strains at concentrations of 1-2μM for Gram-positive and 4-16μM for Gram-negative bacteria. The identity of the third head group (trimethylammonium or pyridinium) had minimal effect on colloidal and antibacterial activity. The antibacterial activity of several binary combinations of amphiphiles from this study was higher than activity of individual amphiphiles, indicating that these combinations are synergistic. These amphiphiles show promise as novel antibacterial agents that could be used in a variety of applications. Copyright © 2015 Elsevier Ltd. All rights reserved.

Inhibition of rabbit platelet activation in vitro by antagonists of platelet-activating factor (PAF)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cox, C.P.; Wood, K.L.

1986-03-05

The authors used washed, (/sup 3/H)serotonin-labeled rabbit platelets to study the in vitro aggregation and secretion responses induced by graded doses of PAF in the presence or absence of specific antagonists of PAF. These antagonists included CV-3988, L-652,731, triazolam and alprazolam. Platelets were pretreated with either an antagonist or the appropriate diluent for 60 sec prior to the addition of PAF (2 x 10/sup -10/ to 2 x 10/sup -7/ M). Aggregation was monitored continuously and recorded as the height of the aggregation tracing at 60 sec post-PAF. Secretion of (/sup 3/H)-serotonin was measured in a sample of the plateletsmore » removed at 60 sec post-PAF. When 2 x 10/sup -10/ M PAF was used as the stimulus, the concentration of antagonist needed for 50% inhibition (IC/sub 50/) of secretion was obtained at 0.05 ..mu..M, 0.15 ..mu..M, 0.6 ..mu..M and 2.5 ..mu..M, respectively, for L-652,731, CV-3988, triazolam and alprazolam. The corresponding IC/sub 50/ for aggregation was obtained at 0.2 ..mu..M, 0.1 ..mu..M, 1.5 ..mu..M and 6.5 ..mu..M, respectively. The inhibitory effects of these antagonists could be overcome by increasing the dose of PAF used. Although all of the antagonists were capable of completely inhibiting platelet aggregation and secretion, L-652,731 was the most potent PAF antagonist on a molar basis.« less

Multitarget Therapeutic Leads for Alzheimer's Disease: Quinolizidinyl Derivatives of Bi- and Tricyclic Systems as Dual Inhibitors of Cholinesterases and β-Amyloid (Aβ) Aggregation.

PubMed

Tonelli, Michele; Catto, Marco; Tasso, Bruno; Novelli, Federica; Canu, Caterina; Iusco, Giovanna; Pisani, Leonardo; Stradis, Angelo De; Denora, Nunzio; Sparatore, Anna; Boido, Vito; Carotti, Angelo; Sparatore, Fabio

2015-06-01

Multitarget therapeutic leads for Alzheimer's disease were designed on the models of compounds capable of maintaining or restoring cell protein homeostasis and of inhibiting β-amyloid (Aβ) oligomerization. Thirty-seven thioxanthen-9-one, xanthen-9-one, naphto- and anthraquinone derivatives were tested for the direct inhibition of Aβ(1-40) aggregation and for the inhibition of electric eel acetylcholinesterase (eeAChE) and horse serum butyrylcholinesterase (hsBChE). These compounds are characterized by basic side chains, mainly quinolizidinylalkyl moieties, linked to various bi- and tri-cyclic (hetero)aromatic systems. With very few exceptions, these compounds displayed inhibitory activity on both AChE and BChE and on the spontaneous aggregation of β-amyloid. In most cases, IC50 values were in the low micromolar and sub-micromolar range, but some compounds even reached nanomolar potency. The time course of amyloid aggregation in the presence of the most active derivative (IC50 =0.84 μM) revealed that these compounds might act as destabilizers of mature fibrils rather than mere inhibitors of fibrillization. Many compounds inhibited one or both cholinesterases and Aβ aggregation with similar potency, a fundamental requisite for the possible development of therapeutics exhibiting a multitarget mechanism of action. The described compounds thus represent interesting leads for the development of multitarget AD therapeutics. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

In Vitro Effects of Serotonin, Melatonin, and Other Related Indole Compounds on Amyloid-β Kinetics and Neuroprotection.

PubMed

Hornedo-Ortega, Ruth; Da Costa, Grégory; Cerezo, Ana B; Troncoso, Ana M; Richard, Tristan; Garcia-Parrilla, M Carmen

2018-02-01

Amyloid-β peptide is the main component of senile plaques in Alzheimer's disease. The inhibition of amyloid-β peptide assembly, the destabilization of amyloid-β peptide aggregates, and the decrease of its cytotoxicity for the prevention of neuronal death are considered neuroprotective effects. In this work, the protective effects against amyloid-β peptide aggregation and cytotoxicity of eight indolic compounds are evaluated: tryptophan, tryptamine, serotonin, tryptophol, N-acetylserotonin, 3-indoleacetic acid, tryptophan ethyl ester, and melatonin. Thioflavin T spectroscopic assay, transmission electron microscopy, western blotting, circular dichroism, NMR, cell viability (thiazolyl blue tetrazolium bromide assay), quantitative PCR, and heme oxygenase activity are used. Serotonin is the most effective compound for inhibiting amyloid-β peptide aggregation. Almost all the indolic compounds tested prevent amyloid-β peptide-induced and increase cell viability, being between 9 and 25%. Melatonin and serotonin are the most active. Moreover, serotonin increased the expression of SIRT-1 and 2, heat shock protein 70, and heme oxygenase activity, this being a possible mechanism underlying the observed neuroprotective effect. Melatonin and other related indolic compounds, mainly serotonin, show an inhibitory and destabilizing effect on amyloid-β peptide fibril formation and they possess neuroprotective properties related to the vitagenes system. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Secondary Metabolites in Ramalina terebrata Detected by UHPLC/ESI/MS/MS and Identification of Parietin as Tau Protein Inhibitor.

PubMed

Cornejo, Alberto; Salgado, Francisco; Caballero, Julio; Vargas, Reinaldo; Simirgiotis, Mario; Areche, Carlos

2016-08-18

Liquid chromatography coupled with mass spectrometry is an outstanding methodology for fast analysis of phenolic compounds in biological samples. Twenty two compounds were quickly and accurately identified in the methanolic extract of the Antarctic lichen Ramalina terebrata for the first time using ultra high pressure liquid chromatography coupled with photodiode array detector and high resolution mass spectrometry (UHPLC-PDA-Q/Orbitrap/MS/MS). In addition, the extract and the four compounds isolated from this species were tested for the inhibitory activity of tau protein aggregation, which is a protein involved in Alzheimer's disease (AD). All compounds showed null activity with the exception of parietin, which it was able to inhibit aggregation process of tau in a concentration range between 3 µg/mL (10 µM) to 28 µg/mL (100 µM). In addition, we show how parietin interact with tau (306)VQIVYK(311) hexapeptide inside of the microtubule binding domain (4R) with the help of molecular docking experiments. Finally, the constituents present in the methanolic extract could possibly contribute to the established anti-aggregation activity for this extract and this in-depth analysis of the chemical composition of R. terebrata could guide further research into its medicinal properties and potential uses.

Secondary Metabolites in Ramalina terebrata Detected by UHPLC/ESI/MS/MS and Identification of Parietin as Tau Protein Inhibitor

PubMed Central

Cornejo, Alberto; Salgado, Francisco; Caballero, Julio; Vargas, Reinaldo; Simirgiotis, Mario; Areche, Carlos

2016-01-01

Liquid chromatography coupled with mass spectrometry is an outstanding methodology for fast analysis of phenolic compounds in biological samples. Twenty two compounds were quickly and accurately identified in the methanolic extract of the Antarctic lichen Ramalina terebrata for the first time using ultra high pressure liquid chromatography coupled with photodiode array detector and high resolution mass spectrometry (UHPLC-PDA-Q/Orbitrap/MS/MS). In addition, the extract and the four compounds isolated from this species were tested for the inhibitory activity of tau protein aggregation, which is a protein involved in Alzheimer’s disease (AD). All compounds showed null activity with the exception of parietin, which it was able to inhibit aggregation process of tau in a concentration range between 3 µg/mL (10 µM) to 28 µg/mL (100 µM). In addition, we show how parietin interact with tau 306VQIVYK311 hexapeptide inside of the microtubule binding domain (4R) with the help of molecular docking experiments. Finally, the constituents present in the methanolic extract could possibly contribute to the established anti-aggregation activity for this extract and this in-depth analysis of the chemical composition of R. terebrata could guide further research into its medicinal properties and potential uses. PMID:27548142

The Inhibitory Effects of Cu(2+) on Exopalaemon carinicauda Arginine Kinase via Inhibition Kinetics and Molecular Dynamics Simulations.

PubMed

Si, Yue-Xiu; Lee, Jinhyuk; Yin, Shang-Jun; Gu, Xiao-Xu; Park, Yong-Doo; Qian, Guo-Ying

2015-06-01

We studied the Cu(2+)-mediated inhibition and aggregation of Exopalaemon carinicauda arginine kinase (ECAK). We found that Cu(2+) significantly inactivated ECAK activity and double-reciprocal kinetics demonstrated that Cu(2+) induced noncompetitive inhibition of arginine and ATP (IC50 = 2.27 ± 0.16 μM; K i for arginine = 13.53 ± 3.76; K i for ATP = 4.02 ± 0.56). Spectrofluorometry results showed that Cu(2+) induced ECAK tertiary structural changes including the exposure of hydrophobic surfaces that directly induced ECAK aggregation. The addition of osmolytes such as glycine and proline successfully blocked ECAK aggregation induced by Cu(2+) and recovered ECAK activity. We built a 3D structure for ECAK using the ECAK ORF gene sequence. Molecular dynamics (MD) and docking simulations between ECAK and Cu(2+) were conducted to elucidate the binding mechanisms. The results showed that Cu(2+) blocked the entrance to the ATP active site; these results are consistent with the experimental result that Cu(2+) induced ECAK inactivation. Since arginine kinase (AK) plays an important role in cellular energy metabolism in invertebrates, our study can provide new information about the effect of Cu(2+) on ECAK enzymatic function and unfolding, including aggregation, and the protective effects of osmolytes on ECAK folding to better understand the role of the invertebrate ECAK metabolic enzyme in marine environments.

Toward the Discovery of Effective Polycyclic Inhibitors of α-Synuclein Amyloid Assembly*

PubMed Central

Lamberto, Gonzalo R.; Torres-Monserrat, Valentina; Bertoncini, Carlos W.; Salvatella, Xavier; Zweckstetter, Markus; Griesinger, Christian; Fernández, Claudio O.

2011-01-01

The fibrillation of amyloidogenic proteins is a critical step in the etiology of neurodegenerative disorders such as Alzheimer and Parkinson diseases. There is major interest in the therapeutic intervention on such aberrant aggregation phenomena, and the utilization of polyaromatic scaffolds has lately received considerable attention. In this regard, the molecular and structural basis of the anti-amyloidogenicity of polyaromatic compounds, required to evolve this molecular scaffold toward therapeutic drugs, is not known in detail. We present here biophysical and biochemical studies that have enabled us to characterize the interaction of metal-substituted, tetrasulfonated phthalocyanines (PcTS) with α-synuclein (AS), the major protein component of amyloid-like deposits in Parkinson disease. The inhibitory activity of the assayed compounds on AS amyloid fibril formation decreases in the order PcTS[Ni(II)] ∼ PcTS > PcTS[Zn(II)] ≫ PcTS[Al(III)] ≈ 0. Using NMR and electronic absorption spectroscopies we demonstrated conclusively that the differences in binding capacity and anti-amyloid activity of phthalocyanines on AS are attributed to their relative ability to self-stack through π-π interactions, modulated by the nature of the metal ion bound at the molecule. Low order stacked aggregates of phthalocyanines were identified as the active amyloid inhibitory species, whose effects are mediated by residue specific interactions. Such sequence-specific anti-amyloid behavior of self-stacked phthalocyanines contrasts strongly with promiscuous amyloid inhibitors with self-association capabilities that act via nonspecific sequestration of AS molecules. The new findings reported here constitute an important contribution for future drug discovery efforts targeting amyloid formation. PMID:21795682

Selective serotonin reuptake inhibitors: measurement of effect on platelet function.

PubMed

McCloskey, Donna Jo; Postolache, Teodor T; Vittone, Bernard J; Nghiem, Khanh L; Monsale, Jude L; Wesley, Robert A; Rick, Margaret E

2008-03-01

Selective serotonin reuptake inhibitors (SSRIs) reduce platelet serotonin and are associated with increased gastrointestinal bleeding, an effect that is enhanced when taken with NSAIDs or aspirin. The best method to evaluate hemorrhagic events in patients taking SSRIs has not been determined. Platelet aggregation, which is not widely available, shows SSRI inhibition of platelet function; we tested whether a platelet function analyzer could detect SSRI inhibition of platelet function. Two groups of outpatients with mood disorders were recruited; each patient was taking a stable dose of either an SSRI or bupropion for at least 6 weeks. They were tested using the platelet function analyzer-100 (PFA-100; Dade International Inc, Miami, Fla) concomitantly with platelet aggregation. Fifty-eight patients were analyzed. We detected significant differences between the groups using aggregation methods with arachidonic acid (aggregation, P = 0.00001; release, P = 0.009) and collagen (aggregation, P = 0.016; release, P = 0.006). The PFA-100 did not detect differences between the groups or results outside the reference range. The PFA-100 does not detect the inhibitory effects of SSRIs on platelet function, but it can be used to direct evaluation of bleeding in a patient taking an SSRI. Abnormal PFA-100 results suggest additional evaluation for von Willebrand disease, other platelet inhibitory medications, or underlying intrinsic platelet dysfunction.

Role of Berberine in the Treatment of Methicillin-Resistant Staphylococcus aureus Infections

NASA Astrophysics Data System (ADS)

Chu, Ming; Zhang, Ming-Bo; Liu, Yan-Chen; Kang, Jia-Rui; Chu, Zheng-Yun; Yin, Kai-Lin; Ding, Ling-Yu; Ding, Ran; Xiao, Rong-Xin; Yin, Yi-Nan; Liu, Xiao-Yan; Wang, Yue-Dan

2016-04-01

Berberine is an isoquinoline alkaloid widely used in the treatment of microbial infections. Recent studies have shown that berberine can enhance the inhibitory efficacy of antibiotics against clinical multi-drug resistant isolates of methicillin-resistant Staphylococcus aureus (MRSA). However, the underlying mechanisms are poorly understood. Here, we demonstrated that sub-minimum inhibitory concentrations (MICs) of berberine exhibited no bactericidal activity against MRSA, but affected MRSA biofilm development in a dose dependent manner within the concentration ranging from 1 to 64 μg/mL. Further study indicated that berberine inhibited MRSA amyloid fibrils formation, which consist of phenol-soluble modulins (PSMs). Molecular dynamics simulation revealed that berberine could bind with the phenyl ring of Phe19 in PSMα2 through hydrophobic interaction. Collectively, berberine can inhibit MRSA biofilm formation via affecting PSMs’ aggregation into amyloid fibrils, and thereby enhance bactericidal activity of antibiotics. These findings will provide new insights into the multiple pharmacological properties of berberine in the treatment of microbial-generated amyloid involved diseases.

Development of tacrine-bifendate conjugates with improved cholinesterase inhibitory and pro-cognitive efficacy and reduced hepatotoxicity.

PubMed

Cen, Juan; Guo, Huiyan; Hong, Chen; Lv, Jianwu; Yang, Yacheng; Wang, Ting; Fang, Dong; Luo, Wen; Wang, Chaojie

2018-01-20

A novel series of tacrine-bifendate (THA-DDB) conjugates (7a-e) were synthesized and evaluated as potential anti-Alzheimer's agents. These compounds showed potent cholinesterase and self-induced β-amyloid (Aβ) aggregation inhibitory activities. A Lineweaver-Burk plot and molecular modeling study showed that these compounds can target both catalytic active site (CAS) and peripheral anionic site (PAS) of acetylcholinesterase (AChE). The cytotoxicity of the conjugate 7d against PC12 and HepG2 cells and hepatotoxicity against human hepatocyte cell line (HL-7702) were found to be considerably less compared to THA. Moreover, treatment with 7d did not exhibit significant hepatotoxicity in mice. Finally, in vivo studies confirmed that 7d significantly ameliorates the cognitive performances of scopolamine-treated ICR mice. Therefore, 7d has high potential for the treatment of Alzheimer's disease and warrants further investigation. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Steam-cooking rapidly destroys and reverses onion-induced antiplatelet activity

PubMed Central

2012-01-01

Background Foods in the diet that can aid in the prevention of diseases are of major interest. Onions are key ingredients in many cuisines around the world and moreover, onion demand has trended higher over the past three decades. An important pharmacological aspect of onion is the ability to inhibit platelet aggregation. Raw onions inhibit platelet aggregation; however, when onions are boiled or heated, antiplatelet activity may be abolished. Methods Onion quarters were steamed for 0, 1, 3, 6, 10, and 15 min. The in vitro antiplatelet activity of a yellow hybrid storage onion was examined at these times on the blood of 12 human subjects using in vitro whole blood aggregometry. Results Contrary to findings reported for boiling, antiplatelet activity was destroyed between 3 and 6 min of steaming, and at 10 min of steaming, cooked onions stimulated platelet activity. Extracts from cooked onion had the potential to reverse the inhibitory effect on blood platelets by 25%. Responses were consistent across all donors. Total polyphenolic concentration and soluble solids were not affected by steaming time. Conclusions The potential value of cooked onion preparations may result in destruction or reversal of antiplatelet activity, without affecting the polyphenolic concentration. PMID:22992282

Steam-cooking rapidly destroys and reverses onion-induced antiplatelet activity.

PubMed

Hansen, Emilie A; Folts, John D; Goldman, Irwin L

2012-09-20

Foods in the diet that can aid in the prevention of diseases are of major interest. Onions are key ingredients in many cuisines around the world and moreover, onion demand has trended higher over the past three decades. An important pharmacological aspect of onion is the ability to inhibit platelet aggregation. Raw onions inhibit platelet aggregation; however, when onions are boiled or heated, antiplatelet activity may be abolished. Onion quarters were steamed for 0, 1, 3, 6, 10, and 15 min. The in vitro antiplatelet activity of a yellow hybrid storage onion was examined at these times on the blood of 12 human subjects using in vitro whole blood aggregometry. Contrary to findings reported for boiling, antiplatelet activity was destroyed between 3 and 6 min of steaming, and at 10 min of steaming, cooked onions stimulated platelet activity. Extracts from cooked onion had the potential to reverse the inhibitory effect on blood platelets by 25%. Responses were consistent across all donors. Total polyphenolic concentration and soluble solids were not affected by steaming time. The potential value of cooked onion preparations may result in destruction or reversal of antiplatelet activity, without affecting the polyphenolic concentration.

A biophysical insight into the formation of aggregates upon trifluoroethanol induced structural and conformational changes in garlic cystatin.

PubMed

Siddiqui, Mohd Faizan; Bano, Bilqees

2018-06-06

Intrinsic and extrinsic factors are responsible for the transition of soluble proteins into aggregated form. Trifluoroethanol is among such potent extrinsic factor which facilitates the formation of aggregated structure. It disrupts the interactive forces and destabilizes the native structure of the protein. The present study investigates the effect of trifluoroethanol (TFE) on garlic cystatin. Garlic cystatin was incubated with increasing concentration of TFE (0-90% v/v) for 4 h. Incubation of GPC with TFE induces structural changes thereby resulting in the formation of aggregates. Inactivation of garlic phytocystatin was confirmed by cysteine proteinase inhibitory activity. Garlic cystatin at 30% TFE exhibits native-like secondary structure and high ANS fluorescence, thus suggesting the presence of molten globule state. Circular dichroism and FTIR confirmed the transition of the native alpha-helical structure of garlic cystatin to the beta-sheet structure at 60% TFE. Furthermore, increased ThT fluorescence and redshift in Congo red absorbance assay confirmed the presence of aggregates. Rayleigh and turbidity assay was also performed to validate the aggregation results. Scanning electron microscopy was followed to analyze the morphological changes which confirm the presence of sheath-like structure at 60% TFE. The study sheds light on the conformational behavior of a plant protein when kept under stress condition induced by an extrinsic factor. Copyright © 2018 Elsevier B.V. All rights reserved.

Structure-activity relationship of three synthesized benzimidazole-based oligosaccharides in human platelet activation.

PubMed

Chang, Yi; Hsu, Wen-Hsien; Yang, Wen-Bin; Jayakumar, Thanasekaran; Lee, Tzu-Yin; Sheu, Joen-Rong; Lu, Wan-Jung; Li, Jiun-Yi

2017-11-01

Antiplatelet agents have considerable benefits in the treatment of thromboembolic diseases; however, these agents still have substantial limitations due to their severe side-effects. In this study, the antiplatelet activity of three newly synthesized saccharide based benzimidazole derivatives, M3BIM, Malto-BIM and Melibio-BIM, in collagen and thrombin-stimulated human platelets in vitro was examined. Among the compounds tested, only compound M3BIM exerted concentration (20-60 µM)-dependent inhibitory effects against collagen (1 µg/ml) and thrombin (0.01 U/ml)-induced washed human platelet aggregation. Moreover, at a concentration of 60 µM, M3BIM distinctly abolished collagen-induced adenosine triphosphate (ATP) release and intracellular Ca2+ mobilization. Additionally, this compound attenuated the collagen-induced phosphorylation of p47, a marker of the activation of protein kinase C (PKC) and p38 mitogen-activated protein kinase (MAPK). However, Malto-BIM and Melibio-BIM were not effective in this regard. Moreover, the toxic effects of these compounds were evaluated using zebrafish embryo toxicity (ZET) assay, and the results revealed that all three compounds had no comparative cytotoxicity within the range of 25-200 µM. Overall, the results of this study provide evidence for the inhibitory effects of M3BIM on collagen-induced platelet aggregation in vitro compared to other imidazole derivatives. The presence of 1-imidazolyl moiety at one end with a longer chain length (three sugar moieties) may be mainly responsible for the observed effects of M3BIM. These results suggest that compound M3BIM may be used as a potential candidate for the treatment of aberrant platelet activation-related diseases as it inhibits the activation of p47 and p38 MAPK, and reduces ATP release and Ca2+ mobilization.

Design, synthesis, and evaluation of salicyladimine derivatives as multitarget-directed ligands against Alzheimer's disease.

PubMed

Yang, Hua-Li; Cai, Pei; Liu, Qiao-Hong; Yang, Xue-Lian; Fang, Si-Qiang; Tang, Yan-Wei; Wang, Cheng; Wang, Xiao-Bing; Kong, Ling-Yi

2017-11-01

A series of salicyladimine derivatives were designed, synthesized and evaluated as multi-target-directed ligands for the treatment of Alzheimer's disease (AD). Biological activity results demonstrated that some derivatives possessed significant inhibitory activities against amyloid-β (Aβ) aggregation and human monoamine oxidase B (hMAO-B) as well as remarkable antioxidant effects and low cell toxicity. The optimal compound, 5, exhibited excellent potency for inhibition of self-induced Aβ 1-42 aggregation (91.3±2.1%, 25μM), inhibition of hMAO-B (IC 50 , 1.73±0.39μM), antioxidant effects (43.4±2.6μM of IC 50 by DPPH method, 0.67±0.06 trolox equivalent by ABTS method), metal chelation and BBB penetration. Furthermore, compound 5 had neuroprotective effects against ROS generation, H 2 O 2 -induced apoptosis, 6-OHDA-induced cell injury, and a significant in vitro anti-inflammatory activity. Collectively, these findings highlighted that compound 5 was a potential balanced multifunctional neuroprotective agent for the development of anti-AD drugs. Copyright © 2017. Published by Elsevier Ltd.

Microwave-induced formation of oligomeric amyloid aggregates.

PubMed

Lee, Wonseok; Choi, Yeseong; Lee, Sang Won; Kim, Insu; Lee, Dongtak; Hong, Yoochan; Lee, Gyudo; Yoon, Dae Sung

2018-08-24

Amyloid aggregates have emerged as a significant hallmark of neurodegenerative diseases such as Alzheimer's and Parkinson's diseases. Although it has been recently reported that microwave heating induces amyloid aggregation compared with conventional heating methods, the mechanism of amyloid aggregate induction has remained unclear. In this study, we investigated the formation of oligomeric amyloid aggregates (OAAs) by microwave irradiation at microscale volumes of solution. Microwave irradiation of protein monomer solution triggered rapid formation of OAAs within 7 min. We characterized the formation of OAAs using atomic force microscopy, thioflavin T fluorescent assay and circular dichroism. In the microwave system, we also investigated the inhibitory effect on the formation of amyloid aggregates by L-ascorbic acid as well as enhanced amyloid aggregation by silver nanomaterials such as nanoparticles and nanowires. We believe that microwave technology has the potential to facilitate the study of amyloid aggregation in the presence of chemical agents or nanomaterials.

Inhibitory effect of Campomanesia xanthocarpa in platelet aggregation: Comparison and synergism with acetylsalicylic acid.

PubMed

Otero, Juliana Soares; Hirsch, Gabriela Elisa; Klafke, Jonatas Zeni; Porto, Fernando Garcez; de Almeida, Amanda Spring; Nascimento, Sabrina; Schmidt, Aline; da Silva, Brenda; Pereira, Roberta Lelis Dias; Jaskulski, Mônica; Parisi, Mariana Migliorini; Dos Santos Guarda, Naiara; Moresco, Rafael Noal; Aita, Carlos Alberto Mayora; Viecili, Paulo Ricardo Nazário

2017-06-01

Cardiovascular diseases of thrombotic origin are related to high mortality and standard therapeutic agent used in this case is acetylsalicylic acid (ASA), but serious adverse events may occur. However, recent data has suggested the plant Campomanesia xanthocarpa has antiplatelet activity and could be a viable alternative. In this study we investigated the effects of the encapsulated powder of this plant in human platelet aggregation. 23 healthy subjects were randomly divided into three groups: (1) ASA (100mg), (2) C. xanthocarpa (1000mg) or (3) synergism (500mg of C. xanthocarpa plush 50mg of ASA); daily for five days. Antiplatelet activity was determined by turbidimetric method using ADP or arachidonic acid (AA) agonists before, 5 and 8days after treatments. Treatment with C. xanthocarpa and synergism caused a reduction of 8±13.5% and 12.5±5% in platelet aggregation induced by ADP after 5days of treatment, respectively, returning to basal levels after 8days. For AA agonist, 5days of treatment with C. xanthocarpa, ASA or synergism caused a reduction of 46±15%, 36±12% and 69.3±6% in platelet aggregation, respectively, and first two groups returned to baseline values 8days after treatment ended. Synergism group prolonged antiplatelet effect maintaining aggregation reduction after 8days the end of treatment. C. xanthocarpa showed antiplatelet action when stimulated by agonist AA, and contributed to the antiplatelet effect when associated with ASA for both agonists, allowing dose reduction to 50mg. Copyright © 2017 Elsevier Ltd. All rights reserved.

Pharmacological studies on proglumetacin maleate, a new non-steroidal anti-inflammatory drug (4). Mode of action on anti-inflammatory activity.

PubMed

Ono, N; Yamasaki, Y; Yamamoto, N; Sunami, A; Miyake, H

1986-11-01

The possible mechanism of the anti-inflammatory activity of proglumetacin maleate (PGM), a new indomethacin (IND) derivative interacting with arachidonic acid (AA) metabolism, was investigated to elucidate the contributions of PGM itself and its two major metabolites, desproglumideproglumetacin maleate (DPP) and IND. PGM caused much less inhibition of PGE2 formation by sheep seminal vesicle microsomes (IC50 = 310 microM) and TXB2 formation by a washed rabbit platelet suspension (IC50 = 6.3 microM) than IND. DPP also caused less inhibition of cyclooxygenase than IND. Moreover, PGM had less effect on sodium arachidonate (SAA)-induced rat platelet aggregation ex vivo and AA-induced sudden death in rabbits than IND. These results show that PGM has anti-inflammatory activity after its conversion to the active metabolite IND. However, the inhibitory effects of PGM and DPP were as strong as that of IND on SAA- or collagen-induced rabbit platelet aggregation in vitro. These activities are considered to be associated with platelet membrane interaction. Moreover, unlike IND, PGM (IC50 = 1.5 microM) and DPP (IC50 = 16.3 microM) strongly inhibited 5-HETE formation by the cytosol of guinea pig polymorphonuclear leukocytes. This unique activity of PGM on 5-lipoxygenase may contribute to its anti-inflammatory activity.

Substitution-inert trinuclear platinum complexes efficiently condense/aggregate nucleic acids and inhibit enzymatic activity**

PubMed Central

Malina, Jaroslav; Farrell, Nicholas P.; Brabec, Viktor

2015-01-01

The trinuclear platinum complexes ([{Pt(NH3)3}2-μ-{trans-Pt(NH3)2(NH2(CH2)6NH2)2}]6+, TriplatinNC‐A; [{trans-Pt(NH3)2(NH2(CH2)6NH3+)}2-μ-{trans-Pt(NH3)2(NH2(CH2)6NH2)2}]8+, TriplatinNC) belong to a class of biologically active agents that bind to DNA via nonbonding noncovalent (hydrogen bonding, electrostatic) interactions. Charge delocalization (6+ to 8+) in these linear trinuclear platinum complexes results in a high cellular uptake and promising cytotoxic activity in several carcinoma cell lines. We show in the present work with the aid of the methods of biophysical chemistry that in particular TriplatinNC condenses DNA with unprecedented potency which is much higher than that of conventional DNA condensing agents. In addition, in contrast to other DNA condensing agents, both platinum complexes induce aggregation of small transfer RNA molecules. We also demonstrate for the first time that TriplatinNC-A and TriplatinNC in particular completely inhibit DNA transcriptional activity at markedly lower concentration than naturally occurring spermine. Notably, the topoisomerase I-mediated relaxation of supercoiled DNA was inhibited by TriplatinNC-A and TriplatinNC at ~60-fold and ~250-fold lower concentration than that of spermine, respectively. We suggest that the general mechanisms of biological activity of TriplatinNC-A and TriplatinNC may be associated with their unique ability to condense/aggregate nucleic acids with consequent inhibitory effect on crucial enzymatic activities. PMID:25256921

A novel ruthenium (II)-derived organometallic compound, TQ-6, potently inhibits platelet aggregation: Ex vivo and in vivo studies.

PubMed

Hsia, Chih-Hsuan; Velusamy, Marappan; Sheu, Joen-Rong; Khamrang, Themmila; Jayakumar, Thanasekaran; Lu, Wan-Jung; Lin, Kuan-Hung; Chang, Chao-Chien

2017-08-25

Arterial thrombosis plays a key role in cardiovascular diseases. Hence, developing more effective antithrombotic agents is necessary. We designed a ruthenium (II)-derived complex, [Ru(η 6 -cymene)2-(1H-benzoimidazol-2-yl)-quinoline Cl]BF 4 (TQ-6), as a new antiplatelet drug. TQ-6 (0.3 µM) exhibited extremely strong inhibitory activity against platelet aggregation, Src, and Syk phosphorylation stimulated by agonists in human platelets. In collagen-activated platelets, TQ-6 also inhibited ATP-release, [Ca +2 ]i, P-selectin expression, FITC-PAC-1 binding, and hydroxyl radical formation, as well as the phosphorylation of phospholipase Cγ2, protein kinase C, mitogen-activated protein kinases, and Akt. Neither FITC-JAQ1 nor FITC-triflavin binding or integrin β 3 phosphorylation stimulated by immobilized fibrinogen were diminished by TQ-6. Furthermore, TQ-6 had no effects in cyclic nucleotide formation. Moreover, TQ-6 substantially prolonged the closure time in whole blood, increased the occlusion time of thrombotic platelet plug formation and bleeding time in mice. In conclusion, TQ-6 has a novel role in inhibiting platelet activation through the inhibition of the agonist receptors-mediated inside-out signaling such as Src-Syk-PLCγ2 cascade and subsequent suppression of granule secretion, leading to disturb integrin α IIb β 3 -mediated outside-in signaling, and ultimately inhibiting platelet aggregation. Therefore, TQ-6 has potential to develop as a therapeutic agent for preventing or treating thromboembolic disorders.

Triflavin, an Arg‐Gly‐Asp‐containing Antiplatelet Peptide Inhibits Cell‐substratum Adhesion and Melanoma Cell‐induced Lung Colonization

PubMed Central

Sheu, Joen R.; Lin, Chao H.; Chung, Jih L.; Teng, Che M.

1992-01-01

Triflavin, an Arg‐Gly‐Asp (RGD) containing peptide purified from Trimeresurus flavoviridis snake venom, inhibits human platelet aggregation by blocking fibrinogen binding to fibrinogen receptors associated with glycoprotein Ilb/IIIa complex. In this study, we show that triflavin (1‐30 μg/mouse) inhibits B16‐F10 melanoma cell‐induced lung colonization in C57BL/6 mice in a dose‐dependent manner. In vitro, triflavin dose‐dependently inhibits adhesion of B16‐F10 melanoma cells to extracellular matrices (ECMs; i.e., fibronectin, fibrinogen, vitronectin, and collagen type I). Triflavin is approximately 600‐800 times more potent than GRGDS at inhibiting cell adhesion. In addition, triflavin dose‐dependently inhibits B16‐F10 cell‐induced platelet aggregation. These results imply that the inhibitory effect of triflavin on the adhesion of tumor cells to ECMs (e.g., fibronectin, vitronectin and collagen type I) and/or tumor cell‐induced platelet aggregation may be partially responsible for its antimetastatic activity in C57BL/6 mice. PMID:1399825

Design, synthesis and evaluation of coumarin-pargyline hybrids as novel dual inhibitors of monoamine oxidases and amyloid-β aggregation for the treatment of Alzheimer's disease.

PubMed

Yang, Hua-Li; Cai, Pei; Liu, Qiao-Hong; Yang, Xue-Lian; Li, Fan; Wang, Jin; Wu, Jia-Jia; Wang, Xiao-Bing; Kong, Ling-Yi

2017-09-29

A series of coumarin-pargyline hybrids (4a-x) have been designed, synthesized and evaluated as novel dual inhibitors of Alzheimer's disease (AD). Most of the compounds exhibited a potent ability to inhibit amyloid-β (Aβ) aggregation and monoamine oxidases. In particular, compound 4x exhibited remarkable inhibitory activities against monoamine oxidases (IC 50 , 0.027 ± 0.004 μM for MAO-B; 3.275 ± 0.040 μM for MAO-A) and Aβ 1-42 aggregation (54.0 ± 1.1%, 25 μM). Moreover, compound 4x showed low toxicity according to in vitro cell toxicity test. The results of the parallel artificial membrane permeability assay for blood-brain barrier indicated that compound 4x would be potent to cross the blood-brain barrier. Collectively, these findings demonstrate that compound 4x was an effective and promising candidate for AD therapy. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Dual/multitargeted xanthone derivatives for Alzheimer's disease: where do we stand?

PubMed

Cruz, Maria I; Cidade, Honorina; Pinto, Madalena

2017-09-01

To date, the current therapy for Alzheimer's disease (AD) based on acetylcholinesterase inhibitors is only symptomatic, being its efficacy limited. Hence, the recent research has been focused in the development of different pharmacological approaches. Here we discuss the potential of xanthone derivatives as new anti-Alzheimer agents. The interference of xanthone derivatives with acetylcholinesterase and other molecular targets and cellular mechanisms associated with AD have been recently systematically reported. Therefore, we report xanthones with anticholinesterase, monoamine oxidase and amyloid β aggregation inhibitory activities as well as antioxidant properties, emphasizing xanthone derivatives with dual/multitarget activity as potential agents to treat AD. We also propose the structural features for these activities that may guide the design of new, more effective xanthone derivatives. [Formula: see text].

A Novel Variant in the Platelet Endothelial Aggregation Receptor-1 Gene is Associated with Increased Platelet Aggregabili

PubMed Central

Herrera-Galeano, J. Enrique; Becker, Diane M.; Wilson, Alexander F.; Yanek, Lisa R.; Bray, Paul; Vaidya, Dhananjay; Faraday, Nauder; Becker, Lewis C

2009-01-01

Objective: Platelet endothelial aggregation receptor-1 (PEAR1) is a recently identified platelet transmembrane protein that becomes activated by platelet contact. We looked for novel genetic variants in PEAR1 and studied their association with agonist-induced native platelet aggregation and with aspirin's inhibitory effect on platelets. Methods and Results: We genotyped PEAR1 for 10 single nucleotide polymorphisms (SNPs), selected for optimal gene coverage at a density of 4kb, in 1486 apparently healthy individuals from two generations of families with premature CAD. Subjects had a mean age of 45 years; 62% were white and 38% African American. Platelet aggregation to collagen, epinephrine, and ADP was measured in platelet rich plasma, at baseline and after 2 weeks of aspirin (ASA, 81 mg/day), and genotype-phenotype associations were examined separately by ethnicity using multivariable generalized linear models adjusted for covariates. The C allele of SNP rs2768759 [A/C], located in the promoter region of the gene, was common in whites and uncommon in African Americans (allele frequency 70.2% vs 17.7%). The C allele was generally associated in both ethnic groups with increased aggregation of native platelets to each agonist. Following ASA, the associations were stronger and more consistent, and remained significant when post ASA aggregation was adjusted for baseline aggregation, consistent with a relationship between the C allele and reduced platelet responsiveness to ASA. The PEAR1 SNP explained up to 6.9% of the locus specific genetic variance in African Americans and up to 2.5% of the genetic variance in whites following ASA. Conclusion: PEAR1 appears to play an important role in agonist-induced platelet aggregation and in the response to ASA in both whites and African Americans. PMID:18511696

Evaluation of the stability and antimicrobial activity of an ethanolic extract of Libidibia ferrea

PubMed Central

de Oliveira Marreiro, Raquel; Bandeira, Maria Fulgência Costa Lima; de Souza, Tatiane Pereira; de Almeida, Mailza Costa; Bendaham, Katiana; Venâncio, Gisely Naura; Rodrigues, Isis Costa; Coelho, Cristiane Nagai; Milério, Patrícia Sâmea Lêdo Lima; de Oliveira, Glauber Palma; de Oliveira Conde, Nikeila Chacon

2014-01-01

Biofilm is a dense, whitish, noncalcified aggregate of bacteria, with desquamated epithelial cells and food debris creating conditions for an imbalance of resident oral microflora and favoring the destruction of hard and soft tissues by development of caries and gingivitis. The aim of this study was to obtain and characterize an extract of Libidibia ferrea, ex Caesalpinia ferrea L. and to evaluate its feasibility for formulation as a mouthwash, according to current legislation. For this purpose, pH, sedimentation, density, and stability were evaluated, along with microbiological testing of the extract. The microbiological test was used to verify the presence of Staphylococcus aureus, Pseudomonas aeruginosa, fungi, yeasts, coliforms, and minimum inhibitory concentrations of Streptococcus mutans and Streptococcus oralis strains. Characterization, microbiological evaluation, and minimum inhibitory concentration results were tabulated and described using descriptive statistics. The L. ferrea extract showed stable characteristics, product quality, and antibacterial activity against the microorganisms tested irrespective of experimental time intervals. According to these results, it can be concluded that formulation of a mouthwash containing L. ferrea extract to control biofilm is feasible, but further studies are needed. PMID:24501546

Discovery of novel propargylamine-modified 4-aminoalkyl imidazole substituted pyrimidinylthiourea derivatives as multifunctional agents for the treatment of Alzheimer's disease.

PubMed

Xu, Yi-Xiang; Wang, Huan; Li, Xiao-Kang; Dong, Sheng-Nan; Liu, Wen-Wen; Gong, Qi; Wang, Tian-Duan-Yi; Tang, Yun; Zhu, Jin; Li, Jian; Zhang, Hai-Yan; Mao, Fei

2018-01-01

A series of novel propargylamine-modified pyrimidinylthiourea derivatives (1-3) were designed and synthesized as multifunctional agents for Alzheimer's disease (AD) therapy, and their potential was evaluated through various biological experiments. Among these derivatives, compound 1b displayed good selective inhibitory activity against AChE (vs BuChE, IC 50  = 0.324 μM, SI > 123) and MAO-B (vs MAO-A, IC 50  = 1.427 μM, SI > 35). Molecular docking study showed that the pyrimidinylthiourea moiety of 1b could bind to the catalytic active site (CAS) of AChE, and the propargylamine moiety interacted directly with the flavin adenine dinucleotide (FAD) of MAO-B. Moreover, 1b demonstrated mild antioxidant ability, good copper chelating property, effective inhibitory activity against Cu 2+ -induced Aβ 1-42 aggregation, moderate neuroprotection, low cytotoxicity, and appropriate blood-brain barrier (BBB) permeability in vitro and was capable of ameliorating scopolamine-induced cognitive impairment in mice. These results indicated that 1b has the potential to be a multifunctional candidate for the treatment of Alzheimer's disease. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Novel iridium (III)‑derived organometallic compound for the inhibition of human platelet activation.

PubMed

Shyu, Kou-Gi; Velusamy, Marappan; Hsia, Chih-Wei; Yang, Chih-Hao; Hsia, Chih-Hsuan; Chou, Duen-Suey; Jayakumar, Thanasekaran; Sheu, Joen-Rong; Li, Jiun-Yi

2018-05-01

Since cisplatin achieved clinical success, transition metal platinum (Pt) drugs have been effectively used for the treatment of cancer. Iridium (Ir) compounds are considered to be potential alternatives to Pt compounds, as they possess promising anticancer effects with minor side effects. Platelet activation is associated with the metastasis and progression of cancer, and also with arterial thrombosis. Therefore, it is necessary to develop novel, effective antithrombotic agents. An Ir (III)‑derived complex, [Ir (Cp*) 1‑(2‑pyridyl)‑3‑(3‑methoxyphenyl)imidazo[1,5‑a]pyridine Cl]BF4 (Ir‑3), was developed as a novel antiplatelet drug. Ir‑3 exerted more potent inhibitory activity on platelet aggregation stimulated by collagen compared with other agonists, including thrombin. In collagen‑activated platelets, Ir‑3 also inhibited adenosine trisphosphate release, intracellular Ca+2 mobilization and surface P‑selectin expression, as well as the phosphorylation of phospholipase Cγ2 (PLCγ2), protein kinase C (PKC), protein kinase B (Akt) and c‑Jun N‑terminal kinase (JNK) 1, but not p38 mitogen‑activated protein kinase or extracellular signal‑regulated kinases. Ir‑3 did not markedly affect phorbol 12, 13‑dibutyrate‑stimulated platelet aggregation. Neither the adenylate cyclase inhibitor SQ22536 nor the guanylate cyclase inhibitor 1H‑[1, 2, 4] oxadiazolo [4,3‑a]quinoxalin‑1‑one significantly reversed the Ir‑3‑mediated inhibition of platelet aggregation. Furthermore, Ir‑3 had no considerable diminishing effects on OH radical signals in collagen‑stimulated platelets or Fenton reaction solution. In conclusion, Ir‑3 serves a novel function in the inhibition of platelet aggregation through inhibiting the PLCγ2‑PKC cascade, and the subsequent suppression of Akt and JNK1 activation. Therefore, Ir‑3 may be a potential novel therapeutic agent for the treatment of thromboembolic disorders, or the interplay between platelets and tumor cells which contributes to tumor cell proliferation and progression.

Platelet Aggregation Inhibitory Effects and Pharmacokinetics of Prasugrel Used in Combination With Aspirin in Healthy Japanese Subjects.

PubMed

Umemura, Kazuo; Ikeda, Yasuhiko; Matsushima, Nobuko; Kondo, Kazunao

2017-07-01

We evaluated the pharmacokinetics and pharmacodynamics of prasugrel used in combination with aspirin in healthy Japanese subjects. All subjects received aspirin 100 mg/day. Subsequently, in the single-administration study, 23 subjects also received prasugrel 20 or 30 mg, and in the multiple-administration study, 20 subjects received a loading dose of prasugrel 20 or 30 mg on day 1, followed by a maintenance dose of prasugrel 5 or 7.5 mg/day, respectively, on days 2-5. In both studies, the plasma concentration of the active metabolite of prasugrel, R-138727, reached a maximum 0.5 hours after administration and rapidly decreased within 4 hours. In the single-administration study, the inhibitory effect on adenosine diphosphate-induced platelet aggregation was significantly higher in the prasugrel 20- and 30-mg groups than in the placebo group at all times (1-144 hours) after administration. In the multiple-administration study, a similar antiplatelet effect was found after both the loading dose and the maintenance dose and was maintained for 3-6 days after the last administration. There were study drug-related adverse events; however, all were mild, and none was clinically significant. © 2016 The Authors. Clinical Pharmacology in Drug Development Published by Wiley Periodicals, Inc. on behalf of The American College of Clinical Pharmacology.

Stabilizing Off-pathway Oligomers by Polyphenol Nanoassemblies for IAPP Aggregation Inhibition

NASA Astrophysics Data System (ADS)

Nedumpully-Govindan, Praveen; Kakinen, Aleksandr; Pilkington, Emily H.; Davis, Thomas P.; Chun Ke, Pu; Ding, Feng

2016-01-01

Experimental studies have shown that many naturally occurring polyphenols have inhibitory effect on the aggregation of several proteins. Here, we use discrete molecular dynamics (DMD) simulations and high-throughput dynamic light scattering (DLS) experiments to study the anti-aggregation effects of two polyphenols, curcumin and resveratrol, on the aggregation of islet amyloid polypeptide (IAPP or amylin). Our DMD simulations suggest that the aggregation inhibition is caused by stabilization of small molecular weight IAPP off-pathway oligomers by the polyphenols. Our analysis indicates that IAPP-polyphenol hydrogen bonds and π-π stacking combined with hydrophobic interactions are responsible for the stabilization of oligomers. The presence of small oligomers is confirmed with DLS measurements in which nanometer-sized oligomers are found to be stable for up to 7.5 hours, the time frame within which IAPP aggregates in the absence of polyphenols. Our study offers a general anti-aggregation mechanism for polyphenols, and further provides a computational framework for the future design of anti-amyloid aggregation therapeutics.

Inhibitory activity of aspirin on von Willebrand factor-induced platelet aggregation.

PubMed

Homoncik, M; Jilma, B; Eichelberger, B; Panzer, S

2000-09-01

The effect of aspirin (ASA) on vWF induced platelet - platelet interaction is unknown. We therefore tested the response of platelets to von Willebrand factor (vWF) coated beads induced platelet aggregation before and after i.v. and oral ASA. 1000 mg ASA was infused to 10 healthy individuals and after a wash-out period 7 volunteers received 100 mg ASA orally over a period of 11 days. Prior to ASA and in regular intervals thereafter we tested the reactivity to vWF-coated beads to assess platelet adhesion/aggregation and the fade-out time of ASA effects on platelets. Considerable interindividual variability in response to vWF-coated beads was observed, both before ASA and after treatment with ASA. The maximal response to vWF-coated beads (Tmax), the time lag, and the slope of the curve were significantly affected by i.v. ASA, whereas 100 mg of ASA had only inconstant effect on Tmax and slope. The absolute reduction of Tmax after ASA depended on the pre-ASA level, while the percentage of the reduction was similar in all individuals. Thus, platelet aggregation induced by vWF-coated beads is impaired by ASA. Furthermore, our data indicate a large interindividual variability of the response to ASA shortly after treatment induction, which becomes more constant after prolonged treatment.

Ingestion of onion soup high in quercetin inhibits platelet aggregation and essential components of the collagen-stimulated platelet activation pathway in man: a pilot study.

PubMed

Hubbard, Gary P; Wolffram, Siegfried; de Vos, Ric; Bovy, Arnaud; Gibbins, Jonathan M; Lovegrove, Julie A

2006-09-01

Epidemiological data suggest that those who consume a diet rich in quercetin-containing foods may have a reduced risk of CVD. Furthermore, in vitro and ex vivo studies have observed the inhibition of collagen-induced platelet activation by quercetin. The aim of the present study was to investigate the possible inhibitory effects of quercetin ingestion from a dietary source on collagen-stimulated platelet aggregation and signalling. A double-blind randomised cross-over pilot study was undertaken. Subjects ingested a soup containing either a high or a low amount of quercetin. Plasma quercetin concentrations and platelet aggregation and signalling were assessed after soup ingestion. The high-quercetin soup contained 69 mg total quercetin compared with the low-quercetin soup containing 5 mg total quercetin. Plasma quercetin concentrations were significantly higher after high-quercetin soup ingestion than after low-quercetin soup ingestion and peaked at 2.59 (sem 0.42) mumol/l. Collagen-stimulated (0.5 mug/ml) platelet aggregation was inhibited after ingestion of the high-quercetin soup in a time-dependent manner. Collagen-stimulated tyrosine phosphorylation of a key component of the collagen-signalling pathway via glycoprotein VI, Syk, was significantly inhibited by ingestion of the high-quercetin soup. The inhibition of Syk tyrosine phosphorylation was correlated with the area under the curve for the high-quercetin plasma profile. In conclusion, the ingestion of quercetin from a dietary source of onion soup could inhibit some aspects of collagen-stimulated platelet aggregation and signalling ex vivo. This further substantiates the epidemiological data suggesting that those who preferentially consume high amounts of quercetin-containing foods have a reduced risk of thrombosis and potential CVD risk.

Chemokine interactome mapping enables tailored intervention in acute and chronic inflammation.

PubMed

von Hundelshausen, Philipp; Agten, Stijn M; Eckardt, Veit; Blanchet, Xavier; Schmitt, Martin M; Ippel, Hans; Neideck, Carlos; Bidzhekov, Kiril; Leberzammer, Julian; Wichapong, Kanin; Faussner, Alexander; Drechsler, Maik; Grommes, Jochen; van Geffen, Johanna P; Li, He; Ortega-Gomez, Almudena; Megens, Remco T A; Naumann, Ronald; Dijkgraaf, Ingrid; Nicolaes, Gerry A F; Döring, Yvonne; Soehnlein, Oliver; Lutgens, Esther; Heemskerk, Johan W M; Koenen, Rory R; Mayo, Kevin H; Hackeng, Tilman M; Weber, Christian

2017-04-05

Chemokines orchestrate leukocyte trafficking and function in health and disease. Heterophilic interactions between chemokines in a given microenvironment may amplify, inhibit, or modulate their activity; however, a systematic evaluation of the chemokine interactome has not been performed. We used immunoligand blotting and surface plasmon resonance to obtain a comprehensive map of chemokine-chemokine interactions and to confirm their specificity. Structure-function analyses revealed that chemokine activity can be enhanced by CC-type heterodimers but inhibited by CXC-type heterodimers. Functional synergism was achieved through receptor heteromerization induced by CCL5-CCL17 or receptor retention at the cell surface via auxiliary proteoglycan binding of CCL5-CXCL4. In contrast, inhibitory activity relied on conformational changes (in CXCL12), affecting receptor signaling. Obligate CC-type heterodimers showed high efficacy and potency and drove acute lung injury and atherosclerosis, processes abrogated by specific CCL5-derived peptide inhibitors or knock-in of an interaction-deficient CXCL4 variant. Atheroprotective effects of CCL17 deficiency were phenocopied by a CCL5-derived peptide disrupting CCL5-CCL17 heterodimers, whereas a CCL5 α-helix peptide mimicked inhibitory effects on CXCL12-driven platelet aggregation. Thus, formation of specific chemokine heterodimers differentially dictates functional activity and can be exploited for therapeutic targeting. Copyright © 2017, American Association for the Advancement of Science.

Novel multipotent phenylthiazole-tacrine hybrids for the inhibition of cholinesterase activity, β-amyloid aggregation and Ca²⁺ overload.

PubMed

Wang, Yue; Wang, Fang; Yu, Jun-Ping; Jiang, Feng-Chao; Guan, Xin-Lei; Wang, Can-Ming; Li, Lei; Cao, Hui; Li, Ming-Xing; Chen, Jian-Guo

2012-11-01

In this study, a series of multipotent phenylthiazole-tacrine hybrids (7a-7e, 8, and 9a-9m) were synthesized and biologically evaluated. Screening results showed that phenylthiazole-tacrine hybrids were potent cholinesterase inhibitors with pIC(50) (-logIC(50)) value ranging from 5.78 ± 0.05 to 7.14 ± 0.01 for acetylcholinesterase (AChE), and from 5.75 ± 0.03 to 10.35 ± 0.15 for butyrylcholinesterase (BuChE). The second series of phenylthiazole-tacrine hybrids (9a-9m) could efficiently prevent Aβ(1-42) self-aggregation. The structure-activity relationship revealed that their inhibitory potency relied on the type of middle linker and substitutions at 4'-position of 4-phenyl-2-aminothiazole. In addition, 7a and 7c also displayed the Ca(2+) overload blockade effect in the primary cultured cortical neurons. Consequently, these compounds emerged as promising molecules for the therapy of Alzheimer's disease. Copyright © 2012 Elsevier Ltd. All rights reserved.

Novel Tacrine-Benzofuran Hybrids as Potent Multitarget-Directed Ligands for the Treatment of Alzheimer's Disease: Design, Synthesis, Biological Evaluation, and X-ray Crystallography.

PubMed

Zha, Xiaoming; Lamba, Doriano; Zhang, Lili; Lou, Yinghan; Xu, Changxu; Kang, Di; Chen, Li; Xu, Yungen; Zhang, Luyong; De Simone, Angela; Samez, Sarah; Pesaresi, Alessandro; Stojan, Jure; Lopez, Manuela G; Egea, Javier; Andrisano, Vincenza; Bartolini, Manuela

2016-01-14

Twenty-six new tacrine-benzofuran hybrids were designed, synthesized, and evaluated in vitro on key molecular targets for Alzheimer's disease. Most hybrids exhibited good inhibitory activities on cholinesterases and β-amyloid self-aggregation. Selected compounds displayed significant inhibition of human β-secretase-1 (hBACE-1). Among the 26 hybrids, 2e showed the most interesting profile as a subnanomolar selective inhibitor of human acetylcholinesterase (hAChE) (IC50 = 0.86 nM) and a good inhibitor of both β-amyloid aggregation (hAChE- and self-induced, 61.3% and 58.4%, respectively) and hBACE-1 activity (IC50 = 1.35 μM). Kinetic studies showed that 2e acted as a slow, tight-binding, mixed-type inhibitor, while X-ray crystallographic studies highlighted the ability of 2e to induce large-scale structural changes in the active-site gorge of Torpedo californica AChE (TcAChE), with significant implications for structure-based drug design. In vivo studies confirmed that 2e significantly ameliorates performances of scopolamine-treated ICR mice. Finally, 2e administration did not exhibit significant hepatotoxicity.

Design, synthesis and biological evaluation of 4'-aminochalcone-rivastigmine hybrids as multifunctional agents for the treatment of Alzheimer's disease.

PubMed

Xiao, Ganyuan; Li, Yan; Qiang, Xiaoming; Xu, Rui; Zheng, Yunxiaozhu; Cao, Zhongcheng; Luo, Li; Yang, Xia; Sang, Zhipei; Su, Fu; Deng, Yong

2017-02-01

A series of 4'-aminochalcone-revastigmine hybrids were designed, synthesized and evaluated as multifunctional agents for the treatment of Alzheimer's disease. The results showed that most of these compounds exhibited good multifunctional activities. In particular, compound 6c displayed the best inhibitory potency on acetylcholinesterase (IC 50 =4.91μM), and significant antioxidative activity with a value 2.83-fold of Trolox. The kinetic analysis of AChE inhibition revealed that 6c showed mixed-type inhibition, binding simultaneously to the catalytic active site and peripheral anionic site of AChE. In addition, 6c inhibited self-induced Aβ 1-42 aggregation and Cu 2+ -induced Aβ 1-42 aggregation by 89.5% and 79.7% at 25μM respectively, as well as acted as a selective monoamine oxidase B inhibitor (IC 50 =0.29μM) and a selective biometal chelator. Furthermore, 6c could cross the blood-brain barrier in vitro. Based on these results, Compound 6c could be considered as a very promising lead compound for Alzheimer's disease. Copyright © 2016 Elsevier Ltd. All rights reserved.

PbO2(s, plattnerite) reductive dissolution by natural organic matter: reductant and inhibitory subfractions.

PubMed

Shi, Zhi; Stone, Alan T

2009-05-15

Natural organic matter (NOM) is a diverse collection of molecules, each possessing its own reductant, complexant, and adsorption properties. Here, we are interested in the ability of NOM to bring about the reductive dissolution of Pb(IV)O2(s). Adding the coagulants FeCl3 or Al2(SO4)3 followed by membrane filtration is one way to remove a subset of NOM molecules from surface water samples. Another is to pass water samples through a granular activated carbon (GAC) column. Results from applying these treatments to Great Dismal Swamp water (DSW) and Nequasset Bog Water (NBW) can best be explained as follows: (i) GAC column treatment is more efficient at removing the NOM fraction most responsible for reductive dissolution. (ii) Coagulation/filtration, with either coagulant, is most efficient at removing a second, inhibitory fraction. Inhibition may arise from (i) adsorption at the mineral/water interface, which blocks approach of reductant molecules and (ii) a micelle-like aggregate nature, which provides hydrophobic pockets that capture reductantmolecules, again keeping them away from the mineral/water interface. Hypotheses regarding reductant and inhibitory fractions are further evaluated using representative low-molecular-weight compounds. Substituted hydroquinones are used as mimics of the reductant fraction, and malonic acid, quinic acid, trehalose, alginic acid, and polygalacturonic acid are used as mimics of the inhibitory fraction.

Neisseria gonorrhoeae Aggregation Reduces Its Ceftriaxone Susceptibility.

PubMed

Wang, Liang-Chun; Litwin, Madeline; Sahiholnasab, Zahraossadat; Song, Wenxia; Stein, Daniel C

2018-06-15

Antibiotic resistance in Neisseria gonorrhoeae (GC) has become an emerging threat worldwide and heightens the need for monitoring treatment failures. N. gonorrhoeae , a gram-negative bacterium responsible for gonorrhea, infects humans exclusively and can form aggregates during infection. While minimal inhibitory concentration (MIC) tests are often used for determining antibiotic resistance development and treatment, the knowledge of the true MIC in individual patients and how it relates to this laboratory measure is not known. We examined the effect of aggregation on GC antibiotic susceptibility and the relationship between bacterial aggregate size and their antibiotic susceptibility. Aggregated GC have a higher survival rate when treated with ceftriaxone than non-aggregated GC, with bacteria in the core of the aggregates surviving the treatment. GC lacking opacity-associated protein or pili, or expressing a truncated lipooligosaccharide, three surface molecules that mediate GC-GC interactions, reduce both aggregation and ceftriaxone survival. This study demonstrates that the aggregation of N. gonorrhoeae can reduce the susceptibility to antibiotics, and suggests that antibiotic utilization can select for GC surface molecules that promote aggregation which in turn drive pathogen evolution. Inhibiting aggregation may be a potential way of increasing the efficacy of ceftriaxone treatment, consequently reducing treatment failure.

Biotransformation of glycyrrhizin by human intestinal bacteria and its relation to biological activities.

PubMed

Kim, D H; Hong, S W; Kim, B T; Bae, E A; Park, H Y; Han, M J

2000-04-01

The relationship between the metabolites of glycyrrhizin (18beta-glycyrrhetinic acid-3-O-beta-D-glucuronopyranosyl-(1-->2)-beta-D-glucuronide, GL) and their biological activities was investigated. By human intestinal microflora, GL was metabolized to 18beta-glycyrrhetinic acid (GA) as a main product and to 18beta-glycyrrhetinic acid-3-O-beta-D-glucuronide (GAMG) as a minor product. The former reaction was catalyzed by Eubacterium L-8 and the latter was by Streptococcus LJ-22. Among GL and its metabolites, GA and GAMG had more potent in vitro anti-platelet aggregation activity than GL. GA also showed the most potent cytotoxicity against tumor cell lines and the potent inhibitory activity on rotavirus infection as well as growth of Helicobacter pylori. GAMG, the minor metabolite of GL, was the sweetest.

Human Brain-Derived Aβ Oligomers Bind to Synapses and Disrupt Synaptic Activity in a Manner That Requires APP.

PubMed

Wang, Zemin; Jackson, Rosemary J; Hong, Wei; Taylor, Walter M; Corbett, Grant T; Moreno, Arturo; Liu, Wen; Li, Shaomin; Frosch, Matthew P; Slutsky, Inna; Young-Pearse, Tracy L; Spires-Jones, Tara L; Walsh, Dominic M

2017-12-06

Compelling genetic evidence links the amyloid precursor protein (APP) to Alzheimer's disease (AD) and several theories have been advanced to explain the relationship. A leading hypothesis proposes that a small amphipathic fragment of APP, the amyloid β-protein (Aβ), self-associates to form soluble aggregates that impair synaptic and network activity. Here, we used the most disease-relevant form of Aβ, protein isolated from AD brain. Using this material, we show that the synaptotoxic effects of Aβ depend on expression of APP and that the Aβ-mediated impairment of synaptic plasticity is accompanied by presynaptic effects that disrupt the excitatory/inhibitory (E/I) balance. The net increase in the E/I ratio and inhibition of plasticity are associated with Aβ localizing to synapses and binding of soluble Aβ aggregates to synapses requires the expression of APP. Our findings indicate a role for APP in AD pathogenesis beyond the generation of Aβ and suggest modulation of APP expression as a therapy for AD. SIGNIFICANCE STATEMENT Here, we report on the plasticity-disrupting effects of amyloid β-protein (Aβ) isolated from Alzheimer's disease (AD) brain and the requirement of amyloid precursor protein (APP) for these effects. We show that Aβ-containing AD brain extracts block hippocampal LTP, augment glutamate release probability, and disrupt the excitatory/inhibitory balance. These effects are associated with Aβ localizing to synapses and genetic ablation of APP prevents both Aβ binding and Aβ-mediated synaptic dysfunctions. Our results emphasize the importance of APP in AD and should stimulate new studies to elucidate APP-related targets suitable for pharmacological manipulation. Copyright © 2017 the authors 0270-6474/17/3711947-20$15.00/0.

Anticholinesterases and antioxidant alkamides from Piper nigrum fruits.

PubMed

Tu, Yanbei; Zhong, Yujiao; Du, Hongjian; Luo, Wei; Wen, Yaya; Li, Qin; Zhu, Chao; Li, Yanfang

2016-09-01

The anticholinesterase and antioxidant effects of five different extracts of Piper nigrum were evaluated. Twenty-one known alkamides were isolated from active ethyl acetate extract and investigated for their cholinesterase inhibitory and antioxidant effects. Among them, piperine (2), piperettine (5) and piperettyline (20) exhibited dual inhibition against AChE and BChE, and feruperine (18) was the most potent selective inhibitor of BChE. Molecular docking simulation was performed to get insight into the binding interactions of the ligands and enzymes. In addition, N-trans-feruloyltyramine (3) contributed to the strongest DPPH radical-scavenging activity. The self-induced Aβ aggregation inhibition of 2, 5 and 18 was further evaluated. Results indicated that some alkamides could be multifunctional lead candidates for Alzheimer's disease therapy.

Inhibition of amyloid β aggregation and protective effect on SH-SY5Y cells by triterpenoid saponins from the cactus Polaskia chichipe.

PubMed

Fujihara, Koji; Koike, Shin; Ogasawara, Yuki; Takahashi, Kunio; Koyama, Kiyotaka; Kinoshita, Kaoru

2017-07-01

Alzheimer's disease (AD) destroys brain function, especially in the hippocampus, and is a social problem worldwide. A major pathogenesis of AD is related to the accumulation of amyloid beta (Aβ) peptides, resulting in neuronal cell death in the brain. Here, we isolated four saponins (1-4) and elucidated their structures from 1D and 2D NMR and HRFABMS spectral data. The structures of 1 and 2 were determined as new saponins which have cochalic acid as the aglycon, and 3 was determined as a new saponin with oleanolic acid as the aglycon. Compound 4 was confirmed as the known saponin chikusetsusaponin V (=ginsenoside R 0 ). Isolated saponins (1-4) and six previously reported saponins (5-10) were tested for their inhibitory effects of Aβ aggregation and their protective effects on SH-SY5Y cells against Aβ-associated toxicity. As the results, compounds 3 and 4 showed inhibitory effect of Aβ aggregation and compounds 5-8 exerted the protective effects on SH-SY5Y cells against Aβ-associated toxicity. Copyright © 2017 Elsevier Ltd. All rights reserved.

Isolation and characterization of bacterial isolates algicidal against a harmful bloom-forming cyanobacterium Microcystis aeruginosa.

PubMed

Li, Yang; Hongyi, Wei; Komatsu, Masaharu; Ishibashi, Kenichi; Jinsan, Lin; Ito, Tatsuo; Yoshikawa, Takeshi; Maeda, Hiroto

2012-01-01

Algicidal bacteria MaI11-2, MaI11-5 and MaI11-10, which inhibited the growth of a harmful bloom-forming cyanobacterium Microcystis aeruginosa, were isolated from a sewage treatment plant. The isolate MaI11-5 was phylogenetically affiliated into the genus Pedobacter, while MaI11-2 and MaI11-10 were closely related to Bacillus aerophilus, Bacillus altitudinis and Bacillus stratosphericus with 100% identity based on 16S ribosomal RNA sequences. Co-cultivation of M. aeruginosa with the algicidal isolates showed their high algicidal activity. MaI11-5 showed the highest inhibitory effect on the cyanobacterial growth: the inhibitory effect exceeded 50% after 2 days, and reached to 75-85% after 10 days, regardless of the bacterial cell density. The cyanobacterial cells aggregated and produced mucilaginous, glycocalyx-like compounds when attacked by the algicidal bacteria. These results suggest that the algicidal bacteria isolated in the present study are potentially useful as biocontrol agents against M. aeruginosa bloom.

Antiamyloidogenic Activity of Aβ42-Binding Peptoid in Modulating Amyloid Oligomerization.

PubMed

Zhao, Zijian; Zhu, Ling; Li, Haiyun; Cheng, Peng; Peng, Jiaxi; Yin, Yudan; Yang, Yang; Wang, Chen; Hu, Zhiyuan; Yang, Yanlian

2017-01-01

The oligomerization and aggregation of amyloid β (Aβ) play central role in the pathogenesis of Alzheimer's disease (AD). Molecular binding agents for modulating the formation of Aβ oligomers and fibrils have promising application potential in AD therapies. By screening a peptoid library using surface plasmon resonance imaging, amyloid inhibitory peptoid 1 (AIP1) that has high affinity to Aβ42 is identified. AIP1 is demonstrated to inhibit Aβ42 oligomerization and fibrillation and to rescue Aβ42-induced cytotoxicity through decreasing the content of Aβ42 oligomers that is related to cell membrane permeability. Molecular docking suggests that the binding sites of AIP1 may be at the N-terminus of Aβ42. The blood-brain barrier (BBB) permeability of AIP1 using an in vitro BBB model is also revealed. This work provides a strategy for the design and development of peptoid-based antiamyloidogenic agents. The obtained amyloid inhibitory peptoid shows prospects in the therapeutic application in AD. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Inhibition of p53 Mutant Peptide Aggregation In Vitro by Cationic Osmolyte Acetylcholine Chloride.

PubMed

Chen, Zhaolin; Kanapathipillai, Mathumai

2017-01-01

Mutations of tumor suppressor protein p53 are present in almost about 50% of all cancers. It has been reported that the p53 mutations cause aggregation and subsequent loss of p53 function, leading to cancer progression. Here in this study we focus on the inhibitory effects of cationic osmolyte molecules acetylcholine chloride, and choline on an aggregation prone 10 amino acid p53 mutant peptide WRPILTIITL, and the corresponding wildtype peptide RRPILTIITL in vitro. The characterization tools used for this study include Thioflavin- T (ThT) induced fluorescence, transmission electron microscopy (TEM), congo red binding, turbidity, dynamic light scattering (DLS), and cell viability assays. The results show that acetylcholine chloride in micromolar concentrations significantly inhibit p53 mutant peptide aggregation in vitro, and could be promising candidate for p53 mutant/ misfolded protein aggregation inhibition. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Mechanisms of anaphylaxis in human low-affinity IgG receptor locus knock-in mice.

PubMed

Gillis, Caitlin M; Jönsson, Friederike; Mancardi, David A; Tu, Naxin; Beutier, Héloïse; Van Rooijen, Nico; Macdonald, Lynn E; Murphy, Andrew J; Bruhns, Pierre

2017-04-01

Anaphylaxis can proceed through distinct IgE- or IgG-dependent pathways, which have been investigated in various mouse models. We developed a novel mouse strain in which the human low-affinity IgG receptor locus, comprising both activating (hFcγRIIA, hFcγRIIIA, and hFcγRIIIB) and inhibitory (hFcγRIIB) hFcγR genes, has been inserted into the equivalent murine locus, corresponding to a locus swap. We sought to determine the capabilities of hFcγRs to induce systemic anaphylaxis and identify the cell types and mediators involved. hFcγR expression on mouse and human cells was compared to validate the model. Passive systemic anaphylaxis was induced by injection of heat-aggregated human intravenous immunoglobulin and active systemic anaphylaxis after immunization and challenge. Anaphylaxis severity was evaluated based on hypothermia and mortality. The contribution of receptors, mediators, or cell types was assessed based on receptor blockade or depletion. The human-to-mouse low-affinity FcγR locus swap engendered hFcγRIIA/IIB/IIIA/IIIB expression in mice comparable with that seen in human subjects. Knock-in mice were susceptible to passive and active anaphylaxis, accompanied by downregulation of both activating and inhibitory hFcγR expression on specific myeloid cells. The contribution of hFcγRIIA was predominant. Depletion of neutrophils protected against hypothermia and mortality. Basophils contributed to a lesser extent. Anaphylaxis was inhibited by platelet-activating factor receptor or histamine receptor 1 blockade. Low-affinity FcγR locus-switched mice represent an unprecedented model of cognate hFcγR expression. Importantly, IgG-related anaphylaxis proceeds within a native context of activating and inhibitory hFcγRs, indicating that, despite robust hFcγRIIB expression, activating signals can dominate to initiate a severe anaphylactic reaction. Copyright © 2016 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.

Anti-aggregatory effect of boswellic acid in high-fat fed rats: involvement of redox and inflammatory cascades

PubMed Central

2016-01-01

Introduction A high-fat diet is one of the main dietary factors promoting platelet aggregation. The present study was conducted to elucidate the involvement of boswellic acid (BA) on the platelet hyperaggregability in HFD-fed rats. As platelet hyperaggregability in HFD rats is closely linked to inflammation and enhanced free radical production, the present study was extended to evaluate the anti-inflammatory and anti-oxidative effect of BA on HFD-promoted platelet aggregation. Material and methods Rats were assigned to normal, HFD-fed, aspirin-treated (30 mg/kg), and BA-treated (250 and 500 mg/kg) groups. Results Boswellic acid administration in a high dose was effective in attenuating the severity of hyperlipidemia and platelet aggregation, indicated by lower collagen/epinephrine-induced platelet aggregation, as evidenced by the significant increase (p < 0.05) in the circulating platelet count and reduction in the number of thrombi in the lungs. Moreover, it attenuated the oxidative stress and the intensity of inflammatory mediators associated with platelet hyperaggregability, as evidenced by the inhibitory effects on interlukin-1β, COX-2 and tumor necrosis factor-α, indicating that the antiplatelet activity of BA is likely a consequence of controlling oxidative stress and inflammation. Conclusions The present data suggest that BA shows a promising anti-aggregatory effect by attenuating the enhanced hyperlipidemia, oxidative stress and inflammation associated with HFD. PMID:27904529

Salvia miltiorrhiza Bunge (Danshen) extract attenuates permanent cerebral ischemia through inhibiting platelet activation in rats.

PubMed

Fei, Yu-Xiang; Wang, Si-Qi; Yang, Li-Jian; Qiu, Yan-Ying; Li, Yi-Ze; Liu, Wen-Yuan; Xi, Tao; Fang, Wei-Rong; Li, Yun-Man

2017-07-31

Danshen is a crude herbal drug isolated from dried roots of Salvia miltiorrhiza Bunge. This plant is widely used in oriental medicine for the treatment of cardiovascular and cerebrovascular diseases. The supercritical CO 2 extract from Danshen (SCED) (57.85%, 5.67% and 4.55% for tanshinone IIA, tanshinone I and cryptotanshinone respectively) was studied in this article, whose potential molecular mechanism remains unclear, especially in anti-thrombosis. The present study was designed to observe the protective effect of SCED on ischemic stroke in rats and to explore the underlying anti-thrombosis mechanism. Following induction of cerebral ischemia in rats by permanent middle cerebral artery occlusion (pMCAO). Neurological defect score, cerebral blood flow, infarct size, and brain edema were measured to evaluate the injury. Arteriovenous shunt thrombosis model and adenosine 5'-diphosphate (ADP) induced acute pulmonary embolism model were conducted to estimate the antithrombotic effect of SCED. In order to investigate the effects of SCED on platelet aggregation, rat platelet-rich-plasma (PRP) were incubated with SCED prior to the addition of the stimuli (ADP or 9, 11-dideoxy-11α, 9α-epoxymethanoprostaglandin F2α (U46619)). Aggregation was monitored in a light transmission aggregometer. Inhibitory effect of SCED on thromboxane A2 (TXA 2 ) release was detected by ELISA kit. Phospholipase C (PLC)/ Protein kinase C (PKC) signaling pathway was analyzed by a Western blot technique. The effect of the SCED was also studied in vivo on bleeding time in mice. SCED improved the neurological defect score, increased cerebral blood flow, reduced infarct size and alleviated brain edema in rats exposed to pMCAO. After administration of SCED, thrombosis formation in arteriovenous shunt was inhibited and recovery time in pulmonary embolism was shortened. The inhibitory effect of SCED on platelet activation was further confirmed by TXB 2 ELISA kit and Western blot analysis of PLC/PKC signaling pathway. SCED attenuates cerebral ischemic injury. The possible mechanism is that SCED inhibits thrombosis formation, platelet aggregation and activation of PLC/PKC pathway. On this basis, this new extract could be a promising agent to inhibit thrombosis formation and protect against cerebral ischemia injury. Copyright © 2017 Elsevier Ireland Ltd. All rights reserved.

[27- Hydroxycholesterol reverses estradiol induced inhibition of platelet aggregation in postmenopausal women].

PubMed

Rocha, Gladys; Sierralta, Walter; Valladares, Luis

2016-11-01

The decline of estrogen levels increases cardiovascular risk in women. Platelets express estrogen receptors and 17β-estradiol- (E2) can produce a protective effect on thrombus formation. The hydroxylation of cholesterol generates several sterols and 27-hydroxycholesterol (27HC) predominates in circulation. To evaluate the effect of 27HC as an endogenous antagonist of the anti-aggregating properties of E2 in platelets of postmenopausal women. Platelet function of postmenopausal women was evaluated ex-vivo. Platelets pre-incubated with 27HC in the presence or absence of E2, were stimulated with collagen. Aggregation was evaluated using turbidimetry using a Chrono-log aggregometer. Collagen-stimulated platelet aggregation was significantly inhibited by E2. The inhibitory effect of E2 on collagen-stimulated platelet aggregation was significantly reversed in the presence of 27HC. The suppressive effect of E2 on platelet aggregation is inhibited by 27HC, which could contribute to increase cardiovascular risk in postmenopausal women.

Potent antiplatelet activity of sesamol in an in vitro and in vivo model: pivotal roles of cyclic AMP and p38 mitogen-activated protein kinase.

PubMed

Chang, Chao C; Lu, Wan J; Chiang, Cheng W; Jayakumar, Thanasekaran; Ong, Eng T; Hsiao, George; Fong, Tsorng H; Chou, Duen S; Sheu, Joen R

2010-12-01

Sesamol is a potent phenolic antioxidant which possesses antimutagenic, antihepatotoxic and antiaging properties. Platelet activation is relevant to a variety of acute thrombotic events and coronary heart diseases. There have been few studies on the effect of sesamol on platelets. Therefore, the aim of this study was to systematically examine the detailed mechanisms of sesamol in preventing platelet activation in vitro and in vivo. Sesamol (2.5-5 μM) exhibited more potent activity of inhibiting platelet aggregation stimulated by collagen than other agonists. Sesamol inhibited collagen-stimulated platelet activation accompanied by [Ca(2+)](i) mobilization, thromboxane A(2) (TxA(2)) formation, and phospholipase C (PLC)γ2, protein kinase C (PKC) and mitogen-activated protein kinase (MAPK) phosphorylation in washed platelets. Sesamol markedly increased cAMP and cGMP levels, endothelial nitric oxide synthase (eNOS) expression and NO release, as well as vasodilator-stimulated phosphoprotein (VASP) phosphorylation. SQ22536, an inhibitor of adenylate cyclase, markedly reversed the sesamol-mediated inhibitory effects on platelet aggregation and p38 MAPK phosphorylation, and sesamol-mediated stimulatory effects on VASP and eNOS phosphorylation, and NO release. Sesamol also reduced hydroxyl radical (OH(●)) formation in platelets. In an in vivo study, sesamol (5 mg/kg) significantly prolonged platelet plug formation in mice. The most important findings of this study demonstrate for the first time that sesamol possesses potent antiplatelet activity, which may involve activation of the cAMP-eNOS/NO-cGMP pathway, resulting in inhibition of the PLCγ2-PKC-p38 MAPK-TxA(2) cascade, and, finally, inhibition of platelet aggregation. Sesamol treatment may represent a novel approach to lowering the risk of or improving function in thromboembolism-related disorders. Copyright © 2010 Elsevier Inc. All rights reserved.

Effects of structural modifications on the metal binding, anti-amyloid activity, and cholinesterase inhibitory activity of chalcones.

PubMed

Fosso, Marina Y; LeVine, Harry; Green, Keith D; Tsodikov, Oleg V; Garneau-Tsodikova, Sylvie

2015-09-28

As the number of individuals affected with Alzheimer's disease (AD) increases and the availability of drugs for AD treatment remains limited, the need to develop effective therapeutics for AD becomes more and more pressing. Strategies currently pursued include inhibiting acetylcholinesterase (AChE) and targeting amyloid-β (Aβ) peptides and metal-Aβ complexes. This work presents the design, synthesis, and biochemical evaluation of a series of chalcones, and assesses the relationship between their structures and their ability to bind metal ions and/or Aβ species, and inhibit AChE/BChE activity. Several chalcones were found to exhibit potent disaggregation of pre-formed N-biotinyl Aβ1-42 (bioAβ42) aggregates in vitro in the absence and presence of Cu(2+)/Zn(2+), while others were effective at inhibiting the action of AChE.

Procoagulant Platelets Form an α-Granule Protein-covered “Cap” on Their Surface That Promotes Their Attachment to Aggregates*

PubMed Central

Abaeva, Anastasia A.; Canault, Matthias; Kotova, Yana N.; Obydennyy, Sergey I.; Yakimenko, Alena O.; Podoplelova, Nadezhda A.; Kolyadko, Vladimir N.; Chambost, Herve; Mazurov, Aleksei V.; Ataullakhanov, Fazoil I.; Nurden, Alan T.; Alessi, Marie-Christine; Panteleev, Mikhail A.

2013-01-01

Strongly activated “coated” platelets are characterized by increased phosphatidylserine (PS) surface expression, α-granule protein retention, and lack of active integrin αIIbβ3. To study how they are incorporated into thrombi despite a lack of free activated integrin, we investigated the structure, function, and formation of the α-granule protein “coat.” Confocal microscopy revealed that fibrin(ogen) and thrombospondin colocalized as “cap,” a single patch on the PS-positive platelet surface. In aggregates, the cap was located at the point of attachment of the PS-positive platelets. Without fibrin(ogen) retention, their ability to be incorporated in aggregates was drastically reduced. The surface fibrin(ogen) was strongly decreased in the presence of a fibrin polymerization inhibitor GPRP and also in platelets from a patient with dysfibrinogenemia and a fibrinogen polymerization defect. In contrast, a fibrinogen-clotting protease ancistron increased the amount of fibrin(ogen) and thrombospondin on the surface of the PS-positive platelets stimulated with collagen-related peptide. Transglutaminases are also involved in fibrin(ogen) retention. However, platelets from patients with factor XIII deficiency had normal retention, and a pan-transglutaminase inhibitor T101 had only a modest inhibitory effect. Fibrin(ogen) retention was normal in Bernard-Soulier syndrome and kindlin-3 deficiency, but not in Glanzmann thrombasthenia lacking the platelet pool of fibrinogen and αIIbβ3. These data show that the fibrin(ogen)-covered cap, predominantly formed as a result of fibrin polymerization, is a critical mechanism that allows coated (or rather “capped”) platelets to become incorporated into thrombi despite their lack of active integrins. PMID:23995838

Lactobacillus fermentum ATCC 23271 Displays In vitro Inhibitory Activities against Candida spp.

PubMed Central

do Carmo, Monique S.; Noronha, Francisca M. F.; Arruda, Mariana O.; Costa, Ênnio P. da Silva; Bomfim, Maria R. Q.; Monteiro, Andrea S.; Ferro, Thiago A. F.; Fernandes, Elizabeth S.; Girón, Jorge A.; Monteiro-Neto, Valério

2016-01-01

Lactobacilli are involved in the microbial homeostasis in the female genital tract. Due to the high prevalence of many bacterial diseases of the female genital tract and the resistance of microorganisms to various antimicrobial agents, alternative means to control these infections are necessary. Thus, this study aimed to evaluate the probiotic properties of well-characterized Lactobacillus species, including L. acidophilus (ATCC 4356), L. brevis (ATCC 367), L. delbrueckii ssp. delbrueckii (ATCC 9645), L. fermentum (ATCC 23271), L. paracasei (ATCC 335), L. plantarum (ATCC 8014), and L. rhamnosus (ATCC 9595), against Candida albicans (ATCC 18804), Neisseria gonorrhoeae (ATCC 9826), and Streptococcus agalactiae (ATCC 13813). The probiotic potential was investigated by using the following criteria: (i) adhesion to host epithelial cells and mucus, (ii) biofilm formation, (iii) co-aggregation with bacterial pathogens, (iv) inhibition of pathogen adhesion to mucus and HeLa cells, and (v) antimicrobial activity. Tested lactobacilli adhered to mucin, co-aggregated with all genital microorganisms, and displayed antimicrobial activity. With the exception of L. acidophilus and L. paracasei, they adhered to HeLa cells. However, only L. fermentum produced a moderate biofilm and a higher level of co-aggregation and mucin binding. The displacement assay demonstrated that all Lactobacillus strains inhibit C. albicans binding to mucin (p < 0.001), likely due to the production of substances with antimicrobial activity. Clinical isolates belonging to the most common Candida species associated to vaginal candidiasis were inhibited by L. fermentum. Collectively, our data suggest that L. fermentum ATCC 23271 is a potential probiotic candidate, particularly to complement candidiasis treatment, since presented with the best probiotic profile in comparison with the other tested lactobacilli strains. PMID:27833605

Role of pyridoxamine in the formation of the Amadori/Heyns compounds and aggregates during the glycation of beta-lactoglobulin with galactose and tagatose.

PubMed

Corzo-Martínez, Marta; Moreno, F Javier; Olano, Agustín; Villamiel, Mar

2010-01-13

The effect of pyridoxamine on the Maillard reaction during the formation of conjugates of beta-lactoglobulin with galactose and tagatose under controlled conditions (pH 7, 0.44 aw, 40 and 50 degrees C, for 6 days) has been studied, for the first time, by means of the changes in reducing carbohydrates, formation of Amadori or Heyns compounds, and aggregates and browning development. The results showed the formation of interaction products between pyridoxamine and galactose or tagatose either in the presence or in the absence of beta-lactoglobulin, indicating that pyridoxamine competes with the free amino groups of beta-lactoglobulin for the carbonyl group of both carbohydrates. Thus, a small inhibitory effect of pyridoxamine on the initial stages of the Maillard reaction was pointed out. Furthermore, much lower aggregation and color formation rates were observed in the conjugates of beta-lactoglobulin galactose/tagatose with pyridoxamine than without this compound, supporting its potent inhibitory effect on the advanced and final stages of the Maillard reaction. These findings reveal the usefulness of food-grade inhibitors of the advanced stages of the Maillard reaction, such as pyridoxamine, that, in combination with mild storage conditions, could lead to the formation of safer neoglycoconjugates without impairing their nutritional quality.

A cell surface aggregation-promoting factor from Lactobacillus gasseri contributes towards inhibition of Trichomonas vaginalis adhesion to human vaginal ectocervical cells.

PubMed

Phukan, Niha; Brooks, Anna E S; Simoes-Barbosa, Augusto

2018-05-21

Trichomoniasis, a prevalent sexually transmitted infection, is commonly symptomatic in women. The causative agent is Trichomonas vaginalis , an extracellular protozoan parasite. The host-protective mechanisms and molecules of vaginal lactobacilli that could counteract with this pathogen are largely unknown. This study examines the inhibition promoted by Lactobacillus gasseri against the adhesion of T. vaginalis to host cells, a critical virulence aspect of this pathogen. We observed that the vaginal L. gasseri ATCC 9857 is highly inhibitory by various contact-dependent mechanisms and surface proteins are largely responsible for this inhibitory phenotype. We found that the aggregation-promoting factor APF-2 from these bacteria significantly contributes towards inhibiting the adhesion of T. vaginalis to human vaginal ectocervical cells. Understanding the molecules and mechanisms used by lactobacilli to protect the host against T. vaginalis might help in the development of novel and specific therapeutic strategies that take advantage of the natural microbiota. Copyright © 2018 American Society for Microbiology.

Negative feedback regulation of human platelets via autocrine activation of the platelet-derived growth factor alpha-receptor.

PubMed

Vassbotn, F S; Havnen, O K; Heldin, C H; Holmsen, H

1994-05-13

Human platelets contain platelet-derived growth factor (PDGF) in their alpha-granules which is released during platelet exocytosis. We show by immunoprecipitation and 125I-PDGF binding experiments that human platelets have functionally active PDGF alpha-receptors, but not beta-receptors. The PDGF alpha-receptor (PDGFR-alpha) was identified as a 170-kDa glycosylated protein-tyrosine kinase as found in other cell types. Stimulation of platelets with 0.1 unit/ml thrombin resulted in a significant increase (2-5-fold) of the tyrosine phosphorylation of the PDGFR-alpha, as determined by immunoprecipitation with phosphotyrosine antiserum as well as with PDGFR-alpha antiserum. The observed thrombin-induced autophosphorylation of the PDGFR-alpha was inhibited by the addition of a neutralizing monoclonal PDGF antibody. Thus, our results suggest that the platelet PDGFR-alpha is stimulated in an autocrine manner by PDGF secreted during platelet activation. Preincubation of platelets with PDGF inhibited thrombin-induced platelet aggregation and secretion of ATP + ADP and beta-hexosaminidase. Thrombin-induced platelet aggregation was also reversed when PDGF was added 30 s after thrombin stimulation. Inhibition of the autocrine PDGF pathway during platelet activation by the PDGF antibody led to a potentiation of thrombin-induced beta-hexosaminidase secretion. Thus, the PDGFR-alpha takes part in a negative feedback regulation during platelet activation. Our demonstration of PDGF alpha-receptors on human platelets and its inhibitory function during platelet activation identifies a new possible role of PDGF in the regulation of thrombosis.

Phthalocyanines as Molecular Scaffolds to Block Disease-Associated Protein Aggregation.

PubMed

Valiente-Gabioud, Ariel A; Miotto, Marco C; Chesta, María E; Lombardo, Verónica; Binolfi, Andres; Fernández, Claudio O

2016-05-17

The aggregation of proteins into toxic conformations plays a critical role in the development of different neurodegenerative diseases such as Alzheimer's disease (AD), Parkinson's disease (PD), and Creutzfled-Jakob's disease (CJD). These disorders share a common pathological mechanism that involves the formation of aggregated protein species including toxic oligomers and amyloid fibrils. The aggregation of alpha-synuclein (αS) in PD and the amyloid beta peptide (Aβ) and tau protein in AD results in neuronal death and disease onset. In the case of CJD, the misfolding of the physiological prion protein (PrP) induces a chain reaction that results in accumulation of particles that elicit brain damage. Currently, there is no preventive therapy for these diseases and the available therapeutic approaches are based on the treatment of the symptoms rather than the underlying causes of the disease. Accordingly, the aggregation pathway of these proteins represents a useful target for therapeutic intervention. Therefore, understanding the mechanism of amyloid formation and its inhibition is of high clinical importance. The design of small molecules that efficiently inhibit the aggregation process and/or neutralize its associated toxicity constitutes a promising tool for the development of therapeutic strategies against these disorders. In this accounts, we discuss current knowledge on the anti-amyloid activity of phthalocyanines and their potential use as drug candidates in neurodegeneration. These tetrapyrrolic compounds modulate the amyloid assembly of αS, tau, Aβ, and the PrP in vitro, and protect cells from the toxic effects of amyloid aggregates. In addition, in scrapie-infected mice, these compounds showed important prophylactic antiscrapie properties. The structural basis for the inhibitory effect of phthalocyanines on amyloid filament assembly relies on specific π-π interactions between the aromatic ring system of these molecules and aromatic residues in the amyloidogenic proteins. Analysis of the structure-activity relationship in phthalocyanines revealed that their anti-amyloid activity is highly dependent on the type of metal ion coordinated to the tetrapyrrolic system but is not sensitive to the number of peripheral charged substituents. The tendency of phthalocyanines to oligomerize (self-association) via aromatic-aromatic stacking interactions correlates precisely with their binding capabilities to target proteins and, more importantly, determines their efficiency as anti-amyloid agents. The ability to block different types of disease-associated protein aggregation raises the possibility that these cyclic tetrapyrrole compounds have a common mechanism of action to impair the formation of a variety of pathological aggregates. Because the structural and molecular basis for the anti-amyloid effects of these molecules is starting to emerge, combined efforts from the fields of structural, cellular, and animal biology will result critical for the rational design and discovery of new drugs for the treatment of amyloid related neurological disorders.

Disease-modifying anti-Alzheimer's drugs: inhibitors of human cholinesterases interfering with β-amyloid aggregation.

PubMed

Brogi, Simone; Butini, Stefania; Maramai, Samuele; Colombo, Raffaella; Verga, Laura; Lanni, Cristina; De Lorenzi, Ersilia; Lamponi, Stefania; Andreassi, Marco; Bartolini, Manuela; Andrisano, Vincenza; Novellino, Ettore; Campiani, Giuseppe; Brindisi, Margherita; Gemma, Sandra

2014-07-01

We recently described multifunctional tools (2a-c) as potent inhibitors of human Cholinesterases (ChEs) also able to modulate events correlated with Aβ aggregation. We herein propose a thorough biological and computational analysis aiming at understanding their mechanism of action at the molecular level. We determined the inhibitory potency of 2a-c on Aβ1-42 self-aggregation, the interference of 2a with the toxic Aβ oligomeric species and with the postaggregation states by capillary electrophoresis analysis and transmission electron microscopy. The modulation of Aβ toxicity was assessed for 2a and 2b on human neuroblastoma cells. The key interactions of 2a with Aβ and with the Aβ-preformed fibrils were computationally analyzed. 2a-c toxicity profile was also assessed (human hepatocytes and mouse fibroblasts). Our prototypical pluripotent analogue 2a interferes with Aβ oligomerization process thus reducing Aβ oligomers-mediated toxicity in human neuroblastoma cells. 2a also disrupts preformed fibrils. Computational studies highlighted the bases governing the diversified activities of 2a. Converging analytical, biological, and in silico data explained the mechanism of action of 2a on Aβ1-42 oligomers formation and against Aβ-preformed fibrils. This evidence, combined with toxicity data, will orient the future design of safer analogues. © 2014 John Wiley & Sons Ltd.

Amyloid β-sheet mimics that antagonize protein aggregation and reduce amyloid toxicity

NASA Astrophysics Data System (ADS)

Cheng, Pin-Nan; Liu, Cong; Zhao, Minglei; Eisenberg, David; Nowick, James S.

2012-11-01

The amyloid protein aggregation associated with diseases such as Alzheimer's, Parkinson's and type II diabetes (among many others) features a bewildering variety of β-sheet-rich structures in transition from native proteins to ordered oligomers and fibres. The variation in the amino-acid sequences of the β-structures presents a challenge to developing a model system of β-sheets for the study of various amyloid aggregates. Here, we introduce a family of robust β-sheet macrocycles that can serve as a platform to display a variety of heptapeptide sequences from different amyloid proteins. We have tailored these amyloid β-sheet mimics (ABSMs) to antagonize the aggregation of various amyloid proteins, thereby reducing the toxicity of amyloid aggregates. We describe the structures and inhibitory properties of ABSMs containing amyloidogenic peptides from the amyloid-β peptide associated with Alzheimer's disease, β2-microglobulin associated with dialysis-related amyloidosis, α-synuclein associated with Parkinson's disease, islet amyloid polypeptide associated with type II diabetes, human and yeast prion proteins, and Tau, which forms neurofibrillary tangles.

Sulfur Nanoparticles with Novel Morphologies Coupled with Brain-Targeting Peptides RVG as a New Type of Inhibitor Against Metal-Induced Aβ Aggregation.

PubMed

Sun, Jing; Xie, Wenjie; Zhu, Xufeng; Xu, Mengmeng; Liu, Jie

2018-04-18

Functionalized nanomaterials, which have been applied widely to inhibit amyloid-β protein (Aβ) aggregation, show enormous potential in the field of prevention and treatment of Alzheimer's disease (AD). A significant body of data has demonstrated that the morphology and size of nanomaterials have remarkable effects on their biological behaviors. In this work, we proposed and designed three kinds of brain-targeting sulfur nanoparticles (RVG@Met@SNPs) with novel morphologies (volute-like, tadpole-like, and sphere-like) and investigated the effect of different RVG@Met@SNPs on Aβ-Cu 2+ complex aggregation and their corresponding neurotoxicity. Among them, the sphere-like nanoparticles (RVG@Met@SS) exhibited the most effective inhibitory activity, due to their unique mini size effect, and they reduced 61.6% the Aβ-Cu 2+ complex aggregation and increased 92.4% SH-SY5Y cell viability in a dose of 10 μg/mL. In vitro and in vivo, the abilities of different morphologies of RVG@Met@SNPs to cross the blood-brain barrier (BBB) and target brain parenchymal cells were significantly different. Moreover, improvements in learning disability and cognitive loss were shown in the transgenic AD mice model using the Morris water maze test after multiple doses of RVG@Met@SNPs treatment. In general, the purpose of this research is to develop a biological application of sulfur nanoparticles and to provide a novel functionalized nanomaterial to treat AD.

Differential inhibitory action of apixaban on platelet and fibrin components of forming thrombi: Studies with circulating blood and in a platelet-based model of thrombin generation.

PubMed

Pujadas-Mestres, Lluis; Lopez-Vilchez, Irene; Arellano-Rodrigo, Eduardo; Reverter, Joan Carles; Lopez-Farre, Antonio; Diaz-Ricart, Maribel; Badimon, Juan Jose; Escolar, Gines

2017-01-01

Mechanisms of action of direct oral anticoagulants (DOAC) suggest a potential therapeutic use in the prevention of thrombotic complications in arterial territories. However, effects of DOACs on platelet activation and aggregation have not been explored in detail. We have investigated the effects of apixaban on platelet and fibrin components of thrombus formation under static and flow conditions. We assessed the effects of apixaban (10, 40 and 160 ng/mL) on: 1) platelet deposition and fibrin formation onto a thrombogenic surface, with blood circulating at arterial shear-rates; 2) viscoelastic properties of forming clots, and 3) thrombin generation in a cell-model of coagulation primed by platelets. In studies with flowing blood, only the highest concentration of apixaban, equivalent to the therapeutic Cmax, was capable to significantly reduce thrombus formation, fibrin association and platelet-aggregate formation. Apixaban significantly prolonged thromboelastometry parameters, but did not affect clot firmness. Interestingly, results in a platelet-based model of thrombin generation under more static conditions, revealed a dose dependent persistent inhibitory action by apixaban, with concentrations 4 to 16 times below the therapeutic Cmax significantly prolonging kinetic parameters and reducing the total amount of thrombin generated. Our studies demonstrate the critical impact of rheological conditions on the antithrombotic effects of apixaban. Studies under flow conditions combined with modified thrombin generation assays could help discriminating concentrations of apixaban that prevent excessive platelet accumulation, from those that deeply impair fibrin formation and may unnecessarily compromise hemostasis.

Differential inhibitory action of apixaban on platelet and fibrin components of forming thrombi: Studies with circulating blood and in a platelet-based model of thrombin generation

PubMed Central

Arellano-Rodrigo, Eduardo; Reverter, Joan Carles; Lopez-Farre, Antonio; Diaz-Ricart, Maribel; Badimon, Juan Jose; Escolar, Gines

2017-01-01

Introduction Mechanisms of action of direct oral anticoagulants (DOAC) suggest a potential therapeutic use in the prevention of thrombotic complications in arterial territories. However, effects of DOACs on platelet activation and aggregation have not been explored in detail. We have investigated the effects of apixaban on platelet and fibrin components of thrombus formation under static and flow conditions. Methods We assessed the effects of apixaban (10, 40 and 160 ng/mL) on: 1) platelet deposition and fibrin formation onto a thrombogenic surface, with blood circulating at arterial shear-rates; 2) viscoelastic properties of forming clots, and 3) thrombin generation in a cell-model of coagulation primed by platelets. Results In studies with flowing blood, only the highest concentration of apixaban, equivalent to the therapeutic Cmax, was capable to significantly reduce thrombus formation, fibrin association and platelet-aggregate formation. Apixaban significantly prolonged thromboelastometry parameters, but did not affect clot firmness. Interestingly, results in a platelet-based model of thrombin generation under more static conditions, revealed a dose dependent persistent inhibitory action by apixaban, with concentrations 4 to 16 times below the therapeutic Cmax significantly prolonging kinetic parameters and reducing the total amount of thrombin generated. Conclusions Our studies demonstrate the critical impact of rheological conditions on the antithrombotic effects of apixaban. Studies under flow conditions combined with modified thrombin generation assays could help discriminating concentrations of apixaban that prevent excessive platelet accumulation, from those that deeply impair fibrin formation and may unnecessarily compromise hemostasis. PMID:28192448

Prominent dominant negative effect of a mutant Fas molecule lacking death domain on cell-mediated induction of apoptosis.

PubMed

Yokota, Aya; Takeuchi, Emiko; Iizuka, Misao; Ikegami, Yuko; Takayama, Hajime; Shinohara, Nobukata

2005-01-01

Using a panel of transfectant B lymphoma cells expressing varying amounts of the mutant Fas together with the endogenous wild type Fas, semi-quantitative studies on the dominant negative effect of a murine mutant Fas molecule lacking death domain were carried out. In anti-Fas antibody-mediated induction of apoptosis, the mutant molecules exerted significant dominant-negative effect only when their expression level was comparable to or higher than that of wild type molecules, or when exposed to low amounts of the antibody. The inhibitory effect was accompanied by the failure in DISC formation in spite of Fas aggregation. When they were subjected to T cell-mediated Fas-based induction of apoptosis, however, the dominant negative effect was prominent such that the expression of even a small amount of the mutant molecules resulted in significant inhibition. Such a strong inhibitory effect explains the dominant phenotype of this type of mutant Fas molecules in ALPS heterozygous patients and also implies that the physiological effectors for Fas in vivo are cells, i.e., FasL-expressing activated T cells.

[Anti-platelet actions of salicylates: in vivo, ex vivo and in vitro effects of choline salicylate].

PubMed

Irino, O; Saitoh, K; Ohkubo, K

1985-07-01

Effects of choline salicylate, sodium salicylate, choline chloride and acetylsalicylic acid on platelet aggregation in vivo, ex vivo and in vitro in mice were studied. These drugs all inhibited adenosine diphosphate (ADP)-induced respiratory depression, which is closely related to platelet aggregation in vivo, with choline salicylate showing the strongest inhibitory effect. Choline salicylate had a tendency to reduce the mortality of animals injected intravenously with endotoxin, but the other drugs had no such effect. The inhibitory effects of these drugs on ADP-induced platelet aggregation ex vivo were in the order of choline salicylate greater than acetylsalicylic acid congruent to sodium salicylate greater than choline chloride congruent to no effect, and plasma concentrations of protein-unbound salicylic acid at 1 hr after oral administration of drugs were in the order of choline salicylate greater than acetylsalicylic acid congruent to sodium salicylate. The in vitro effects of these drugs were in the order of choline salicylate congruent to sodium salicylate greater than choline chloride congruent to acetylsalicylic acid congruent to no effect. Therefore, it was considered that salicylic acid played an important role on the in vivo, ex vivo and in vitro effects of choline salicylate and that choline increased plasma concentrations of salicylic acid and consequently enhanced the in vivo and ex vivo effects of salicylic acid. Furthermore, the ex vivo effects of choline salicylate were found when ADP-induced platelet aggregation was measured with platelet-rich plasma prepared from blood collected with heparin as anti-coagulant, but not when blood was collected with citrate.(ABSTRACT TRUNCATED AT 250 WORDS)

Inhibitory mechanisms of CME-1, a novel polysaccharide from the mycelia of Cordyceps sinensis, in platelet activation.

PubMed

Chang, Yi; Hsu, Wen-Hsien; Lu, Wan-Jung; Jayakumar, Thanasekaran; Liao, Jiun-Cheng; Lin, Mei-Jiun; Wang, Shwu-Huey; Geraldine, Pitchairaj; Lin, Kuan-Hung; Sheu, Joen-Rong

2015-01-01

CME-1 is a polysaccharide purified from the mycelia of medicinal mushroom Cordyceps sinensis, its molecular weight was determined to be 27.6 kDa by using nuclear magnetic resonance and gas chromatography-mass spectrometry. The initiation of arterial thromboses is relevant to various cardiovascular diseases (CVDs) and is believed to involve platelet activation. Our recent study exhibited that CME-1 has potent antiplatelet activity via the activation of adenylate cyclase/cyclic AMP ex vivo and in vivo. The aggregometry, and immunoblotting were used in this study. In this study, the mechanisms of CME-1 in platelet activation is further investigated and found that CME-1 inhibited platelet aggregation as well as the ATP-release reaction, relative intracellular [Ca(+2)] mobilization, and the phosphorylation of phospholipase C (PLC)γ2 and protein kinase C (PKC) stimulated by collagen. CME-1 has no effects on inhibiting either convulxin, an agonist of glycoprotein VI, or aggretin, an agonist of integrin α2β1 stimulated platelet aggregation. Moreover, this compound markedly diminished thrombin and arachidonic acid (AA) induced phosphorylation of p38 mitogen-activated protein kinase (MAPK), extracellular signal-regulated kinase 2, c-Jun N-terminal kinase 1, and Akt. Treatment with SQ22536, an inhibitor of adenylate cyclase, markedly diminished the CME-1-mediated increasing of cyclic AMP level and reversed prostaglandin E1- or CME-1-mediated inhibition of platelet aggregation and p38 MAPK and Akt phosphorylation stimulated by thrombin or AA. Furthermore, phosphodiesterase activity of human platelets was not altered by CME-1. The crucial finding of this study is that the antiplatelet activity of CME-1 may initially inhibit the PLCγ2-PKC-p47 cascade, and inhibit PI3-kinase/Akt and MAPK phosphorylation through adenylate cyclase/ cyclic AMP activation, then inhibit intracellular [Ca(+2)] mobilization, and, ultimately, inhibit platelet activation. The novel role of CME-1 in antiplatelet activity indicates that this compound exhibits high therapeutic potential for treating or preventing CVDs.

Structure-Antiplatelet Activity Relationships of Novel Ruthenium (II) Complexes: Investigation of Its Molecular Targets.

PubMed

Hsia, Chih-Hsuan; Jayakumar, Thanasekaran; Sheu, Joen-Rong; Tsao, Shin-Yi; Velusamy, Marappan; Hsia, Chih-Wei; Chou, Duen-Suey; Chang, Chao-Chien; Chung, Chi-Li; Khamrang, Themmila; Lin, Kao-Chang

2018-02-22

The regulation of platelet function by pharmacological agents that modulate platelet signaling has proven to be a positive approach to the prevention of thrombosis. Ruthenium complexes are fascinating for the development of new drugs, as they possess numerous chemical and biological properties. The present study aims to evaluate the structure-activity relationship (SAR) of newly synthesized ruthenium (II) complexes, TQ-1, TQ-2 and TQ-3 in agonists-induced washed human platelets. Silica gel column chromatography, aggregometry, immunoblotting, NMR, and X-ray analyses were performed in this study. Of the three tested compounds, TQ-3 showed a concentration (1-5 μM) dependent inhibitory effect on platelet aggregation induced by collagen (1 μg/mL) and thrombin (0.01 U/mL) in washed human platelets; however, TQ-1 and TQ-2 had no response even at 250 μM of collagen and thrombin-induced aggregation. TQ-3 was effective with inhibiting collagen-induced ATP release, calcium mobilization ([Ca 2+ ]i) and P-selectin expression without cytotoxicity. Moreover, TQ-3 significantly abolished collagen-induced Lyn-Fyn-Syk, Akt-JNK and p38 mitogen-activated protein kinases (p38 MAPKs) phosphorylation. The compound TQ-3 containing an electron donating amino group with two phenyl groups of the quinoline core could be accounted for by its hydrophobicity and this nature might be the reason for the noted antiplatelet effects of TQ-3. The present results provide a molecular basis for the inhibition by TQ-3 in collagen-induced platelet aggregation, through the suppression of multiple machineries of the signaling pathway. These results may suggest that TQ-3 can be considered a potential agent for the treatment of vascular diseases.

Effect of diazepam and clonazepam on the function of isolated rat platelet and neutrophil.

PubMed

Rajtar, Grazyna; Zółkowska, Dorota; Kleinrok, Zdzisław

2002-04-01

Benzodiazepine binding sites distinct from the GABA-receptor-chloride-complex in the central nervous system have been recognized in many peripheral tissues, but their physiological role remains unexplained. Our study was undertaken to examine the effects of diazepam, clonazepam, and PK 11195, a peripheral benzodiazepine receptor antagonist, on the functional and biochemical responses of platelets and neutrophils stimulated by different physiological agonists. The experiments were conducted on isolated washed rat platelets activated by arachidonic acid (AA), adenosine 5'-diphosphate (ADP), or thrombin and on isolated rat neutrophils activated by a chemotactic peptide, formyl methionyl leucyl phenylalanine (fMLP). The results showed that neither diazepam nor clonazepam nor PK 11195 alone augmented the response of resting platelets or modified neutrophil response, but diazepam and clonazepam in a concentration-dependent manner inhibited thrombin, ADP or AA-stimulated platelet aggregation and the thrombin-induced increase in free intracellular Ca2+. Both drugs also exerted an inhibitory effect on reactive oxygen species (ROS) produced by fMLP-stimulated neutrophils. However, diazepam was about 10 times more effective than clonazepam. PK11195 did not influence platelet and neutrophil function stimulated by agonists, but reversed the inhibitory action of both benzodiazepines on platelet activation and ROS production. The results indicated that in vitro diazepam, and in a much smaller degree clonazepam, may down-regulate platelet activation and release of some proinflammatory mediators by stimulated neutrophils. These effects are probably exerted by a specific benzodiazepine binding sites.

Retarded protein folding of deficient human α1-antitrypsin D256V and L41P variants

PubMed Central

Jung, Chan-Hun; Na, Yu-Ran; Im, Hana

2004-01-01

α1-Antitrypsin is the most abundant protease inhibitor in plasma and is the archetype of the serine protease inhibitor superfamily. Genetic variants of human α1-antitrypsin are associated with early-onset emphysema and liver cirrhosis. However, the detailed molecular mechanism for the pathogenicity of most variant α1-antitrypsin molecules is not known. Here we examined the structural basis of a dozen deficient α1-antitrypsin variants. Unlike most α1-antitrypsin variants, which were unstable, D256V and L41P variants exhibited extremely retarded protein folding as compared with the wild-type molecule. Once folded, however, the stability and inhibitory activity of these variant proteins were comparable to those of the wild-type molecule. Retarded protein folding may promote protein aggregation by allowing the accumulation of aggregation-prone folding intermediates. Repeated observations of retarded protein folding indicate that it is an important mechanism causing α1-antitrypsin deficiency by variant molecules, which have to fold into the metastable native form to be functional. PMID:14767073

Relative activities on and uptake by human blood platelets of 5-hydroxytryptamine and several analogues

PubMed Central

Born, G. V. R.; Juengjaroen, Kanchana; Michal, F.

1972-01-01

1. The specificity of platelet receptor sites for 5-HT uptake and for the rapid morphological change and aggregation was investigated with 5-hydroxy-tryptamine (5-HT) and seventeen analogues as well as with some antagonists of 5-HT. 2. The analogues, with the exception of 5-hydroxy-N'N'-dibutyltryptamine, caused the rapid morphological change in platelets. In concentrations below those needed to produce the agonistic action (viz. 0.05-2.0 μM), these analogues themselves inhibited competitively the shape change caused by 5-HT. 3. The velocity of change in shape caused by 5-HT was reduced in low Na media. 4. Ten analogues produced platelet aggregation; three of these, viz. 5-methoxy-α-methyltryptamine, 5-hydroxy-α-methyltryptamine and 5-hydroxy-N'N'-diisopropyltryptamine), were approximately equipotent with 5-HT. Six analogues did not induce platelet aggregation. 5. All the analogues which prevented the initial change in shape of platelets caused by 5-HT also inhibited its aggregating effect, apparently competitively with low Ki values (0.02-1.6 μM). 6. As with the inhibition of shape change, the inhibition of aggregation shows relatively low structural specificity of the receptor site. 7. Methysergide was a potent inhibitor of shape change and aggregation (Ki∼0.03 μM); imipramine was much less inhibitory (Ki∼5-10 μM). 8. Only one analogue (5-hydroxy-α-methyltryptamine) was taken up like 5-HT by platelets. All the other analogues inhibited the uptake of 5-HT by platelets (Ki=0.2-2.7 μM). 9. Methysergide was a weak inhibitor of 5-HT uptake (Ki∼125 μM) whereas imipramine was very effective (Ki∼0.3 μM). 10. Our results show that the initial change in shape of platelets is required for and precedes aggregation. The structural specificity of the platelet receptor concerned with shape change and aggregation caused by 5-HT appears low whereas the uptake mechanism is a highly specific one. The uptake probably proceeds through more than one step, the relationship between the steps is not yet clear. PMID:5015032

Isolation of Bioactive Compounds That Relate to the Anti-Platelet Activity of Cymbopogon ambiguus

PubMed Central

Grice, I. Darren; Rogers, Kelly L.; Griffiths, Lyn R.

2011-01-01

Infusions and decoctions of Cymbopogon ambiguus have been used traditionally in Australia for the treatment of headache, chest infections and muscle cramps. The aim of the present study was to screen and identify bioactive compounds from C. ambiguus that could explain this plant's anti-headache activity. A dichloromethane extract of C. ambiguus was identified as having activity in adenosine-diphosphate-induced human platelet aggregation and serotonin-release inhibition bioassays. Subsequent fractionation of this extract led to the isolation of four phenylpropenoids, eugenol, elemicin, eugenol methylether and trans-isoelemicin. While both eugenol and elemicin exhibited dose-dependent inhibition of ADP-induced human platelet serotonin release, only eugenol displayed potent inhibitory activity with an IC50 value of 46.6 μM, in comparison to aspirin, with an IC50 value of 46.1 μM. These findings provide evidence to support the therapeutic efficacy of C. ambiguus in the non-conventional treatment of headache and inflammatory conditions. PMID:20047890

Design and synthesis of theranostic antibiotic nanodrugs that display enhanced antibacterial activity and luminescence

PubMed Central

Xie, Sheng; Manuguri, Sesha; Proietti, Giampiero; Romson, Joakim; Fu, Ying; Inge, A. Ken; Wu, Bin; Zhang, Yang; Häll, Daniel; Ramström, Olof; Yan, Mingdi

2017-01-01

We report the modular formulation of ciprofloxacin-based pure theranostic nanodrugs that display enhanced antibacterial activities, as well as aggregation-induced emission (AIE) enhancement that was successfully used to image bacteria. The drug derivatives, consisting of ciprofloxacin, a perfluoroaryl ring, and a phenyl ring linked by an amidine bond, were efficiently synthesized by a straightforward protocol from a perfluoroaryl azide, ciprofloxacin, and an aldehyde in acetone at room temperature. These compounds are propeller-shaped, and upon precipitation into water, readily assembled into stable nanoaggregates that transformed ciprofloxacin derivatives into AIE-active luminogens. The nanoaggregates displayed increased luminescence and were successfully used to image bacteria. In addition, these nanodrugs showed enhanced antibacterial activities, lowering the minimum inhibitory concentration (MIC) by more than one order of magnitude against both sensitive and resistant Escherichia coli. The study represents a strategy in the design and development of pure theranostic nanodrugs for combating drug-resistant bacterial infections. PMID:28743748

Collagenases in human synovial fluid

PubMed Central

Harris, Edward D.; DiBona, Donald R.; Krane, Stephen M.

1969-01-01

An enzyme which degrades native collagen at neutral pH has been isolated from cultures of rheumatoid synovium in vitro, but little or no collagenolytic activity has been found in homogenates of fresh rheumatoid synovium. Similar to most other mammalian collagenases this synovial enzyme is readily inhibited by serum proteins. Proteins of synovial fluid are derived largely from serum and synovial fluid from noninflamed joints was found to inhibit synovial collagenase; the inhibitor was destroyed by trypsin, but not by hyaluronidase. Inhibitory activity was reduced in approximately one-half of the fluids from patients with rheumatoid arthritis. In a total of nine synovial fluids, collagenolytic activity was detectable. This activity was not present in constant amounts in synovial fluids aspirated at different times from the same patient and tended to vary inversely with the titer of inhibitory proteins. The collagenolytic activity in the synovial fluids from different patients was variably inhibited by serum proteins. Two distinct collagenases were detected in some rheumatoid synovial fluids and separated by gel filtration. One, labeled “B” enzyme, with an estimated molecular weight 20,000-25,000 resembled the collagenase obtained from synovial cultures. The other, labeled “A” enzyme degraded collagen fibrils as well as collagen in solution. Disc electrophoresis on acrylamide gels and electron microscopy of segment long spacing (SLS) aggregates of reaction products of the enzymes at 27°C demonstrated that both “A” and “B” enzymes cleaved collagen molecules at a point three-quarters from the amino terminal end of the molecule. Thus collagen degradation in rheumatoid arthritis could result from the operation of these two collagenases. Images PMID:4309955

Eukaryotic polypeptide elongation system and its sensitivity to the inhibitory substances of plant origin.

PubMed

Gałasiński, W

1996-05-01

The structural and functional characteristics of the elongation system (ribosomes and elongation factors) are presented. The immunochemical and diagnostic meaning of the ribosome investigations is considered. Evidence of the participation of ribosomes in the first step of protein glycosylation is presented. The heterogeneous elongation factor eEF-1, isolated from Guerin epithelioma, can be separated into three fractions: one of them functionally corresponds to EF-1 alpha, the second on to EF-1 beta gamma, and the third is an unidentified, active aggregate named EF-1B, which contains the subunit forms EF-1 alpha and EF-1 beta gamma, and other polypeptides showing protein kinase activity. The aggregate EF-1B can be autophosphorylated, while the subunit forms EF-1 alpha and EF-1 beta gamma can neither become autophosphorylated nor phosphorylate other polypeptides. The subunit form EF-beta gamma consists from two polypeptides of 32 and 51 kDa, corresponding to other eukaryotic beta and gamma polypeptides, respectively. EF-1 beta gamma is thermostable and protects against thermal inactivation of EF-1 alpha in the EF-1 alpha-EF-1 beta gamma complex. Pure eEF-2 preparations isolated from normal and neoplastic tissues show different structural features. The existence of eEF-2 in multiple forms, differing in molecular mass, have been found. The eEF-2 with molecular weight of about 100 kDa can be phosphorylated, while eEF-2 of about 65 kDa was not phosphorylated by protein kinase eEF-2. The phosphorylated eEF-2 lost its activity, and this effect was reversed by dephosphorylation. The eEF-2 (65 kDa) was isolated from the active polyribosomes, and it may directly participate in the translocation step of the peptide elongation. It was noted that the components of elongation system can be inhibited, in separate steps, by the substances isolated from various sources of plant origin. Alkaloids emetine and cepheline, cardiac remedy digoxin, saponin glycoside, and its aglycon directly inactivated ribosomes. Quercetin inhibited eEF-1 activity by directly influencing its subunit form EF-1 alpha. eEF-2 was shown to be a target site of the inhibitory action of the glycoside isolated from Melissa officinalis leaves.

O-GlcNAc modification blocks the aggregation and toxicity of the protein α-synuclein associated with Parkinson's disease

NASA Astrophysics Data System (ADS)

Marotta, Nicholas P.; Lin, Yu Hsuan; Lewis, Yuka E.; Ambroso, Mark R.; Zaro, Balyn W.; Roth, Maxwell T.; Arnold, Don B.; Langen, Ralf; Pratt, Matthew R.

2015-11-01

Several aggregation-prone proteins associated with neurodegenerative diseases can be modified by O-linked N-acetyl-glucosamine (O-GlcNAc) in vivo. One of these proteins, α-synuclein, is a toxic aggregating protein associated with synucleinopathies, including Parkinson's disease. However, the effect of O-GlcNAcylation on α-synuclein is not clear. Here, we use synthetic protein chemistry to generate both unmodified α-synuclein and α-synuclein bearing a site-specific O-GlcNAc modification at the physiologically relevant threonine residue 72. We show that this single modification has a notable and substoichiometric inhibitory effect on α-synuclein aggregation, while not affecting the membrane binding or bending properties of α-synuclein. O-GlcNAcylation is also shown to affect the phosphorylation of α-synuclein in vitro and block the toxicity of α-synuclein that was exogenously added to cells in culture. These results suggest that increasing O-GlcNAcylation may slow the progression of synucleinopathies and further support a general function for O-GlcNAc in preventing protein aggregation.

Inhibition of ovarian cancer cell proliferation by a cell cycle inhibitory peptide fused to a thermally responsive polypeptide carrier.

PubMed

Massodi, Iqbal; Moktan, Shama; Rawat, Aruna; Bidwell, Gene L; Raucher, Drazen

2010-01-15

Current treatment of solid tumors is limited by normal tissue tolerance, resulting in a narrow therapeutic index. To increase drug specificity and efficacy and to reduce toxicity in normal tissues, we have developed a polypeptide carrier for a cell cycle inhibitory peptide, which has the potential to be thermally targeted to the tumor site. The design of this polypeptide is based on elastin-like polypeptide (ELP). The coding sequence of ELP was modified by the addition of the cell penetrating peptide Bac-7 at the N-terminus and a 23 amino acid peptide derived from p21 at the C-terminus (Bac-ELP1-p21). Bac-ELP1-p21 is soluble in aqueous solutions below physiological temperature (37 degrees C) but aggregates when the temperature is raised above 39 degrees C, making it a promising thermally responsive therapeutic carrier that may be actively targeted to solid tumors by application of focused hyperthermia. While Bac-ELP1-p21 at 37 degrees C did not have any effect on SKOV-3 cell proliferation, the use of hyperthermia increased the antiproliferative effect of Bac-ELP1-p21 compared with a thermally unresponsive control polypeptide. Bac-ELP1-p21 displayed both a cytoplasmic and nuclear distribution in the SKOV-3 cells, with nuclear-localized polypeptide enriched in the heated cells, as revealed by confocal microscopy. Using Western blotting, we show that Bac-ELP1-p21 caused a decrease in Rb phosphorylation levels in cells treated at 42 degrees C. The polypeptide also induced caspase activation, PARP cleavage, and cell cycle arrest in S-phase and G2/M-phase. These studies indicate that ELP is a promising macromolecular carrier for the delivery of cell cycle inhibitory peptides to solid tumors.

Disaggregation of Amylin Aggregate by Novel Conformationally Restricted Aminobenzoic Acid containing α/β and α/γ Hybrid Peptidomimetics

PubMed Central

Paul, Ashim; Kalita, Sourav; Kalita, Sujan; Sukumar, Piruthivi; Mandal, Bhubaneswar

2017-01-01

Diabetes has emerged as a threat to the current world. More than ninety five per cent of all the diabetic population has type 2 diabetes mellitus (T2DM). Aggregates of Amylin hormone, which is co-secreted with insulin from the pancreatic β-cells, inhibit the activities of insulin and glucagon and cause T2DM. Importance of the conformationally restricted peptides for drug design against T2DM has been invigorated by recent FDA approval of Symlin, which is a large conformationally restricted peptide. However, Symlin still has some issues including solubility, oral bioavailability and cost of preparation. Herein, we introduced a novel strategy for conformationally restricted peptide design adopting a minimalistic approach for cost reduction. We have demonstrated efficient inhibition of amyloid formation of Amylin and its disruption by a novel class of conformationally restricted β-sheet breaker hybrid peptidomimetics (BSBHps). We have inserted β, γ and δ -aminobenzoic acid separately into an amyloidogenic peptide sequence, synthesized α/β, α/γ and α/δ hybrid peptidomimetics, respectively. Interestingly, we observed the aggregation inhibitory efficacy of α/β and α/γ BSBHps, but not of α/δ analogues. They also disrupt existing amyloids into non-toxic forms. Results may be useful for newer drug design against T2DM as well as other amyloidoses and understanding amyloidogenesis. PMID:28054630

Disaggregation of Amylin Aggregate by Novel Conformationally Restricted Aminobenzoic Acid containing α/β and α/γ Hybrid Peptidomimetics

NASA Astrophysics Data System (ADS)

Paul, Ashim; Kalita, Sourav; Kalita, Sujan; Sukumar, Piruthivi; Mandal, Bhubaneswar

2017-01-01

Diabetes has emerged as a threat to the current world. More than ninety five per cent of all the diabetic population has type 2 diabetes mellitus (T2DM). Aggregates of Amylin hormone, which is co-secreted with insulin from the pancreatic β-cells, inhibit the activities of insulin and glucagon and cause T2DM. Importance of the conformationally restricted peptides for drug design against T2DM has been invigorated by recent FDA approval of Symlin, which is a large conformationally restricted peptide. However, Symlin still has some issues including solubility, oral bioavailability and cost of preparation. Herein, we introduced a novel strategy for conformationally restricted peptide design adopting a minimalistic approach for cost reduction. We have demonstrated efficient inhibition of amyloid formation of Amylin and its disruption by a novel class of conformationally restricted β-sheet breaker hybrid peptidomimetics (BSBHps). We have inserted β, γ and δ -aminobenzoic acid separately into an amyloidogenic peptide sequence, synthesized α/β, α/γ and α/δ hybrid peptidomimetics, respectively. Interestingly, we observed the aggregation inhibitory efficacy of α/β and α/γ BSBHps, but not of α/δ analogues. They also disrupt existing amyloids into non-toxic forms. Results may be useful for newer drug design against T2DM as well as other amyloidoses and understanding amyloidogenesis.

A Critical Role for the Transient Receptor Potential Channel Type 6 in Human Platelet Activation

PubMed Central

Conlon, Christine; Khasawneh, Fadi T.

2015-01-01

While calcium signaling is known to play vital roles in platelet function, the mechanisms underlying its receptor-operated calcium entry component (ROCE) remain poorly understood. It has been proposed, but never proven in platelets, that the canonical transient receptor potential channel-6 (TRPC6) mediates ROCE. Nonetheless, we have previously shown that the mouse TRPC6 regulates hemostasis, thrombogenesis by regulating platelet aggregation. In the present studies, we used a pharmacological approach to characterize the role of TRPC6 in human platelet biology. Thus, interestingly, we observed that a TRPC6 inhibitor exerted significant inhibitory effects on human platelet aggregation in a thromboxane receptor (TPR)-selective manner; no additional inhibition was observed in the presence of the calcium chelator BAPTA. This inhibitor also significantly inhibited human platelet secretion (dense and alpha granules), integrin IIb-IIIa, Akt and ERK phosphorylation, again, in a TPR-selective manner; no effects were observed in response to ADP receptor stimulation. Furthermore, there was a causal relationship between these inhibitory effects, and the capacity of the TRPC6 inhibitor to abrogate elevation in intracellular calcium, that was again found to be TPR-specific. This effect was not found to be due to antagonism of TPR, as the TRPC6 inhibitor did not displace the radiolabeled antagonist [3H]SQ29,548 from its binding sites. Finally, our studies also revealed that TRPC6 regulates human clot retraction, as well as physiological hemostasis and thrombus formation, in mice. Taken together, our findings demonstrate, for the first time, that TRPC6 directly regulates TPR-dependent ROCE and platelet function. Moreover, these data highlight TRPC6 as a novel promising therapeutic strategy for managing thrombotic disorders. PMID:25928636

The heterotrimeric G protein Gβ1 interacts with the catalytic subunit of protein phosphatase 1 and modulates G protein-coupled receptor signaling in platelets.

PubMed

Pradhan, Subhashree; Khatlani, Tanvir; Nairn, Angus C; Vijayan, K Vinod

2017-08-11

Thrombosis is caused by the activation of platelets at the site of ruptured atherosclerotic plaques. This activation involves engagement of G protein-coupled receptors (GPCR) on platelets that promote their aggregation. Although it is known that protein kinases and phosphatases modulate GPCR signaling, how serine/threonine phosphatases integrate with G protein signaling pathways is less understood. Because the subcellular localization and substrate specificity of the catalytic subunit of protein phosphatase 1 (PP1c) is dictated by PP1c-interacting proteins, here we sought to identify new PP1c interactors. GPCRs signal via the canonical heterotrimeric Gα and Gβγ subunits. Using a yeast two-hybrid screen, we discovered an interaction between PP1cα and the heterotrimeric G protein Gβ 1 subunit. Co-immunoprecipitation studies with epitope-tagged PP1c and Gβ 1 revealed that Gβ 1 interacts with the PP1c α, β, and γ1 isoforms. Purified PP1c bound to recombinant Gβ 1 -GST protein, and PP1c co-immunoprecipitated with Gβ 1 in unstimulated platelets. Thrombin stimulation of platelets induced the dissociation of the PP1c-Gβ 1 complex, which correlated with an association of PP1c with phospholipase C β3 (PLCβ3), along with a concomitant dephosphorylation of the inhibitory Ser 1105 residue in PLCβ3. siRNA-mediated depletion of GNB1 (encoding Gβ 1 ) in murine megakaryocytes reduced protease-activated receptor 4, activating peptide-induced soluble fibrinogen binding. Thrombin-induced aggregation was decreased in PP1cα -/- murine platelets and in human platelets treated with a small-molecule inhibitor of Gβγ. Finally, disruption of PP1c-Gβ 1 complexes with myristoylated Gβ 1 peptides containing the PP1c binding site moderately decreased thrombin-induced human platelet aggregation. These findings suggest that Gβ 1 protein enlists PP1c to modulate GPCR signaling in platelets.

Brain region-dependent differential expression of alpha-synuclein.

PubMed

Taguchi, Katsutoshi; Watanabe, Yoshihisa; Tsujimura, Atsushi; Tanaka, Masaki

2016-04-15

α-Synuclein, the major constituent of Lewy bodies (LBs), is normally expressed in presynapses and is involved in synaptic function. Abnormal intracellular aggregation of α-synuclein is observed as LBs and Lewy neurites in neurodegenerative disorders, such as Parkinson's disease (PD) or dementia with Lewy bodies. Accumulated evidence suggests that abundant intracellular expression of α-synuclein is one of the risk factors for pathological aggregation. Recently, we reported differential expression patterns of α-synuclein between excitatory and inhibitory hippocampal neurons. Here we further investigated the precise expression profile in the adult mouse brain with special reference to vulnerable regions along the progression of idiopathic PD. The results show that α-synuclein was highly expressed in the neuronal cell bodies of some early PD-affected brain regions, such as the olfactory bulb, dorsal motor nucleus of the vagus, and substantia nigra pars compacta. Synaptic expression of α-synuclein was mostly accompanied by expression of vesicular glutamate transporter-1, an excitatory presynaptic marker. In contrast, expression of α-synuclein in the GABAergic inhibitory synapses was different among brain regions. α-Synuclein was clearly expressed in inhibitory synapses in the external plexiform layer of the olfactory bulb, globus pallidus, and substantia nigra pars reticulata, but not in the cerebral cortex, subthalamic nucleus, or thalamus. These results suggest that some neurons in early PD-affected human brain regions express high levels of perikaryal α-synuclein, as happens in the mouse brain. Additionally, synaptic profiles expressing α-synuclein are different in various brain regions. © 2015 Wiley Periodicals, Inc.

Hemostatic and toxinological diversities in venom of Micrurus tener tener, Micrurus fulvius fulvius and Micrurus isozonus coral snakes.

PubMed

Salazar, Ana M; Vivas, Jeilyn; Sánchez, Elda E; Rodríguez-Acosta, Alexis; Ibarra, Carlos; Gil, Amparo; Carvajal, Zoila; Girón, María E; Estrella, Amalid; Navarrete, Luis F; Guerrero, Belsy

2011-07-01

The coral snake Micrurus tener tener (Mtt) from the Elapidae family inhabits the southwestern United States and produces severe cases of envenomations. Although the majority of Mtt venom components are neurotoxins and phospholipase A₂s, this study demonstrated, by SDS-PAGE and molecular exclusion chromatography (MEC), that these venoms also contain high-molecular-weight proteins between 50 and 150 kDa that target the hemostatic system. The biological aspects of other Micrurus venoms were also studied, such as the LD₅₀s of Micrurus isozonus (from 0.52 to 0.61 mg/kg). A pool from these venoms presented a LD₅₀ of 0.57 mg/kg, Micrurus f. fulvius (Mff) and Mtt had LD₅₀s of 0.32 and 0.78 mg/kg, respectively. These venoms contained fibrino(geno)lytic activity, they inhibited platelet aggregation, as well as factor Xa and/or plasmin-like activities. M. isozonus venoms from different Venezuelan geographical regions inhibited ADP-induced platelet aggregation (from 50 to 68%). Micrurus tener tener venom from the United States was the most active with a 95.2% inhibitory effect. This venom showed thrombin-like activity on fibrinogen and human plasma. Fractions of Mtt showed fibrino(geno)lytic activity and inhibition on plasmin amidolytic activity. Several fractions degraded the fibrinogen Aα chains, and fractions F2 and F7 completely degraded both fibrinogen Aα and Bβ chains. To our knowledge, this is the first report on thrombin-like and fibrino(geno)lytic activity and plasmin or factor Xa inhibitors described in Micrurus venoms. Further purification and characterization of these Micrurus venom components could be of therapeutic use in the treatment of hemostatic disorders. Copyright © 2011 Elsevier Ltd. All rights reserved.

Anti-platelet and anti-thrombotic effect of a traditional herbal medicine Kyung-Ok-Ko.

PubMed

Kim, Tae-Ho; Lee, Kyoung Mee; Hong, Nam Doo; Jung, Yi-Sook

2016-02-03

Kyung-Ok-Ko (KOK), a traditional herbal prescription, contains six main ingredients; Rehmannia glutinosa var. purpurae, Lycium chinense, Aquillaria agallocha, Poria cocos, Panax ginseng, and honey. KOK has been widely taken as a traditional oriental medicine for improving blood circulation or age-related symptoms, such as dementia and stroke. However, the effect of KOK on platelet activity has not been clarified. To evaluate the effect of KOK on platelet function, we evaluated its effect on functional markers of platelet activation such as aggregation and shape change. As a mechanism study for the effect of KOK, we examined its effect on granule secretion, intracellular Ca(2+) increase, and PLCγ and Akt activation. To investigate the effect of orally administered KOK (0.5, 1, 2 g/kg), we examined its ex vivo effect on platelet aggregation in rat, and its in vivo anti-thrombotic effect in mice thromboembolism model. Furthermore, the effect of KOK on bleeding time was examined to estimate its potential side effect. KOK (0.3, 1, 3, 10 mg/ml) inhibited collagen-induced platelet aggregation and shape change in rat platelets in a concentration-dependent manner. The mechanism for the anti-platelet effect of KOK seems to involve the inhibition of ATP release, intracellular Ca(2+) elevation, and the phosphorylation of PLCγ and Akt. In rat ex vivo study, KOK (2 g/kg, p.o. for 1 day, and 0.5, 1, 2 g/kg, p.o. for 7 days) also had significant inhibitory effects on collagen-induced platelet aggregation. In addition, KOK showed a significant protective effect against thrombosis attack in mice. The prolongation of bleeding time by KOK was much less than that by ASA, suggesting a beneficial potential of KOK than ASA in view of side effect. These findings suggest that KOK elicits remarkable anti-platelet and anti-thrombotic effects with less side effect of bleeding, and therefore, it may have a therapeutic potential for the prevention of platelet-associated cardiovascular diseases. Copyright © 2015. Published by Elsevier Ireland Ltd.

Synthesis and bioevaluation of new tacrine-cinnamic acid hybrids as cholinesterase inhibitors against Alzheimer's disease.

PubMed

Chen, Yao; Zhu, Jie; Mo, Jun; Yang, Hongyu; Jiang, Xueyang; Lin, Hongzhi; Gu, Kai; Pei, Yuqiong; Wu, Liang; Tan, Renxiang; Hou, Jing; Chen, Jingyi; Lv, Yang; Bian, Yaoyao; Sun, Haopeng

2018-12-01

Small molecule cholinesterases inhibitor (ChEI) provides an effective therapeutic strategy to treat Alzheimer's disease (AD). Currently, the discovery of new ChEI with multi-target effect is still of great importance. Herein, we report the synthesis, structure-activity relationship study and biological evaluation of a series of tacrine-cinnamic acid hybrids as new ChEIs. All target compounds are evaluated for their in vitro cholinesterase inhibitory activities. The representatives which show potent activity on cholinesterase, are evaluated for the amyloid β-protein self-aggregation inhibition and in vivo assays. The optimal compound 19, 27, and 30 (human AChE IC 50  = 10.2 ± 1.2, 16.5 ± 1.7, and 15.3 ± 1.8 nM, respectively) show good performance in ameliorating the scopolamine-induced cognition impairment and preliminary safety in hepatotoxicity evaluation. These compounds deserve further evaluation for the development of new therapeutic agents against AD.

The possible involvement of protein phosphatase 1 in thrombin-induced Ca2+ influx of human platelets.

PubMed

Murata, K; Sakon, M; Kambayashi, J; Yukawa, M; Yano, Y; Fujitani, K; Kawasaki, T; Shiba, E; Mori, T

1993-04-01

Protein phosphatase 1 is considered to be involved in thrombin-induced platelet activation (Murata et al., Biochem Int 26:327-334, 1992). To clarify the mechanism, we examined the effects of protein phosphatase 1 and 2A inhibitors (calyculin A, tautomycin, okadaic acid) on Ca2+ influx. In the presence of 1 mM Ca2+, thrombin- (0.1 U/ml) induced platelet aggregation and ATP release were inhibited by calyculin A, while this inhibitory effect was abolished in the absence of Ca2+ (EGTA 1 mM). Furthermore, thrombin-induced Mn2+ influx but not intracellular Ca2+ mobilization was inhibited by calyculin A in a dose-related manner. Calyculin A also blocked the ongoing Ca2+ influx when added 3 min after thrombin stimulation. Similar inhibitory effects were observed with okadaic acid and tautomycin in the same potency sequence as the reported one for protein phosphatase 1 (calyculin A > tautomycin > okadaic acid). These results suggest that the anti-platelet effects of phosphatase inhibitors are due to the inhibition of Ca2+ influx and that protein phosphatase 1 plays a key role in the regulation of receptor operated Ca2+ channel of human platelets.

Dichotomous Dynamics in E-I Networks with Strongly and Weakly Intra-connected Inhibitory Neurons

PubMed Central

Rich, Scott; Zochowski, Michal; Booth, Victoria

2017-01-01

The interconnectivity between excitatory and inhibitory neural networks informs mechanisms by which rhythmic bursts of excitatory activity can be produced in the brain. One such mechanism, Pyramidal Interneuron Network Gamma (PING), relies primarily upon reciprocal connectivity between the excitatory and inhibitory networks, while also including intra-connectivity of inhibitory cells. The causal relationship between excitatory activity and the subsequent burst of inhibitory activity is of paramount importance to the mechanism and has been well studied. However, the role of the intra-connectivity of the inhibitory network, while important for PING, has not been studied in detail, as most analyses of PING simply assume that inhibitory intra-connectivity is strong enough to suppress subsequent firing following the initial inhibitory burst. In this paper we investigate the role that the strength of inhibitory intra-connectivity plays in determining the dynamics of PING-style networks. We show that networks with weak inhibitory intra-connectivity exhibit variations in burst dynamics of both the excitatory and inhibitory cells that are not obtained with strong inhibitory intra-connectivity. Networks with weak inhibitory intra-connectivity exhibit excitatory rhythmic bursts with weak excitatory-to-inhibitory synapses for which classical PING networks would show no rhythmic activity. Additionally, variations in dynamics of these networks as the excitatory-to-inhibitory synaptic weight increases illustrates the important role that consistent pattern formation in the inhibitory cells serves in maintaining organized and periodic excitatory bursts. Finally, motivated by these results and the known diversity of interneurons, we show that a PING-style network with two inhibitory subnetworks, one strongly intra-connected and one weakly intra-connected, exhibits organized and periodic excitatory activity over a larger parameter regime than networks with a homogeneous inhibitory population. Taken together, these results serve to better articulate the role of inhibitory intra-connectivity in generating PING-like rhythms, while also revealing how heterogeneity amongst inhibitory synapses might make such rhythms more robust to a variety of network parameters. PMID:29326558

Anti-thrombosis Repertoire of Blood-feeding Horsefly Salivary Glands*

PubMed Central

Ma, Dongying; Wang, Yipeng; Yang, Hailong; Wu, Jing; An, Shu; Gao, Li; Xu, Xueqing; Lai, Ren

2009-01-01

Blood-feeding arthropods rely heavily on the pharmacological properties of their saliva to get a blood meal and suppress immune reactions of hosts. Little information is available on antihemostatic substances in horsefly salivary glands although their saliva has been thought to contain wide range of physiologically active molecules. In traditional Eastern medicine, horseflies are used as anti-thrombosis material for hundreds of years. By proteomics coupling transcriptome analysis with pharmacological testing, several families of proteins or peptides, which exert mainly on anti-thrombosis functions, were identified and characterized from 60,000 pairs of salivary glands of the horsefly Tabanus yao Macquart (Diptera, Tabanidae). They are: (I) ten fibrin(ogen)olytic enzymes, which hydrolyze specially alpha chain of fibrin(ogen) and are the first family of fibrin(ogen)olytic enzymes purified and characterized from arthropods; (II) another fibrin(ogen)olytic enzyme, which hydrolyzes both alpha and beta chain of fibrin(ogen); (III) ten Arg-Gly-Asp-motif containing proteins acting as platelet aggregation inhibitors; (IV) five thrombin inhibitor peptides; (V) three vasodilator peptides; (VI) one apyrase acting as platelet aggregation inhibitor; (VII) one peroxidase with both platelet aggregation inhibitory and vasodilator activities. The first three families are belonging to antigen five proteins, which show obvious similarity with insect allergens. They are the first members of the antigen 5 family found in salivary glands of blood sucking arthropods to have anti-thromobosis function. The current results imply a possible evolution from allergens of blood-sucking insects to anti-thrombosis agents. The extreme diversity of horsefly anti-thrombosis components also reveals the anti-thrombosis molecular mechanisms of the traditional Eastern medicine insect material. PMID:19531497

Fluorine Functionalized Graphene Quantum Dots as Inhibitor against hIAPP Amyloid Aggregation.

PubMed

Yousaf, Maryam; Huang, Huan; Li, Ping; Wang, Chen; Yang, Yanlian

2017-06-21

Fibrillar deposits of the human islet amyloid polypeptide (hIAPP) are considered as a root of Type II diabetes mellitus. Fluorinated graphene quantum dots (FGQDs) are new carbon nanomaterials with unique physicochemical properties containing highly electronegative F atoms. Herein we report a single step synthesis method of FGQDs with an inhibitory effect on aggregation and cytotoxicity of hIAPP in vitro. Highly fluorescent and water dispersible FGQDs, less than 3 nm in size, were synthesized by the microwave-assisted hydrothermal method. Efficient inhibition capability of FGQDs to amyloid aggregation was demonstrated. The morphologies of hIAPP aggregates were observed to change from the entangled long fibrils to short thin fibrils and amorphous aggregates in the presence of FGQDs. In thioflavin T fluorescence analysis, inhibited aggregation with prolonged lag time and reduced fluorescence intensity at equilibrium were observed when hIAPP was incubated together with FGQDs. Circular dichroism spectrum results reveal that FGQDs could inhibit conformational transition of the peptide from native structure to β-sheets. FGQDs could also rescue the cytotoxicity of INS-1 cells induced by hIAPP in a dose dependent manner. This study could be beneficial for design and preparation of inhibitors for amyloids, which is important for prevention and treatment of amyloidosis.

Zoanthid mucus as new source of useful biologically active proteins.

PubMed

Guarnieri, Míriam Camargo; de Albuquerque Modesto, Jeanne Claíne; Pérez, Carlos Daniel; Ottaiano, Tatiana Fontes; Ferreira, Rodrigo da Silva; Batista, Fabrício Pereira; de Brito, Marlon Vilela; Campos, Ikaro Henrique Mendes Pinto; Oliva, Maria Luiza Vilela

2018-03-01

Palythoa caribaeorum is a very common colonial zoanthid in the coastal reefs of Brazil. It is known for its massive production of mucus, which is traditionally used in folk medicine by fishermen in northeastern Brazil. This study identified biologically active compounds in P. caribaerum mucus. Crude mucus was collected during low tides by the manual scraping of colonies; samples were maintained in an ice bath, homogenized, and centrifuged at 16,000 g for 1 h at 4 °C; the supernatant (mucus) was kept at -80 °C until use. The enzymatic (proteolytic and phospholipase A 2 ), inhibitory (metallo, cysteine and serine proteases), and hemagglutinating (human erythrocyte) activities were determined. The results showed high levels of cysteine and metallo proteases, intermediate levels of phosholipase A 2 , low levels of trypsin, and no elastase and chymotrypsin like activities. The mucus showed potent inhibitory activity on snake venom metalloproteases and cysteine proteinase papain. In addition, it showed agglutinating activity towards O + , B + , and A + erythrocyte types. The hemostatic results showed that the mucus prolongs the aPTT and PT, and strongly inhibited platelet aggregation induced by arachidonic acid, collagen, epinephrine, ADP, and thrombin. The antimicrobial activity was tested on 15 strains of bacteria and fungi through the radial diffusion assay in agar, and no activity was observed. Compounds in P. caribaeorum mucus were analyzed for the first time in this study, and our results show potential pharmacological activities in these compounds, which are relevant for use in physiopathological investigations. However, the demonstration of these activities indicates caution in the use of crude mucus in folk medicine. Furthermore, the present or absent activities identified in this mucus suggest that the studied P. caribaeorum colonies were in thermal stress conditions at the time of sample collection; these conditions may precede the bleaching process in zoanthids. Hence, the use of mucus as an indicator of this process should be evaluated in the future. Copyright © 2018. Published by Elsevier Ltd.

Chemoreception to aggregation pheromones in the common bed bug, Cimex lectularius.

PubMed

Liu, Feng; Xiong, Caixing; Liu, Nannan

2017-03-01

The common bed bug, Cimex lectularius, is an obligate blood-feeding insect that is resurgent worldwide, posing a threat to human beings through its biting nuisance and disease transmission. Bed bug aggregation pheromone is considered a very promising attractant for use in the monitoring and management of bed bugs, but as yet little is known regarding the sensory physiology of bed bugs related to this pheromone. This study examined how the individual components of aggregation pheromone are perceived by the olfactory receptor neurons (ORNs) housed in different types of olfactory sensilla in bed bugs and the molecular basis for the ORNs' responses to the aggregation pheromone. We found that the ORNs in the D olfactory sensilla played a predominant role in detecting all the components of aggregation pheromone except for histamine, which was only recognized by the C sensilla. Bed bugs' E sensilla, which include four functionally distinct groups, showed only a very weak but variant sensitivity (both excitatory and inhibitory) to the components of aggregation pheromone. Functional tests of 15 odorant receptors (ORs) in response to the components of aggregation pheromone revealed that most of these components were encoded by multiple ORs with various tuning properties. This study provides a comprehensive understanding of how bed bug aggregation pheromone is perceived and recognized in the peripheral olfactory system and will contribute useful information to support the development of synthetic attractants for bed bug monitoring and control. Copyright © 2017 Elsevier Ltd. All rights reserved.

Fluorometric immunoassay for human serum albumin based on its inhibitory effect on the immunoaggregation of quantum dots with silver nanoparticles

NASA Astrophysics Data System (ADS)

Marukhyan, Seda S.; Gasparyan, Vardan K.

2017-02-01

Quantitative determination of HSA was conducted by competitive immunoassay. Inhibition of aggregation of antibody conjugated quantum dots (QD) with albumin conjugated silver nanoparticles (AgNPs) in the presence of HSA was conducted. If antibody-loaded CdSe QDs aggregate with HSA-coated silver nanoparticles the distance between the two kinds of nanoparticles will be reduced enough to cause fluorescence resonance energy transfer (FRET). In this case the yellow fluorescence of the Ab-QDs is quenched. However if HSA (antigen) is added to the Ab-QDs their surface will be blocked and they cannot aggregate any longer with the HSA-AgNPs. Hence, fluorescence will not be quenched. The drop of the intensity of fluorescence (peaking at 570 nm) is inversely correlated with the concentration of HSA in the sample. The method allows to determine HSA in the 30-600 ng·mL-1 concentration range.

(-)-Meptazinol-melatonin hybrids as novel dual inhibitors of cholinesterases and amyloid-β aggregation with high antioxidant potency for Alzheimer's therapy.

PubMed

Cheng, Shaobing; Zheng, Wei; Gong, Ping; Zhou, Qiang; Xie, Qiong; Yu, Lining; Zhang, Peiyi; Chen, Liangkang; Li, Juan; Chen, Jianxing; Chen, Hailin; Chen, Hongzhuan

2015-07-01

The multifactorial pathogenesis of Alzheimer's disease (AD) implicates that multi-target-directed ligands (MTDLs) intervention may represent a promising therapy for AD. Amyloid-β (Aβ) aggregation and oxidative stress, two prominent neuropathological hallmarks in patients, play crucial roles in the neurotoxic cascade of this disease. In the present study, a series of novel (-)-meptazinol-melatonin hybrids were designed, synthesized and biologically characterized as potential MTDLs against AD. Among them, hybrids 7-7c displayed higher dual inhibitory potency toward cholinesterases (ChEs) and better oxygen radical absorbance capacity (ORAC) than the parental drugs. Furthermore, compound 7c could effectively inhibit Aβ self-aggregation, showed favorable safety and the blood-brain barrier (BBB) permeability. Therefore, 7c may serve as a valuable candidate that is worthy of further investigations in the treatment of AD. Copyright © 2015 Elsevier Ltd. All rights reserved.

Traces of pFc' in IVIG interact with human IgG Fc domains and counteract aggregation.

PubMed

Rispens, Theo; Himly, Martin; Ooievaar-De Heer, Pleuni; den Bleker, Tamara H; Aalberse, Rob C

2010-04-16

To prevent multimer formation, intravenous immunoglobulin (IVIG) is often treated with traces of pepsin. So far, the mechanism behind this treatment has been unclear. Recently, we reported that human IgG4 binds other IgG molecules via Fc-Fc interactions. Here we show that IVIG treated with traces of pepsin (Nanogam) inhibits these interactions. We found that--besides IgG4--peptides corresponding to IgG1 and IgG2 pFc' (products of limited pepsin digestion) are responsible for the inhibitory action. Using radiolabeled pFc', it was found that pFc' binds directly to IgG1. Furthermore, recombinant CH3 fragments were found to also possess binding activity, and potencies of inhibition varied over 3 orders of magnitude amongst the subclasses, IgG4 being most potent. We propose that pFc' formation explains how limited pepsin digestion diminishes adverse effects of IVIG. In particular, the presence of this fragment can enhance the stability of IgG products including IVIG and therapeutical monoclonal antibodies. Indeed, using a model system it was found that acid-induced aggregation of IgG is reduced in the presence of pFc', suggesting a 'chaperone-like' activity of this fragment. Thus, pFc' can modulate Fc interactions and may therefore reduce adverse effects of IVIG, in particular by preventing oligomerization. 2010 Elsevier B.V. All rights reserved.

Occurrence State and Molecular Structure Analysis of Extracellular Proteins with Implications on the Dewaterability of Waste-Activated Sludge.

PubMed

Wu, Boran; Ni, Bing-Jie; Horvat, Kristine; Song, Liyan; Chai, Xiaoli; Dai, Xiaohu; Mahajan, Devinder

2017-08-15

The occurrence state and molecular structure of extracellular proteins were analyzed to reveal the influencing factors on the water-holding capacities of protein-like substances in waste-activated sludge (WAS). The gelation process of extracellular proteins verified that advanced oxidation processes (AOPs) for WAS dewaterability improvement eliminated the water affinity of extracellular proteins and prevented these macromolecules from forming stable colloidal aggregates. Isobaric tags for relative and absolute quantitation proteomics identified that most of the extracellular proteins were originally derived from the intracellular part and the proteins originally located in the extracellular part were mainly membrane-associated. The main mechanism of extracellular protein transformation during AOPs could be represented by the damage of the membrane or related external encapsulating structure and the release of intracellular substances. For the selected representative extracellular proteins, the strong correlation (R 2 > 0.97, p < 0.03) between the surface hydrophilicity index and α-helix percentages in the secondary structure indicated that the water affinity relied more on the spatial distribution of hydrophilic functional groups rather than the content. Destructing the secondary structure represented by the α-helix and stretching the polypeptide aggregation in the water phase through disulfide bond removal might be the key to eliminating the inhibitory effects of extracellular proteins on the interstitial water removal from WAS.

Syntheses of coumarin-tacrine hybrids as dual-site acetylcholinesterase inhibitors and their activity against butylcholinesterase, Aβ aggregation, and β-secretase.

PubMed

Sun, Qi; Peng, Da-Yong; Yang, Sheng-Gang; Zhu, Xiao-Lei; Yang, Wen-Chao; Yang, Guang-Fu

2014-09-01

Exploring small-molecule acetylcholinesterase (AChE) inhibitors to slow the breakdown of acetylcholine (Ach) represents the mainstream direction for Alzheimer's disease (AD) therapy. As the first acetylcholinesterase inhibitor approved for the clinical treatment of AD, tacrine has been widely used as a pharmacophore to design hybrid compounds in order to combine its potent AChE inhibition with other multi-target profiles. In present study, a series of novel tacrine-coumarin hybrids were designed, synthesized and evaluated as potent dual-site AChE inhibitors. Moreover, compound 1g was identified as the most potent candidate with about 2-fold higher potency (Ki=16.7nM) against human AChE and about 2-fold lower potency (Ki=16.1nM) against BChE than tacrine (Ki=35.7nM for AChE, Ki=8.7nM for BChE), respectively. In addition, some of the tacrine-coumarin hybrids showed simultaneous inhibitory effects against both Aβ aggregation and β-secretase. We therefore conclude that tacrine-coumarin hybrid is an interesting multifunctional lead for the AD drug discovery. Copyright © 2014 Elsevier Ltd. All rights reserved.

New flavone-cyanoacetamide hybrids with combination of cholinergic, antioxidant, modulation β-amyloid aggregation and neuroprotection properties as innovative multifunctional therapeutic candidates for Alzheimer's disease and unraveling their mechanism of action with acetylcholinesterase.

PubMed

Jeelan Basha, Shaik; Mohan, Penumala; Yeggoni, Daniel Pushparaju; Babu, Zinka Raveendra; Kumar, Palaka Bhagath; Dinakara Rao, Ampasala; Subramanyam, Rajagopal; Damu, Amooru Gangaiah

2018-05-10

In line with the modern multi target-directed ligand paradigm of Alzheimer's disease (AD), a series of nineteen compounds composed of flavone and cyanoacetamide groups have been synthesized and evaluated as multifunctional agents against AD. Biological evaluation demonstrated that compounds 7j, 7n, 7o, 7r and 7s exhibited excellent inhibitory potency (AChE, IC50 0.271 ± 0.012 to ± 0.075 M) and good selectivity toward acetylcholinesterase, significant antioxidant activity, good modulation effects on self-induced A aggregation, low cytotoxicity and neuroprotection in human neuroblastoma SK-N-SH cells. Further, an inclusive study on the interaction of 7j, 7n, 7o, 7r and 7s with AChE at physiological pH 7.2 using fluorescence, circular dichroism and molecular docking methods suggesting that these derivatives bind strongly to peripheral anionic site of AChE mostly through hydrophobic interactions. Overall, the multifunctional profiles and strong AChE binding affinity highlight these compounds as promising prototypes for further pursuit of innovative multifunctional drugs for AD.

Design, synthesis and evaluation of novel cinnamic acid derivatives bearing N-benzyl pyridinium moiety as multifunctional cholinesterase inhibitors for Alzheimer's disease.

PubMed

Lan, Jin-Shuai; Hou, Jian-Wei; Liu, Yun; Ding, Yue; Zhang, Yong; Li, Ling; Zhang, Tong

2017-12-01

A novel family of cinnamic acid derivatives has been developed to be multifunctional cholinesterase inhibitors against AD by fusing N-benzyl pyridinium moiety and different substituted cinnamic acids. In vitro studies showed that most compounds were endowed with a noteworthy ability to inhibit cholinesterase, self-induced Aβ (1-42) aggregation, and to chelate metal ions. Especially, compound 5l showed potent cholinesterase inhibitory activity (IC 50 , 12.1 nM for eeAChE, 8.6 nM for hAChE, 2.6 μM for eqBuChE and 4.4 μM for hBuChE) and the highest selectivity toward AChE over BuChE. It also showed good inhibition of Aβ (1-42) aggregation (64.7% at 20 μM) and good neuroprotection on PC12 cells against amyloid-induced cell toxicity. Finally, compound 5l could penetrate the BBB, as forecasted by the PAMPA-BBB assay and proved in OF1 mice by ex vivo experiments. Overall, compound 5l seems to be a promising lead compound for the treatment of Alzheimer's diseases.

Vitamin C Prevents Cigarette Smoke-Induced Leukocyte Aggregation and Adhesion to Endothelium in vivo

NASA Astrophysics Data System (ADS)

Lehr, Hans-Anton; Frei, Balz; Arfors, Karl-E.

1994-08-01

A common feature of cigarette-smoke (CS)-associated diseases such as atherosclerosis and pulmonary emphysema is the activation, aggregation, and adhesion of leukocytes to micro- and macrovascular endothelium. A previous study, using a skinfold chamber model for intravital fluorescence microscopy in awake hamsters, has shown that exposure of hamsters to the smoke generated by one research cigarette elicits the adhesion of fluorescently labeled leukocytes to the endothelium of arterioles and small venules. By the combined use of intravital microscopy and scanning electron microscopy, we now demonstrate in the same animal model that (i) CS-induced leukocyte adhesion is not confined to the microcirculation, but that leukocytes also adhere singly and in clusters to the aortic endothelium; (ii) CS induces the formation in the bloodstream of aggregates between leukocytes and platelets; and (iii) CS-induced leukocyte adhesion to micro- and macrovascular endothelium and leukocyte-platelet aggregate formation are almost entirely prevented by dietary or intravenous pretreatment with the water-soluble antioxidant vitamin C (venules, 21.4 ± 11.0 vs. 149.6 ± 38.7 leukocytes per mm^2, P < 0.01; arterioles, 8.5 ± 4.2 vs. 54.3 ± 21.6 leukocytes per mm^2, P < 0.01; aortas, 0.8 ± 0.4 vs. 12.4 ± 5.6 leukocytes per mm^2, P < 0.01; means ± SD of n = 7 animals, 15 min after CS exposure). No inhibitory effect was observed by pretreatment of the animals with the lipid-soluble antioxidants vitamin E or probucol. The protective effects of vitamin C on CS-induced leukocyte adhesion and aggregation were seen at vitamin C plasma levels (55.6 ± 22.2 μM, n = 7) that can easily be reached in humans by dietary means or supplementation, suggesting that vitamin C effectively contributes to protection from CS-associated cardiovascular and pulmonary diseases in humans.

In vitro and in vivo antithrombotic and cytotoxicity effects of ferulic acid.

PubMed

Choi, Jun-Hui; Park, Jong-Kook; Kim, Ki-Man; Lee, Hyo-Jeong; Kim, Seung

2018-01-01

We discovered recently in vitro and in vivo antithrombotic and cytotoxicity effects of ferulic acid. The cytotoxicity assays showed that ferulic acid (∼300 μg/mL) did not cause any significant toxicity on three cell lines, platelets, leukocytes, and erythrocytes. In vitro assays showed inhibitory effects of ferulic acid on thrombin (THR)- or collagen/epinephrine-stimulated platelet activation by inhibiting platelet aggregation, and decreasing clot retraction activity. The in vitro effect of ferulic acid on THR-stimulated platelet activation was proved by the decrease in the secretion of serotonin from the platelets. The anticoagulant effects of ferulic acid were confirmed by the prolongation of the intrinsic or/and extrinsic pathways and the delay of recalcification time in plasma coagulation. Ferulic acid had antithrombotic effect in acute thromboembolism model in vivo, and decreased the expression of α IIb β 3 /FIB and phosphorylation of AKT in THR-stimulated platelet activation in vivo, and their antithrombotic efficacies hold promise for therapeutic targeting in our ongoing studies. © 2017 Wiley Periodicals, Inc.

A common standard is inappropriate for determining the potency of ultra low molecular weight heparins such as semuloparin and bemiparin.

PubMed

Jeske, Walter P; Hoppensteadt, Debra; Gray, Angel; Walenga, Jeanine M; Cunanan, Josephine; Myers, Lauren; Fareed, Jawed; Bayol, Alain; Rigal, Hélène; Viskov, Christian

2011-10-01

Lower low-molecular-weight heparins are being developed to improve on the safety and efficacy of antithrombotic therapy. Semuloparin and bemiparin are two depolymerized heparins produced by distinct manufacturing processes. The objective of this investigation was to determine whether a common standard could be used to define their potency. Activities were compared using typical clinical coagulation assays and pharmacological assays required for potency assessment. The activity of semuloparin and bemiparin was comparable in FXa-based assays (anti-FXa, Heptest). However, bemiparin produced a stronger effect in the aPTT, ACT and anti-thrombin assays. Assessment of the parallelism of the concentration-response curves indicated that bemiparin and semuloparin are not equivalent in terms of anti-FIIa activity. Bemiparin had a stronger inhibitory effect on thrombin induced platelet aggregation, and a stronger interaction with HIT antibodies. These data demonstrate that depolymerized heparins can exhibit a range of biologic activities making them unique agents. Pharmacopoeial parameters such as anti-IIa and anti-Xa potency and molecular weight are insufficient to characterize such agents. Copyright © 2011 Elsevier Ltd. All rights reserved.

Synthesis and evaluation of 7-substituted coumarin derivatives as multimodal monoamine oxidase-B and cholinesterase inhibitors for the treatment of Alzheimer's disease.

PubMed

Joubert, Jacques; Foka, Germaine B; Repsold, Benjamin P; Oliver, Douglas W; Kapp, Erika; Malan, Sarel F

2017-01-05

A series of 7-substituted coumarin derivatives were designed and synthesised to display ChE and MAO-B inhibitory activity. The compounds consisted out of a coumarin structure (MAO-B inhibitor) and benzyl-, piperidine-, N-benzylpiperidine- or p-bromo-N-benzylpiperizine moiety, resembling the N-benzylpiperidine function of donepezil (ChE inhibitor), connected via an alkyl ether linkage at the 7 position. The biological assay results indicated that all the compounds (1-25) displayed selective inhibition to hMAO-B over hMAO-A, with the benzyloxy series (1-8, 10-13) showing nano-molar hMAO-B inhibition (IC 50 : 0.5-73 nM). Limited ChE inhibitory activity was however observed for the benzyloxy series with the exception of 2 and especially 3 showing selective BuChE inhibition. From this series 3 showed the best multifunctional activity (eqBuChE IC 50  = 0.96 μM, hMAO-A IC 50  = 2.13 μM, hMAO-B IC 50  = 0.0021 μM). Within the N-benzylpiperidine (16-19) and p-bromo-N-benzylpiperizine (21-24) series the compounds in general showed moderate ChE and MAO-B inhibitory activity. Of these compounds 19 was the most potent multifunctional agent showing good eeAChE and eqBuChE inhibition (IC 50  = 9.10 μM and 5.90 μM, respectively), and relatively potent and selective hMAO-B inhibition (IC 50  = 0.30 μM, SI = >33). Molecular modeling revealed that 19 was able to bind simultaneously to the CAS, mid-gorge and PAS sites of AChE and BuChE suggesting that it will be able to inhibit AChE induced Aβ aggregation. From this study, compounds that 3 and 19 can be considered as promising multifunctional lead compounds. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Assessment of Characteristics and Functional Properties of Lactobacillus Species Isolated from Kimchi for Dairy Use

PubMed Central

Baick, Seung-Chun

2015-01-01

The objective of this study was to identify lactic acid bacteria (LAB) isolated from kimchi and to evaluate its characteristics and functional properties for application in fermented dairy products as a probiotic or commercial starter culture. Eight stains isolated from kimchi were selected through an investigation of phenotypic characteristics. Two strains (DK211 and DK303) were identified as Lactobacillus plantarum, another two (DK207 and DK215) as Lactobacillus paracasei, and one (DK301) as Lactobacillus sakei. The remaining three strains were identified as species of Weissella. All selected Lactobacillus strains had acid and bile tolerance, even though there was wide variation in the ability of each strain. DK303 showed a remarkably higher proteolytic activity. There were no significant differences in β-galactosidase activity among the tested strains, except that DK301 showed no activity. Auto-aggregation varied between 82.1 and 90.0%, and hydrophobicity values ranged from 0.5 to 51.6%.The strongest auto-aggregation and hydrophobicity were observed in DK211. All selected strains showed better 1,1-diphenyl-2-picrylhydrzyl (DPPH) scavenging activity than commercial strains. DK211, DK215, DK301, and DK303 had effective inhibitory activity against all pathogens tested except E. coli. When selected strains were used for yogurt preparation as a single starter culture, the time required to reach target titratable acidity (0.9) was 11-12 h. The yogurt fermented with DK211 had favorable panelists ratings for most sensory attributes, which were comparable with yogurt fermented with a commercial strain. The results suggest that strains isolated from kimchi could be potential probiotic and starter cultures for use in yogurt manufacturing. PMID:26761848

Stability of Curcuma longa rhizome lectin: Role of N-linked glycosylation.

PubMed

Biswas, Himadri; Chattopadhyaya, Rajagopal

2016-04-01

Curcuma longa rhizome lectin, a mannose-binding protein of non-seed portions of turmeric, is known to have antifungal, antibacterial and α-glucosidase inhibitory activities. We studied the role of complex-type glycans attached to asparagine (Asn) 66 and Asn 110 to elucidate the role of carbohydrates in lectin activity and stability. Apart from the native lectin, the characteristics of a deglycosylated Escherichia coli expressed lectin, high-mannose oligosaccharides at both asparagines and its glycosylation mutants N66Q and N110Q expressed in Pichia pastoris, were compared to understand the relationship between glycosylation and activity. Far UV circular dichroism (CD) spectra, fluorescence emission maximum, hemagglutination assay show no change in secondary or tertiary structures or sugar-binding properties between wild-type and aforementioned recombinant lectins under physiological pH. But reduced agglutination activity and loss of tertiary structure are observed in the acidic pH range for the deglycosylated and the N110Q protein. In thermal and guanidine hydrochloride (GdnCl)-induced unfolding, the wild-type and high-mannose lectins possess higher stability compared with the deglycosylated recombinant lectin and both mutants, as measured by a higher Tm of denaturation or a greater free energy change, respectively. Reversibility experiments after thermal denaturation reveal that deglycosylated proteins tend to aggregate during thermal inactivation but the wild type shows a much greater recovery to the native state upon refolding. These results suggest that N-glycosylation in turmeric lectin is important for the maintenance of its proper folding upon changes in pH, and that the oligosaccharides help in maintaining the active conformation and prevent aggregation in unfolded or partially folded molecules. © The Author 2015. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Platelet inhibitory effects of juices from Pachyrhizus erosus L. root and Psidium guajava L. fruit: a randomized controlled trial in healthy volunteers.

PubMed

Thaptimthong, Thitiporn; Kasemsuk, Thitima; Sibmooh, Nathawut; Unchern, Supeenun

2016-08-03

The purpose of this study is to investigate cardiovascular benefits of juices obtained from two commonly consumed fruits in Thailand, Pachyrhizus erosus, L. (yam bean) and Psidium guajava, L. (guava), by examining their acute cardiovascular effects in healthy volunteers. Possible involvements of the dietary nitrate on their effects were investigated as well. Thirty healthy volunteers were randomly divided into three groups of 10 subjects per group and each group was allocated to drink 500 ml of freshly prepared yam bean root juice, guava fruit juice, or water. Systemic nitrate and nitrite concentrations, heart rate, systolic and diastolic blood pressure, serum K(+) concentrations, ex vivo platelet aggregation, and plasma cGMP concentrations were monitored at the baseline and at various time points after the intake of juices or water. Data were compared by repeated measures ANOVA. Following the ingestion of both yam bean root juice and guava fruit juice, collagen-induced but not ADP-induced platelet aggregation was attenuated. Ingestion of yam bean root juice increased systemic nitrate and nitrite concentrations whereby elevated nitrite concentrations correlated with the extent of inhibiting collagen-induced platelet aggregation. In addition, positive correlation between systemic nitrite and plasma cGMP concentrations and negative correlation between plasma cGMP concentrations and the extent of collagen-induced platelet aggregation were revealed. Nevertheless, yam bean root juice reduced only diastolic blood pressure while guava fruit juice reduced heart rate, systolic and diastolic blood pressure. The present study has illustrated, for the first time, acute inhibitory effects of yam bean root juice and guava fruit juice on ex vivo collagen-induced platelet aggregation in healthy subjects. Dietary nitrate was shown to underlie the effect of yam bean root juice but not that of guava fruit juice. Following yam bean root juice ingestion, systemic nitrate apparently converts to nitrite and further to NO which may attenuate platelet responses to collagen stimulation. Cardiovascular benefits of juices from yam bean root and guava fruit are noteworthy in term of the cardiovascular health-promoting approach. Randomized controlled trial TCTR20150228001 .

Inhibitory effects of yuzu and its components on human platelet aggregation.

PubMed

Kim, Tae-Ho; Kim, Hye-Min; Park, Se Won; Jung, Yi-Sook

2015-03-01

Our previous study demonstrated that yuzu has an anti-platelet effect in rat blood. In the present study, we examined whether the anti-platelet effect of yuzu can be extended to human blood by investigating its ability to inhibit aggregations induced by various agonists in human platelet rich plasma (PRP). This study also investigated the underlying mechanism of yuzu focusing on ADP granule secretion, TXB2 formations, and PLCγ/Akt signaling. The results from this study showed that ethanolic yuzu extract (YE), and its components, hesperidin and naringin, inhibited human platelet aggregation in a concentration-dependent manner. YE, hesperidin and naringin also inhibited TXB2 formation and ADP release. The phosphorylation of PLCγ and Akt was significantly inhibited by YE, heperidin and naringin. Furthermore, we demonstrated that YE, heperidin and naringin has anti-platelet effects in rat ex vivo studies, and lower side effects in mice tail bleeding time studies. The results from this study suggest that YE, hesperidin and naringin can inhibit human platelet aggregation, at least partly through the inhibition of PLCγ and Akt, leading to a decrease in TXB2 formation and granule secretion.

Effect of steeping temperature on antioxidant and inhibitory activities of green tea extracts against α-amylase, α-glucosidase and intestinal glucose uptake.

PubMed

Liu, Shuyuan; Ai, Zeyi; Qu, Fengfeng; Chen, Yuqiong; Ni, Dejiang

2017-11-01

The objective of the present study was to evaluate the effect of steeping temperature on the biological activities of green tea, including the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging capacity, α-glucosidase and α-amylase inhibitory activities, and glucose uptake inhibitory activity in Caco-2 cells. Results showed that, with increasing extraction temperature, the polyphenol content increased, which contributed to enhance antioxidant activity and inhibitory effects on α-glucosidase and α-amylase. Green tea steeped at 100°C showed the highest DPPH radical-scavenging activity and inhibitory effects on α-glucosidase and α-amylase activities with EC 50 or IC 50 values of 6.15μg/mL, 0.09mg/mL, and 6.31mg/mL, respectively. However, the inhibitory potential on glucose uptake did not show an upward trend with increasing extraction temperature. Green tea steeped at 60°C had significantly stronger glucose uptake inhibitory activity (p<0.05). The integrated data suggested that steeping temperature should be considered when evaluating the biological activities of green tea. Copyright © 2017 Elsevier Ltd. All rights reserved.

Rational design, synthesis and biological screening of triazine-triazolopyrimidine hybrids as multitarget anti-Alzheimer agents.

PubMed

Jameel, Ehtesham; Meena, Poonam; Maqbool, Mudasir; Kumar, Jitendra; Ahmed, Waqar; Mumtazuddin, Syed; Tiwari, Manisha; Hoda, Nasimul; Jayaram, B

2017-08-18

In our endeavor towards the development of potent multitarget ligands for the treatment of Alzheimer's disease, a series of triazine-triazolopyrimidine hybrids were designed, synthesized and characterized by various spectral techniques. Docking and scoring techniques were used to design the inhibitors and to display their interaction with key residues of active site. Organic synthesis relied upon convergent synthetic routes were mono and di-substituted triazines were connected with triazolopyrimidine using piperazine as a linker. In total, seventeen compounds were synthesized in which the di-substituted triazine-triazolopyrimidine derivatives 9a-d showed better acetylcholinesterase (AChE) inhibitory activity than the corresponding tri-substituted triazine-triazolopyrimidine derivatives 10a-f. Out of the disubstituted triazine-triazolopyrimidine based compounds, 9a and 9b showed encouraging inhibitory activity on AChE with IC 50 values 0.065 and 0.092 μM, respectively. Interestingly, 9a and 9b also demonstrated good inhibition selectivity towards AChE over BuChE by ∼28 folds. Furthermore, kinetic analysis and molecular modeling studies showed that 9a and 9b target both catalytic active site as well as peripheral anionic site of AChE. In addition, these derivatives effectively modulated Aβ self-aggregation as investigated through CD spectroscopy, ThT fluorescence assay and electron microscopy. Besides, these compounds exhibited potential antioxidants (2.15 and 2.91 trolox equivalent by ORAC assay) and metal chelating properties. In silico ADMET profiling highlighted that, these novel triazine derivatives have appropriate drug like properties and possess very low toxic effects in the primarily pharmacokinetic study. Overall, the multitarget profile exerted by these novel triazine molecules qualified them as potential anti-Alzheimer drug candidates in AD therapy. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Microwave-assisted synthesis and tyrosinase inhibitory activity of chalcone derivatives.

PubMed

Liu, Jinbing; Chen, Changhong; Wu, Fengyan; Zhao, Liangzhong

2013-07-01

A series of chalcones and their derivatives were synthesized, and their inhibitory effects on the diphenolase activity of mushroom tyrosinase were evaluated. The results showed that some of the synthesized compounds exhibited significant inhibitory activity, and four compounds exhibited more potent tyrosinase inhibitory activity than the reference standard inhibitor kojic acid (5-hydroxy-2-(hydroxymethyl)-4H-pyran-4-one). Specifically, 1-(-1-(4-methoxyphen- yl)-3-phenylallylidene)thiosemicarbazide (18) exhibited the most potent tyrosinase inhibitory activity with IC₅₀ value of 0.274 μM. The inhibition mechanism analysis of 1-(-1-(2,4-dihydroxyphenyl)-3-phenylallylidene) thiosemicarbazide (16) and 1-(-1-(4-methoxyphenyl)-3-phenylallylidene) thiosemicarbazide (18) demonstrated that the inhibitory effects of the two compounds on the tyrosinase were irreversible. Preliminary structure activity relationships' analysis suggested that further development of such compounds might be of interest. © 2013 John Wiley & Sons A/S.

Identification of ACE-inhibitory peptides from Phaseolus vulgaris after in vitro gastrointestinal digestion.

PubMed

Tagliazucchi, Davide; Martini, Serena; Bellesia, Andrea; Conte, Angela

2015-01-01

The objective of this study was to identify the angiotensin I-converting enzyme (ACE)-inhibitory peptides released from thermally treated Phaseolus vulgaris (pinto) whole beans after in vitro gastrointestinal digestion. The degree of hydrolysis increased during digestion reaching a value of 50% at the end of the pancreatic digestion. The <3 kDa fraction of the postpancreatic sample showed high ACE-inhibitory activity (IC50 = 105.6 ± 2.1 μg of peptides/mL). Peptides responsible for the ACE-inhibitory activity were isolated by reverse-phase high-performance liquid chromatography (HPLC). Three fractions, showing the highest inhibitory activity, were selected for tandem mass spectrometry (MS/MS) experiments. Eleven of the identified sequences have previously been described as ACE-inhibitors. Most of the identified bioactive peptides have a hydrophobic amino acid, (iso)leucine or phenylalanine, or proline at the C-terminal position, which is crucial for their ACE-inhibitory activity. The sequence of some peptides allowed us to anticipate the presence of ACE-inhibitory activity.

α-Synuclein aggregation, seeding and inhibition by scyllo-inositol

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ibrahim, Tarek; Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, M4N 3M5, ON; McLaurin, JoAnne, E-mail: jmclaurin@sri.utoronto.ca

2016-01-15

Recent literature demonstrates the accelerated aggregation of α-synuclein, a protein implicated in the pathogenesis of Parkinson's disease (PD), by the presence of preformed fibrillar conformers in vitro. Furthermore, these preformed fibrillar seeds are suggested to accelerate pathological induction in vivo when injected into the brains of mice. Variation in the results of in vivo studies is proposed to be caused by α-synuclein conformational variants. To investigate the impact of amino acid sequence on seeding efficiency, human and mouse α-synuclein seeds, which vary at 7 amino acid residues, were generated and cross-seeding kinetics studied. Using transmission electron microscopy (TEM), we confirmed that mouse α-synucleinmore » aggregated more rapidly than human α-synuclein. Subsequently, we determined that seeding of human and mouse α-synuclein was more rapid in the presence of seeds generated from the same species. In addition, an established amyloid inhibitor, scyllo-inositol, was examined for potential inhibitory effects on α-synuclein aggregation. TEM analysis of protein:inhibitor assays demonstrated that scyllo-inositol inhibits the aggregation of α-synuclein, suggesting the therapeutic potential of the small molecule in PD. - Highlights: • Mouse α-syn fibrillizes in a significantly shorter timeframe than human α-syn. • Seeding of monomers is more efficient when seeds originate from the same species. • scyllo-Inositol has anti-aggregation effects on mouse and human α-syn.« less

Feeding deterrent and growth inhibitory activities of PONNEEM, a newly developed phytopesticidal formulation against Helicoverpa armigera (Hubner)

PubMed Central

Packiam, Soosaimanickam Maria; Baskar, Kathirvelu; Ignacimuthu, Savarimuthu

2014-01-01

Objective To assess the feeding deterrent, growth inhibitory and egg hatchability effects of PONNEEM on Helicoverpa armigera (H. armigera). Methods Five oil formulations were prepared at different ratios to assess the feeding deterrent, growth inhibitory and egg hatchability effects on H. armigera. Results Invariably all the newly formulated phytopesticidal oil formulations showed the feeding deterrent and growth inhibitory activities against H. armigera. The maximum feeding deterrent activity of 88.44% was observed at 15 µL/L concentration of PONNEEM followed by formulation A (74.54%). PONNEEM was found to be effective in growth inhibitory activities and egg hatchability at 10 µL/L concentration. It exhibited statistically significant feeding deterrent activity and growth inhibitory activity compared with all the other treatments. Conclusions PONNEEM was found to be effective phytopesticidal formulation to control the larval stage of H. armigera. This is the first report for the feeding deterrent activity of PONNEEM against H. armigera. This newly formulated phytopesticide was patented in India. PMID:25183105

High-throughput screening for modulators of ACVR1 transcription: discovery of potential therapeutics for fibrodysplasia ossificans progressiva

PubMed Central

Cappato, Serena; Tonachini, Laura; Giacopelli, Francesca; Tirone, Mario; Galietta, Luis J. V.; Sormani, Martina; Giovenzana, Anna; Spinelli, Antonello E.; Canciani, Barbara; Brunelli, Silvia; Ravazzolo, Roberto

2016-01-01

ABSTRACT The ACVR1 gene encodes a type I receptor of bone morphogenetic proteins (BMPs). Activating mutations in ACVR1 are responsible for fibrodysplasia ossificans progressiva (FOP), a rare disease characterized by congenital toe malformation and progressive heterotopic endochondral ossification leading to severe and cumulative disability. Until now, no therapy has been available to prevent soft-tissue swelling (flare-ups) that trigger the ossification process. With the aim of finding a new therapeutic strategy for FOP, we developed a high-throughput screening (HTS) assay to identify inhibitors of ACVR1 gene expression among drugs already approved for the therapy of other diseases. The screening, based on an ACVR1 promoter assay, was followed by an in vitro and in vivo test to validate and characterize candidate molecules. Among compounds that modulate the ACVR1 promoter activity, we selected the one showing the highest inhibitory effect, dipyridamole, a drug that is currently used as a platelet anti-aggregant. The inhibitory effect was detectable on ACVR1 gene expression, on the whole Smad-dependent BMP signaling pathway, and on chondrogenic and osteogenic differentiation processes by in vitro cellular assays. Moreover, dipyridamole reduced the process of heterotopic bone formation in vivo. Our drug repositioning strategy has led to the identification of dipyridamole as a possible therapeutic tool for the treatment of FOP. Furthermore, our study has also defined a pipeline of assays that will be useful for the evaluation of other pharmacological inhibitors of heterotopic ossification. PMID:27125279

Molecules of the quinoline family block tau self-aggregation: implications toward a therapeutic approach for Alzheimer's disease.

PubMed

Navarrete, Leonardo P; Guzmán, Leonardo; San Martín, Aurelio; Astudillo-Saavedra, Luis; Maccioni, Ricardo B

2012-01-01

The neurofibrillary tangles (NFTs) generated by self-aggregation of anomalous forms of tau represent a neuropathological hallmark of Alzheimer's disease (AD). These lesions begin to form long before the clinical manifestation of AD, and its severity is correlated with cognitive impairment in patients. We focused on the search for molecules that interact with aggregated tau of the Alzheimer's type and that may block its aggregation before the formation of NFTs. We show that molecules from a family of quinolines interact specifically with oligomeric forms of tau, inhibiting their assembly into AD filaments. The quinolines 2-(4-methylphenyl)-6-methyl quinoline (THQ-4S) and 2-(4-aminophenyl)-6-methylquinoline (THQ-55) inhibited in vitro aggregation of heparin-induced polymers of purified brain tau and aggregates of human recombinant tau. They also interact with paired helical filaments (PHFs) purified from AD postmortem brains. In vitro studies indicated a significantly lower inhibitory effect of amyloid-β42 on the aggregation, suggesting that tau aggregates are specific targets for quinoline interactions. These compounds showed highly lipophilic properties as corroborated with the analysis of total polar surface areas, and evaluation of their molecular properties. Moreover, these quinolines exhibit physical chemical properties similar to drugs able to penetrate the human brain blood barrier. Docking studies based on tau modeling, as a structural approach to the analysis of the interaction of tau-binding ligands, indicated that a C-terminal tau moiety, involved in the formation of PHFs, seems to be a site for binding of quinolines. Studies suggest the potential clinical use of these quinolines and of their derivatives to inhibit tau aggregation and possible therapeutic routes for AD.

Studies on the in vitro and in vivo antiurolithic activity of Holarrhena antidysenterica.

PubMed

Khan, Aslam; Khan, Saeed R; Gilani, Anwar H

2012-12-01

Holarrhena antidysenterica has a traditional use in the treatment of urolithiasis, therefore, its crude extract has been investigated for possible antiurolithic effect. The crude aqueous-methanolic extract of Holarrhena antidysenterica (Ha.Cr) was studied using the in vitro and in vivo methods. In the in vitro experiments, Ha.Cr demonstrated a concentration-dependent (0.25-4 mg/ml) inhibitory effect on the slope of aggregation. It decreased the size of crystals and transformed the calcium oxalate monohydrate (COM) to calcium oxalate dehydrate (COD) crystals, in calcium oxalate metastable solutions. It also showed concentration-dependent antioxidant effect against 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radicals and lipid peroxidation induced in rat kidney tissue homogenate. Ha.Cr (0.3 mg/ml) reduced (p < 0.05) the cell toxicity and LDH release in renal epithelial cells (MDCK) exposed to oxalate (0.5 mM) and COM (66 μg/cm(2)) crystals. In male Wistar rats, receiving 0.75 % ethylene glycol (EG) for 21 days along with 1 % ammonium chloride (AC) in drinking water, Ha.Cr treatment (30-100 mg/kg) prevented the toxic changes caused by lithogenic agents; EG and AC, like loss of body weight, polyurea, oxaluria, raised serum urea and creatinine levels and crystal deposition in kidneys compared to their respective controls. These data indicate that Holarrhena antidysenterica possesses antiurolithic activity, possibly mediated through the inhibition of CaOx crystal aggregation, antioxidant and renal epithelial cell protective activities and may provide base for designing future studies to establish its efficacy and safety for clinical use.

Comparative Effect of Quercetin and Quercetin-3-O-β-d-Glucoside on Fibrin Polymers, Blood Clots, and in Rodent Models.

PubMed

Choi, Jun-Hui; Kim, Kyung-Je; Kim, Seung

2016-11-01

The present study evaluates the in vitro, in vivo, and ex vivo antithrombotic and anticoagulant effect of two flavonoids: quercetin and quercetin-3-O-β-d-glucoside (isoquercetin). The present results have shown that quercetin and isoquercetin inhibit the enzymatic activity of thrombin and FXa and suppress fibrin clot formation and blood clotting. The prolongation effect of quercetin and isoquercetin against epinephrine and collagen-induced platelet activation may have been caused by intervention in intracellular signaling pathways including coagulation cascade and aggregation response on platelets and blood. The in vivo and ex vivo anticoagulant efficacy of quercetin and isoquercetin was evaluated in thrombin-induced acute thromboembolism model and in ICR mice. Our findings showed that in vitro and in vivo inhibitory effects of quercetin were slightly higher than that of quercetin glucoside, whereas in vitro and ex vivo anticoagulant effects of quercetin were weaker than that of quercetin glucoside because of their structural characteristics. © 2016 Wiley Periodicals, Inc.

Testosterone 5alpha-reductase inhibitory active constituents of Piper nigrum leaf.

PubMed

Hirata, Noriko; Tokunaga, Masashi; Naruto, Shunsuke; Iinuma, Munekazu; Matsuda, Hideaki

2007-12-01

Previously we reported that Piper nigrum leaf extract showed a potent stimulation effect on melanogenesis and that (-)-cubebin (1) and (-)-3,4-dimethoxy-3,4-desmethylenedioxycubebin (2) were isolated as active constituents. As a part of our continuous studies on Piper species for the development of cosmetic hair-care agents, testosterone 5alpha-reductase inhibitory activity of aqueous ethanolic extracts obtained from several different parts of six Piper species, namely Piper nigrum, P. methysticum, P. betle, P. kadsura, P. longum, and P. cubeba, were examined. Among them, the extracts of P. nigrum leaf, P. nigrum fruit and P. cubeba fruit showed potent inhibitory activity. Activity-guided fractionation of P. nigrum leaf extract led to the isolation of 1 and 2. Fruits of P. cubeba contain 1 as a major lignan, thus inhibitory activity of the fruit may be attributable to 1. As a result of further assay on other known constituents of the cited Piper species, it was found that piperine, a major alkaloid amide of P. nigrum fruit, showed potent inhibitory activity, thus a part of the inhibitory activity of P. nigrum fruit may depend on piperine. The 5alpha-reductase inhibitory activities of 1 and piperine were found for the first time. In addition, the P. nigrum leaf extract showed in vivo anti-androgenic activity using the hair regrowth assay in testosterone sensitive male C57Black/6CrSlc strain mice.

Lactobacillus crispatus Dominant Vaginal Microbiome Is Associated with Inhibitory Activity of Female Genital Tract Secretions against Escherichia coli

PubMed Central

Chen, Zigui; Buckley, Niall; Lo, Yungtai; Ratner, Adam J.

2014-01-01

Objective Female genital tract secretions inhibit E. coli ex vivo and the activity may prevent colonization and provide a biomarker of a healthy microbiome. We hypothesized that high E. coli inhibitory activity would be associated with a Lactobacillus crispatus and/or jensenii dominant microbiome and differ from that of women with low inhibitory activity. Study Design Vaginal swab cell pellets from 20 samples previously obtained in a cross-sectional study of near-term pregnant and non-pregnant healthy women were selected based on having high (>90% inhibition) or low (<20% inhibition) anti-E. coli activity. The V6 region of the 16S ribosomal RNA gene was amplified and sequenced using the Illumina HiSeq 2000 platform. Filtered culture supernatants from Lactobacillus crispatus, Lactobacillus iners, and Gardnerella vaginalis were also assayed for E. coli inhibitory activity. Results Sixteen samples (10 with high and 6 with low activity) yielded evaluable microbiome data. There was no difference in the predominant microbiome species in pregnant compared to non-pregnant women (n = 8 each). However, there were significant differences between women with high compared to low E. coli inhibitory activity. High activity was associated with a predominance of L. crispatus (p<0.007) and culture supernatants from L. crispatus exhibited greater E. coli inhibitory activity compared to supernatants obtained from L. iners or G. vaginalis. Notably, the E. coli inhibitory activity varied among different strains of L. crispatus. Conclusion Microbiome communities with abundant L. crispatus likely contribute to the E. coli inhibitory activity of vaginal secretions and efforts to promote this environment may prevent E. coli colonization and related sequelae including preterm birth. PMID:24805362

Design, synthesis and multitarget biological profiling of second-generation anti-Alzheimer rhein-huprine hybrids.

PubMed

Pérez-Areales, Francisco Javier; Betari, Nibal; Viayna, Antonio; Pont, Caterina; Espargaró, Alba; Bartolini, Manuela; De Simone, Angela; Rinaldi Alvarenga, José Fernando; Pérez, Belén; Sabate, Raimon; Lamuela-Raventós, Rosa Maria; Andrisano, Vincenza; Luque, Francisco Javier; Muñoz-Torrero, Diego

2017-06-01

Simultaneous modulation of several key targets of the pathological network of Alzheimer's disease (AD) is being increasingly pursued as a promising option to fill the critical gap of efficacious drugs against this condition. A short series of compounds purported to hit multiple targets of relevance in AD has been designed, on the basis of their distinct basicities estimated from high-level quantum mechanical computations, synthesized, and subjected to assays of inhibition of cholinesterases, BACE-1, and Aβ42 and tau aggregation, of antioxidant activity, and of brain permeation. Using, as a template, a lead rhein-huprine hybrid with an interesting multitarget profile, we have developed second-generation compounds, designed by the modification of the huprine aromatic ring. Replacement by [1,8]-naphthyridine or thieno[3,2-e]pyridine systems resulted in decreased, although still potent, acetylcholinesterase or BACE-1 inhibitory activities, which are more balanced relative to their Aβ42 and tau antiaggregating and antioxidant activities. Second-generation naphthyridine- and thienopyridine-based rhein-huprine hybrids emerge as interesting brain permeable compounds that hit several crucial pathogenic factors of AD.

Design, synthesis and biological evaluation of multifunctional tacrine-curcumin hybrids as new cholinesterase inhibitors with metal ions-chelating and neuroprotective property.

PubMed

Liu, Zhikun; Fang, Lei; Zhang, Huan; Gou, Shaohua; Chen, Li

2017-04-15

Total sixteen tacrine-curcumin hybrid compounds were designed and synthesized for the purpose of searching for multifunctional anti-Alzheimer agents. In vitro studies showed that these hybrid compounds showed good cholinesterase inhibitory activity. Particularly, the potency of K 3-2 is even beyond tacrine. Some of the compounds exhibited different selectivity on acetylcholinesterase or butyrylcholinesterase due to the structural difference. Thus, the structure and activity relationship is summarized and further discussed based on molecular modeling studies. The ORAC and MTT assays indicated that the hybrid compounds possessed pronounced antioxidant activity and could effectively protect PC12 cells from the H 2 O 2 /Aβ42-induced toxicity. Moreover, the hybrid compounds also showed positive metal ions-chelating ability in vitro, suggesting a potential to halt ion-induced Aβ aggregation. All the obtained results demonstrated that the tacrine-curcumin hybrid compounds, in particular compound K 3-2 , can be considered as potential therapeutic agents for Alzheimer's disease. Copyright © 2017 Elsevier Ltd. All rights reserved.

Iron(II) supramolecular helicates condense plasmid DNA and inhibit vital DNA-related enzymatic activities.

PubMed

Malina, Jaroslav; Hannon, Michael J; Brabec, Viktor

2015-07-27

The dinuclear iron(II) supramolecular helicates [Fe2 L3 ]Cl4 (L=C25 H20 N4 ) bind to DNA through noncovalent (i.e., hydrogen-bonding, electrostatic) interactions and exhibit antimicrobial and anticancer effects. In this study, we show that the helicates condense plasmid DNA with a much higher potency than conventional DNA-condensing agents. Notably, molecules of DNA in the presence of the M enantiomer of [Fe2 L3 ]Cl4 do not form intermolecular aggregates typically formed by other condensing agents, such as spermidine or spermine. The helicates inhibit the activity of several DNA-processing enzymes, such as RNA polymerase, DNA topoisomerase I, deoxyribonuclease I, and site-specific restriction endonucleases. However, the results also indicate that the DNA condensation induced by the helicates does not play a crucial role in these inhibition reactions. The mechanisms for the inhibitory effects of [Fe2 L3 ]Cl4 helicates on DNA-related enzymatic activities have been proposed. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Triflavin, an Arg‐Gly‐Asp‐containing Peptide, Inhibits Tumor Cell‐induced Platelet Aggregation

PubMed Central

Sheu, Joen R.; Lin, Chao H.; Peng, Hui C.; Teng, Che M.

1993-01-01

In this study, we examined the effect of triflavin, an Arg‐Gly‐Asp (RGD)‐containing snake venom peptide, on human cervical carcinoma (HeLa) cell‐ and B16‐F10 mouse melanoma cell‐induced platelet aggregation (TCIPA) in heparinized platelet‐rich plasma. TCIPA appears to play an important role in the development of certain experimental tumor metastases. Two ADP‐scavenging agents, apyrase (10 U/ml) and creatine phosphate (CP) (5 mM)/creatine phosphokinase (CPK) (5 U/ml) completely inhibited B16‐F10 TCIPA, but hirudin (5 U/ml) had no effect. In contrast, apyrase and CP/CPK did not inhibit HeLa TCIPA while hirudin completely inhibited it. Furthermore, HeLa cells initially induced platelet aggregation and then blood coagulation at a later stage. In addition, HeLa cells shortened, in a concentration‐dependent manner, the recalcification time of normal as well as factor VIII‐ and IX‐deficient human plasma, but did not affect the recalciflcation time of factor VII‐deficient plasma. This suggests that HeLa TCIPA occurs via activation of the extrinsic pathway, probably owing to tumor cell expression of tissue factor‐like activity. HeLa cell‐induced thrombin generation was confirmed by detection of amidolytic activity towards a chromogenic substrate, S‐2238 (H‐D‐Phe‐Pip‐Arg‐p‐NA). Triflavin and GRGDS inhibited, in a dose‐dependent manner, TCIPA caused by either cell line. On a molar basis, triflavin was 10,000–30,000 times more potent than GRGDS in this regard. Moreover, monoclonal antibodies raised against glycoprotein (GP) IIb/IIIa complex (i.e., 7E3 and AP2) and against GP Ib (i.e., AP1) completely inhibited HeLa TCIPA. 7E3 and AP2 inhibited B16‐F10 TCIPA by up to 80% whereas AP1 showed only 30% inhibition of B16‐F10 TCIPA. In conclusion, the inhibitory effect of triflavin on HeLa and B16‐F10 TCIPA may be mediated principally by the binding of triflavin to the fibrinogen receptor associated with GP IIb/IIIa complex on the platelet surface. However, GP Ib is also involved in HeLa TCIPA as thrombin formation is the key factor in triggering platelet aggregation caused by HeLa cells. PMID:8226281

Soluble Aβ aggregates can inhibit prion propagation.

PubMed

Sarell, Claire J; Quarterman, Emma; Yip, Daniel C-M; Terry, Cassandra; Nicoll, Andrew J; Wadsworth, Jonathan D F; Farrow, Mark A; Walsh, Dominic M; Collinge, John

2017-11-01

Mammalian prions cause lethal neurodegenerative diseases such as Creutzfeldt-Jakob disease (CJD) and consist of multi-chain assemblies of misfolded cellular prion protein (PrP C ). Ligands that bind to PrP C can inhibit prion propagation and neurotoxicity. Extensive prior work established that certain soluble assemblies of the Alzheimer's disease (AD)-associated amyloid β-protein (Aβ) can tightly bind to PrP C , and that this interaction may be relevant to their toxicity in AD. Here, we investigated whether such soluble Aβ assemblies might, conversely, have an inhibitory effect on prion propagation. Using cellular models of prion infection and propagation and distinct Aβ preparations, we found that the form of Aβ assemblies which most avidly bound to PrP in vitro also inhibited prion infection and propagation. By contrast, forms of Aβ which exhibit little or no binding to PrP were unable to attenuate prion propagation. These data suggest that soluble aggregates of Aβ can compete with prions for binding to PrP C and emphasize the bidirectional nature of the interplay between Aβ and PrP C in Alzheimer's and prion diseases. Such inhibitory effects of Aβ on prion propagation may contribute to the apparent fall-off in the incidence of sporadic CJD at advanced age where cerebral Aβ deposition is common. © 2017 The Authors.

Novel pH responsive polymethacrylic acid-chitosan-polyethylene glycol nanoparticles for oral peptide delivery.

PubMed

Sajeesh, S; Sharma, Chandra P

2006-02-01

In present study, novel pH sensitive polymethacrylic acid-chitosan-polyethylene glycol (PCP) nanoparticles were prepared under mild aqueous conditions via polyelectrolyte complexation. Free radical polymerization of methacrylic acid (MAA) was carried out in presence of chitosan (CS) and polyethylene glycol (PEG) using a water-soluble initiator and particles were obtained spontaneously during polymerization without using organic solvents or surfactants/steric stabilizers. Dried particles were analyzed by scanning electron microscopy (SEM) and particles dispersed in phosphate buffer (pH 7.0) were visualized under transmission electron microscope (TEM). SEM studies indicated that PCP particles have an aggregated and irregular morphology, however, TEM revealed that these aggregated particles were composed of smaller fragments with size less than 1 micron. Insulin and bovine serum albumin (BSA) as model proteins were incorporated into the nanoparticles by diffusion filling method and their in vitro release characteristics were evaluated at pH 1.2 and 7.4. PCP nanoparticles exhibited good protein encapsulation efficiency and pH responsive release profile was observed under in vitro conditions. Trypsin inhibitory effect of these PCP nanoparticles was studied using casein substrate and these particles displayed lesser inhibitory effect than reference polymer carbopol. Preliminary investigation suggests that these particles can serve as good candidate for oral peptide delivery. Copyright 2005 Wiley Periodicals, Inc.

Separation and Characterization of Angiotensin I Converting Enzyme (ACE) Inhibitory Peptides from Saurida elongata Proteins Hydrolysate by IMAC-Ni2.

PubMed

Sun, Lixia; Wu, Shanguang; Zhou, Liqin; Wang, Feng; Lan, Xiongdiao; Sun, Jianhua; Tong, Zhangfa; Liao, Dankui

2017-02-15

Lizard fish protein hydrolysates (LFPH) were prepared from Lizard fish ( Saurida elongata ) proteins possessing powerful angiotensin I converting enzyme (ACE) inhibitory activity and the fraction (LFPH-I) with high ACE inhibitory activity was obtained through ultrafiltration. The active Fraction (F2) was isolated from LFPH-I using immobilized metal affinity chromatography (IMAC - Ni 2+ ). Analysis of amino acid levels revealed that F2 eluted from IMAC was enriched in Met, His, Tyr, Pro, Ile, and Leu compared to the crude peptide LFPH-I. F2 with the high ACE inhibitory activity (IC 50 of 0.116 mg·mL -1 ) was further separated by a reverse-phase column to yield a novel ACE inhibitory peptide with IC 50 value of 52 μM. The ACE inhibitory peptide was identified as Arg-Tyr-Arg-Pro, RYRP. The present study demonstrated that IMAC may be a useful tool for the separation of ACE inhibitory peptides from protein hydrolysate.

The persistent inhibitory properties of saxagliptin on renal dipeptidyl peptidase-4: Studies with HK-2 cells in vitro and normal rats in vivo.

PubMed

Uchii, Masako; Sakai, Mariko; Hotta, Yuhei; Saeki, Satoshi; Kimoto, Naoya; Hamaguchi, Akinori; Kitayama, Tetsuya; Kunori, Shunji

2017-11-01

Saxagliptin, a potent and selective DPP-4 inhibitor, exhibits a slow dissociation from DPP-4. We investigated the sustained effects of saxagliptin on renal DPP-4 activity in a washout study using renal tubular (HK-2) cells, and in a pharmacodynamic study using normal rats. In HK-2 cells, the inhibitory potency of saxagliptin on DPP-4 activity persisted after washout, while that of sitagliptin was clearly reduced. In normal rats, a single treatment of saxagliptin or sitagliptin inhibited the plasma DPP-4 activity to similar levels. The inhibitory action of saxagliptin on the renal DPP-4 activity was retained, even when its inhibitory effect on the plasma DPP-4 activity disappeared. However, the inhibitory action of sitagliptin on the renal DPP-4 activity was abolished in correlation with the inhibition of the plasma DPP-4 activity. In situ staining showed that saxagliptin suppressed the DPP-4 activity in both glomerular and tubular cells and its inhibitory effects were significantly higher than those of sitagliptin. Saxagliptin exerted a sustained inhibitory effect on the renal DPP-4 activity in vitro and in vivo. The long binding action of saxagliptin in renal tubular cells might involve the sustained inhibition of renal DPP-4. Copyright © 2017 The Authors. Production and hosting by Elsevier B.V. All rights reserved.

Novel sarsasapogenin-triazolyl hybrids as potential anti-Alzheimer's agents: Design, synthesis and biological evaluation.

PubMed

Wang, Wenbao; Wang, Wei; Yao, Guodong; Ren, Qiang; Wang, Di; Wang, Zedan; Liu, Peng; Gao, Pinyi; Zhang, Yan; Wang, Shaojie; Song, Shaojiang

2018-05-10

Sarsasapogenin, an active ingredient in Rhizoma anemarrhenae, is a promising bioactive lead compound in the treatment of Alzheimer's disease. To search for more efficient anti-Alzheimer agents, a series of novel sarsasapogenin-triazolyl hybrids were designed, synthesized, and evaluated for their Aβ 1-42 aggregation inhibitory activities. Most of these new hybrids displayed potent Aβ 1-42 aggregation inhibition. In particular, the promising compounds 6j and 6o displayed a better ability to interrupt the formation of Aβ 1-42 fibrils than curcumin. Moreover, 6j and 6o exhibited moderate neuroprotective effects against H 2 O 2 -induced neurotoxicity in SH-SY5Y cells. To investigate whether 6j and 6o could improve cognitive deficits, we performed behavioral tests to examine the learning and memory impairments induced by intracerebroventricular injection of Aβ 1-42 (ICV-Aβ 1-42 ) in mice and TUNEL staining to observe neuronal apoptosis in the hippocampus. The results obtained indicated that oral treatment with 6j and 6o significantly ameliorated cognitive impairments in behavioral tests and TUNEL staining showed that 6j and 6o attenuated neuronal loss in the brain. Taken together, the results we obtained showed that the sarsasapogenin skeleton could be a promising structural template for the development of new anti-Alzheimer drug candidates, and compounds 6j and 6o have the potential to be important lead compounds for further research. Copyright © 2018 Elsevier Masson SAS. All rights reserved.

Modulation of α-synuclein fibrillization by ring-fused 2-pyridones: templation and inhibition involve oligomers with different structure.

PubMed

Horvath, Istvan; Sellstedt, Magnus; Weise, Christoph; Nordvall, Lina-Maria; Krishna Prasad, G; Olofsson, Anders; Larsson, Göran; Almqvist, Fredrik; Wittung-Stafshede, Pernilla

2013-04-15

In a recent study we discovered that a ring-fused 2-pyridone compound triggered fibrillization of a key protein in Parkinson's disease, α-synuclein. To reveal how variations in compound structure affect protein aggregation, we now prepared a number of strategic analogs and tested their effects on α-synuclein amyloid fiber formation in vitro. We find that, in contrast to the earlier templating effect, some analogs inhibit α-synuclein fibrillization. For both templating and inhibiting compounds, the key species formed in the reactions are α-synuclein oligomers that contain compound. Despite similar macroscopic appearance, the templating and inhibiting oligomers are distinctly different in secondary structure content. When the inhibitory oligomers are added in seed amounts, they inhibit fresh α-synuclein aggregation reactions. Our study demonstrates that small chemical changes to the same central fragment can result in opposite effects on protein aggregation. Copyright © 2013 Elsevier Inc. All rights reserved.

The inhibition of Clostridium botulinum type C by other bacteria in wetland sediments

USGS Publications Warehouse

Sandler, Renee J.; Rocke, Tonie E.; Yuill, Thomas M.

1998-01-01

Bacteria with inhibitory activity against Clostridium botulinum type C were isolated from 32% of sediment samples (n = 1600) collected from 10 marshes in a northern California wetland over a 12 mo period. Aerobic and anaerobic bacteria with inhibitory activity were isolated from 12% and 23% of the samples, respectively. Bacteria with inhibitory activity were isolated from all 10 study sites and throughout the year. This study demonstrates that bacteria with inhibitory activity against C. botulinum type C occur naturally in wetland sediments.

Synthesis, characterization and cholinesterase enzymes inhibitory activity of 1-[3-methyl-5-(2,6,6-trimethyl-cyclohex-1-enyl)-4,5-dihydro-pyrazol-1-yl]-ethanone

NASA Astrophysics Data System (ADS)

Mehdi, Sayed Hasan; Ghalib, Raza Murad; Hashim, Rokiah; da Silva, M. Fátima C. Guedes; Sulaiman, Othman; Murugaiyah, Vikneswaran; Marimuthu, Mani Maran; Naqvi, Mehnaz

2013-10-01

The crystal structure of the title compound, 1-[3-methyl-5-(2,6,6-trimethyl-cyclohex-1-enyl)-4,5-dihydro-pyrazol-1-yl]-ethanone has been determined by single crystal X-ray diffraction. It crystallizes in the orthorhombic space group P212121. The FTIR as well as the 1H and 13C NMR spectra of the compound were also recorded and briefly discussed. Compound 1 demonstrated good inhibitory activity against butyrylcholinesterase (BChE; IC50 = 46.42 μM) comparable to physostigmine. However it showed moderate inhibitory activity against acetylcholinesterase (AChE; IC50 = 157.31 μM). It showed moderate inhibitory activity against acetylcholinesterase and selective inhibitory activity towards butyrylcholinesterase enzyme.

Synthesis of Amide and Ester Derivatives of Cinnamic Acid and Its Analogs: Evaluation of Their Free Radical Scavenging and Monoamine Oxidase and Cholinesterase Inhibitory Activities.

PubMed

Takao, Koichi; Toda, Kazuhiro; Saito, Takayuki; Sugita, Yoshiaki

2017-01-01

A series of cinnamic acid derivatives, amides (1-12) and esters (13-22), were synthesized, and structure-activity relationships for antioxidant activity, and monoamine oxidases (MAO) A and B, acetylcholinesterase, and butyrylcholinesterase (BChE) inhibitory activities were analyzed. Among the synthesized compounds, compounds 1-10, 12-18, and rosmarinic acid (23), which contained catechol, o-methoxyphenol or 5-hydroxyindole moieties, showed potent 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging activity. Compounds 9-11, 15, 17-22 showed potent and selective MAO-B inhibitory activity. Compound 20 was the most potent inhibitor of MAO-B. Compounds 18 and 21 showed moderate BChE inhibitory activity. In addition, compound 18 showed potent antioxidant activity and MAO-B inhibitory activity. In a comparison of the cinnamic acid amides and esters, the amides exhibited more potent DPPH free radical scavenging activity, while the esters showed stronger inhibitory activities against MAO-B and BChE. These results suggested that cinnamic acid derivatives such as compound 18, p-coumaric acid 3,4-dihydroxyphenethyl ester, and compound 20, p-coumaric acid phenethyl ester, may serve as lead compounds for the development of novel MAO-B inhibitors and candidate lead compounds for the prevention or treatment of Alzheimer's disease.

Pharmacologic antagonism of thromboxane A2 receptors by trimetoquinol analogs in vitro and in vivo

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shin, Y.; Romstedt, K.J.; Doyle, K.

1991-01-01

Although (-)-(S)-trimetoquinol (1-(3,4,5-trimethoxy-benzyl)- 6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline; TMQ) is recognized as a potent bronchodilator, (+)-(R)-TMQ is a selective antagonist of human platelet aggregation and serotonin secretion induced by thromboxane A2 (TXA2) agonists. To confirm the pharmacological actions of TMQ analogs, the interaction of the drugs with TXA2 receptors was examined in human platelets and in a mouse sudden death model. The inhibitory potencies of TMQ analogs (pIC50 values) for displacement of (3H)SQ 29,548 binding to platelets showed excellent correlation with the respective pIC50 (-log IC50) values for U46619-induced aggregation (r = 0.99, P less than 0.01) and serotonin secretion (r = 0.99, Pmore » less than 0.01) in human platelet-rich plasma and for whole blood aggregation (r = 0.99, P less than 0.01). In each system, the rank order of inhibitory potencies was rac-iodoTMQ greater than or equal to (+)-(R)-TMQ greater than rac-TMQ much greater than (-)-(S)-TMQ. Antithrombotic effects of TMQ analogs were evaluated in a mouse sudden death model. In vivo antithrombotic potencies of these compounds were consistent with the in vitro potencies as TXA2 receptor antagonists in platelet systems. Administration of rac-iodoTMQ, (+)-(R)-TMQ and rac-TMQ 15 min before the injection of U46619 (800 micrograms/kg, iv) protected mice against U46619-induced sudden death. On the other hand, (-)-(S)-TMQ did not protect animals against death. Protection of U46619-induced cardiopulmonary thrombosis by TMQ analogs was seen at doses of 3-100 mg/kg.« less

Crystallization and preliminary X-ray diffraction studies of BmooPLA2-I, a platelet-aggregation inhibitor and hypotensive phospholipase A2 from Bothrops moojeni venom

PubMed Central

Salvador, Guilherme H. M.; Marchi-Salvador, Daniela P.; Silveira, Lucas B.; Soares, Andreimar M.; Fontes, Marcos R. M.

2011-01-01

Phospholipases A2 (PLA2s) are enzymes that cause the liberation of fatty acids and lysophospholipids by the hydrolysis of membrane phospholipids. In addition to their catalytic action, a wide variety of pharmacological activities have been described for snake-venom PLA2s. BmooPLA2-I is an acidic, nontoxic and catalytic PLA2 isolated from Bothrops moojeni snake venom which exhibits an inhibitory effect on platelet aggregation, an immediate decrease in blood pressure, inducing oedema at a low concentration, and an effective bactericidal effect. BmooPLA2-I has been crystallized and X-ray diffraction data have been collected to 1.6 Å resolution using a synchrotron-radiation source. The crystals belonged to space group C2221, with unit-cell parameters a = 39.7, b = 53.2, c = 89.2 Å. The molecular-replacement solution of BmooPLA2-I indicated a monomeric conformation, which is in agreement with nondenaturing electrophoresis and dynamic light-scattering experiments. A comparative study of this enzyme with the acidic PLA2 from B. jararacussu (BthA-I) and other toxic and nontoxic PLA2s may provide important insights into the functional aspects of this class of proteins. PMID:21821890

The transformation of hexabromocyclododecane using zerovalent iron nanoparticle aggregates.

PubMed

Tso, Chih-ping; Shih, Yang-hsin

2014-07-30

Hexabromocyclododecane (HBCD), an emerging contaminant, is a brominated flame retardant that has been widely detected in the environment. In this study, nanoscale zerovalent iron (NZVI) aggregates are firstly used to treat HBCD and its removal under different geochemical conditions is evaluated. HBCD is almost removed from solutions by NZVI, with a kSA of 4.22×10(-3)Lm(-2)min(-1). An increase in the iron dosage and temperature increases the removal rate. The activation energy for the removal of HBCD by NZVI is 30.2kJmol(-1), which suggests that a surface-chemical reaction occurs on NZVI. HBCD is adsorbed on the NZVI surface, where electrons were transferred to HBCD, and consequently forms byproducts with less bromide. Three common groundwater anions decrease the reaction kinetics and efficiency of NZVI. The kobs of HBCD in the presence of anions is in the order: pure water >Cl(-)>NO3(-)≒HCO3(-). The inhibitory effect of these anions may be a result of the possible complexation of anions with the oxidized iron surface. The oxidized sites on NZVI and oxidized species of iron also contribute to the removal of HBCD by adsorption on NZVI from solutions. Copyright © 2014 Elsevier B.V. All rights reserved.

Inhibitory Effects of Yuzu and Its Components on Human Platelet Aggregation

PubMed Central

Kim, Tae-Ho; Kim, Hye-Min; Park, Se Won; Jung, Yi-Sook

2015-01-01

Our previous study demonstrated that yuzu has an anti-platelet effect in rat blood. In the present study, we examined whether the anti-platelet effect of yuzu can be extended to human blood by investigating its ability to inhibit aggregations induced by various agonists in human platelet rich plasma (PRP). This study also investigated the underlying mechanism of yuzu focusing on ADP granule secretion, TXB2 formations, and PLCγ/Akt signaling. The results from this study showed that ethanolic yuzu extract (YE), and its components, hesperidin and naringin, inhibited human platelet aggregation in a concentration-dependent manner. YE, hesperidin and naringin also inhibited TXB2 formation and ADP release. The phosphorylation of PLCγ and Akt was significantly inhibited by YE, heperidin and naringin. Furthermore, we demonstrated that YE, heperidin and naringin has anti-platelet effects in rat ex vivo studies, and lower side effects in mice tail bleeding time studies. The results from this study suggest that YE, hesperidin and naringin can inhibit human platelet aggregation, at least partly through the inhibition of PLCγ and Akt, leading to a decrease in TXB2 formation and granule secretion. PMID:25767683

[Aluminum dissolution and changes of pH in soil solution during sorption of copper by aggregates of paddy soil].

PubMed

Xu, Hai-Bo; Zhao, Dao-Yuan; Qin, Chao; Li, Yu-Jiao; Dong, Chang-Xun

2014-01-01

Size fractions of soil aggregates in Lake Tai region were collected by the low-energy ultrasonic dispersion and the freeze-desiccation methods. The dissolution of aluminum and changes of pH in soil solution during sorption of Cu2+ and changes of the dissolution of aluminum at different pH in the solution of Cu2+ by aggregates were studied by the equilibrium sorption method. The results showed that in the process of Cu2+ sorption by aggregates, the aluminum was dissoluted and the pH decreased. The elution amount of aluminum and the decrease of pH changed with the sorption of Cu2+, both increasing with the increase of Cu2+ sorption. Under the same conditions, the dissolution of aluminum and the decrease of pH were in the order of coarse silt fraction > silt fraction > sand fraction > clay fraction, which was negatively correlated with the amount of iron oxide, aluminum and organic matter. It suggested that iron oxide, aluminum and organic matters had inhibitory and buffering effect on the aluminum dissolution and the decrease of pH during the sorption of Cu2+.

Time-dependent inhibition by glyceryl trinitrate of platelet aggregation caused by U46619 (a thromboxane/endoperoxide receptor agonist).

PubMed Central

Kampf, G; Ritter, J M

1994-01-01

Glyceryl trinitrate is a weak inhibitor of platelet aggregation in vitro. Its effect on platelet aggregation in response to U46619 (a thromboxane/endoperoxide receptor agonist) was studied turbidometrically in platelet-rich plasma from healthy volunteers. The object was to determine whether inhibition was influenced by a period of preincubation between preparation of platelet-rich plasma and addition of glyceryl trinitrate. Incubation was performed at 37 degrees C and 22 degrees C. Samples were removed at intervals and transferred to an aggregometer cuvette at 37 degrees C. Glyceryl trinitrate (100 microM) or an equal volume of distilled water was added 5 min before U46619 (2 microM), and aggregation recorded as change in light transmission. Inhibition by glyceryl trinitrate was markedly time and temperature dependent, with a progressive increase in inhibitory potency between 120 and 300 min preincubation at 37 degrees C but not at 22 degrees C. The explanation of this is unknown but the effect was not influenced by lipopolysaccharide or by cycloheximide, so it does not appear to be due to exposure to endotoxin or to enzyme induction in vitro. PMID:7946941

Oxyresveratrol, a Stilbene Compound from Morus alba L. Twig Extract Active Against Trichophyton rubrum.

PubMed

Lu, Hai-Peng; Jia, Ya-Nan; Peng, Ya-Lin; Yu, Yan; Sun, Si-Long; Yue, Meng-Ting; Pan, Min-Hui; Zeng, Ling-Shu; Xu, Li

2017-12-01

Morus alba L. (mulberry) twig is known to have an inhibitory effect on pathogens in traditional Chinese medicine. In the present study, the dermophytic fungus, Trichophyton rubrum, was used to evaluate the inhibitory effect of total M. alba twig extract and extracts obtained using solvents with different polarities by the method of 96-well MTT colorimetry. The main active substance was isolated and identified by tracking its activity. In addition, the inhibitory effects of active extracts and a single active substance were investigated in combination with miconazole nitrate. Our data indicated that ethyl acetate extracts of mulberry twig (TEE) exhibited a desired inhibitory activity on T. rubrum with the minimum inhibitory concentration (MIC) of 1.000 mg/mL. With activity tracking, the main substance showing antimicrobial activity was oxyresveratrol (OXY), which was isolated from TEE. Its MIC for inhibiting the growth of T. rubrum was 0.500 mg/mL. The combined use of miconazole nitrate and OXY showed a synergistic inhibitory effect, as shown by a significant decrease in the MIC of both components. Based on the OXY content in TEE, the contribution rate of OXY to the inhibitory effect of TEE on T. rubrum was 80.52%, so it was determined to be the main antimicrobial substance in M. alba twig. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

Mechanistic insights into mode of action of potent natural antagonists of BACE-1 for checking Alzheimer’s plaque pathology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dhanjal, Jaspreet Kaur; Goyal, Sukriti; Sharma, Sudhanshu

2014-01-17

Highlights: •Accumulation of Aβ plaques is one of the major pathology associated with Alzheimer’s disease. •Inhibition of β-Secretase or BACE-1 offers a viable prospect to check the growth of these plaques. •A large virtual dataset of natural compounds was screened against BACE-1. •Top two hits were analyzed for thermodynamic and structural stability using MD simulations. •Their detailed binding mode of actions were elucidated. -- Abstract: Alzheimer’s is a neurodegenerative disorder resulting in memory loss and decline in cognitive abilities. Accumulation of extracellular beta amyloidal plaques is one of the major pathology associated with this disease. β-Secretase or BACE-1 performs themore » initial and rate limiting step of amyloidic pathway in which 37–43 amino acid long peptides are generated which aggregate to form plaques. Inhibition of this enzyme offers a viable prospect to check the growth of these plaques. Numerous efforts have been made in recent years for the generation of BACE-1 inhibitors but many of them failed during the preclinical or clinical trials due to drug related or drug induced toxicity. In the present work, we have used computational methods to screen a large dataset of natural compounds to search for small molecules having BACE-1 inhibitory activity with low toxicity to normal cells. Molecular dynamics simulations were performed to analyze molecular interactions between the screened compounds and the active residues of the enzyme. Herein, we report two natural compounds of inhibitory nature active against β-secretase enzyme of amyloidic pathway and are potent lead molecules against Alzheimer’s disease.« less

Platelet Activation by Streptococcus pyogenes Leads to Entrapment in Platelet Aggregates, from Which Bacteria Subsequently Escape

PubMed Central

Svensson, Lisbeth; Baumgarten, Maria; Mörgelin, Matthias

2014-01-01

Platelet activation and aggregation have been reported to occur in response to a number of Gram-positive pathogens. Here, we show that platelet aggregates induced by Streptococcus pyogenes were unstable and that viable bacteria escaped from the aggregates over time. This was not due to differential activation in response to the bacteria compared with physiological activators. All the bacterial isolates induced significant platelet activation, including integrin activation and alpha and dense-granule release, at levels equivalent to those induced by potent physiological platelet activators that induced stable aggregates. The ability to escape the aggregates and to resist the antibacterial effects of platelets was dependent on active protein synthesis by the bacteria within the aggregate. We conclude that S. pyogenes bacteria can temporarily cover themselves with activated platelets, and we propose that this may facilitate survival of the bacteria in the presence of platelets. PMID:25069984

Characterization of angiotensin-converting enzyme inhibitory activity of fermented milk produced by Lactobacillus helveticus.

PubMed

Chen, Yongfu; Li, Changkun; Xue, Jiangang; Kwok, Lai-yu; Yang, Jie; Zhang, Heping; Menghe, Bilige

2015-08-01

Hypertension affects up to 30% of the adult population in most countries. It is a known risk factor for cardiovascular diseases, including coronary heart disease, peripheral artery disease, and stroke. Owing to the increased health awareness of consumers, the application of angiotensin-converting enzyme (ACE)-inhibitory peptides produced by Lactobacillushelveticus to prevent or control high blood pressure has drawn wide attention. A total of 59 L. helveticus strains were isolated from traditional fermented dairy products and the ACE-inhibitory activity of the fermented milks produced with the isolated microorganisms was assayed. The ACE-inhibitory activity of 38 L. helveticus strains was more than 50%, and 3 strains (IMAU80872, IMAU80852, and IMAU80851) expressing the highest ACE-inhibitory activity were selected for further studies. Particularly, the gastrointestinal protease tolerance and thermostability of the ACE-inhibitory activity in the fermented milks were assessed. Based on these 2 criteria, IMAU80872 was found to be superior over the other 2 strains. Furthermore, IMAU80872 exhibited a high in vitro ACE-inhibitory activity at the following fermentation conditions: fermentation temperature at 40°C, inoculation concentration of 1×10(6) cfu/mL, and fermentation for 18h. Finally, by using ultra-performance liquid chromatography coupled with electrospray ionization quadrupole time-of-flight tandem mass spectrometry analysis, we observed changes of the metabolome along the milk fermentation process of IMAU80872. Furthermore, 6 peptides were identified, which might have ACE-inhibitory activity. In conclusion, we identified a novel ACE-inhibitory L. helveticus strain suitable for the production of fermented milk or other functional dairy products. Copyright © 2015 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

In vitro effect of sodium nitrite on platelet aggregation in human platelet rich plasma--preliminary report.

PubMed

Kadan, M; Doğanci, S; Yildirim, V; Özgür, G; Erol, G; Karabacak, K; Avcu, F

2015-10-01

The role of nitrates and nitric oxide on platelet functions has obtained an increasing attention with respect to their potential effects on cardiovascular disorders. In this study we aimed to analyze the effect of sodium nitrite on platelet functions in human platelets. This in vitro study was designed to show the effect of sodium nitrite on platelet functions in seven healthy volunteers. Blood samples were centrifuged to prepare platelet rich plasma and platelet poor plasma. Platelet rich plasma was diluted with the platelet poor plasma to have a final count of 300,000 ± 25,000 platelets. Platelet rich plasma was incubated with six different increasing doses (from 10 μM to 5 mM) of sodium nitrite for 1 hour at 37°C. Then stimulating agents including collagen (3 μg ml-1), adenosine diphosphate (10 μM), and epinephrine (10 μM) were added to the cuvette. Changes in light transmission were observed for 10 minutes. In addition spontaneous aggregation were performed in control group with all aggregating agents separately. Effect of sodium nitrite on agonist-induced platelet aggregation depends on the concentration of sodium nitrite. Compared with control group, agonist-induced platelet aggregations were significantly suppressed by sodium nitrite at the concentration of 5, 1.0 and 0.5 mM. Our results suggested that sodium nitrite has inhibitory effects in vitro on platelet aggregation in a dose-dependent manner.

Activity-driven changes in the mechanical properties of fire ant aggregations

NASA Astrophysics Data System (ADS)

Tennenbaum, Michael; Fernandez-Nieves, Alberto

2017-11-01

Fire ant aggregations are active materials composed of individual constituents that are able to transform internal energy into work. We find using rheology and direct visualization that the aggregation undergoes activity cycles that affect the mechanical properties of the system. When the activity is high, the aggregation approximately equally stores and dissipates energy, it is more homogeneous, and exerts a high outward force. When the activity is low, the aggregation is predominantly elastic, it is more heterogeneous, and it exerts a small outward force. We rationalize our results using a simple kinetic model where the number of active ants within the aggregation is the essential quantity.

REM Theta Activity Enhances Inhibitory Control in Typically Developing Children but not Children with ADHD Symptoms

PubMed Central

Cremone, Amanda; Lugo-Candelas, Claudia I.; Harvey, Elizabeth A.; McDermott, Jennifer M.; Spencer, Rebecca M. C.

2017-01-01

Sleep disturbances impair cognitive functioning in typically developing populations. Children with attention-deficit/hyperactivity disorder (ADHD), a disorder characterized by impaired inhibitory control and attention, commonly experience sleep disturbances. Whether inhibitory impairments are related to sleep deficits in children with ADHD is unknown. Children with ADHD (n = 18; Mage = 6.70 years) and typically developing controls (n = 15; Mage = 6.73 years) completed a Go/No-Go task to measure inhibitory control and sustained attention before and after polysomnography-monitored overnight sleep. Inhibitory control and sustained attention were improved following overnight sleep in typically developing children. Moreover, morning inhibitory control was positively correlated with rapid eye movement (REM) theta activity in this group. Although REM theta activity was greater in children with ADHD compared to typically developing children, it was functionally insignificant. Neither inhibitory control nor sustained attention were improved following overnight sleep in children with ADHD symptoms, and neither of these behaviors was associated with REM theta activity in this group. Taken together, these results indicate that elevated REM theta activity may be functionally related to ADHD symptomology, possibly reflecting delayed cortical maturation. PMID:28246970

The neural networks of inhibitory control in posttraumatic stress disorder

PubMed Central

Falconer, Erin; Bryant, Richard; Felmingham, Kim L.; Kemp, Andrew H.; Gordon, Evian; Peduto, Anthony; Olivieri, Gloria; Williams, Leanne M.

2008-01-01

Objective Posttraumatic stress disorder (PTSD) involves deficits in information processing that may reflect hypervigilence and deficient inhibitory control. To date, however, no PTSD neuroimaging study has directly examined PTSD-related changes in executive inhibition. Our objective was to investigate the hypothesis that executive inhibitory control networks are compromised in PTSD. Methods Functional magnetic resonance imaging (fMRI) was used during a Go/No-Go inhibition task completed by a sample of patients with PTSD (n = 23), a matched sample of healthy (i.e. without trauma exposure) control participants (n = 23) and a sample of control participants with trauma exposure who did not meet criteria for PTSD (n = 17). Results Participants with PTSD showed more inhibition-related errors than did individuals without trauma exposure. During inhibition, control participants activated a right-lateralized cortical inhibitory network, whereas patients with PTSD activated only the left lateral frontal cortex. PTSD was associated with a reduction in right cortical activation and increased activation of striatal and somatosensory regions. Conclusion The increased inhibitory error and reduced right frontal cortical activation are consistent with compromised inhibitory control in PTSD, while the increased activation of brain regions associated with sensory processing and a greater demand on inhibitory control may reflect enhanced stimulus processing in PTSD, which may undermine cortical control mechanisms. PMID:18787658

Testosterone and dihydrotestosterone reduce platelet activation and reactivity in older men and women.

PubMed

Karolczak, Kamil; Konieczna, Lucyna; Kostka, Tomasz; Witas, Piotr J; Soltysik, Bartlomiej; Baczek, Tomasz; Watala, Cezary

2018-05-02

The cardiovascular effects of testosterone and dihydrotestosterone are generally attributed to their modulatory action on lipid and glucose metabolism. However, no ex vivo studies suggest that circulating androgen levels influence the activation and reactivity of blood platelets - one of the main components of the haemostasis system directly involved in atherosclerosis. The levels of testosterone, dihydrotestosterone and oestradiol in plasma from men and women aged from 60 to 65 years were measured by LC-MS; the aim was to identify any potential relationships between sex steroid levels and the markers of platelet activation (surface membrane expression of GPII/IIIa complex and P-selectin) and platelet reactivity in response to arachidonate, collagen or ADP, monitored with whole blood aggregometry and flow cytometry. The results of the ex vivo part of the study indicate that the concentrations of testosterone and its reduced form, dihydrotestosterone are significantly negatively associated with platelet activation and reactivity. These observations were confirmed in an in vitro model: testosterone and dihydrotestosterone significantly inhibited platelet aggregation triggered by arachidonate or collagen. Our findings indicate that testosterone and dihydrotestosterone are significant haemostatic steroids with inhibitory action on blood platelets in older people.

Evaluation of antioxidant and xanthine oxidase inhibitory activity of different solvent extracts of leaves of Citrullus colocynthis

PubMed Central

Nessa, Fazilatun; Khan, Saeed A.

2014-01-01

Background: Citrullus colocynthis is a folk medicinal plan of United Arab Emirates. Several studies on this plant reported and focused on the biological and toxicological profile of fruits pulp. The present study focused on the antioxidant potency of leaf extract of this plant. Aim: To evaluate the antioxidant and xanthine oxidase (XO) inhibitory activities of C. colocynthis by chemical method. Materials and Methods: Four different solvent extracts (methanol-CCM, methanol: water (1:1)-CCMW, chloroform-CCC and hexane-CCH) of leaves of C. colocynthis were investigated for their free radical scavenging activity using DPPH radical as a substrate, lipid peroxidation (LPO) inhibitory activity using a model system consisting of β-carotene-linoleic acid, superoxide radical scavenging activity (enzymatically/nonenzymatically) and XO inhibitory activity. A dose response curve was plotted for determining SC50 and IC50 values for expressing the results of free radical scavenging activity and XO inhibitory activities respectively. Results: The high polyphenolic content of CCM and CCMW extract showed highest antioxidant activity irrespective the method used for this investigation. The overall results decreased in the order of: CCM > CCMW > CCC > CCH. CCH extract was inactive towards chemically generated superoxide radical and poor DPPH radical scavengers. The results of LPO inhibitory activities of leaves extract (0.1, 0.5 and 1.0 mg/mL) also decreased in the order of: CCM > CCMW > CCC > CCH. Overall 1.0 mg/mL leaves extract showed highest antioxidant potency amongst the studied concentration. Conclusion: CCMW and CCM extract of C. colocynthis exhibited promising antioxidants and XO inhibitory activities. PMID:25002802

Polyclonal antibody against a complement-activating pectin from the roots of Angelica acutiloba.

PubMed

Wang, N L; Kiyohara, H; Matsumoto, T; Otsuka, H; Hirano, M; Yamada, H

1994-10-01

Anti-sera against a complement-activating pectin (AR-2IIb), which was purified from the roots of Angelica acutiloba Kitagawa, were obtained by immunization of rabbits, and a polyclonal anti-AR-2IIb antibody of the IgG class was purified by affinity chromatography on AR-2IIb-immobilized Sepharose and Protein G-Sepharose. Periodate oxidation of AR-2IIb significantly reduced its inhibitory activity on the reactivity of AR-2IIb to anti-AR-2IIb-IgG, but pronase digestion of AR-2IIb did not affect its inhibitory activity. Other pharmacologically active pectins from A. autiloba, Bupleurum falcatum, and Glycyrrhiza uralensis and the complement-activating pectic arabinogalactan from A. autiloba also showed significant inhibitory activities on the reactivity of AR-2IIb to anti-AR-2IIb-IgG, but these inhibitory activities were lower than that of AR-2IIb. Other pectins, polygalacturonic acid, arabinogalactan, galactan, and araban tested had negligible inhibitory activity. Endo-a-(1-->4)-polygalacturonase digestion of AR-2IIb indicated that its "ramified" region (rhamnogalacturonan core possessing neutral oligosaccharide side-chains) contained epitopes for anti-AR-2IIb-IgG, but that 2-keto-3-deoxyoctulosonic acid (KDO)-containing regions and oligogalacturonides obtained from AR-2IIb were not recognized by anti-AR-2IIb-IgG. Although carboxyl-reduction of galacturonic acid in the "ramified" region decreased the inhibitory activity of the "ramified" on its reactivity to anti-AR-2IIb, an acidic tetrasaccharide unit in the rhamnogalacturonan core had negligible inhibitory activity.

[Platelet hyperreactivity and antiaggregatory properties of nootropic drugs under conditions of alloxan-induced diabetes in rats].

PubMed

Zhiliuk, V I; Levykh, A É; Mamchur, V I

2012-01-01

The effects of nootropic drugs (noopept, pentoxifylline, piracetam, pramiracetam, Ginkgo biloba extract, entrop, cerebrocurin and citicoline) on platelet aggregation in rats with experimental diabetes have been studied. It is established that all these drugs exhibit an inhibitory action of various degrees against platelet hyperreactivity under conditions of chronic hyperglycemia. The maximum universality of the antiaggregatory action is characteristic of pramiracetam, entrop and Ginkgo biloba extract.

Enzymatic activity inside and outside of water-stable aggregates in soils under different land use

NASA Astrophysics Data System (ADS)

Garbuz, S. A.; Yaroslavtseva, N. V.; Kholodov, V. A.

2016-03-01

A method is presented for assessing the distribution of enzymatic activity inside and outside of water-stable aggregates. Two samples of water-stable aggregates >1 mm have been isolated from dry aggregates of 1-2 mm. To determine the enzymatic activity, a substrate has been added to one of the samples without disaggregation; the other sample has been preliminarily disaggregated. Enzymatic activity within waterstable aggregates has been assessed from the difference between the obtained results under the supposition that the penetration of substrate within the water-saturated aggregates is hampered, and enzymatic reactions occur only at the periphery. The levels and distributions of enzymatic (peroxidase, polyphenol oxidase, and catalase) activities in water-stable aggregates of soddy-podzolic soils under forest and plowland and typical chernozems of long-term field experiments have been studied. The peroxidase, polyphenol oxidase, and catalase activities of water-stable aggregates vary from 6 to 23, from 7 to 30, and from 5 to 7 mmol/(g h), respectively. The ratio between the enzymatic activities inside and outside of soil aggregates showed a higher dependence on soil type and land use, as well as on the input of organic matter and the structural state, than the general activity level in water-stable aggregates.

Crystal structure of the human natural killer cell inhibitory receptor KIR2DL1-HLA-Cw4 complex.

PubMed

Fan, Q R; Long, E O; Wiley, D C

2001-05-01

Inhibitory natural killer (NK) cell receptors down-regulate the cytotoxicity of NK cells upon recognition of specific class I major histocompatibility complex (MHC) molecules on target cells. We report here the crystal structure of the inhibitory human killer cell immunoglobulin-like receptor 2DL1 (KIR2DL1) bound to its class I MHC ligand, HLA-Cw4. The KIR2DL1-HLA-Cw4 interface exhibits charge and shape complementarity. Specificity is mediated by a pocket in KIR2DL1 that hosts the Lys80 residue of HLA-Cw4. Many residues conserved in HLA-C and in KIR2DL receptors make different interactions in KIR2DL1-HLA-Cw4 and in a previously reported KIR2DL2-HLA-Cw3 complex. A dimeric aggregate of KIR-HLA-C complexes was observed in one KIR2DL1-HLA-Cw4 crystal. Most of the amino acids that differ between human and chimpanzee KIRs with HLA-C specificities form solvent-accessible clusters outside the KIR-HLA interface, which suggests undiscovered interactions by KIRs.

Inhibitory effects of Cyperus digitatus extract on human platelet function in vitro.

PubMed

Fuentes, Eduardo; Forero-Doria, Oscar; Alarcón, Marcelo; Palomo, Iván

2015-01-01

The purpose of this research was to investigate the mechanisms of antiplatelet action of Cyperus digitatus. The antiplatelet action of C. digitatus was studied on platelet function: secretion, adhesion, aggregation, and sCD40L release. The platelet ATP secretion and aggregation were significantly inhibited by CDA (ethyl acetate extract) at 0.1 mg/ml and after the incubation of whole blood with CDA, the platelet coverage was inhibited by 96 ± 3% (p < 0.001). At the same concentration, CDA significantly decreased sCD40L levels. The mechanism of antiplatelet action of CDA could be by NF-κB inhibition and that is cAMP independent. In conclusion, C. digitatus extract may serve as a new source of antiplatelet agents for food and nutraceutical applications.

Inhibitory effects of Citrus hassaku extract and its flavanone glycosides on melanogenesis.

PubMed

Itoh, Kimihisa; Hirata, Noriko; Masuda, Megumi; Naruto, Shunsuke; Murata, Kazuya; Wakabayashi, Keitaro; Matsuda, Hideaki

2009-03-01

The 50% ethanolic extract (CH-ext) obtained from the unripe fruit of Citrus hassaku exhibited significant tyrosinase inhibitory activity. The CH-ext showed antioxidant activity, such as superoxide dismutase (SOD)-like activity and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging activity. Activity-guided fractionation of the CH-ext indicated that flavanone glycoside-rich fractions showed potent tyrosinase inhibitory activity. Further examination revealed that the tyrosinase inhibitory activity and antioxidant activity of the CH-ext were attributable to naringin and neohesperidin, respectively. The CH-ext showed inhibition of melanogenesis without any effects on cell proliferation in cultured murine B16 melanoma cells after glucosamine exposure. The topical application of the CH-ext to the dorsal skin of brownish guinea pigs showed in vivo preventive effects against UVB-induced pigmentation.

Identification of dipeptidyl peptidase-IV inhibitory peptides from mare whey protein hydrolysates.

PubMed

Song, J J; Wang, Q; Du, M; Ji, X M; Mao, X Y

2017-09-01

Inhibition of dipeptidyl peptidase-IV (DPP-IV) activity is a promising strategy for treatment of type 2 diabetes. In the current study, DPP-IV inhibitory peptides were identified from mare whey protein hydrolysates obtained by papain. The results showed that all the mare whey protein hydrolysates obtained at various hydrolysis durations possessed more potent DPP-IV inhibitory activity compared with intact whey protein. The 4-h hydrolysates showed the greatest DPP-IV inhibitory activity with half-maximal inhibitory concentration of 0.18 mg/mL. The 2 novel peptides from 4-h hydrolysate fractions separated by successive chromatographic steps were characterized by liquid chromatography-electrospray ionization tandem mass spectrometry. The novel peptides Asn-Leu-Glu-Ile-Ile-Leu-Arg and Thr-Gln-Met-Val-Asp-Glu-Glu-Ile-Met-Glu-Lys-Phe-Arg, which corresponded to β-lactoglobulin 1 f(71-77) and β-lactoglobulin 1 f(143-155), demonstrated DPP-IV inhibitory activity with half-maximal inhibitory concentrations of 86.34 and 69.84 μM, respectively. The DPP-IV inhibitory activity of the 2 peptides was retained or even improved after simulated gastrointestinal digestion in vitro. Our findings indicate that mare whey protein-derived peptides may possess potential as functional food ingredients in the management of type 2 diabetes. Copyright © 2017 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Ajoene inhibits both primary tumor growth and metastasis of B16/BL6 melanoma cells in C57BL/6 mice.

PubMed

Taylor, Peter; Noriega, Raquel; Farah, Carla; Abad, María-Jesús; Arsenak, Miriam; Apitz, Rafael

2006-08-08

Ajoene is an organosulphur compound derived from garlic with important effects on several membrane-associated processes such as platelet aggregation, as well as being cytotoxic for tumor cell lines in vitro. In the present study, we investigated the effect of ajoene on different cell types in vitro, as well as its inhibitory effects on both primary tumors and metastasis in a mouse model. We found ajoene to inhibit tumor cell growth in vitro, but also to inhibit strongly metastasis to lung in the B16/BL6 melanoma tumor model in C57BL/6 mice. As far as we are aware, this is the first report of the anti-metastatic effect of ajoene. Ajoene also inhibited tumor-endothelial cell adhesion, as well as the in vivo TNF-alpha response to lipopolysaccharide. Possible mechanisms of its antitumoral activity are discussed in the light of these results.

5-((3-Amidobenzyl)oxy)nicotinamides as Sirtuin 2 Inhibitors.

PubMed

Ai, Teng; Wilson, Daniel J; More, Swati S; Xie, Jiashu; Chen, Liqiang

2016-04-14

Derived from our previously reported human sirtuin 2 (SIRT2) inhibitors that were based on a 5-aminonaphthalen-1-yloxy nicotinamide core structure, 5-((3-amidobenzyl)oxy)nicotinamides offered excellent activity against SIRT2 and high isozyme selectivity over SIRT1 and SIRT3. Selected compounds also exhibited generally favorable in vitro absorption, distribution, metabolism, and excretion properties. Kinetic studies revealed that a representative SIRT2 inhibitor acted competitively against both NAD(+) and the peptide substrate, an inhibitory modality that was supported by our computational study. More importantly, two selected compounds exhibited significant protection against α-synuclein aggregation-induced cytotoxicity in SH-SY5Y cells. Therefore, 5-((3-amidobenzyl)oxy)nicotinamides represent a new class of SIRT2 inhibitors that are attractive candidates for further lead optimization in our continued effort to explore selective inhibition of SIRT2 as a potential therapy for Parkinson's disease.

Influence of Aluminium and EGCG on Fibrillation and Aggregation of Human Islet Amyloid Polypeptide

PubMed Central

Xu, Zhi-Xue; Zhang, Qiang; Ma, Gong-Li; Chen, Cong-Heng; He, Yan-Ming; Xu, Li-Hui; Zhang, Yuan; Zhou, Guang-Rong; Li, Zhen-Hua

2016-01-01

The abnormal fibrillation of human islet amyloid polypeptide (hIAPP) has been implicated in the development of type II diabetes. Aluminum is known to trigger the structural transformation of many amyloid proteins and induce the formation of toxic aggregate species. The (−)-epigallocatechin gallate (EGCG) is considered capable of binding both metal ions and amyloid proteins with inhibitory effect on the fibrillation of amyloid proteins. However, the effect of Al(III)/EGCG complex on hIAPP fibrillation is unclear. In the present work, we sought to view insight into the structures and properties of Al(III) and EGCG complex by using spectroscopic experiments and quantum chemical calculations and also investigated the influence of Al(III) and EGCG on hIAPP fibrillation and aggregation as well as their combined interference on this process. Our studies demonstrated that Al(III) could promote fibrillation and aggregation of hIAPP, while EGCG could inhibit the fibrillation of hIAPP and lead to the formation of hIAPP amorphous aggregates instead of the ordered fibrils. Furthermore, we proved that the Al(III)/EGCG complex in molar ratio of 1 : 1 as Al(EGCG)(H2O)2 could inhibit the hIAPP fibrillation more effectively than EGCG alone. The results provide the invaluable reference for the new drug development to treat type II diabetes. PMID:28074190

Studies on the in vitro and in vivo antiurolithic activity of Holarrhena antidysenterica

PubMed Central

Khan, Aslam; Khan, Saeed R.; Gilani, Anwar H.

2013-01-01

Background Holarrhena antidysenterica has a traditional use in the treatment of urolithiasis, therefore, its crude extract has been investigated for possible antiurolithic effect. Materials and methods The crude aqueous-methanolic extract of Holarrhena antidysenterica (Ha.Cr) was studied using the in vitro and in vivo methods. Results In the in vitro experiments, Ha.Cr demonstrated a concentration-dependent (0.25–4 mg/ml) inhibitory effect on the slope of aggregation. It decreased the size of crystals and transformed the calcium oxalate monohydrate (COM) to calcium oxalate dehydrate (COD) crystals, in calcium oxalate metastable solutions. It also showed concentration-dependent antioxidant effect against 2,2-diphenyl-1-picrylhydrazyl free radical (DPPH) free radicals and lipid peroxidation induced in rat kidney tissue homogenate. Ha.Cr (0.3 mg/ml) reduced (p < 0.05) the cell toxicity and LDH release in renal epithelial cells (MDCK) exposed to oxalate (0.5 mM) and COM (66 μg/cm2) crystals. In male Wistar rats, receiving 0.75% ethylene glycol (EG) for 21 days along with 1% ammonium chloride (AC) in drinking water, Ha.Cr treatment (30–100 mg/kg) prevented the toxic changes caused by lithogenic agents; EG and AC, like loss of body weight, polyurea, oxaluria, raised serum urea and creatinine levels and crystal deposition in kidneys compared to their respective controls. Conclusion These data indicate that Holarrhena antidysenterica possesses antiurolithic activity, possibly mediated through inhibition of CaOx crystal aggregation, antioxidant and renal epithelial cell protective activities and may provide base for designing future studies to establish its efficacy and safety for clinical use. PMID:22622371

Inhibitory effects of some plant essential oils against Arcobacter butzleri and potential for rosemary oil as a natural food preservative.

PubMed

Irkin, Reyhan; Abay, Secil; Aydin, Fuat

2011-03-01

We investigated the inhibitory activity of commercially marketed essential oils of mint, rosemary, orange, sage, cinnamon, bay, clove, and cumin against Arcobacter butzleri and Arcobacter skirrowii and the effects of the essential oil of rosemary against A. butzleri in a cooked minced beef system. Using the disc diffusion method to determine the inhibitory activities of these plant essential oils against strains of Arcobacter, we found that those of rosemary, bay, cinnamon, and clove had strong inhibitory activity against these organisms, whereas the essential oils of cumin, mint, and sage failed to show inhibitory activity against most of the Arcobacter strains tested. The 0.5% (vol/wt) essential oil of rosemary was completely inhibitory against A. butzleri in the cooked minced beef system at 4°C. These essential oils may be further investigated as a natural solution to the food industry by creating an additional barrier (hurdle technology) to inhibit the growth of Arcobacter strains.

Coordinated maturational regulation of PHEX and renal phosphate transport inhibitory activity: evidence for the pathophysiological role of PHEX in X-linked hypophosphatemia.

PubMed

Nesbitt, T; Fujiwara, I; Thomas, R; Xiao, Z S; Quarles, L D; Drezner, M K

1999-12-01

The mechanism by which inactivating mutations of PHEX (phosphate-regulating gene with homologies to endopeptidases on the X chromosome) cause X-linked hypophosphatemia remains unknown. However, recent reports suggest errant PHEX activity in osteoblasts may fail to inactivate a phosphaturic factor produced by these cells. To test this possibility, we examined coordinated maturational expression of PHEX and production of phosphate transport inhibitory activity in osteoblasts from normal and hyp-mice. We assessed the inhibitory activity in conditioned medium by examining the effects on opossum kidney cell phosphate transport and osteoblast PHEX expression by reverse transcriptase-polymerase chain reaction during a 17-day maturational period. Inhibitory activity increased as a function of osteoblast maturational stage, with no activity after 3 days and persistent activity by 6 days of culture. More significantly, equal phosphate transport inhibitory activity in conditioned medium from normal and hyp-mouse osteoblasts (control 1.90 +/- 0.12, normal 1.48 +/- 0.10, hyp 1.45 +/- 0.04 nmol/mg of protein/minute) was observed at 6 days. However, by 10 days hyp-mouse osteoblasts exhibited greater inhibitory activity than controls, and by 17 days the difference in phosphate transport inhibition maximized (control 2.08 +/- 0.09, normal 1.88 +/- 0.06, hyp 1.58 +/- 0.06 nmol/mg of protein/minute). Concurrently, we observed absent PHEX expression in normal osteoblasts after 3 days, limited production at 6 days, and significant production by day 10 of culture, while hyp-mouse osteoblasts exhibited limited PHEX activity secondary to an inactivating mutation. The data suggest that the presence of inactivating PHEX mutations results in the enhanced renal phosphate transport inhibitory activity exhibited by hyp-mouse osteoblasts.

Discrimination and Nitric Oxide Inhibitory Activity Correlation of Ajwa Dates from Different Grades and Origin.

PubMed

Abdul-Hamid, Nur Ashikin; Mediani, Ahmed; Maulidiani, M; Abas, Faridah; Ismail, Intan Safinar; Shaari, Khozirah; Lajis, Nordin H

2016-10-28

This study was aimed at examining the variations in the metabolite constituents of the different Ajwa grades and farm origins. It is also targeted at establishing the correlations between the metabolite contents and the grades and further to the nitric oxide (NO) inhibitory activity. Identification of the metabolites was generated using ¹H-NMR spectroscopy metabolomics analyses utilizing multivariate methods. The NO inhibitory activity was determined using a Griess assay. Multivariate data analysis, for both supervised and unsupervised approaches, showed clusters among different grades of Ajwa dates obtained from different farms. The compounds that contribute towards the observed separation between Ajwa samples were suggested to be phenolic compounds, ascorbic acid and phenylalanine. Ajwa dates were shown to have different metabolite compositions and exhibited a wide range of NO inhibitory activity. It is also revealed that Ajwa Grade 1 from the al-Aliah farm exhibited more than 90% NO inhibitory activity compared to the other grades and origins. Phenolic compounds were among the compounds that played a role towards the greater capacity of NO inhibitory activity shown by Ajwa Grade 1 from the al-Aliah farm.

Ex vivo and in vivo studies of CME-1, a novel polysaccharide purified from the mycelia of Cordyceps sinensis that inhibits human platelet activation by activating adenylate cyclase/cyclic AMP.

PubMed

Lu, Wan-Jung; Chang, Nen-Chung; Jayakumar, Thanasekaran; Liao, Jiun-Cheng; Lin, Mei-Jiun; Wang, Shwu-Huey; Chou, Duen-Suey; Thomas, Philip Aloysius; Sheu, Joen-Rong

2014-12-01

CME-1, a novel water-soluble polysaccharide, was purified from the mycelia of Cordyceps sinensis, and its chemical structure was characterized to contain mannose and galactose in a ratio of 4:6 (27.6 kDa). CME-1 was originally observed to exert a potent inhibitory effect on tumor migration and a cytoprotective effect against oxidative stress. Activation of platelets caused by arterial thrombosis is relevant to various cardiovascular diseases (CVDs). However, no data are available concerning the effects of CME-1 on platelet activation. Hence, the purpose of this study was to examine the ex vivo and in vivo antithrombotic effects of CME-1 and its possible mechanisms in platelet activation. The aggregometry, immunoblotting, flow cytometric analysis and platelet functional analysis were used in this study. CME-1 (2.3-7.6 μM) exhibited highly potent activity in inhibiting human platelet aggregation when stimulated by collagen, thrombin, and arachidonic acid but not by U46619. CME-1 inhibited platelet activation accompanied by inhibiting Akt, mitogen-activated protein kinases (MAPKs), thromboxane B2 (TxB2) and hydroxyl radical (OH(●)) formation. However, CME-1 interrupted neither FITC-triflavin nor FITC-collagen binding to platelets. CME-1 markedly increased cyclic AMP levels, but not cyclic GMP levels, and stimulated vasodilator-stimulated phosphoprotein (VASP) phosphorylation. SQ22536, an inhibitor of adenylate cyclase, but not ODQ, an inhibitor of guanylate cyclase, obviously reversed the CME-1-mediated effects on platelet aggregation and vasodilator-stimulated phosphoprotein (VASP), Akt, p38 MAPK phosphorylation, and TxB2 formation. CME-1 substantially prolonged the closure time of whole blood and the occlusion time of platelet plug formation. This study demonstrates for the first time that CME-1 exhibits highly potent antiplatelet activity that may initially activate adenylate cyclase/cyclic AMP and, subsequently, inhibit intracellular signals (such as Akt and MAPKs), ultimately inhibiting platelet activation. This novel role of CME-1 indicates that CME-1 exhibits high potential for application in treating and preventing CVDs. Copyright © 2014 Elsevier Ltd. All rights reserved.

Production of the angiotensin I converting enzyme inhibitory peptides and isolation of four novel peptides from jellyfish (Rhopilema esculentum) protein hydrolysate.

PubMed

Liu, Xin; Zhang, Miansong; Shi, Yaping; Qiao, Ruojin; Tang, Wei; Sun, Zhenliang

2016-07-01

Angiotensin I converting enzyme (ACE) plays an important role in regulating blood pressure in the human body. ACE inhibitory peptides derived from food proteins could exert antihypertensive effects without side effects. Jellyfish (Rhopilema esculentum) is an important fishery resource suitable for production of ACE inhibitory peptides. The objective of this study was to optimize the hydrolysis conditions for production of protein hydrolysate from R. esculentum (RPH) with ACE inhibitory activity, and to isolate and identify the ACE inhibitory peptides from RPH. Rhopilema esculentum protein was hydrolyzed with Compound proteinase AQ to produce protein hydrolysate with ACE inhibitory activity, and the hydrolysis conditions were optimized using response surface methodology. The optimum parameters for producing peptides with the highest ACE inhibitory activity were as follows: hydrolysis time 3.90 h, hydrolysis temperature 58 °C, enzyme:substrate ratio 2.8% and pH 7.60. Under these conditions, the ACE inhibitory rate reached 32.21%. In addition, four novel ACE inhibitory peptides were isolated, and their amino acids sequences were identified as Val-Gly-Pro-Tyr, Phe-Thr-Tyr-Val-Pro-Gly, Phe-Thr-Tyr-Val-Pro-Gly-Ala and Phe-Gln-Ala-Val-Trp-Ala-Gly, respectively. The IC50 value of the purified peptides for ACE inhibitory activity was 8.40, 23.42, 21.15 and 19.11 µmol L(-1) . These results indicate that the protein hydrolysate prepared from R. esculentum might be a commercial competitive source of ACE inhibitory ingredients to be used in functional foods. © 2015 Society of Chemical Industry. © 2015 Society of Chemical Industry.

Plasminogen-induced aggregation of PANC-1 cells requires conversion to plasmin and is inhibited by endogenous plasminogen activator inhibitor-1.

PubMed

Deshet, Naamit; Lupu-Meiri, Monica; Espinoza, Ingrid; Fili, Oded; Shapira, Yuval; Lupu, Ruth; Gershengorn, Marvin C; Oron, Yoram

2008-09-01

PANC-1 cells express proteinase-activated receptors (PARs)-1, -2, and respond to their activation by transient elevation of cytosolic [Ca(2+)] and accelerated aggregation (Wei et al., 2006, J Cell Physiol 206:322-328). We studied the effect of plasminogen (PGN), an inactive precursor of the PAR-1-activating protease, plasmin (PN) on aggregation of pancreatic adenocarcinoma (PDAC) cells. A single dose of PGN time- and dose-dependently promoted PANC-1 cells aggregation in serum-free medium, while PN did not. PANC-1 cells express urokinase plasminogen activator (uPA), which continuously converted PGN to PN. This activity and PGN-induced aggregation were inhibited by the uPA inhibitor amiloride. PGN-induced aggregation was also inhibited by alpha-antiplasmin and by the PN inhibitor epsilon-aminocaproic acid (EACA). Direct assay of uPA activity revealed very low rate, markedly enhanced in the presence of PGN. Moreover, in PGN activator inhibitor 1-deficient PANC-1 cells, uPA activity and PGN-induced aggregation were markedly potentiated. Two additional human PDAC cell lines, MiaPaCa and Colo347, were assayed for PGN-induced aggregation. Both cell lines responded by aggregation and exhibited PGN-enhanced uPA activity. We hypothesized that the continuous conversion of PGN to PN by endogenous uPA is limited by PN's degradation and negatively controlled by endogenously produced PAI-1. Indeed, we found that PANC-1 cells inactivate PN with t1/2 of approximately 7 h, while the continuous addition of PN promoted aggregation. Our data suggest that PANC-1 cells possess intrinsic, PAI-1-sensitive mechanism for promotion of aggregation and differentiation by prolonged exposure to PGN and, possibly, additional precursors of PARs agonists.

Identification of an ACE-Inhibitory Peptide from Walnut Protein and Its Evaluation of the Inhibitory Mechanism.

PubMed

Wang, Cong; Tu, Maolin; Wu, Di; Chen, Hui; Chen, Cheng; Wang, Zhenyu; Jiang, Lianzhou

2018-04-11

In the present study, a novel angiotensin I-converting enzyme inhibitory (ACE inhibitory) peptide, EPNGLLLPQY, derived from walnut seed storage protein, fragment residues 80-89, was identified by ultra-high performance liquid chromatography electrospray ionization quadrupole time of flight mass spectrometry (UPLC-ESI-Q-TOF-MS/MS) from walnut protein hydrolysate. The IC 50 value of the peptide was 233.178 μM, which was determined by the high performance liquid chromatography method by measuring the amount of hippuric acid (HA) generated from the ACE decomposition substrate (hippuryl-l-histidyl-l-leucine (HHL) to assess the ACE activity. Enzyme inhibitory kinetics of the peptide against ACE were also conducted, by which the inhibitory mechanism of ACE-inhibitory peptide was confirmed. Moreover, molecular docking was simulated by Discovery Studio 2017 R2 software to provide the potential mechanisms underlying the ACE-inhibitory activity of EPNGLLLPQY.

Population activity structure of excitatory and inhibitory neurons

PubMed Central

Doiron, Brent

2017-01-01

Many studies use population analysis approaches, such as dimensionality reduction, to characterize the activity of large groups of neurons. To date, these methods have treated each neuron equally, without taking into account whether neurons are excitatory or inhibitory. We studied population activity structure as a function of neuron type by applying factor analysis to spontaneous activity from spiking networks with balanced excitation and inhibition. Throughout the study, we characterized population activity structure by measuring its dimensionality and the percentage of overall activity variance that is shared among neurons. First, by sampling only excitatory or only inhibitory neurons, we found that the activity structures of these two populations in balanced networks are measurably different. We also found that the population activity structure is dependent on the ratio of excitatory to inhibitory neurons sampled. Finally we classified neurons from extracellular recordings in the primary visual cortex of anesthetized macaques as putative excitatory or inhibitory using waveform classification, and found similarities with the neuron type-specific population activity structure of a balanced network with excitatory clustering. These results imply that knowledge of neuron type is important, and allows for stronger statistical tests, when interpreting population activity structure. PMID:28817581

Toxic and inhibitory effects of trichloroethylene aerobic co-metabolism on phenol-grown aerobic granules.

PubMed

Zhang, Yi; Tay, JooHwa

2015-04-09

Aerobic granule, a form of microbial aggregate, exhibits good potential in degrading toxic and recalcitrant substances. In this study, the inhibitory and toxic effects of trichloroethylene (TCE), a model compound for aerobic co-metabolism, on phenol-grown aerobic granules were systematically studied, using respiratory activities after exposure to TCE as indicators. High TCE concentration did not exert positive or negative effects on the subsequent endogenous respiration rate or phenol dependent specific oxygen utilization rate (SOUR), indicating the absence of solvent stress and induction effect on phenol-hydroxylase. Phenol-grown aerobic granules exhibited a unique response to TCE transformation product toxicity, that small amount of TCE transformation enhanced the subsequent phenol SOUR. Granules that had transformed between 1.3 and 3.7 mg TCE gSS(-1) showed at most 53% increase in the subsequent phenol SOUR, and only when the transformation exceeded 6.6 mg TCE gSS(-1) did the SOUR dropped below that of the control. This enhancing effect was found to sustain throughout several phenol dosages, and TCE transformation below the toxicity threshold also lessened the granules' sensitivity to higher phenol concentration. The unique toxic effect was possibly caused by the granule's compact structure as a protection barrier against the diffusive transformation product(s) of TCE co-metabolism. Copyright © 2015 Elsevier B.V. All rights reserved.

The design and delivery of a PKA inhibitory polypeptide to treat SCA1.

PubMed

Hearst, Scoty M; Shao, Qingmei; Lopez, Mariper; Raucher, Drazen; Vig, Parminder J S

2014-10-01

Spinocerebellar ataxia-1 (SCA1) is a neurodegenerative disease that primarily targets Purkinje cells (PCs) of the cerebellum. The exact mechanism of PC degeneration is unknown, however, it is widely believed that mutant ataxin-1 becomes toxic because of the phosphorylation of its serine 776 (S776) residue by cAMP-dependent protein kinase A (PKA). Therefore, to directly modulate mutant ATXN1 S776 phosphorylation and aggregation, we designed a therapeutic polypeptide to inhibit PKA. This polypeptide comprised of a thermally responsive elastin-like peptide (ELP) carrier, which increases peptide half-life, a PKA inhibitory peptide (PKI), and a cell-penetrating peptide (Synb1). We observed that our therapeutic polypeptide, Synb1-ELP-PKI, inhibited PKA activity at concentrations similar to the PKI peptide. Additionally, Synb1-ELP-PKI significantly suppressed mutant ATXN1 S776 phosphorylation and intranuclear inclusion formation in cell culture. Further, Synb1-ELP-PKI treatment improved SCA1 PC morphology in cerebellar slice cultures. Furthermore, the Synb1-ELP peptide carrier crossed the blood-brain barrier and localized to the cerebellum via the i.p. or intranasal route. Here, we show the intranasal delivery of ELP-based peptides to the brain as a novel delivery strategy. We also demonstrate that our therapeutic polypeptide has a great potential to target the neurotoxic S776 phosphorylation pathway in the SCA1 disease. © 2014 International Society for Neurochemistry.

Curcumin, an antibiotic resistance breaker against a multiresistant clinical isolate of Mycobacterium abscessus.

PubMed

Marini, Emanuela; Di Giulio, Mara; Magi, Gloria; Di Lodovico, Silvia; Cimarelli, Maria Enrica; Brenciani, Andrea; Nostro, Antonia; Cellini, Luigina; Facinelli, Bruna

2018-03-01

Curcumin, a phenolic compound extracted from Curcuma longa, exerts multiple pharmacological effects, including an antimicrobial action. Mycobacterium abscessus, an environmental, nontuberculous, rapidly growing mycobacterium, is an emerging human pathogen causing serious lung infections and one of the most difficult to treat, due to its multidrug resistance and biofilm-forming ability. We wanted to evaluate the antimicrobial and antivirulence activity of curcumin and its ability to synergize with antibiotics against a clinical M. abscessus strain (29904), isolated from the bronchoaspirate of a 66-year-old woman admitted to hospital for suspected tuberculosis. Curcumin [minimum inhibitory concentrations (MIC) = 128 mg/L] was synergic (fractional inhibitory concentration index ≤0.5) with amikacin, clarithromycin, ciprofloxacin, and linezolid, to which strain 29904 showed resistance/intermediate susceptibility. Curcumin at 1/8 × MIC significantly reduced motility, whereas at 4 × MIC, it completely inhibited 4- and 8-day mature biofilms. Synergistic combinations of curcumin and amikacin induced a general reduction in microbial aggregates and substantial loss in cell viability. Disruption of 4- and 8-day biofilms was the main effect detected when curcumin was the predominant compound. The present findings support previous evidence that curcumin is a potential antibiotic resistance breaker. Curcumin, either alone or combined with antibiotics, could provide a novel strategy to combat antibiotic resistance and virulence of M. abscessus. Copyright © 2017 John Wiley & Sons, Ltd.

Proteasome inhibitory, antioxidant, and synergistic antibacterial and anticandidal activity of green biosynthesized magnetic Fe3O4 nanoparticles using the aqueous extract of corn (Zea mays L.) ear leaves.

PubMed

Patra, Jayanta Kumar; Ali, Md Sarafat; Oh, In-Gyung; Baek, Kwang-Hyun

2017-03-01

Herein, Fe 3 O 4 nanoparticles synthesized using aqueous extract of corn ear leaves were investigated for proteasome inhibitory activity, antioxidant activity, synergistic antibacterial, and anticandidal potential. The UV-Vis spectrum displayed an absorption band at 355 nm that indicated the formation of nano-sized Fe 3 O 4 particles. Vibrating sample magnetometer analysis revealed its superparamagnetic nature. Fe 3 O 4 nanoparticles exhibited strong proteasome inhibitory potential and antioxidant activity and exerted strong synergistic antibacterial and anticandidal activity. Its significant proteasome inhibitory potential could be useful in cancer treatment and drug delivery. Furthermore, strong antioxidant, antibacterial, and anticandidal activity make them a promising candidate for biomedical and pharmaceutical applications.

Porritoxins, metabolites of Alternaria porri, as anti-tumor-promoting active compounds.

PubMed

Horiuchi, Masayuki; Tokuda, Harukuni; Ohnishi, Keiichiro; Yamashita, Masakazu; Nishino, Hoyoku; Maoka, Takashi

2006-02-01

To search for possible cancer chemopreventive agents from natural sources, we performed primary screening of metabolites of Alternaria porri by examining their possible inhibitory effects on Epstein-Barr virus early antigen (EBV-EA) activation induced by 12-O-tetradecanoylphorbol-13-acetate (TPA) in Raji cells. The ethyl acetate extract of A. porri showed the inhibitory effect on EBV-EA activation. Three porritoxins (1-3) were obtained as inhibitory active compounds for EBV-EA from ethyl acetate extract. 6-(3',3'-Dimethylallyloxy)-4-methoxy-5-methylphthalide (2) showed the strongest activity among them. Inhibitory effect of porritoxin (1) and (2) was superior to that of beta-carotene, a well-known anti-tumor promoter. Furthermore, the structure-activity correlation of porritoxins and their related compounds were discussed.

Multilingual Stroop Performance: Effects of Trilingualism and Proficiency on Inhibitory Control

ERIC Educational Resources Information Center

Marian, Viorica; Blumenfeld, Henrike K.; Mizrahi, Elena; Kania, Ursula; Cordes, Anne-Kristin

2013-01-01

Previous research suggests that multilinguals' languages are constantly co-activated and that experience managing this co-activation changes inhibitory control function. The present study examined language interaction and inhibitory control using a colour-word Stroop task. Multilingual participants were tested in their three most proficient…

Convergence of inhibitory neural inputs regulate motor activity in the murine and monkey stomach

PubMed Central

Shaylor, Lara A.; Hwang, Sung Jin; Sanders, Kenton M.

2016-01-01

Inhibitory motor neurons regulate several gastric motility patterns including receptive relaxation, gastric peristaltic motor patterns, and pyloric sphincter opening. Nitric oxide (NO) and purines have been identified as likely candidates that mediate inhibitory neural responses. However, the contribution from each neurotransmitter has received little attention in the distal stomach. The aims of this study were to identify the roles played by NO and purines in inhibitory motor responses in the antrums of mice and monkeys. By using wild-type mice and mutants with genetically deleted neural nitric oxide synthase (Nos1−/−) and P2Y1 receptors (P2ry1−/−) we examined the roles of NO and purines in postjunctional inhibitory responses in the distal stomach and compared these responses to those in primate stomach. Activation of inhibitory motor nerves using electrical field stimulation (EFS) produced frequency-dependent inhibitory junction potentials (IJPs) that produced muscle relaxations in both species. Stimulation of inhibitory nerves during slow waves terminated pacemaker events and associated contractions. In Nos1−/− mice IJPs and relaxations persisted whereas in P2ry1−/− mice IJPs were absent but relaxations persisted. In the gastric antrum of the non-human primate model Macaca fascicularis, similar NO and purine neural components contributed to inhibition of gastric motor activity. These data support a role of convergent inhibitory neural responses in the regulation of gastric motor activity across diverse species. PMID:27634009

Convergence of inhibitory neural inputs regulate motor activity in the murine and monkey stomach.

PubMed

Shaylor, Lara A; Hwang, Sung Jin; Sanders, Kenton M; Ward, Sean M

2016-11-01

Inhibitory motor neurons regulate several gastric motility patterns including receptive relaxation, gastric peristaltic motor patterns, and pyloric sphincter opening. Nitric oxide (NO) and purines have been identified as likely candidates that mediate inhibitory neural responses. However, the contribution from each neurotransmitter has received little attention in the distal stomach. The aims of this study were to identify the roles played by NO and purines in inhibitory motor responses in the antrums of mice and monkeys. By using wild-type mice and mutants with genetically deleted neural nitric oxide synthase (Nos1 -/- ) and P2Y1 receptors (P2ry1 -/- ) we examined the roles of NO and purines in postjunctional inhibitory responses in the distal stomach and compared these responses to those in primate stomach. Activation of inhibitory motor nerves using electrical field stimulation (EFS) produced frequency-dependent inhibitory junction potentials (IJPs) that produced muscle relaxations in both species. Stimulation of inhibitory nerves during slow waves terminated pacemaker events and associated contractions. In Nos1 -/- mice IJPs and relaxations persisted whereas in P2ry1 -/- mice IJPs were absent but relaxations persisted. In the gastric antrum of the non-human primate model Macaca fascicularis, similar NO and purine neural components contributed to inhibition of gastric motor activity. These data support a role of convergent inhibitory neural responses in the regulation of gastric motor activity across diverse species. Copyright © 2016 the American Physiological Society.

Competition and cooperation among similar representations: toward a unified account of facilitative and inhibitory effects of lexical neighbors.

PubMed

Chen, Qi; Mirman, Daniel

2012-04-01

One of the core principles of how the mind works is the graded, parallel activation of multiple related or similar representations. Parallel activation of multiple representations has been particularly important in the development of theories and models of language processing, where coactivated representations (neighbors) have been shown to exhibit both facilitative and inhibitory effects on word recognition and production. Researchers generally ascribe these effects to interactive activation and competition, but there is no unified explanation for why the effects are facilitative in some cases and inhibitory in others. We present a series of simulations of a simple domain-general interactive activation and competition model that is broadly consistent with more specialized domain-specific models of lexical processing. The results showed that interactive activation and competition can indeed account for the complex pattern of reversals. Critically, the simulations revealed a core computational principle that determines whether neighbor effects are facilitative or inhibitory: strongly active neighbors exert a net inhibitory effect, and weakly active neighbors exert a net facilitative effect.

Synthesis of chiral pyrazolo[4,3-e][1,2,4]triazine sulfonamides with tyrosinase and urease inhibitory activity.

PubMed

Mojzych, Mariusz; Tarasiuk, Paweł; Kotwica-Mojzych, Katarzyna; Rafiq, Muhammad; Seo, Sung-Yum; Nicewicz, Michał; Fornal, Emilia

2017-12-01

A new series of sulfonamide derivatives of pyrazolo[4,3-e][1,2,4]triazine with chiral amino group has been synthesized and characterized. The compounds were tested for their tyrosinase and urease inhibitory activity. Evaluation of prepared derivatives demonstrated that compounds (8b) and (8j) are most potent mushroom tyrosinase inhibitors whereas all of the obtained compounds showed higher urease inhibitory activity than the standard thiourea. The compounds (8a), (8f) and (8i) exhibited excellent enzyme inhibitory activity with IC 50 0.037, 0.044 and 0.042 μM, respectively, while IC 50 of thiourea is 20.9 μM.

Acetylcholinesterase-inhibitory activities of the extracts from sponges collected in mauritius waters.

PubMed

Beedessee, Girish; Ramanjooloo, Avin; Surnam-Boodhun, Rashmee; van Soest, Rob W M; Marie, Daniel E P

2013-03-01

Patients diagnosed with Alzheimer's disease (AD) show a characteristic neurochemical deficit of acetylcholine, especially in the basal forebrains. The use of acetylcholinesterase (AChE) inhibitors to retard the hydrolysis of acetylcholine has been suggested as a promising strategy for AD treatment. In this study, we evaluated the acetylcholinesterase inhibitory (AChEI) activities of 134 extracts obtained from 45 species of marine sponges. Thin-layer chromatography (TLC) and microplate assays reveal potent acetylcholinsterase inhibitory activities of two AcOEt extracts from the sponges Pericharax heteroraphis and Amphimedon navalis PULITZER-FINALI. We further investigated the inhibitory kinetics of the extracts and found them to display mixed competitive/noncompetitive inhibition and associated their inhibitory activity partly to terpenoids. Acetylcholinesterase inhibitors from marine organisms have been rarely studied, and this study demonstrated the potential of marine sponges as a source of pharmaceutical leads against neurodegenerative diseases. Copyright © 2013 Verlag Helvetica Chimica Acta AG, Zürich.

Inhibition of carrageenin-induced rat paw oedema by crotapotin, a polypeptide complexed with phospholipase A2.

PubMed Central

Landucci, E C; Antunes, E; Donato, J L; Faro, R; Hyslop, S; Marangoni, S; Oliveira, B; Cirino, G; de Nucci, G

1995-01-01

1. The effect of purified crotapotin, a non-toxic non-enzymatic chaperon protein normally complexed to a phospholipase A2 (PLA2) in South America rattlesnake venom, was studied in the acute inflammatory response induced by carrageenin (1 mg/paw), compound 48/80 (3 micrograms/paw) and 5-hydroxytryptamine (5-HT) (3 micrograms/paw) in the rat hind-paw. The effects of crotapotin on platelet aggregation, mast cell degranulation and eicosanoid release from guinea-pig isolated lung were also investigated. 2. Subplantar co-injection of crotapotin (1 and 10 micrograms/paw) with carrageenin or injection of crotapotin (10 micrograms/paw) into the contralateral paw significantly inhibited the carrageenin-induced oedema. This inhibition was also observed when crotapotin (10-30 micrograms/paw) was administered either intraperitoneally or orally. Subplantar injection of heated crotapotin (15 min at 60 degrees C) failed to inhibit carrageenin-induced oedema. Subplantar injection of crotapotin (10 micrograms/paw) also significantly inhibited the rat paw oedema induced by compound 48/80, but it did not affect 5-HT-induced oedema. 3. In adrenalectomized animals, subplantar injection of crotapotin markedly inhibited the oedema induced by carrageenin. The inhibitory effect of crotapotin was also observed in rats depleted of histamine and 5-HT stores. 4. Crotapotin (30 micrograms/paw) had no effect on either the histamine release induced by compound 48/80 in vitro or on the platelet aggregation induced by both arachidonic acid (1 nM) and platelet activating factor (1 microM) in human platelet-rich plasma. The platelet aggregation and thromboxane B2 (TXB2) release induced by thrombin (100 mu ml-1) in washed human platelets were also not affected by crotapotin.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7537590

Salivary Antigen-5/CAP Family Members Are Cu2+-dependent Antioxidant Enzymes That Scavenge O2⨪ and Inhibit Collagen-induced Platelet Aggregation and Neutrophil Oxidative Burst*

PubMed Central

Assumpção, Teresa C. F.; Ma, Dongying; Schwarz, Alexandra; Reiter, Karine; Santana, Jaime M.; Andersen, John F.; Ribeiro, José M. C.; Nardone, Glenn; Yu, Lee L.; Francischetti, Ivo M. B.

2013-01-01

The function of the antigen-5/CAP family of proteins found in the salivary gland of bloodsucking animals has remained elusive for decades. Antigen-5 members from the hematophagous insects Dipetalogaster maxima (DMAV) and Triatoma infestans (TIAV) were expressed and discovered to attenuate platelet aggregation, ATP secretion, and thromboxane A2 generation by low doses of collagen (<1 μg/ml) but no other agonists. DMAV did not interact with collagen, glycoprotein VI, or integrin α2β1. This inhibitory profile resembles the effects of antioxidants Cu,Zn-superoxide dismutase (Cu,Zn-SOD) in platelet function. Accordingly, DMAV was found to inhibit cytochrome c reduction by O2⨪ generated by the xanthine/xanthine oxidase, implying that it exhibits antioxidant activity. Moreover, our results demonstrate that DMAV blunts the luminescence signal of O2⨪ generated by phorbol 12-myristate 13-acetate-stimulated neutrophils. Mechanistically, inductively coupled plasma mass spectrometry and fluorescence spectroscopy revealed that DMAV, like Cu,Zn-SOD, interacts with Cu2+, which provides redox potential for catalytic removal of O2⨪. Notably, surface plasmon resonance experiments (BIAcore) determined that DMAV binds sulfated glycosaminoglycans (e.g. heparin, KD ∼100 nmol/liter), as reported for extracellular SOD. Finally, fractions of the salivary gland of D. maxima with native DMAV contain Cu2+ and display metal-dependent antioxidant properties. Antigen-5/CAP emerges as novel family of Cu2+-dependent antioxidant enzymes that inhibit neutrophil oxidative burst and negatively modulate platelet aggregation by a unique salivary mechanism. PMID:23564450

New multipotent tetracyclic tacrines with neuroprotective activity.

PubMed

Marco-Contelles, José; León, Rafael; de los Ríos, Cristóbal; García, Antonio G; López, Manuela G; Villarroya, Mercedes

2006-12-15

The synthesis and the biological evaluation (neuroprotection, voltage dependent calcium channel blockade, AChE/BuChE inhibitory activity and propidium binding) of new multipotent tetracyclic tacrine analogues (5-13) are described. Compounds 7, 8 and 11 showed a significant neuroprotective effect on neuroblastoma cells subjected to Ca(2+) overload or free radical induced toxicity. These compounds are modest AChE inhibitors [the best inhibitor (11) is 50-fold less potent than tacrine], but proved to be very selective, as for most of them no BuChE inhibition was observed. In addition, the propidium displacement experiments showed that these compounds bind AChE to the peripheral anionic site (PAS) of AChE and, consequently, are potential agents that can prevent the aggregation of beta-amyloid. Overall, compound 8 is a modest and selective AChE inhibitor, but an efficient neuroprotective agent against 70mM K(+) and 60microM H(2)O(2). Based on these results, some of these molecules can be considered as lead candidates for the further development of anti-Alzheimer drugs.

Structural and antioxidant modification of wheat peptides modified by the heat and lipid peroxidation product malondialdehyde.

PubMed

Tang, Xue; Wu, Qiuping; Le, Guowei; Wang, Jiao; Yin, Kaijian; Shi, Yonghui

2012-01-01

Wheat peptides, the biological active peptides derived from foods, has an array of biological actions, including antiobesity, antimicrobial, and angiotensin I-converting enzyme inhibitory effects in mammalian species. Recent studies showed that some wheat peptides may show the noteworthy antioxidant potency against the peroxidation of lipids or fatty acids, but the effect of oxidation on its antioxidant activities is unclear. In the present study, we demonstrate that heat and malandialdehyde (MDA)-oxidized wheat peptides lose its surface hydrophobicity and reducing power, and show a relatively lower free radical-scavenging activitiy in vitro. Those modifications also lead to gradual formation of aggregates in wheat peptides and induce more reactive oxygen species (ROS) production in vivo. These findings indicate that oxidation may influence the functional properties and directly alter the structure of wheat peptides, and lead to the loss of its antioxidant potency both in vitro and in vivo, thereby providing a novel explanation for some of the potential health risks proposed for oxidized food in human. © 2011 Institute of Food Technologists®

Improvement of ACE inhibitory activity of casein hydrolysate by Maillard reaction with xylose.

PubMed

Hong, Xu; Meng, Jun; Lu, Rong-Rong

2015-01-01

The Maillard reaction is widely used to improve the functional properties or biological activities of food. The purpose of this study was to investigate the effect of the Maillard reaction on angiotensin I converting enzyme (ACE) inhibitory activity in a casein hydrolysate-xylose system. Two-step hydrolysis was used to prepare casein ACE inhibitory peptides. Maillard reaction products (MRPs) were prepared by heating hydrolyzed casein with xylose at pH 8.0, 110 °C for up to 16 h. The results showed that the content of free amino group decreased (P < 0.05); however, browning intensity and absorbance at 294 nm increased because of the Maillard reaction (P < 0.05). The ACE inhibitory activity improved greatly within 2 h (from 63.48% to 90.23%), which was mainly due to carbonyl ammonia condensation reaction in the MRPs. The study shows that the Maillard reaction under appropriate conditions can improve the ACE inhibitory activity of casein hydrolysate effectively. © 2014 Society of Chemical Industry.

High-Throughput and Rapid Screening of Novel ACE Inhibitory Peptides from Sericin Source and Inhibition Mechanism by Using in Silico and in Vitro Prescriptions.

PubMed

Sun, Huaju; Chang, Qing; Liu, Long; Chai, Kungang; Lin, Guangyan; Huo, Qingling; Zhao, Zhenxia; Zhao, Zhongxing

2017-11-22

Several novel peptides with high ACE-I inhibitory activity were successfully screened from sericin hydrolysate (SH) by coupling in silico and in vitro approaches for the first time. Most screening processes for ACE-I inhibitory peptides were achieved through high-throughput in silico simulation followed by in vitro verification. QSAR model based predicted results indicated that the ACE-I inhibitory activity of these SH peptides and six chosen peptides exhibited moderate high ACE-I inhibitory activities (log IC 50 values: 1.63-2.34). Moreover, two tripeptides among the chosen six peptides were selected for ACE-I inhibition mechanism analysis which based on Lineweaver-Burk plots indicated that they behave as competitive ACE-I inhibitors. The C-terminal residues of short-chain peptides that contain more H-bond acceptor groups could easily form hydrogen bonds with ACE-I and have higher ACE-I inhibitory activity. Overall, sericin protein as a strong ACE-I inhibition source could be deemed a promising agent for antihypertension applications.

Effects of Pasteurella haemolytica leukotoxic culture supernatant on bovine neutrophil aggregation.

PubMed

Conlon, P; Gervais, M; Chaudhari, S; Conlon, J

1992-07-01

Pasteurella haemolytica A1 leukotoxic culture supernatant was evaluated for its ability to cause aggregation of bovine peripheral neutrophils. Neutrophils were isolated by a hypotonic lysis method and incubated with zymosan-activated plasma (ZAP), leukotoxic culture supernatant, antileukotoxin serum, calcium and magnesium-free media, p-bromophenacyl bromide and protein kinase C inhibitors. Aggregation was evaluated by changes in infrared light transmittance. Leukotoxic culture supernatant caused neutrophils to aggregate, and this effect was significantly removed by preincubation with antileukotoxin serum. Aggregation to ZAP and leukotoxin was dependent on the presence of extra-cellular calcium. Activation of protein kinase C by phorbol myristate acetate induced aggregation which was reduced by staurosporine; however, aggregation to leukotoxin did not involve protein kinase C activation. Phospholipase A2 inhibition did not alter the aggregation response to ZAP or to leukotoxin. The in vitro measurement of neutrophil aggregation induced by the leukotoxin of P. haemolytica reflects cytoskeletal and other activation events that may contribute to the intense inflammatory process which this organism induces in the lungs of cattle.

Screening for antimalarial and acetylcholinesterase inhibitory activities of some Iranian seaweeds

PubMed Central

Ghannadi, A; Plubrukarn, A; Zandi, K; Sartavi, K; Yegdaneh, A

2013-01-01

Alcoholic extracts of 8 different types of seaweeds from Iran’s Persian Gulf were tested for their antimalarial and acetylcholinesterase enzyme (AChE) inhibitory activities for the first time. A modified Ellman and Ingkaninan method was used for measuring AChE inhibitory activity in which galanthamine was used as the reference. The antimalarial assay was performed using microculture radioisotope technique. Mefloquine and dihydroartemisinin were uased as the standards. The extract of Sargassum boveanum (Sargasseae family) showed the highest AChE inhibitory activity (IC50 equals to 1 mg ml-1) while Cystoseira indica (Cystoseiraceae family) exhibited the least activity (IC50 of 11 mg ml-1). The species from Rhodophyta (Gracilaria corticata and Gracilaria salicornia) also showed moderate activities (IC509.5, 8.7 mg ml-1, respectively). All extracts were inactive in antimalarial assay. PMID:24019820

[Investigation on Inhibitory Capacities of Seventeen Herbal Extracts on Oxidative Stress using Ultraviolet and Fluorescence Spectroscopy].

PubMed

Hou, Guang-yue; Zheng, Zhong; Song, Feng-rui; Liu, Zhi-qiang; Zhao, Bing

2015-03-01

Diabetic patients usually suffer from complications and the long-term secondary complications are the main cause of morbidity and mortality. The hyperglycemia-induced oxidative stress is one of the important pathogenesis of diabetic complications, while the oxidative stress is associated with the lipid peroxidation reaction and the formation of advanced glycation end products (AGEs). Our study was focus on the pathogenesis of diabetic complications and based on the oxidative stress reaction. In this research, the oxidative stress inhibiting effects of seventeen herbal extracts were studied based on spectroscopic methodology. The capacities of herbal extracts against the lipid peroxidation reaction of rat liver in vitro were investigated using spectrophotometric method. It showed that the inhibitory activity of Radix Scutellariae and Flos Sophorae Immaturus were better than other herbal extracts. Additionally, the herbal extracts rich in flavonoids, alkaloids and lignanoids showed good inhibitory activities on the lipid peroxidation reaction. On the contrary, the saponin-rich herbal extracts possessed weak inhibitory effects. We applied the BSA/glucose (fructose) system combined with fluorescent spectroscopy to determine the inhibitory activities of herbal extracts in glycation model reactions. The results showed that the AGEs formation inhibitory activity of Flos Sophorae Immaturus, Radix Scutellariae and Rhizoma Anemarrhenae were better than others in the BSA/glucose (fructose) system by fluorescene analysis. The results demonstrated that the herbal extracts rich in flavonoids were found to be more effective than that of those herbal extracts as alkaloids and terpenoids class in inhibiting oxidative stress, while the saponin-rich herbal extracts showed weak inhibitory activities against oxidative stress. The Flos Sophorae Immaturus and Radix Scutellariae extracts had better inhibitory activity to the oxidative stress, so their pharmacological activity could be explored in further investigations. These results demonstrated in this assay could provide a reference for the study of pharmacological activity, and thus lays the foundation for the further study of the application of natural products in the prevention and treatment of diabetic complications.

Angiotensin-I Converting Enzyme (ACE) Inhibitory and Anti-Oxidant Activities of Sea Cucumber (Actinopyga lecanora) Hydrolysates

PubMed Central

Ghanbari, Raheleh; Zarei, Mohammad; Ebrahimpour, Afshin; Abdul-Hamid, Azizah; Ismail, Amin; Saari, Nazamid

2015-01-01

In recent years, food protein-derived hydrolysates have received considerable attention because of their numerous health benefits. Amongst the hydrolysates, those with anti-hypertensive and anti-oxidative activities are receiving special attention as both activities can play significant roles in preventing cardiovascular diseases. The present study investigated the angiotensin-I converting enzyme (ACE) inhibitory and anti-oxidative activities of Actinopyga lecanora (A. lecanora) hydrolysates, which had been prepared by alcalase, papain, bromelain, flavourzyme, pepsin, and trypsin under their optimum conditions. The alcalase hydrolysate showed the highest ACE inhibitory activity (69.8%) after 8 h of hydrolysis while the highest anti-oxidative activities measured by 2,2-diphenyl 1-1-picrylhydrazyl radical scavenging (DPPH) (56.00%) and ferrous ion-chelating (FIC) (59.00%) methods were exhibited after 24 h and 8 h of hydrolysis, respectively. The ACE-inhibitory and anti-oxidative activities displayed dose-dependent trends, and increased with increasing protein hydrolysate concentrations. Moreover, strong positive correlations between angiotensin-I converting enzyme (ACE) inhibitory and anti-oxidative activities were also observed. This study indicates that A. lecanora hydrolysate can be exploited as a source of functional food owing to its anti-oxidant as well as anti-hypertension functions. PMID:26690117

Factors affecting the activity of guanylate cyclase in lysates of human blood platelets.

PubMed Central

Adams, A F; Haslam, R J

1978-01-01

1. Under optimal ionic conditions (4 mM-MnCl2) the specific activity of guanylate cyclase in fresh platelet lysates was about 10nmol of cyclic GMP formed/20 min per mg of protein at 30 degrees C. Activity was 15% of optimum with 10mM-MgCl2 and negligible with 4mM-CaCl2. Synergism between MnCl2 and MgCl2 or CaCl2 was observed when [MnCl2] less than or equal to [GPT]. 2. Lower than optimal specific activities were obtained in assays containing large volumes of platelet lysate, owing to the presence of inhibitory factors that could be removed by ultrafiltration. Adenine nucleotides accounted for less than 50% of the inhibitory activity. 3. Preincubation of lysate for 1 h at 30 degrees C increased the specific activity of platelet guanylate cyclase by about 2-fold. 4. Lubrol PX (1%, w/v) stimulated guanylate cyclase activity by 3--5-fold before preincubation and by about 2-fold after preincubation. Triton X-100 was much less effective. 5. Dithiothreitol inhibited the guanylate cyclase activity of untreated, preincubated and Lubrol PX-treated lysates and prevented activation by preincubation provided that it was added beforehand. 6. Oleate stimulated guanylate cyclase activity 3--4-fold and arachidonate 2--3-fold, whereas palmitate was almost inactive. Pretreatment of lysate with indomethacin did not inhibit this effect of arachidonate. Oleate and arachidonate caused marked stimulation of guanylate cyclase in preincubated lysate, but inhibited the enzyme in Lubrol PX-treated lysate. 7. NaN3 (10mM) increased guanylate cyclase activity by up to 7-fold; this effect was both time- and temperature-dependent. NaN3 did not further activate the enzyme in Lubrol PX-treated lysate. 8. The results indicated that preincubation, Lubrol PX, fatty acids and NaN3 activated platelet guanylate cyclase by different mechanisms. 9. Platelet particulate fractions contained no guanylate cyclase activity detectable in the presence or absence of Lubrol PX that could not be accounted for by contaminating soluble enzyme, suggesting that physiological aggregating agents may increase cyclic GMP in intact platelets through the effects of intermediary factors. The activated and inhibited states of the enzyme described in the present paper may be relevant to the actions of these factors. PMID:29607

Factors affecting the activity of guanylate cyclase in lysates of human blood platelets.

PubMed

Adams, A F; Haslam, R J

1978-07-15

1. Under optimal ionic conditions (4 mM-MnCl2) the specific activity of guanylate cyclase in fresh platelet lysates was about 10nmol of cyclic GMP formed/20 min per mg of protein at 30 degrees C. Activity was 15% of optimum with 10mM-MgCl2 and negligible with 4mM-CaCl2. Synergism between MnCl2 and MgCl2 or CaCl2 was observed when [MnCl2] less than or equal to [GPT]. 2. Lower than optimal specific activities were obtained in assays containing large volumes of platelet lysate, owing to the presence of inhibitory factors that could be removed by ultrafiltration. Adenine nucleotides accounted for less than 50% of the inhibitory activity. 3. Preincubation of lysate for 1 h at 30 degrees C increased the specific activity of platelet guanylate cyclase by about 2-fold. 4. Lubrol PX (1%, w/v) stimulated guanylate cyclase activity by 3--5-fold before preincubation and by about 2-fold after preincubation. Triton X-100 was much less effective. 5. Dithiothreitol inhibited the guanylate cyclase activity of untreated, preincubated and Lubrol PX-treated lysates and prevented activation by preincubation provided that it was added beforehand. 6. Oleate stimulated guanylate cyclase activity 3--4-fold and arachidonate 2--3-fold, whereas palmitate was almost inactive. Pretreatment of lysate with indomethacin did not inhibit this effect of arachidonate. Oleate and arachidonate caused marked stimulation of guanylate cyclase in preincubated lysate, but inhibited the enzyme in Lubrol PX-treated lysate. 7. NaN3 (10mM) increased guanylate cyclase activity by up to 7-fold; this effect was both time- and temperature-dependent. NaN3 did not further activate the enzyme in Lubrol PX-treated lysate. 8. The results indicated that preincubation, Lubrol PX, fatty acids and NaN3 activated platelet guanylate cyclase by different mechanisms. 9. Platelet particulate fractions contained no guanylate cyclase activity detectable in the presence or absence of Lubrol PX that could not be accounted for by contaminating soluble enzyme, suggesting that physiological aggregating agents may increase cyclic GMP in intact platelets through the effects of intermediary factors. The activated and inhibited states of the enzyme described in the present paper may be relevant to the actions of these factors.

Cholinesterase inhibitors from the roots of Harpagophytum procumbens.

PubMed

Bae, Yoon Ho; Cuong, To Dao; Hung, Tran Manh; Kim, Jeong Ah; Woo, Mi Hee; Byeon, Jeong Su; Choi, Jae Sue; Min, Byung Sun

2014-01-01

Inhibition of cholinesterase has been proposed to be a therapeutic target for the treatment of Alzheimer's diseases. In our preliminary screening study on the acetylcholinesterase (AChE) inhibitory activity, an ethyl acetate soluble fraction of the roots of Harpagophytum procumbens (Pedaliaceae) was found to inhibit AChE activity at the concentration of 100 μg/mL. Ten compounds (1-10) were isolated from the active fraction and evaluated for their inhibitory effect on AChE and butyrylcholinesterase (BChE). Among the isolates, verbascosides (5, 6, and 8) containing a caffeoyl and a 3,4-dihydroxyphenethyl groups in their structures, showed effective AChE inhibitory activity and also possessed BChE inhibitory activity. The findings suggest that verbascoside derivatives may be partially related to the anti-Alzheimer effect of this medicinal plant.

Application of microalgal fucoxanthin for the reduction of colon cancer risk: inhibitory activity of fucoxanthin against beta-glucuronidase and DLD-1 cancer cells.

PubMed

Kawee-Ai, Arthitaya; Kim, Sang Moo

2014-07-01

Intestinal bacterial beta-glucuronidases are capable of retoxifying compounds that have been detoxified by liver glucuronidation and are also known to accelerate colon cancer invasion and metastasis. In this study, fucoxanthin extracted from the microalga Phaeodactylum tricornutum was investigated for its inhibitory activity against Escherichia coli beta-glucuronidase and DLD-1 cancer cells. Fucoxanthin inhibited beta-glucuronidase in a concentration-dependent manner with an IC50 value of 2.32 mM and a mixed inhibition type. Fucoxanthin had more potent inhibitory activity on beta-glucuronidase at 37 degrees C and in alkaline conditions. Fucoxanthin also inhibited the beta-glucuronidase activity of DLD-1 cancer cells at a concentration of 20-50 microM. The presence of beta-glucuronidase and substrate in the medium decreased the inhibitory activity of fucoxanthin against DLD-1 cancer cells. Therefore, microalgal fucoxanthin might prevent colon cancer because of its strong beta-glucuronidase inhibitory activity and could be utilized as a novel functional ingredient of food and pharmaceutical supplements.

Quantitative Structure-Activity Relationship Modeling Coupled with Molecular Docking Analysis in Screening of Angiotensin I-Converting Enzyme Inhibitory Peptides from Qula Casein Hydrolysates Obtained by Two-Enzyme Combination Hydrolysis.

PubMed

Lin, Kai; Zhang, Lanwei; Han, Xue; Meng, Zhaoxu; Zhang, Jianming; Wu, Yifan; Cheng, Dayou

2018-03-28

In this study, Qula casein derived from yak milk casein was hydrolyzed using a two-enzyme combination approach, and high angiotensin I-converting enzyme (ACE) inhibitory activity peptides were screened by quantitative structure-activity relationship (QSAR) modeling integrated with molecular docking analysis. Hydrolysates (<3 kDa) derived from combinations of thermolysin + alcalase and thermolysin + proteinase K demonstrated high ACE inhibitory activities. Peptide sequences in hydrolysates derived from these two combinations were identified by liquid chromatography-tandem mass spectrometry (LC-MS/MS). On the basis of the QSAR modeling prediction, a total of 16 peptides were selected for molecular docking analysis. The docking study revealed that four of the peptides (KFPQY, MPFPKYP, MFPPQ, and QWQVL) bound the active site of ACE. These four novel peptides were chemically synthesized, and their IC 50 was determined. Among these peptides, KFPQY showed the highest ACE inhibitory activity (IC 50 = 12.37 ± 0.43 μM). Our study indicated that Qula casein presents an excellent source to produce ACE inhibitory peptides.

Identification of a xanthine oxidase-inhibitory component from Sophora flavescens using NMR-based metabolomics.

PubMed

Suzuki, Ryuichiro; Hasuike, Yuka; Hirabayashi, Moeka; Fukuda, Tatsuo; Okada, Yoshihito; Shirataki, Yoshiaki

2013-10-01

We demonstrate that NMR-based metabolomics studies can be used to identify xanthine oxidase-inhibitory compounds in the diethyl ether soluble fraction prepared from a methanolic extract of Sophora flavescens. Loading plot analysis, accompanied by direct comparison of 1H NMR spectraexhibiting characteristic signals, identified compounds exhibiting inhibitory activity. NMR analysis indicated that these characteristic signals were attributed to flavanones such as sophoraflavanone G and kurarinone. Sophoraflavanone G showed inhibitory activity towards xanthine oxidase in an in vitro assay.

In vitro and in vivo characterization of a calcium modulator of the diphenylalkylamine type with selective coronary dilatory properties.

PubMed

Caldirola, P; Monteil, A; Zandberg, P; Mannhold, R; Timmerman, H

1997-11-01

VUF 8929 (N-¿2-[bis(p-fluorophenyl)methoxy]ethyl¿-(2-phenyl)ethylamine maleate, CAS 140890-71-7) is a diphenylalkylamine derivative structurally related to prenylamine. The calcium antagonistic properties of this compound have been studied in in vitro and in vivo systems. VUF 8929 has affinity for the voltage-operated calcium channel. Its pKD for the displacement of [3H]nitrendipine bound to cerebral rat cortex is 6.27 (+/- 0.17). The compound influences the [3H]nitrendipine binding through an allosteric interaction with a site adjacent to the dihydropyridine binding site. Competitive experiments with the additional presence of the phenylalkylamine gallopamil showed that this allosteric site is a property common to diphenyl- and phenylalkylamines. It was further observed that VUF 8929 has a high affinity for calmodulin as it shows high potency in inhibiting the calmodulin mediated activation of PDE. The inhibition of K+ (IC50 0.5 mumol/l)- and noradrenaline (IC50 1.3 mumol/l)-induced contractions of rabbit aorta rings was in the same concentration range as found for the calmodulin inhibitory activity. In vitro platelet aggregation was also inhibited in the same concentration range when washed platelets were used. Thus calmodulin antagonism may contribute to the observed effects on aorta ring contractions and platelets aggregation. Platelet aggregation, however, in media in which albumin was added or in platelet rich plasma was not affected. It is assumed that due to the high lipophilicity, common to many diphenylalkylamines, VUF 8929 has a strong binding to plasma proteins. This may also explain why orally administered VUF 8929 did not affect the alpha 2-induced pressor response in pithed rats and the ex vivo collagen induced aggregation response. The haemodynamic profile in anaesthetized dogs showed that intravenous injected VUF 8929 reduced the workload of the heart while coronary blood flow increases at a dose of 0.3 mg/kg. Reversible occlusion of the coronary artery, which leads to S-T segment elevation and local venous acidosis, were reduced by VUF 8929 indicating that the compound has anti-ischaemic properties. VUF 8929 is a calcium antagonist which has anti-ischaemic properties, reduces the workload of the heart and increases coronary flow. Due to these properties VUF 8929 is a potential cardioprotective agent.

Influence of aggregate size on the binding and activation of the first component of human complement by soluble IgG aggregates.

PubMed Central

Doekes, G; Vanes, L A; Daha, M R

1982-01-01

The interaction between small aggregates of human IgG and the first component of human complement was studied. Stabilized soluble IgG aggregates of restricted size were prepared by heat aggregation of human IgG, followed by sucrose-density ultracentrifugation. Human C1 was isolated in its precursor form by euglobulin precipitation, followed by gel filtration and immunoadsorption. A C1 preparation was obtained of which more than 90% was still in its unactivated form. Soluble aggregates containing 20, 10 or 5 molecules IgG, and monomeric IgG were tested for their ability to bind and to activate C1. The binding of C1 was determined by C1 consumption, whereas the activation of C1 was measured as the increased ability of the C1 preparation to consume purified human C4 after the incubation with the aggregates. The three aggregates tested and monomeric IgG were all able to bind and to activate C1, but the efficiency of both processes markedly increased with increasing aggregate-size. Furthermore, it was found that all four preparations activated an appreciable amount of C1 at concentrations that did not result in any detectable C1 fixation. These results confirm earlier suggestion that C1 can be activated during a short, transient binding to small aggregates or immune complexes that have a low avidity for C1, after which the activated form, C1, is released into the medium. PMID:7068172

Anticholinesterase activity of 7-methoxyflavones isolated from Kaempferia parviflora.

PubMed

Sawasdee, Pattara; Sabphon, Chalisa; Sitthiwongwanit, Duangporn; Kokpol, Udom

2009-12-01

The rhizome of Kaempferia parviflora or kra-chai-dum (in Thai) is used traditionally as a folk medicine. The preliminary cholinesterase inhibitory screening of this plant extract exhibited significant acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitory activities. Thirteen known methoxyflavones (1-13) were isolated and their structures were completely elucidated based on NMR analysis and compared with literature reports. Minor compounds 12-13 were reported for the first time from this species. The cholinesterase inhibitory test results showed that the highest potential inhibitors toward AChE and BChE were 5,7,4'-trimethoxyflavone (6) and 5,7-dimethoxyflavone (7), respectively, with the percentage inhibitory activity varying over 43-85%. The structure-activity relationship study led to the conclusion that compounds bearing 5,7-dimethoxy groups and a free substituent at C-3 had a significant inhibitory effect at a concentration of 0.1 mg/mL, but those bearing a 5-hydroxyl group reduced the inhibitory potency. On the other hand, flavones bearing a 3'- or 5'-methoxy group did not influence the inhibitory effect. Interestingly, 5,7-dimethoxyflavone (7) exhibited strong selectivity for BChE over AChE which may be of great interest to modify as a treatment agent for Alzheimer's disease. Copyright (c) 2009 John Wiley & Sons, Ltd.

Effect of inhibitory feedback on correlated firing of spiking neural network.

PubMed

Xie, Jinli; Wang, Zhijie

2013-08-01

Understanding the properties and mechanisms that generate different forms of correlation is critical for determining their role in cortical processing. Researches on retina, visual cortex, sensory cortex, and computational model have suggested that fast correlation with high temporal precision appears consistent with common input, and correlation on a slow time scale likely involves feedback. Based on feedback spiking neural network model, we investigate the role of inhibitory feedback in shaping correlations on a time scale of 100 ms. Notably, the relationship between the correlation coefficient and inhibitory feedback strength is non-monotonic. Further, computational simulations show how firing rate and oscillatory activity form the basis of the mechanisms underlying this relationship. When the mean firing rate holds unvaried, the correlation coefficient increases monotonically with inhibitory feedback, but the correlation coefficient keeps decreasing when the network has no oscillatory activity. Our findings reveal that two opposing effects of the inhibitory feedback on the firing activity of the network contribute to the non-monotonic relationship between the correlation coefficient and the strength of the inhibitory feedback. The inhibitory feedback affects the correlated firing activity by modulating the intensity and regularity of the spike trains. Finally, the non-monotonic relationship is replicated with varying transmission delay and different spatial network structure, demonstrating the universality of the results.

Plant-soil-microbe interactions regulating soil C storage

NASA Astrophysics Data System (ADS)

Hofmockel, K. S.; Bach, E.; Williams, R.

2016-12-01

Integration across disciplines is required to identify the emergent microbial scale properties that regulate the release or occlusion of plant inputs in soil organic matter. To investigate how micro-scale processes influence soil carbon cycling, we measured microbial community composition and activity within soil aggregates monthly over two growing seasons of a long-term bioenergy field experiment. Using a biologically sensitive sieving technique, soil aggregates were isolated and microbial community activity and composition were measured. This aggregate approach revealed biogeochemical processes regulating C cycling that are not detected using whole soil approaches. Soil aggregation influenced microbe-substrate interactions, where diversified perennial grassland systems supported greater aggregation and reduced severity of aggregate turnover compared to corn systems. Aggregate turnover and concurrent increases in activity resulted in greater microbial biomass and physical protection of soil organic matter in prairie systems, especially fertilized prairies. Fertilized prairie enhanced microbial biomass, enzyme activity, and soil aggregation despite greater root biomass in unfertilized prairie. Independent of ecosystem or sampling date, N-acetyl-glucosaminidase activity and Nitrospirae abundance was greatest in large macroaggregates (>2000 µm), which harbored the highest C:N; cellobiohydrolase activity and Acidobacteria abundance was greatest in microaggregates (<250 µm) which had the lowest C:N. Aggregate fractions differed in microbial community composition (bacteria, archaea, and fungi) and potential enzyme activity, independent of cropping system. Microaggregates harbored significantly greater microbial diversity and richness across all bioenergy cropping systems. Together these results suggest that by mediating access to substrates, soil structure (aggregates) can influence the microbial community composition and extracellular enzyme activity to regulate ecosystem scale decomposition of soil organic matter.

Cross-inhibition between black-pigmented Bacteroides species.

PubMed

Van Winkelhoff, A J; Kippuw, N; De Graaff, J

1987-11-01

Cross-inhibition within the group of black-pigmented Bacteroides, including both oral and non-oral strains, was studied by means of a membrane filter technique. It was found that B. gingivalis possessed the most extended inhibitory capacity among all species tested. B. gingivalis showed inhibitory activity against B. intermedius, B. endodontalis, B. loescheii, and B. melaninogenicus. B. endodontalis was active against some B. intermedius strains. Among the saccharolytic species, some B. melaninogenicus strains were inhibitory for some B. endodontalis strains, some B. gingivalis strains, and some B. intermedius strains. These inhibitory activities observed in vitro may play a role in the colonization of the periodontal pocket.

Inhibitory effect of flavonoids from citrus plants on Epstein-Barr virus activation and two-stage carcinogenesis of skin tumors.

PubMed

Iwase, Y; Takemura, Y; Ju-ichi, M; Ito, C; Furukawa, H; Kawaii, S; Yano, M; Mou, X Y; Takayasu, J; Tokuda, H; Nishino, H

2000-06-01

To search for possible anti-tumor promoters, thirteen flavones (1-13) obtained from the peel of Citrus plants were examined for their inhibitory effects on the Epstein-Barr virus early antigen (EBV-EA) activation by a short-term in vitro assay. Of these flavones, 3,5,6,7,8,3',4'-heptamethoxyflavone (HPT) (13) exhibited significant inhibitory effects on the EBV-EA activation induced by the tumor promoter, 12-O-tetradecanoylphorbol 13-acetate (TPA). Further, compound 13 exhibited remarkable inhibitory effects on mouse skin tumor promotion in an in vivo two-stage carcinogenesis test.

Modeling of chemical inhibition from amyloid protein aggregation kinetics.

PubMed

Vázquez, José Antonio

2014-02-27

The process of amyloid proteins aggregation causes several human neuropathologies. In some cases, e.g. fibrillar deposits of insulin, the problems are generated in the processes of production and purification of protein and in the pump devices or injectable preparations for diabetics. Experimental kinetics and adequate modelling of chemical inhibition from amyloid aggregation are of practical importance in order to study the viable processing, formulation and storage as well as to predict and optimize the best conditions to reduce the effect of protein nucleation. In this manuscript, experimental data of insulin, Aβ42 amyloid protein and apomyoglobin fibrillation from recent bibliography were selected to evaluate the capability of a bivariate sigmoid equation to model them. The mathematical functions (logistic combined with Weibull equation) were used in reparameterized form and the effect of inhibitor concentrations on kinetic parameters from logistic equation were perfectly defined and explained. The surfaces of data were accurately described by proposed model and the presented analysis characterized the inhibitory influence on the protein aggregation by several chemicals. Discrimination between true and apparent inhibitors was also confirmed by the bivariate equation. EGCG for insulin (working at pH = 7.4/T = 37°C) and taiwaniaflavone for Aβ42 were the compounds studied that shown the greatest inhibition capacity. An accurate, simple and effective model to investigate the inhibition of chemicals on amyloid protein aggregation has been developed. The equation could be useful for the clear quantification of inhibitor potential of chemicals and rigorous comparison among them.

Distribution of Sulfate-Reducing and Methanogenic Bacteria in Anaerobic Aggregates Determined by Microsensor and Molecular Analyses

PubMed Central

Santegoeds, Cecilia M.; Damgaard, Lars Riis; Hesselink, Gijs; Zopfi, Jakob; Lens, Piet; Muyzer, Gerard; de Beer, Dirk

1999-01-01

Using molecular techniques and microsensors for H2S and CH4, we studied the population structure of and the activity distribution in anaerobic aggregates. The aggregates originated from three different types of reactors: a methanogenic reactor, a methanogenic-sulfidogenic reactor, and a sulfidogenic reactor. Microsensor measurements in methanogenic-sulfidogenic aggregates revealed that the activity of sulfate-reducing bacteria (2 to 3 mmol of S2− m−3 s−1 or 2 × 10−9 mmol s−1 per aggregate) was located in a surface layer of 50 to 100 μm thick. The sulfidogenic aggregates contained a wider sulfate-reducing zone (the first 200 to 300 μm from the aggregate surface) with a higher activity (1 to 6 mmol of S2− m−3 s−1 or 7 × 10−9 mol s−1 per aggregate). The methanogenic aggregates did not show significant sulfate-reducing activity. Methanogenic activity in the methanogenic-sulfidogenic aggregates (1 to 2 mmol of CH4 m−3 s−1 or 10−9 mmol s−1 per aggregate) and the methanogenic aggregates (2 to 4 mmol of CH4 m−3 s−1 or 5 × 10−9 mmol s−1 per aggregate) was located more inward, starting at ca. 100 μm from the aggregate surface. The methanogenic activity was not affected by 10 mM sulfate during a 1-day incubation. The sulfidogenic and methanogenic activities were independent of the type of electron donor (acetate, propionate, ethanol, or H2), but the substrates were metabolized in different zones. The localization of the populations corresponded to the microsensor data. A distinct layered structure was found in the methanogenic-sulfidogenic aggregates, with sulfate-reducing bacteria in the outer 50 to 100 μm, methanogens in the inner part, and Eubacteria spp. (partly syntrophic bacteria) filling the gap between sulfate-reducing and methanogenic bacteria. In methanogenic aggregates, few sulfate-reducing bacteria were detected, while methanogens were found in the core. In the sulfidogenic aggregates, sulfate-reducing bacteria were present in the outer 300 μm, and methanogens were distributed over the inner part in clusters with syntrophic bacteria. PMID:10508098

Production, optimisation and characterisation of angiotensin converting enzyme inhibitory peptides from sea cucumber (Stichopus japonicus) gonad.

PubMed

Zhong, Chan; Sun, Le-Chang; Yan, Long-Jie; Lin, Yi-Chen; Liu, Guang-Ming; Cao, Min-Jie

2018-01-24

In this study, production of bioactive peptides with angiotensin converting enzyme (ACE) inhibitory activity from sea cucumber (Stichopus japonicus) gonad using commercial protamex was optimised by response surface methodology (RSM). As a result, the optimal condition to achieve the highest ACE inhibitory activity in sea cucumber gonad hydrolysate (SCGH) was hydrolysis for 1.95 h and E/S of 0.75%. For further characterisation, three individual peptides (EIYR, LF and NAPHMR) were purified and identified. The peptide NAPHMR showed the highest ACE inhibitory activity with IC 50 of 260.22 ± 3.71 μM. NAPHMR was stable against simulated gastrointestinal digestion and revealed no significant cytotoxicity toward Caco-2 cells. Molecular docking study suggested that Arg, His and Asn residues in NAPHMR interact with the S2 pocket or Zn 2+ binding motifs of ACE via hydrogen or π-bonds, potentially contributing to ACE inhibitory effect. Sea cucumber gonad is thus a potential resource to produce ACE inhibitory peptides for preparation of functional foods.

Amifostine, a reactive oxigen species scavenger with radiation- and chemo-protective properties, inhibits in vitro platelet activation induced by ADP, collagen or PAF.

PubMed

Porta, C; Maiolo, A; Tua, A; Grignani, G

2000-08-01

Reactive oxygen species (ROS) generation has been suggested to represent an important regulatory mechanism of platelet reactivity in both physiologic and pathologic conditions; consistent with this hypothesis is the observation that free-radical scavengers may inhibit platelet activation, thus contributing to the regulation of their reactivity. The purpose of the present study is to study the in vitro effects of amifostine (WR-2721, ethyol ), a selective cytoprotective agent for normal tissues against the toxicities of chemotherapy and radiation, on platelet activation induced by the physiologic agonists ADP, collagen and PAF. The effect of amifostine, added to the experimental system at final concentrations ranging from 10(-7) M to 10(-5) M, was studied on platelet aggregation induced by the following physiologic agonists at the given concentrations: ADP (1 microM), collagen (2 microg/mL), and PAF (0.1 microg/mL). Platelet aggregation was investigated using a platelet ionized calcium aggregometer and was expressed as the percentage change in light transmission. Furthermore, thromboxane B((2)) (TxB((2))) levels and nitric oxide (NO) production were determined by radioimmunoassay and by evaluating the total nitrite/nitrate concentration using a commercially available colorimetric kit, respectively, both in the control system and after the addition of amifostine. Amifostine inhibited both platelet aggregation and TxB((2)) production induced by ADP, collagen and PAF, in a dose-dependent manner. Amifostine proved to be an effective inhibitor of platelet function and the effect was more pronounced if platelets were stimulated with ADP, intermediate when collagen was the chosen agonist, and less evident, though present, when PAF was used. Platelets stimulated with ADP, collagen or PAF produced significant amounts of NO over the baseline. When amifostine was added at a final concentration of 5 microM, it significantly increased ADP, collagen and PAF-induced NO production, which suggests that NO release by activated platelets was involved in the inhibitory effect of amifostine. Amifostine proved to be an effective inhibitor of platelet activation induced in vitro by physiologic inducers. This previously unrecognized effect was more evident with the weak agonist ADP and was related to reduced NO consumption by free radicals generated during platelet activation. Amifostine proved to be not only a powerful cytoprotectant, but, more generally, a therapeutic agent endowed with several relevant, though largely unknown, biological effects. Finally, our data once again support the concept that oxidative balance is of crucial importance in regulating platelet reactivity in both health and disease.

Structural insight into the active site of mushroom tyrosinase using phenylbenzoic acid derivatives.

PubMed

Oyama, Takahiro; Yoshimori, Atsushi; Takahashi, Satoshi; Yamamoto, Tetsuya; Sato, Akira; Kamiya, Takanori; Abe, Hideaki; Abe, Takehiko; Tanuma, Sei-Ichi

2017-07-01

So far, many inhibitors of tyrosinase have been discovered for cosmetic and clinical agents. However, the molecular mechanisms underlying the inhibition in the active site of tyrosinase have not been well understood. To explore this problem, we examined here the inhibitory effects of 4'-hydroxylation and methoxylation of phenylbenzoic acid (PBA) isomers, which have a unique scaffold to inhibit mushroom tyrosinase. The inhibitory effect of 3-PBA, which has the most potent inhibitory activity among the isomers, was slightly decreased by 4'-hydroxylation and further decreased by 4'-methoxylation against mushroom tyrosinase. Surprisingly, 4'-hydroxylation but not methoxylation of 2-PBA appeared inhibitory activity. On the other hand, both 4'-hydroxylation and methoxylation of 4-PBA increased the inhibitory activity against mushroom tyrosinase. In silico docking analyses using the crystallographic structure of mushroom tyrosinase indicated that the carboxylic acid or 4'-hydroxyl group of PBA derivatives could chelate with cupric ions in the active site of mushroom tyrosinase, and that the interactions of Asn260 and Phe264 in the active site with the adequate-angled biphenyl group are involved in the inhibitory activities of the modified PBAs, by parallel and T-shaped π-π interactions, respectively. Furthermore, Arg268 could fix the angle of the aromatic ring of Phe264, and Val248 is supposed to interact with the inhibitors as a hydrophobic manner. These results may enhance the structural insight into mushroom tyrosinase for the creation of novel tyrosinase inhibitors. Copyright © 2017 Elsevier Ltd. All rights reserved.

Inhibitory activity of homoisoflavonoids from Caesalpinia sappan against Beauveria bassiana.

PubMed

Niranjan Reddy, V L; Ravikanth, V; Jansi Lakshmi, V V N S; Suryanarayan Murty, U; Venkateswarlu, Y

2003-09-01

Four homoisoflavonoids, 4-O-methylsappanol (1), protosappanin A (2), brazilin (3) and caeasalpin J (4), isolated from Caesalpinia sappan, were tested for inhibitory activity against Beauveria bassiana. Compound 1 showed activity against this fungus.

The Candida albicans Inhibitory Activity of the Extract from Papaya (Carica papaya L.) Seed Relates to Mitochondria Dysfunction.

PubMed

Zhang, Tao; Chen, Weijun

2017-08-25

The inhibitory activity of the papaya seed extract (PSE) on Candida albicans ( C. albicans ) was determined by turbidimetry method. The inhibitory mechanisms were also evaluated from the prospective of reactive oxygen species (ROS) generation, mitochondrial membrane potential (MMP) decrease, and the activities of four complex enzymes in mitochondria respiratory chain. Results obtained from this study indicated that the PSE exhibited an effective inhibitory activity on C. albicans and induced significant accumulation of ROS and collapse of MMP. The Complex I and Complex III exhibited continues significant decrease in mitochondrial enzyme activity assays, but the Complex II and Complex IV activities were not positively correlated. Furthermore, the GC-MS analysis demonstrated that the PSE represents a rich and high-purity source of benzyl isothiocyanate (BITC), which indicated the BITC may be responsible for the mitochondrial dysfunction.

Identification and evaluation of magnolol and chrysophanol as the principle protein tyrosine phosphatase-1B inhibitory compounds in a Kampo medicine, Masiningan.

PubMed

Onoda, Toshihisa; Li, Wei; Sasaki, Tatsunori; Miyake, Megumi; Higai, Koji; Koike, Kazuo

2016-06-20

Masiningan is a traditional medicine consisting of six crude drugs that have been used for treating constipation and diabetes mellitus in both Japan and China. Masiningan has been reported to have significant PTP1B inhibitory activity and to affect cells in the insulin-signaling pathway. The aim of the present study is to identify the PTP1B inhibitory compounds in Masiningan. Bioactivity peaks were identified by analytical HPLC profiling and PTP1B inhibitory activity profiling of sub-fractions from Masiningan extract. The bioactive compounds were isolated by tracking two identified bioactive peaks, and the chemical structures were determined by spectroscopic analyses. The bioactive compounds were further investigated for their inhibitory effect against PTP1B by enzymatic kinetic analysis, molecular docking simulation, inhibitory selectivity against other PTPs, and cellular activity in the insulin signal transduction pathway. From Masiningan, magnolol (1) and chrysophanol (2) were isolated as compounds that exhibited significant dose-dependent inhibitory activities against PTP1B, with IC50 values of 24.6 and 12.3μM, respectively. Kinetic analysis revealed that 1 is a non-competitive and that 2 is a competitive PTP1B inhibitor. In the molecular docking simulation, compound 2 was stably positioned in the active pocket of PTP1B, and the CDOCKER energy was calculated to be 24.3411kcal/mol. Both compounds demonstrated remarkably high selectivity against four PTPs and revealed cellular activity against the insulin signal transduction pathway. Magnolol (1) and chrysophanol (2) were identified as the principle PTP1B inhibitory active compounds in Masiningan, and their actions were investigated in detail. These findings demonstrated the effectiveness of Masiningan on diabetes mellitus through the inhibition of PTP1B at a molecular level as well as the potential of magnolol (1) and chrysophanol (2) as lead compounds in future anti-diabetes drug development. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Identification of Potent ACE Inhibitory Peptides from Wild Almond Proteins.

PubMed

Mirzapour, Mozhgan; Rezaei, Karamatollah; Sentandreu, Miguel Angel

2017-10-01

In this study, the production, fractionation, purification and identification of ACE (angiotensin-I-converting enzyme) inhibitory peptides from wild almond (Amygdalus scoparia) proteins were investigated. Wild almond proteins were hydrolyzed using 5 different enzymes (pepsin, trypsin, chymotrypsin, alcalase and flavourzyme) and assayed for their ACE inhibitory activities. The degree of ACE inhibiting activity obtained after hydrolysis was found to be in the following order: alcalase > chymotrypsin > trypsin/pepsin > flavourzyme. The hydrolysates obtained from alcalase (IC 50 = 0.8 mg/mL) were fractionated by sequential ultrafiltration at 10 and 3 kDa cutoff values and the most active fraction (<3 kDa) was further separated using reversed phase high-performance liquid chromatography (RP-HPLC). Peptide sequence identifications were carried out on highly potential fractions obtained from RP-HPLC by means of liquid chromatography coupled to electrospray ionization and tandem mass spectrometry (LC-ESI-MS/MS). Sequencing of ACE inhibitory peptides present in the fraction 26 of RP-HPLC resulted in the identification of 3 peptide sequences (VVNE, VVTR, and VVGVD) not reported previously in the literature. Sequence identification of fractions 40 and 42 from RP-HPLC, which showed the highest ACE inhibitory activities (84.1% and 86.9%, respectively), resulted in the identification of more than 40 potential ACE inhibitory sequences. The results indicate that wild almond protein is a rich source of potential antihypertensive peptides and can be suggested for applications in functional foods and drinks with respect to hindrance and mitigation of hypertension after in vivo assessment. This study has shown the potential of wild almond proteins as good sources for producing ACE-inhibitory active peptides. According to this finding, peptides with higher ACE inhibitory activities could be released during the gastrointestinal digestion and contribute to the health- promoting activities of this natural protein source. © 2017 Institute of Food Technologists®.

Design, synthesis, and antimelanogenic effects of (2-substituted phenyl-1,3-dithiolan-4-yl)methanol derivatives

PubMed Central

Kim, Do Hyun; Kim, Su Jeong; Ullah, Sultan; Yun, Hwi Young; Chun, Pusoon; Moon, Hyung Ryong

2017-01-01

The authors designed and synthesized 17 (2-substituted phenyl-1,3-dithiolan-4-yl) methanol (PDTM) derivatives to find a new chemical scaffold, showing excellent tyrosinase-inhibitory activity. Their tyrosinase-inhibitory activities were evaluated against mushroom tyrosinase at 50 μM, and five of the PDTM derivatives (PDTM3, PDTM7–PDTM9, and PDTM13) were found to inhibit mushroom tyrosinase more than kojic acid or arbutin, the positive controls. Of seventeen PDTMs, PDTM3 (half-maximal inhibitory concentration 13.94±1.76 μM), with a 2,4-dihydroxyphenyl moiety, exhibited greatest inhibitory effects (kojic acid half-maximal inhibitory concentration 18.86±2.14 μM). Interestingly, PDTM compounds with no hydroxyl group, PDTM7–PDTM9, also had stronger inhibitory activities than kojic acid. In silico studies of interactions between tyrosinase and the five PDTMs suggested their binding affinities were closely related to their tyrosinase-inhibitory activities. Cell-based experiments performed using B16F10 mouse-skin melanoma cells showed that PDTM3 effectively inhibited melanogenesis and cellular tyrosinase activity. A cell-viability study conducted using B16F10 cells indicated that the antimelanogenic effect of PDTM3 was not attributable to its cytotoxicity. Kinetic studies showed PDTM3 competitively inhibited tyrosinase, indicating binding to the tyrosinase-active site. We found that PDTM3 with a new chemical scaffold could be a promising candidate for skin-whitening agents, and that the 1,3-dithiolane ring could be used as a chemical scaffold for potent tyrosinase inhibition. PMID:28352157

ACETYL CHOLINESTERASE AND BUTYRYL CHOLINESTERASE INhIBITORY ACTIVITIES OF ZALEYA PENTANDRA.

PubMed

Afzal, Samina; Chaudhry, Bashir Ahmad; Afzal, Khurram; Saeed, Javeria; Akash, Sajd Hamid; Qadir, Muhammad Imran

2017-05-01

The aim of this study was to reveal acetyl cholinesterase (AchE) and butyryl cholinesterase (BchE) inhibitory activities of Zaleya pentandra. The aerial parts of the plant were air, freeze-dried and powdered. The extraction was carried out with methanol at room temperature for 24 h. The extract was concentrated on rotavapor and fractioned by column chromatography. The isolation and purification afforded amorphous solid which was subjected to physical, chemical and spectroscopic techniques i.e., UV, IR, H-NMR, "C-NMR and HREI-MS for the structure elucidation of the isolated compound. The compound was concluded as "Pentandradione" a novel compound. AchE and BchE inhibitory activities were estimated. The result showed that the isolated extract possessed significant activity against butyryl cholinesterase as compared to standard eserine while the extract lacks acetyl cholinesterase inhibitory activity.

The missing piece in the 'use it or lose it' puzzle: is inhibition regulated by activity or does it act on its own accord?

PubMed

Sun, Qian-Quan

2007-01-01

We have gained enormous insight into the mechanisms underlying both activity-dependent and (to a lesser degree) -independent plasticity of excitatory synapses. Recently, cortical inhibition has been shown to play a vital role in the formation of critical periods for sensory plasticity. As such, sculpting of neuronal circuits by inhibition may be a common mechanism by which activity organizes or reorganizes brain circuits. Disturbances in the balance of excitation and inhibition in the neocortex provoke abnormal activities, such as epileptic seizures and abnormal cortical development. However, both the process of experience-dependent postnatal maturation of neocortical inhibitory networks and its underlying mechanisms remain elusive. Mechanisms that match excitation and inhibition are central to achieving balanced function at the level of individual circuits. The goal of this review is to reinforce our understanding of the mechanisms by which developing inhibitory networks are able to adapt to sensory inputs, and to maintain their balance with developing excitatory networks. Discussion is centered on the following questions related to experience-dependent plasticity of neocortical inhibitory networks: 1) What are the roles of GABAergic inhibition in the postnatal maturation of neocortical circuits? 2) Does the maturation of neocortical inhibitory circuits proceed in an activity-dependent manner or do they develop independently of sensory inputs? 3) Does activity regulate inhibitory networks in the same way it regulates excitatory networks? 4) What are the molecular and cellular mechanisms that underlie the activity-dependent maturation of inhibitory networks? 5) What are the functional advantages of experience-dependent plasticity of inhibitory networks to network processing in sensory cortices?

New Indole Alkaloids from the Bark of Rauvolfia Reflexa and their Cholinesterase Inhibitory Activity.

PubMed

Fadaeinasab, Mehran; Basiri, Alireza; Kia, Yalda; Karimian, Hamed; Ali, Hapipah Mohd; Murugaiyah, Vikneswaran

2015-01-01

Rauvolfia reflexa is a member of the Apocynaceae family. Plants from the Apocynaceae family have been traditionally used in the treatment of age-related brain disorders Methods and Results: Two new indole alkaloids, rauvolfine C (1) and 3-methyl-10,11-dimethoxy-6-methoxycarbonyl-β-carboline (2), along with five known, macusine B (3), vinorine (4), undulifoline (5), isoresrpiline (6) and rescinnamine (7) were isolated from the bark of Rauvolfia reflexa. Cholinesterase inhibitory assay and molecular docking were performed to get insight of the inhibitory activity and molecular interactions of the compounds. The compounds showed good to moderate cholinesterase inhibitory activity with IC50 values in the range of 8.06 to 73.23 µM. Compound 7 was found to be the most potent inhibitor of both acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). Compounds 1, 2, 5 and 6 were found to be selective towards BChE, while compounds 3, 4 and 7 were dual inhibitors, having almost equal inhibitory activity on both AChE and BChE. Molecular docking revealed that compounds 6 and 7 interacted differently on AChE and BChE, by means of hydrophobic interactions and hydrogen bonding. In AChE, the indole moiety of both compounds interacted with the residues lining the peripheral anionic site, whereas in BChE, their methoxy groups are primarily responsible for the strong inhibitory activity via interactions with residues at the active site of the enzyme. Two new and five known indole alkaloids were isolated from R. reflexa. Among the compounds, 7 and 6 showed the most potent and promising cholinesterase inhibitory activity, worthy for further investigations. © 2015 S. Karger AG, Basel.

Insulin sensitizing and alpha-glucoamylase inhibitory action of sennosides, rheins and rhaponticin in Rhei Rhizoma.

PubMed

Choi, Soo Bong; Ko, Byoung Seob; Park, Seong Kyu; Jang, Jin Sun; Park, Sunmin

2006-01-25

Extracts from Rhei Rhizoma extracts (RR) have been reported to attenuate metabolic disorders such as diabetic nephropathy, hypercholesterolemia and platelet aggregation. With this study we investigated the anti-diabetic action of 70% ethanol RR extract in streptozotocin-induced diabetic mice, and determined the action mechanism of active compounds of RR in vitro. In the diabetic mice, serum glucose levels at fasting and post-prandial states and glucose area under the curve at modified oral glucose tolerance tests were lowered without altering serum insulin levels, indicating that RR contained potential anti-diabetic agents. The fractions fractionated from RR extracts by XAD-4 column revealed that 60%, 80% and 100% methanol fractions enhanced insulin sensitivity and inhibited alpha-glucoamylase activity. The major compounds of these fractions were sennosides, rhein and rhaponticin. Rhaponticin and rhein enhanced insulin-stimulated glucose uptake in 3T3-L1 adipocytes. Rhaponticin increased adipocytes with a differentiating effect similar to pioglitazone, but rhein and sennoside B decreased triglyceride accumulation. Sennoside A and B inhibited alpha-glucoamylase activity as much as acarbose. In conclusion, a crude extract of RR improves glucose intolerance by enhancing insulin-stimulated glucose uptake and decreasing carbohydrate digestion via inhibiting alpha-glucoamylase activity. Rhein and rhaponticin are potential candidates for hypoglycemic agents.

Destructive effect of non-enzymatic glycation on catalase and remediation via curcumin.

PubMed

Mofidi Najjar, Fayezeh; Taghavi, Fereshteh; Ghadari, Rahim; Sheibani, Nader; Moosavi-Movahedi, Ali Akbar

2017-09-15

Non-enzymatic glycation of proteins is a post-translational modification that is produced by a covalent binding between reducing sugars and amino groups of lysine and arginine residues. In this paper the effect of pathological conditions, derived from hyperglycemia on bovine liver catalase (BLC) as a model protein was considered by measuring enzyme activity, reactive oxygen species (ROS) generation, and changes in catalase conformational properties. We observed that in the presence of glucose, the catalase activity gradually decreased. ROS generation was also involved in the glycation process. Thus, decreased BLC activity was partly considered as a result of ROS generation through glycation. However, in the presence of curcumin the amount of ROS was reduced resulting in increased activity of the glycated catalase. The effect of high glucose level and the potential inhibitory effect of curcumin on aggregation and structural changes of catalase were also investigated. Molecular dynamic simulations also showed that interaction of catalase with curcumin resulted in changes in accessible surface area (ASA) and pKa, two effective parameters of glycation, in potential glycation lysine residues. Thus, the decrease in ASA and increase in pKa of important lysine residues were considered as predominant factors in decreased glycation of BLC by curcumin. Copyright © 2017 Elsevier Inc. All rights reserved.

Inhibitory Effects of Respiration Inhibitors on Aflatoxin Production

PubMed Central

Sakuda, Shohei; Prabowo, Diyan Febri; Takagi, Keiko; Shiomi, Kazuro; Mori, Mihoko; Ōmura, Satoshi; Nagasawa, Hiromichi

2014-01-01

Aflatoxin production inhibitors, which do not inhibit the growth of aflatoxigenic fungi, may be used to control aflatoxin without incurring a rapid spread of resistant strains. A respiration inhibitor that inhibits aflatoxin production was identified during a screening process for natural, aflatoxin-production inhibitors. This prompted us to evaluate respiration inhibitors as potential aflatoxin control agents. The inhibitory activities of four natural inhibitors, seven synthetic miticides, and nine synthetic fungicides were evaluated on aflatoxin production in Aspergillus parasiticus. All of the natural inhibitors (rotenone, siccanin, aptenin A5, and antimycin A) inhibited fungal aflatoxin production with IC50 values around 10 µM. Among the synthetic miticides, pyridaben, fluacrypyrim, and tolfenpyrad exhibited strong inhibitory activities with IC50 values less than 0.2 µM, whereas cyflumetofen did not show significant inhibitory activity. Of the synthetic fungicides, boscalid, pyribencarb, azoxystrobin, pyraclostrobin, and kresoxim-methyl demonstrated strong inhibitory activities, with IC50 values less than 0.5 µM. Fungal growth was not significantly affected by any of the inhibitors tested at concentrations used. There was no correlation observed between the targets of respiration inhibitors (complexes I, II, and III) and their IC50 values for aflatoxin-production inhibitory activity. This study suggests that respiration inhibitors, including commonly used pesticides, are useful for aflatoxin control. PMID:24674936

Absolute Side-chain Structure at Position 13 Is Required for the Inhibitory Activity of Bromein*

PubMed Central

Sawano, Yoriko; Hatano, Ken-ichi; Miyakawa, Takuya; Tanokura, Masaru

2008-01-01

Bromelain isoinhibitor (bromein), a cysteine proteinase inhibitor from pineapple stem, has a unique double-chain structure. The bromein precursor protein includes three homologous inhibitor domains, each containing an interchain peptide between the light and heavy chains. The interchain peptide in the single-chain precursor is immediately processed by bromelain, a target proteinase. In the present study, to clarify the essential inhibitory site of bromein, we constructed 44 kinds of site-directed and deletion mutants and investigated the inhibitory activity of each toward bromelain. As a result, the complete chemical structure of Leu13 in the light chain was revealed to be essential for inhibition. Pro12 prior to the leucine residue was also involved in the inhibitory activity and would control the location of the leucine side chain by the fixed φ dihedral angle of proline. Furthermore, the five-residue length of the interchain peptide was strictly required for the inhibitory activity. On the other hand, no inhibitory activity against bromelain was observed by the substitution of proline for the N terminus residue Thr15 of the interchain peptide. In summary, these mutational analyses of bromein demonstrated that the appropriate position and conformation of Leu13 are absolutely crucial for bromelain inhibition. PMID:18948264

Parathyroid hormone is not an inhibitor of lipoprotein lipase activity.

PubMed

Arnadottir, M; Nilsson-Ehle, P

1994-01-01

The reduced lipoprotein lipase (LPL) activities in uraemia are reflected by increased serum triglyceride concentrations and reduced HDL cholesterol concentrations. Both hyperparathyroidism and circulating inhibitor(s) of LPL have been associated with the disturbances of lipid metabolism in uraemia. The aim of the present study was to investigate if parathyroid hormone (PTH) had an inhibitory effect on LPL activity. Plasma post-heparin LPL activities, plasma LPL inhibitory activities, serum PTHintact and serum PTHC-terminal concentrations were analysed in 20 patients on haemodialysis and 20 healthy controls. The effects of purified, human PTHintact and a carboxyterminal fragment of PTH (PTH39-84) on LPL activities in post-heparin plasma from healthy individuals and on the enzyme activity of purified, bovine milk LPL, activated with apolipoprotein CII, were studied. Patients had significantly higher plasma LPL inhibitory activities than controls, but there was no correlation between plasma LPL inhibitory activities and serum PTH concentrations. Neither PTHintact nor PTH39-84 had a significant effect on LPL activities in vitro. Thus there was no evidence of a direct inhibition of LPL activity by PTH under the present in-vivo or in-vitro conditions.

NP-313, 2-acetylamino-3-chloro-1,4-naphthoquinone, a novel antithrombotic agent with dual inhibition of thromboxane A2 synthesis and calcium entry

PubMed Central

Kuo, Heng-Lan; Lien, Jin-Cherng; Chang, Chien-Hsin; Chung, Ching-Hu; Kuo, Sheng-Chu; Hsu, Chun-Chieh; Peng, Hui-Chin; Huang, Tur-Fu

2011-01-01

BACKGROUND AND PURPOSE 1,4-Naphthoquinones exhibit antiplatelet activity both in vivo and in vitro. In the present study, we investigated the antiplatelet effect of a novel naphthoquinone derivative NP-313, 2-acetylamino-3-chloro-1,4-naphthoquinone and its mechanism of action. EXPERIMENTAL APPROACH We measured platelet aggregation, Ca2+ mobilization, thromboxane B2 formation and P-selectin expression and examined several enzymatic activities. Furthermore, we used the irradiated mesenteric venules in fluorescein sodium–treated mice to monitor the antithrombotic effect of NP-313 in vivo. KEY RESULTS NP-313 concentration-dependently inhibited human platelet aggregation induced by collagen, arachidonic acid, thapsigargin, thrombin and A23187. NP-313 also inhibited P-selectin expression, thromboxane B2 formation and [Ca2+]i elevation in platelets stimulated by thrombin and collagen. NP-313 at 10 µM inhibited cyclooxygenase, thromboxane A2 synthase, and protein kinase Cα, whereas it did not affect phospholipase A2 or phospholipase C activity. In the presence of indomethacin and an adenosine 5-diphosphate scavenger, NP-313 concentration-dependently inhibited thrombin- and A23187-induced [Ca2+]i increase through its inhibitory effects on Ca2+ influx, rather than blocking Ca2+ release from intracellular stores. NP-313 also inhibited thapsigargin-mediated Ca2+ influx through store-operated calcium channel but had no effect on Ca2+ influx through store-independent calcium channel evoked by the diacylglycerol analogue 1-oleoyl-2-acetyl-sn-glycerol. Nevertheless, it had little effect on cyclic AMP and cyclic GMP levels. Also, intravenously administered NP-313 dose-dependently inhibited the thrombus occlusion of the irradiated mesenteric vessels of fluorescein-pretreated mice. CONCLUSIONS AND IMPLICATIONS Taken together, these results indicate that NP-313 exerts its antithrombotic activity through dual inhibition of thromboxane A2 synthesis and Ca2+ influx through SOCC. PMID:21232029

Equol is more active than soy isoflavone itself to compete for binding to thromboxane A(2) receptor in human platelets.

PubMed

Muñoz, Yenny; Garrido, Argelia; Valladares, Luis

2009-03-01

Several dietary intervention studies examining the health effect of soy isoflavones allude to the importance of equol in establishing the cardiovascular response to soy protein. Although, the specific mechanism by which this action occurs has not been established. The aim of this study was to investigate the inhibitory effect of soy-isoflavones and the metabolite of daidzein, equol, on agonist-induced platelet responses dependent on thromboxane A(2) (TxA(2)) receptor. Competitive radioligand binding assay was used to screen for affinity of these compounds to the TxA(2) receptor. The effect of equol on platelet activation, evaluate through of release of the ATP, by analogs of TxA(2) was analyzed. The effect of equol on platelet aggregation was investigated with ADP, U46619 (a TxA(2) mimic) and the calcium ionophore A23187. The data showed that aglycone isoflavones and equol bind to TxA(2) receptor in the micromol/L range, whereas their glucoside derivates had very low binding activity for this receptor. Under equilibrium conditions, the following order of the relative affinity in inhibiting [(3)H]-SQ29585 binding was: equol>genistein>daidzein>glycitein>genistin, daidzin, glycitin. Equol interaction was reversible and competitive for labeled-SQ29548 with not apparent decrease in the number of TxA(2) binding sites. In addition, from platelet activation studies, equol effectively inhibited ATP secretion elicited by the TxA(2) analog U46619. On the other hand, equol inhibited the platelet aggregation induced by U46619 and A23187, while it failed to inhibit that induced by ADP. The aglycone isoflavones from soy, and particularly equol, have been found to have biological effects attributable to thromboxane A(2) receptor antagonism. These findings may help elucidate how dietary isoflavone modulate platelet function and explain why soy-rich foods are claimed to have beneficial effects in the prevention of thrombotic events.

Effects of Pasteurella haemolytica leukotoxic culture supernatant on bovine neutrophil aggregation.

PubMed Central

Conlon, P; Gervais, M; Chaudhari, S; Conlon, J

1992-01-01

Pasteurella haemolytica A1 leukotoxic culture supernatant was evaluated for its ability to cause aggregation of bovine peripheral neutrophils. Neutrophils were isolated by a hypotonic lysis method and incubated with zymosan-activated plasma (ZAP), leukotoxic culture supernatant, antileukotoxin serum, calcium and magnesium-free media, p-bromophenacyl bromide and protein kinase C inhibitors. Aggregation was evaluated by changes in infrared light transmittance. Leukotoxic culture supernatant caused neutrophils to aggregate, and this effect was significantly removed by preincubation with antileukotoxin serum. Aggregation to ZAP and leukotoxin was dependent on the presence of extra-cellular calcium. Activation of protein kinase C by phorbol myristate acetate induced aggregation which was reduced by staurosporine; however, aggregation to leukotoxin did not involve protein kinase C activation. Phospholipase A2 inhibition did not alter the aggregation response to ZAP or to leukotoxin. The in vitro measurement of neutrophil aggregation induced by the leukotoxin of P. haemolytica reflects cytoskeletal and other activation events that may contribute to the intense inflammatory process which this organism induces in the lungs of cattle. PMID:1423054

Degradation of surfactant-associated protein B (SP-B) during in vitro conversion of large to small surfactant aggregates.

PubMed Central

Veldhuizen, R A; Inchley, K; Hearn, S A; Lewis, J F; Possmayer, F

1993-01-01

Pulmonary surfactant obtained from lung lavages can be separated by differential centrifugation into two distinct subfractions known as large surfactant aggregates and small surfactant aggregates. The large-aggregate fraction is the precursor of the small-aggregate fraction. The ratio of the small non-surface-active to large surface-active surfactant aggregates increases after birth and in several types of lung injury. We have utilized an in vitro system, surface area cycling, to study the conversion of large into small aggregates. Small aggregates generated by surface area cycling were separated from large aggregates by centrifugation at 40,000 g for 15 min rather than by the normal sucrose gradient centrifugation. This new separation method was validated by morphological studies. Surface-tension-reducing activity of total surfactant extracts, as measured with a pulsating-bubble surfactometer, was impaired after surface area cycling. This impairment was related to the generation of small aggregates. Immunoblot analysis of large and small aggregates separated by sucrose gradient centrifugation revealed the presence of detectable amounts of surfactant-associated protein B (SP-B) in large aggregates but not in small aggregates. SP-A was detectable in both large and small aggregates. PAGE of cycled and non-cycled surfactant showed a reduction in SP-B after surface area cycling. We conclude that SP-B is degraded during the formation of small aggregates in vitro and that a change in surface area appears to be necessary for exposing SP-B to protease activity. Images Figure 2 Figure 5 Figure 6 Figure 7 PMID:8216208

Monoamine oxidase inhibitory activity in tobacco particulate matter: Are harman and norharman the only physiologically relevant inhibitors?

PubMed

Truman, Penelope; Grounds, Peter; Brennan, Katharine A

2017-03-01

Monoamine oxidase inhibition is significant in smokers, but it is still unclear how the inhibition that is seen in the brains and bodies of smokers is brought about. Our aim was to test the contribution of the harman and norharman in tobacco smoke to MAO-A inhibition from tobacco smoke preparations, as part of a re-examination of harman and norharman as the cause of the inhibition of MAO-A inhibition in the brain. Tobacco smoke particulate matter and cigarette smoke particulate matter were prepared and the amounts of harman and norharman measured. The results were compared with the total monoamine oxidase-A inhibitory activity. At a nicotine concentration of 0.6μM (a "physiological" concentration in blood) the total monoamine oxidase-A inhibitory activity measured in these samples was sufficient to inhibit the enzyme by approximately 10%. Of this inhibitory activity, only a small proportion of the total was found to be due to harman and norharman. These results show that harman and norharman provide only a moderate contribution to the total monoamine oxidase-A inhibitory activity of tobacco smoke, perhaps under 10%. This suggests that other inhibitors (either known or unknown) may be more significant contributors to total inhibitory activity than has yet been established, and deserve closer examination. Copyright © 2017 Elsevier B.V. All rights reserved.

Activation-Dependent Rapid Postsynaptic Clustering of Glycine Receptors in Mature Spinal Cord Neurons

PubMed Central

Eto, Kei; Murakoshi, Hideji; Watanabe, Miho; Hirata, Hiromi; Moorhouse, Andrew J.; Ishibashi, Hitoshi

2017-01-01

Abstract Inhibitory synapses are established during development but continue to be generated and modulated in strength in the mature nervous system. In the spinal cord and brainstem, presynaptically released inhibitory neurotransmitter dominantly switches from GABA to glycine during normal development in vivo. While presynaptic mechanisms of the shift of inhibitory neurotransmission are well investigated, the contribution of postsynaptic neurotransmitter receptors to this shift is not fully elucidated. Synaptic clustering of glycine receptors (GlyRs) is regulated by activation-dependent depolarization in early development. However, GlyR activation induces hyperpolarization after the first postnatal week, and little is known whether and how presynaptically released glycine regulates postsynaptic receptors in a depolarization-independent manner in mature developmental stage. Here we developed spinal cord neuronal culture of rodents using chronic strychnine application to investigate whether initial activation of GlyRs in mature stage could change postsynaptic localization of GlyRs. Immunocytochemical analyses demonstrate that chronic blockade of GlyR activation until mature developmental stage resulted in smaller clusters of postsynaptic GlyRs that could be enlarged upon receptor activation for 1 h in the mature stage. Furthermore, live cell-imaging techniques show that GlyR activation decreases its lateral diffusion at synapses, and this phenomenon is dependent on PKC, but neither Ca2+ nor CaMKII activity. These results suggest that the GlyR activation can regulate receptor diffusion and cluster size at inhibitory synapses in mature stage, providing not only new insights into the postsynaptic mechanism of shifting inhibitory neurotransmission but also the inhibitory synaptic plasticity in mature nervous system. PMID:28197549

Activation-Dependent Rapid Postsynaptic Clustering of Glycine Receptors in Mature Spinal Cord Neurons.

PubMed

Nakahata, Yoshihisa; Eto, Kei; Murakoshi, Hideji; Watanabe, Miho; Kuriu, Toshihiko; Hirata, Hiromi; Moorhouse, Andrew J; Ishibashi, Hitoshi; Nabekura, Junichi

2017-01-01

Inhibitory synapses are established during development but continue to be generated and modulated in strength in the mature nervous system. In the spinal cord and brainstem, presynaptically released inhibitory neurotransmitter dominantly switches from GABA to glycine during normal development in vivo . While presynaptic mechanisms of the shift of inhibitory neurotransmission are well investigated, the contribution of postsynaptic neurotransmitter receptors to this shift is not fully elucidated. Synaptic clustering of glycine receptors (GlyRs) is regulated by activation-dependent depolarization in early development. However, GlyR activation induces hyperpolarization after the first postnatal week, and little is known whether and how presynaptically released glycine regulates postsynaptic receptors in a depolarization-independent manner in mature developmental stage. Here we developed spinal cord neuronal culture of rodents using chronic strychnine application to investigate whether initial activation of GlyRs in mature stage could change postsynaptic localization of GlyRs. Immunocytochemical analyses demonstrate that chronic blockade of GlyR activation until mature developmental stage resulted in smaller clusters of postsynaptic GlyRs that could be enlarged upon receptor activation for 1 h in the mature stage. Furthermore, live cell-imaging techniques show that GlyR activation decreases its lateral diffusion at synapses, and this phenomenon is dependent on PKC, but neither Ca 2+ nor CaMKII activity. These results suggest that the GlyR activation can regulate receptor diffusion and cluster size at inhibitory synapses in mature stage, providing not only new insights into the postsynaptic mechanism of shifting inhibitory neurotransmission but also the inhibitory synaptic plasticity in mature nervous system.

Modeling of the relationship between dipeptide structure and dipeptide stability, permeability, and ACE inhibitory activity.

PubMed

Foltz, Martin; van Buren, Leo; Klaffke, Werner; Duchateau, Guus S M J E

2009-09-01

Selected di- and tripeptides exhibit angiotensin-I converting enzyme (ACE) inhibitory activity in vitro. However, the efficacy in vivo is most likely limited for most peptides due to low bioavailability. The purpose of this study was to identify descriptors of intestinal stability, permeability, and ACE inhibitory activity of dipeptides. A total of 228 dipeptides were synthesized; intestinal stability was obtained by in vitro digestion, intestinal permeability using Caco-2 cells and ACE inhibitory activity by an in vitro assay. Databases were constructed to study the relationship between structure and activity, permeability, and stability. Quantitative structure-activity relationship (QSAR) modeling was performed based on computed models using partial least squares regression based on 400 molecular descriptors. QSAR modeling of dipeptide stability revealed high correlation coefficients (R > 0.65) for models based on Z and X scales. However, amino acid (AA) clustering showed the best results in describing stability of dipeptides. The N-terminal AA residues Asp, Gly, and Pro as well as the C-terminal residues Pro, Ser, Thr, and Asp stabilize dipeptides toward luminal enzymatic peptide hydrolysis. QSAR modeling did not reveal significant correlation models for intestinal permeability. 2D-fingerprint models were identified describing ACE inhibitory activity of dipeptides. The intestinal stability of 12 peptides was predicted. Peptides were synthesized and stability was confirmed in simulated digestion experiments. Based on the results, specific dipeptides can be designed to meet both stability and activity criteria. However, postabsorptive ACE inhibitory activities of dipeptides in vivo are most likely limited due to the very low intestinal permeability of dipeptides.

The impact of fermentation and in vitro digestion on formation angiotensin converting enzyme (ACE) inhibitory peptides from pea proteins.

PubMed

Jakubczyk, Anna; Karaś, Monika; Baraniak, Barbara; Pietrzak, Marlena

2013-12-15

Pea seeds were fermented by Lactobacillus plantarum 299v in monoculture under different time and temperature conditions and the fermented products were digested in vitro under gastrointestinal conditions. After fermentation and digestion ACE inhibitory activity was determined. In all samples after fermentation no ACE inhibitory activity was noted. Potentially antihypertensive peptides were released during in vitro digestion. The highest DH (68.62%) were noted for control sample, although the lowest IC50 value (0.19 mg/ml) was determined for product after 7 days fermentation at 22 °C. The hydrolysate characterised by the highest ACE inhibitory activity was separated on Sephadex G10 and two peptides fractions were obtained. The highest ACE inhibitory activity (IC50=64.04 μg/ml) for the first fraction was noted. This fraction was separated by HPLC and identified by LC-MS/MS and the sequence of peptide derived from pea proteins was determined as KEDDEEEEQGEEE. Copyright © 2013 Elsevier Ltd. All rights reserved.

Inhibitory action of lansoprazole and its analogs against Helicobacter pylori: inhibition of growth is not related to inhibition of urease.

PubMed Central

Nagata, K; Takagi, E; Tsuda, M; Nakazawa, T; Satoh, H; Nakao, M; Okamura, H; Tamura, T

1995-01-01

The proton pump inhibitors omeprazole and lansoprazole and its acid-activated derivative AG-2000, which are potent and specific inhibitors of urease of Helicobacter pylori (K. Nagata, H. Satoh, T. Iwahi, T. Shimoyama, and T. Tamura, Antimicrob. Agents Chemother. 37:769-774, 1993), inhibited the growth of H. pylori. The growth was inhibited not only in urease-positive clinical isolates but also in their urease-negative derivatives which had no urease polypeptides. AG-1789, a derivative of lansoprazole with no inhibitory activity against H. pylori urease, also inhibited the growth of both strains even more strongly than the urease inhibitors lansoprazole and AG-2000. Furthermore, the antibacterial activity of omeprazole and lansoprazole was not affected by glutathione or dithiothreitol, which completely abolished the inhibitory activity of lansoprazole against H. pylori urease. These results indicated that the inhibitory action of these compounds against the growth of H. pylori was independent from the inhibitory action against urease. PMID:7726537

Structural Basis for the Effective Myostatin Inhibition of the Mouse Myostatin Prodomain-Derived Minimum Peptide.

PubMed

Asari, Tomo; Takayama, Kentaro; Nakamura, Akari; Shimada, Takahiro; Taguchi, Akihiro; Hayashi, Yoshio

2017-01-12

Myostatin inhibition is one of the promising strategies for treating muscle atrophic disorders, including muscular dystrophy. It is well-known that the myostatin prodomain derived from the myostatin precursor acts as an inhibitor of mature myostatin. In our previous study, myostatin inhibitory minimum peptide 1 (WRQNTRYSRIEAIKIQILSKLRL-amide) was discovered from the mouse myostatin prodomain. In the present study, alanine scanning of 1 demonstrated that the key amino acid residues for the effective inhibitory activity are rodent-specific Tyr and C-terminal aliphatic residues, in addition to N-terminal Trp residue. Subsequently, we designed five Pro-substituted peptides and examined the relationship between secondary structure and inhibitory activity. As a result, we found that Pro-substitutions of Ala or Gln residues around the center of 1 significantly decreased both α-helicity and inhibitory activity. These results suggested that an α-helical structure possessing hydrophobic faces formed around the C-terminus is important for inhibitory activity.

Teratogen metabolism: activation of thalidomide and thalidomide analogues to products that inhibit the attachment of cells to concanavalin A coated plastic surfaces.

PubMed

Braun, A G; Weinreb, S L

1984-05-01

Thalidomide metabolites inhibited the attachment of tumor cells to concanavalin A coated polyethylene surfaces. Thalidomide, itself, was non-inhibitory. Thalidomide activation to inhibitory products required hepatic microsomes, an NADPH-generating system, and molecular oxygen. Production of inhibitory metabolites was unaffected by either epoxide hydrolase or 1,2-epoxy-3,3,3-trichloropropane (TCPO), an inhibitor of epoxide hydrolase endogenous to hepatic S9 fraction. Therefore, the attachment inhibitor was probably not an arene oxide. Inhibition was not accompanied by cytotoxicity, as judged by trypan blue exclusion. Although uninduced hepatic microsomes from mice, rats and dogs had similar abilities to activate thalidomide, microsomes from Aroclor 1254 induced rats were relatively inactive in the system. Inhibitory metabolites were generated from the thalidomide analogues EM8 , EM12 , EM16 , EM87 , EM136 , EM255 , E350 , phthalimide, phthalimido-phthalimide, indan, 1- indanone and 1,3- indandione . Glutarimide , glutamic acid and phthalic acid did not activate to inhibitory products.

Inhibitory effects of constituents of Morinda citrifolia seeds on elastase and tyrosinase.

PubMed

Masuda, Megumi; Murata, Kazuya; Fukuhama, Akiko; Naruto, Shunsuke; Fujita, Tadashi; Uwaya, Akemi; Isami, Fumiyuki; Matsuda, Hideaki

2009-07-01

A 50% ethanolic extract (MCS-ext) from seeds of Morinda citrifolia ("noni" seeds) showed more potent in vitro inhibition of elastase and tyrosinase, and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity than extracts of M. citrifolia leaves or flesh. Activity-guided fractionation of MCS-ext using in vitro assays led to the isolation of ursolic acid as an active constituent of elastase inhibitory activity. 3,3'-Bisdemethylpinoresinol, americanin A, and quercetin were isolated as active constituents having both tyrosinase inhibitory and radical scavenging activities. Americanin A and quercetin also showed superoxide dismutase (SOD)-like activity. These active compounds were isolated from noni seeds for the first time.

Antioxidative and angiotensin-I-converting enzyme inhibitory potential of a Pacific Hake ( Merluccius productus ) fish protein hydrolysate subjected to simulated gastrointestinal digestion and Caco-2 cell permeation.

PubMed

Samaranayaka, Anusha G P; Kitts, David D; Li-Chan, Eunice C Y

2010-02-10

Pacific hake fish protein hydrolysate (FPH) with promising chemical assay based antioxidative capacity was studied for in vitro angiotensin-I-converting enzyme (ACE)-inhibitory potential, intestinal cell permeability characteristics, and intracellular antioxidative potential using the Caco-2 cell model system. FPH showed substrate-type inhibition of ACE with IC(50) of 161 microg of peptides/mL. HPLC analysis revealed that different peptides were responsible for antioxidative and ACE-inhibitory activity. FPH inhibited 2,2'-azobis(2-amidinopropane) dihydrochloride-induced oxidation in Caco-2 cells at noncytotoxic concentrations. In vitro simulated gastrointestinal digestion increased (P < 0.05) antioxidative capacity; ACE-inhibitory activity of FPH remained unchanged, although individual peptide fractions showed decreased or no activity after digestion. Some FPH peptides passed through Caco-2 cells: the permeates showed 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) radical scavenging activity but no ACE-inhibitory activity. These results suggest the potential for application of Pacific hake FPH to reduce oxidative processes in vivo. Further studies are needed to assess prospective antihypertensive effects.

Human antibodies fix complement to inhibit Plasmodium falciparum invasion of erythrocytes and are associated with protection against malaria.

PubMed

Boyle, Michelle J; Reiling, Linda; Feng, Gaoqian; Langer, Christine; Osier, Faith H; Aspeling-Jones, Harvey; Cheng, Yik Sheng; Stubbs, Janine; Tetteh, Kevin K A; Conway, David J; McCarthy, James S; Muller, Ivo; Marsh, Kevin; Anders, Robin F; Beeson, James G

2015-03-17

Antibodies play major roles in immunity to malaria; however, a limited understanding of mechanisms mediating protection is a major barrier to vaccine development. We have demonstrated that acquired human anti-malarial antibodies promote complement deposition on the merozoite to mediate inhibition of erythrocyte invasion through C1q fixation and activation of the classical complement pathway. Antibody-mediated complement-dependent (Ab-C') inhibition was the predominant invasion-inhibitory activity of human antibodies; most antibodies were non-inhibitory without complement. Inhibitory activity was mediated predominately via C1q fixation, and merozoite surface proteins 1 and 2 were identified as major targets. Complement fixation by antibodies was very strongly associated with protection from both clinical malaria and high-density parasitemia in a prospective longitudinal study of children. Ab-C' inhibitory activity could be induced by human immunization with a candidate merozoite surface-protein vaccine. Our findings demonstrate that human anti-malarial antibodies have evolved to function by fixing complement for potent invasion-inhibitory activity and protective immunity. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

α-Glucosidase inhibitory activity of selected Philippine plants.

PubMed

Lawag, Ivan L; Aguinaldo, Alicia M; Naheed, Suad; Mosihuzzaman, Mohammad

2012-10-31

Antidesma bunius Spreng. (Phyllantaceae), Averrhoa bilimbi L. (Oxalidaceae), Biophytum sensitivum (L.) DC. (Oxalidaceae), Ceriops tagal (Perr.) C.B. Rob. (Rhizophoraceae), Kyllinga monocephala Rottb. (Cyperaceae), and Rhizophora mucronata Lam. (Rhizophoraceae) are used as remedies to control diabetes. In the present study, these plants were screened for their potential α-glucosidase inhibitory activity. The 80% aqueous ethanolic extracts were screened for their α-glucosidase enzyme inhibitory activity using yeast alpha glucosidase enzyme. Except for A. bilimbi with IC(50) at 519.86±3.07, all manifested a significant enzyme inhibitory activity. R. mucronata manifested the highest activity with IC(50) at 0.08±1.82 μg mL(-1), followed by C. tagal with IC(50) at 0.85±1.46 μg mL(-1) and B. sensitivum with IC(50) at 2.24±1.58 μg mL(-1). This is the first report on the α-glucosidase inhibitory effect of the six Philippine plants; thus, partly defining the mechanism on why these medicinal plants possess antidiabetic properties. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

Ultrasonic extraction of polysaccharides from Laminaria japonica and their antioxidative and glycosidase inhibitory activities

NASA Astrophysics Data System (ADS)

Wan, Peng; Yang, Xiaoman; Cai, Bingna; Chen, Hua; Sun, Huili; Chen, Deke; Pan, Jianyu

2015-08-01

In the present study, ultrasonic extraction technique (UET) is used to improve the yield of polysaccharides from Laminaria japonica (LJPs). And their antioxidative as well as glycosidase inhibitory activities are investigated. Box-Behnken design (BBD) combined with response surface methodology (RSM) is applied to optimize ultrasonic extraction for polysaccharides. The optimized conditions are obtained as extraction time at 54 min, ultrasonic power at 1050 W, extraction temperature at 80°C and ratio of material to solvent at 1:50 (g mL-1). Under these optimal ultrasonic extraction conditions, an actual experimental yield (5.75% ± 0.3%) is close to the predicted result (5.67%) with no significant difference ( P > 0.05). Vitro antioxidative and glycosidase inhibitory activities tests indicate that the crude polysaccharides (LJP) and two major ethanol precipitated fractions (LJP1 and LJP2) are in a concentration-dependent manner. LJP2 (30%-60% ethanol precipitated polysaccharides) possesses the strongest α-glucosidase inhibitory activity and moderate scavenging activity against hydroxyl radicals (66.09% ± 2.19%, 3.0 mg mL-1). Also, the inhibitory activity against α-glucosidase (59.08% ± 3.79%, 5.0 mg mL-1) is close to that of acarbose (63.99% ± 3.27%, 5.0 mg mL-1). LJP1 (30% ethanol precipitated polysaccharides) exhibits the strongest scavenging activity against hydroxyl radicals (99.80% ± 0.00%, 3.0 mg mL-1) and moderate α-glucosidase inhibitory activity (47.76% ± 1.92%, 5.0 mg mL-1). LJP shows the most remarkable DPPH scavenging activity (66.20% ± 0.11%, 5.0 mg mL-1) but weakest α-glucosidase inhibitory activity (37.77% ± 1.30%, 5.0 mg mL-1). However, all these LJPs exert weak inhibitory effects against α-amylase. These results show that UET is an effective method for extracting bioactive polysaccharides from seaweed materials. LJP1 and LJP2 can be developed as a potential ingredient in hypoglycemic agents or functional food for the management of diabetes. This study provides scientific evidence and advances in the preparation technology and a hypoglycemic activities evaluation method for seaweed polysaccharides, especially glycosidase inhibition in combination with an antioxidative activity evaluation method.

Potent Inhibitory Effect of Chinese Dietary Spices on Fatty Acid Synthase.

PubMed

Jiang, Bing; Liang, Yan; Sun, Xuebing; Liu, Xiaoxin; Tian, Weixi; Ma, Xiaofeng

2015-09-01

Dietary spices have been adopted in cooking since ancient times to enhance flavor and also as food preservatives and disease remedies. In China, the use of spices and other aromatic plants as food flavoring is an integral part of dietary behavior, but relatively little is known about their functions. Fatty acid synthase (FAS) has been recognized as a remedy target, and its inhibitors might be applied in disease treatment. The present work was designed to assess the inhibitory activities on FAS of spices extracts in Chinese menu. The in vitro inhibitory activities on FAS of 22 extracts of spices were assessed by spectrophotometrically monitoring oxidation of NADPH at 340 nm. Results showed that 20 spices extracts (90.9 %) exhibited inhibitory activities on FAS, with half inhibition concentration (IC(50)) values ranging from 1.72 to 810.7 μg/ml. Among them, seven spices showed strong inhibitory effect with IC(50) values lower than 10 μg/ml. These findings suggest that a large proportion of the dietary spices studied possess promising inhibitory activities on FAS, and subsequently might be applied in the treatment of obesity and obesity-related human diseases.

Relationship between physiological excitatory and inhibitory measures of excitability in the left vs. right human motor cortex and peripheral electrodermal activity.

PubMed

Bracco, Martina; Turriziani, Patrizia; Smirni, Daniela; Mangano, Renata Giuseppa; Oliveri, Massimiliano

2017-02-22

The current study was aimed at investigating the relationships of excitatory and inhibitory circuits of the left vs. right primary motor cortex with peripheral electrodermal activity (EDA). Ten healthy subjects participated in two experimental sessions. In each session, EDA was recorded for 10min from the palmar surface of the left hand. Immediately after EDA recording, Transcranial Magnetic Stimulation (TMS) was used to probe excitatory and inhibitory circuits of the left or right primary motor cortex using two protocols of stimulation: the input-output curve for recording of motor evoked potentials, for testing excitatory circuits; the long-interval cortical inhibition (LICI) protocol, for testing inhibitory circuits. In both cases, motor evoked potentials were recorded with surface electrodes from a contralateral hand muscle. The main results showed that in the right motor cortex, excitatory circuits directly correlate and inhibitory circuits inversely correlate with sympathetic activation. In the left motor cortex, both excitatory and inhibitory circuits are inversely correlated with sympathetic activation. These findings may suggest a bi-hemispheric mode of control of vegetative system by motor cortices, with the right hemisphere mainly involved in sympathetic control. Copyright © 2017. Published by Elsevier B.V.

Parallel language activation and inhibitory control in bimodal bilinguals.

PubMed

Giezen, Marcel R; Blumenfeld, Henrike K; Shook, Anthony; Marian, Viorica; Emmorey, Karen

2015-08-01

Findings from recent studies suggest that spoken-language bilinguals engage nonlinguistic inhibitory control mechanisms to resolve cross-linguistic competition during auditory word recognition. Bilingual advantages in inhibitory control might stem from the need to resolve perceptual competition between similar-sounding words both within and between their two languages. If so, these advantages should be lessened or eliminated when there is no perceptual competition between two languages. The present study investigated the extent of inhibitory control recruitment during bilingual language comprehension by examining associations between language co-activation and nonlinguistic inhibitory control abilities in bimodal bilinguals, whose two languages do not perceptually compete. Cross-linguistic distractor activation was identified in the visual world paradigm, and correlated significantly with performance on a nonlinguistic spatial Stroop task within a group of 27 hearing ASL-English bilinguals. Smaller Stroop effects (indexing more efficient inhibition) were associated with reduced co-activation of ASL signs during the early stages of auditory word recognition. These results suggest that inhibitory control in auditory word recognition is not limited to resolving perceptual linguistic competition in phonological input, but is also used to moderate competition that originates at the lexico-semantic level. Copyright © 2015 Elsevier B.V. All rights reserved.

Identification and the molecular mechanism of a novel myosin-derived ACE inhibitory peptide.

PubMed

Yu, Zhipeng; Wu, Sijia; Zhao, Wenzhu; Ding, Long; Shiuan, David; Chen, Feng; Li, Jianrong; Liu, Jingbo

2018-01-24

The objective of this work was to identify a novel ACE inhibitory peptide from myosin using a number of in silico methods. Myosin was evaluated as a substrate for use in the generation of ACE inhibitory peptides using BIOPEP and ExPASy PeptideCutter. Then the ACE inhibitory activity prediction of peptides in silico was evaluated using the program peptide ranker, following the database search of known and unknown peptides using the program BIOPEP. In addition, the interaction mechanisms of the peptide and ACE were evaluated by DS. All of the tripeptides were predicted to be nontoxic. Results suggested that the tripeptide NCW exerted potent ACE inhibitory activity with an IC 50 value of 35.5 μM. Furthermore, the results suggested that the peptide NCW comes into contact with Zn 701, Tyr 523, His 383, Glu 384, Glu 411, and His 387. The potential molecular mechanism of the NCW/ACE interaction was investigated. Results confirmed that the higher inhibitory potency of NCW might be attributed to the formation of more hydrogen bonds with the ACE's active site. Therefore, the in silico method is effective to predict and identify novel ACE inhibitory peptides from protein hydrolysates.

Structural Requirements of Alkylglyceryl-l-Ascorbic Acid Derivatives for Melanogenesis Inhibitory Activity.

PubMed

Taira, Norihisa; Katsuyama, Yushi; Yoshioka, Masato; Muraoka, Osamu; Morikawa, Toshio

2018-04-10

l-Ascorbic acid has multifunctional benefits on skin aesthetics, including inhibition of melanin production, and is widely used in cosmetics. It, however, has low stability and poor skin penetration. We hypothesize that alkylglyceryl-l-ascorbic acid derivatives, highly stable vitamin C-alkylglycerol conjugates, would have similar anti-melanogenic activity with better stability and penetration. We test 28 alkylglyceryl-l-ascorbic acid derivatives ( 1 - 28 ) on theophylline-stimulated B16 melanoma 4A5 cells to determine if they inhibit melanogenesis and establish any structure-function relationships. Although not the most potent inhibitors, 3- O -(2,3-dihydroxypropyl)-2- O -hexyl-l-ascorbic acid ( 6 , IC 50 = 81.4 µM) and 2- O -(2,3-dihydroxypropyl)-3- O -hexyl-l-ascorbic acid ( 20 , IC 50 = 117 µM) are deemed the best candidate derivatives based on their inhibitory activities and low toxicities. These derivatives are also found to be more stable than l-ascorbic acid and to have favorable characteristics for skin penetration. The following structural requirements for inhibitory activity of alkylglyceryl-l-ascorbic acid derivatives are also determined: (i) alkylation of glyceryl-l-ascorbic acid is essential for inhibitory activity; (ii) the 3- O -alkyl-derivatives ( 2 - 14 ) exhibit stronger inhibitory activity than the corresponding 2- O -alkyl-derivatives ( 16 - 28 ); and (iii) derivatives with longer alkyl chains have stronger inhibitory activities. Mechanistically, our studies suggest that l-ascorbic acid derivatives exert their effects by suppressing the mRNA expression of tyrosinase and tyrosine-related protein-1.

Ultraviolet-Visible (UV-Vis) and Fluorescence Spectroscopic Investigation of the Interactions of Ionic Liquids and Catalase.

PubMed

Dong, Xing; Fan, Yunchang; Yang, Peng; Kong, Jichuan; Li, Dandan; Miao, Juan; Hua, Shaofeng; Hu, Chaobing

2016-11-01

The inhibitory effects of nine ionic liquids (ILs) on the catalase activity were investigated using fluorescence, absorption ultraviolet-visible spectroscopy. The interactions of ILs and catalase on the molecular level were studied. The experimental results indicated that ILs could inhibit the catalase activity and their inhibitory abilities depended on their chemical structures. Fluorescence experiments showed that hydrogen bonding played an important role in the interaction process. The inhibitory abilities of ILs on catalase activity could be simply described by their hydrophobicity and hydrogen bonding abilities. Unexpected less inhibitory effects of trifluoromethanesulfonate (TfO - ) might be ascribed to its larger size, which makes it difficult to go through the substrate channel of catalase to the active site. © The Author(s) 2016.

[Relationship between the growth rate of the liver of young rats and the inhibitory effect of extracts of their liver on the multiplication of cultured cells].

PubMed

Aujard, C; Chany, E; Frayssinet, C

1976-12-08

We have shown that extracts of liver from young Rats are less active, than extracts of liver from adult Rats, in inhibiting the multiplication of cells in culture. This inhibitory activity is at a minimum in livers taken from 10 to 15 days old Rats, which corresponds to the time of maximum increase in weight of the liver. The existence of an inverse relationship between the inhibitory activity of these extracts and the state of proliferation of the liver suggests that the inhibitory substance contained in the liver extracts may act as a regulator of growth of the organ.

Myostatin inhibitory region of fish (Paralichthys olivaceus) myostatin-1 propeptide.

PubMed

Lee, Sang Beum; Kim, Jeong Hwan; Jin, Deuk-Hee; Jin, Hyung-Joo; Kim, Yong Soo

2016-01-01

Myostatin (MSTN) is a potent negative regulator of skeletal muscle growth, and its activity is suppressed by MSTN propeptide (MSTNpro), the N-terminal part of MSTN precursor cleaved during post-translational MSTN processing. The current study examined which region of flatfish (Paralichthys olivaceus) MSTN-1 propeptide (MSTN1pro) is critical for MSTN inhibition. Six different truncated forms of MSTN1pro containing N-terminal maltose binding protein (MBP) as a fusion partner were expressed in Escherichia coli, and partially purified by an affinity chromatography for MSTN-inhibitory activity examination. Peptides covering different regions of flatfish MSTN1pro were also synthesized for MSTN-inhibitory activity examination. A MBP-fused MSTN1pro region consisting of residues 45-100 had the same MSTN-inhibitory potency as the full sequence flatfish MSTN1pro (residues 23-265), indicating that the region of flatfish MSTN1pro consisting of residues 45-100 is sufficient to maintain the full MSTN-inhibitory capacity. A MBP-fused MSTN1pro region consisting of residues 45-80 (Pro45-80) also showed MSTN-inhibitory activity with a lower potency, and the Pro45-80 demonstrated its MSTN binding capacity in a pull-down assay, indicating that the MSTN-inhibitory capacity of Pro45-80 is due to its binding to MSTN. Flatfish MSTN1pro synthetic peptides covering residues 45-65, 45-70, and 45-80 demonstrated MSTN-inhibitory activities, but not the synthetic peptide covering residues 45-54, indicating that residues 45-65 of flatfish MSTN1pro are essential for MSTN inhibition. In conclusion, current study show that like the mammalian MSTNpro, the MSTN-inhibitory region of flatfish MSTN1pro resides near its N-terminus, and imply that smaller sizes of MSTNpro can be effectively used in various applications designed for MSTN inhibition. Copyright © 2016 Elsevier Inc. All rights reserved.

Angiotensin-I-Converting Enzyme (ACE)-Inhibitory Peptides from Plants

PubMed Central

Daskaya-Dikmen, Ceren; Yucetepe, Aysun; Karbancioglu-Guler, Funda; Daskaya, Hayrettin; Ozcelik, Beraat

2017-01-01

Hypertension is an important factor in cardiovascular diseases. Angiotensin-I-converting enzyme (ACE) inhibitors like synthetic drugs are widely used to control hypertension. ACE-inhibitory peptides from food origins could be a good alternative to synthetic drugs. A number of plant-based peptides have been investigated for their potential ACE inhibitor activities by using in vitro and in vivo assays. These plant-based peptides can be obtained by solvent extraction, enzymatic hydrolysis with or without novel food processing methods, and fermentation. ACE-inhibitory activities of peptides can be affected by their structural characteristics such as chain length, composition and sequence. ACE-inhibitory peptides should have gastrointestinal stability and reach the cardiovascular system to show their bioactivity. This paper reviews the current literature on plant-derived ACE-inhibitory peptides including their sources, production and structure, as well as their activity by in vitro and in vivo studies and their bioavailability. PMID:28333109

Purification of a factor from the granules of a rat natural killer cell line (RNK) that reduces tumor cell growth and changes tumor morphology. Molecular identity with a granule serine protease (RNKP-1).

PubMed

Sayers, T J; Wiltrout, T A; Sowder, R; Munger, W L; Smyth, M J; Henderson, L E

1992-01-01

We have purified a protein from the granules of the rat NK leukemia cell line (RNK) that is cytostatic to a variety of tumor cells. This protein shows no species specificity because certain tumor cell lines of mouse, rat, and human origin were equally sensitive to its growth inhibitory effects. Treatment of sensitive cells resulted in a rounding of the cells followed by homotypic aggregation into large aggregates. The granule protein was distinct from cytolysin, Na-Cbz-Lys-thiobenzylester-esterase, or leukolexin. It had a molecular mass of 29 to 31 kDa, bound strongly to heparin, was inactivated by heating at 70 degrees C for 5 min or reduction, but was stable to trypsin treatment. By using molecular sieve chromatography, heparin agarose chromatography, and reverse phase HPLC, this protein was purified to homogeneity. The first 33 amino acids of the N-terminal amino acid sequence showed complete identity to the sequence predicted from a rat serine protease gene recently cloned and designated RNKP-1. Therefore we have purified a novel serine protease and demonstrated that it has effects on the growth and morphology of certain tumor cells. Other serine proteases that were structurally related and have substantial homology with RNKP-1 at the amino acid level showed neither growth inhibitory properties nor affected the morphology of the tumor target cells we used.

Structure activity relationship study of curcumin analogues toward the amyloid-beta aggregation inhibitor.

PubMed

Endo, Hitoshi; Nikaido, Yuri; Nakadate, Mamiko; Ise, Satomi; Konno, Hiroyuki

2014-12-15

Inhibition of the amyloid β aggregation process could possibly prevent the onset of Alzheimer's disease. In this article, we report a structure-activity relationship study of curcumin analogues for anti amyloid β aggregation activity. Compound 7, the ideal amyloid β aggregation inhibitor in vitro among synthesized curcumin analogues, has not only potent anti amyloid β aggregation effects, but also water solubility more than 160 times that of curcumin. In addition, new approaches to improve water solubility of curcumin-type compounds are proposed. Copyright © 2014 Elsevier Ltd. All rights reserved.

Melanogenesis inhibitory activity of a 7-O-9'-linked neolignan from Alpinia galanga fruit.

PubMed

Manse, Yoshiaki; Ninomiya, Kiyofumi; Nishi, Ryosuke; Kamei, Iyori; Katsuyama, Yushi; Imagawa, Takahito; Chaipech, Saowanee; Muraoka, Osamu; Morikawa, Toshio

2016-12-01

An aqueous acetone extract from the fruit of Alpinia galanga (Zingiberaceae) demonstrated inhibitory effects on melanogenesis in theophylline-stimulated murine B16 melanoma 4A5 cells (IC 50 =7.3μg/mL). Through bioassay-guided separation of the extract, a new 7-O-9'-linked neolignan, named galanganol D diacetate (1), was isolated along with 16 known compounds including 14 phenylpropanoids (2-15). The structure of 1, including its absolute stereochemistry in the C-7 position, was elucidated by means of extensive NMR analysis and total synthesis. Among the isolates, 1 (IC 50 =2.5μM), 1'S-1'-acetoxychavicol acetate (2, 5.0μM), and 1'S-1'-acetoxyeugenol acetate (3, 5.6μM) exhibited a relatively potent inhibitory effect without notable cytotoxicity at effective concentrations. The following structural requirements were suggested to enhance the inhibitory activity of phenylpropanoids on melanogenesis: (i) compounds with 4-acetoxy group exhibit higher activity than those with 4-hydroxy group; (ii) 3-methoxy group dose not affect the activity; (iii) acetylation of the 1'-hydroxy moiety enhances the activity; and (iv) phenylpropanoid dimers with the 7-O-9'-linked neolignan skeleton exhibited higher activity than those with the corresponding monomer. Their respective enantiomers [1' (IC 50 =1.9μM) and 2' (4.5μM)] and racemic mixtures [(±)-1 (2.2μM) and (±)-2 (4.4μM)] were found to exhibit melanogenesis inhibitory activities equivalent to those of the naturally occurring optical active compounds (1 and 2). Furthermore, the active compounds 1-3 inhibited tyrosinase, tyrosine-related protein (TRP)-1, and TRP-2 mRNA expressions, which could be the mechanism of melanogenesis inhibitory activity. Copyright © 2016 Elsevier Ltd. All rights reserved.

CD94/NKG2A inhibits NK cell activation by disrupting the actin network at the immunological synapse.

PubMed

Masilamani, Madhan; Nguyen, Connie; Kabat, Juraj; Borrego, Francisco; Coligan, John E

2006-09-15

An adequate immune response is the result of the fine balance between activation and inhibitory signals. The exact means by which inhibitory signals obviate activation signals in immune cells are not totally elucidated. Human CD94/NKG2A is an ITIM-containing inhibitory receptor expressed by NK cells and some CD8+ T cells that recognize HLA-E. We show that the engagement of this receptor prevents NK cell activation by disruption of the actin network and exclusion of lipid rafts at the point of contact with its ligand (inhibitory NK cell immunological synapse, iNKIS). CD94/NKG2A engagement leads to recruitment and activation of src homology 2 domain-bearing tyrosine phosphatase 1. This likely explains the observed dephosphorylation of guanine nucleotide exchange factor and regulator of actin, Vav1, as well as ezrin-radixin-moesin proteins that connect actin filaments to membrane structures. In contrast, NK cell activation by NKG2D induced Vav1 and ezrin-radixin-moesin phosphorylation. Thus, CD94/NKG2A prevents actin-dependent recruitment of raft-associated activation receptors complexes to the activating synapse. This was further substantiated by showing that inhibition of actin polymerization abolished lipid rafts exclusion at the iNKIS, whereas cholesterol depletion had no effect on actin disruption at the iNKIS. These data indicate that the lipid rafts exclusion at the iNKIS is an active process which requires an intact cytoskeleton to maintain lipid rafts outside the inhibitory synapse. The net effect is to maintain an inhibitory state in the proximity of the iNKIS, while allowing the formation of activation synapse at distal points within the same NK cell.

Stimulation of Phenolics, Antioxidant and α-Glucosidase Inhibitory Activities During Barley (Hordeum vulgare L.) Seed Germination.

PubMed

Ha, K-S; Jo, S-H; Mannam, V; Kwon, Y-I; Apostolidis, E

2016-06-01

The rationale of this study was to enhance the nutritional quality of dry barley seeds. In this study we are evaluating the effect of germination on barley seeds relevant to total phenolic contents, antioxidant activity (in terms of DPPH free-radical scavenging) and the in vitro α-glucosidase inhibitory activities. Barley seeds were germinated for 18.5, 24, 30, 48, and 67 h and then extracted in water. The total phenolic contents, antioxidant activities and α-glucosidase inhibitory activities changed with germination time. More specifically, within the first 48 h of germination the total phenolic content increased from 1.1 mg/g fresh weight (0 h) to 3.4 mg/g fresh weight (48 h) and then slightly reduced by 67 h. Similarly, α-glucosidase inhibitory activity was significantly increased from an IC50 128.82 mg/mL (0 h) to an IC50 18.88 mg/mL (48 h) and then slightly reduced by 67 h. Significant maltase inhibitory activity was observed only with 48 h-germinated extract. Antioxidant activities increased continuously from an IC50 15.72 mg/mL at 0 h to and IC50 5.72 mg/mL after 48 h of germination. Based on our observations, barley seed germination was over after 48 h. During the progress of germination phenolic compounds are becoming available and are more easily extracted. After 48 h, lignification is initiated resulting to the decreased total phenolic content and observed antioxidant and carbohydrate hydrolyzing enzyme inhibition activities. The above results indicate the positive effect of germination in barley seeds for enhanced antioxidant and α-glucosidase inhibitory activities.

Discovery of SMP-304, a novel benzylpiperidine derivative with serotonin transporter inhibitory activity and 5-HT1A weak partial agonistic activity showing the antidepressant-like effect.

PubMed

Yoshinaga, Hidefumi; Masumoto, Shuji; Koyama, Koji; Kinomura, Naoya; Matsumoto, Yuji; Kato, Taro; Baba, Satoko; Matsumoto, Kenji; Horisawa, Tomoko; Oki, Hitomi; Yabuuchi, Kazuki; Kodo, Toru

2017-01-01

We report the discovery of a novel benzylpiperidine derivative with serotonin transporter (SERT) inhibitory activity and 5-HT 1A receptor weak partial agonistic activity showing the antidepressant-like effect. The 3-methoxyphenyl group and the phenethyl group of compound 1, which has weak SERT binding activity, but potent 5-HT 1A binding activity, were optimized, leading to compound 35 with potent and balanced dual SERT and 5-HT 1A binding activity, but also potent CYP2D6 inhibitory activity. Replacement of the methoxy group in the left part of compound 35 with a larger alkoxy group, such as ethoxy, isopropoxy or methoxy-ethoxy group ameliorated CYP2D6 inhibition, giving SMP-304 as a candidate. SMP-304 with serotonin uptake inhibitory activity and 5-HT 1A weak partial agonistic activity, which could work as a 5-HT 1A antagonist, displayed faster onset of antidepressant-like effect than a representative SSRI paroxetine in an animal model. Copyright © 2016 Elsevier Ltd. All rights reserved.

ACE Inhibitory and Antioxidant Activities of Collagen Hydrolysates from the Ribbon Jellyfish (Chrysaora sp.).

PubMed

Barzideh, Zoha; Latiff, Aishah Abd; Gan, Chee-Yuen; Abedin, Md Zainul; Alias, Abd Karim

2014-12-01

Collagen isolated from the ribbon jellyfish ( Chrysaora sp.) was hydrolysed using three different proteases ( i.e. trypsin, alcalase and Protamex) to obtain bioactive peptides. Angiotensin-I-converting enzyme (ACE) inhibitory activity and antioxidant activities ( i.e. ferric reducing antioxidant power (FRAP) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity) of the peptides were measured and compared, and the effect of the duration of hydrolysis on the bioactivity (ACE inhibitory and antioxidant activities) of peptides was also evaluated. FRAP activity was the highest in Protamex-induced (25-27 mM) and trypsin-induced hydrolysates (24-26 mM) at 7 and 9 h, respectively. Conversely, hydrolysates produced by trypsin for 1 and 3 h showed the highest DPPH radical scavenging activities (94 and 92%, respectively). Trypsin-induced hydrolysates (at 3 h) also showed the highest ACE inhibitory activity (89%). The peptide sequences with the highest activities were identified using tandem mass spectrometry, and the results show that the hydrolysates had a high content of hydrophobic amino acids as well as unique amino acid sequences, which likely contribute to their biological activities.

New polyacetylenes glycoside from Eclipta prostrate with DGAT inhibitory activity.

PubMed

Meng, Xiao; Li, Ban-Ban; Lin, Xin; Jiang, Yi-Yu; Zhang, Le; Li, Hao-Ze; Cui, Long

2018-06-08

One new polyacetylene glycoside eprostrata Ⅰ (1), together with seven known compounds (2-8), were isolated from Eclipta prostrata. Their structures were elucidated on the basis of spectroscopic and physico-chemical analyses. All the isolates were evaluated inhibitory activity on DGAT in an in vitro assay. Compounds 1-8 were found to exhibit inhibitory activity of DGAT1 with IC 50 values ranging from 74.4 ± 1.3 to 101.1 ± 1.1 μM.

Studies on novel 2-imidazolidinones and tetrahydropyrimidin-2(1H)-ones as potential TACE inhibitors: design, synthesis, molecular modeling, and preliminary biological evaluation.

PubMed

DasGupta, Shirshendu; Murumkar, Prashant R; Giridhar, Rajani; Yadav, Mange Ram

2009-05-15

Compounds belonging to the class of 2-imidazolidinones and tetrahydropyrimidin-2(1H)-ones were synthesized and evaluated for their TACE inhibitory activity. Most of the compounds showed very good TACE inhibitory activity. Docking study clearly indicates importance of the P1' group of the inhibitor for the TACE inhibitory activity. This work proves that these two classes of molecules could be used as potential leads for the development of TACE inhibitors.

2-Aryl benzimidazoles: Synthesis, In vitro α-amylase inhibitory activity, and molecular docking study.

PubMed

Adegboye, Akande Akinsola; Khan, Khalid Mohammed; Salar, Uzma; Aboaba, Sherifat Adeyinka; Kanwal; Chigurupati, Sridevi; Fatima, Itrat; Taha, Mohammad; Wadood, Abdul; Mohammad, Jahidul Isalm; Khan, Huma; Perveen, Shahnaz

2018-04-25

Despite of many diverse biological activities exhibited by benzimidazole scaffold, it is rarely explored for the α-amylase inhibitory activity. For that purpose, 2-aryl benzimidazole derivatives 1-45 were synthesized and screened for in vitro α-amylase inhibitory activity. Structures of all synthetic compounds were deduced by various spectroscopic techniques. All compounds revealed inhibition potential with IC 50 values of 1.48 ± 0.38-2.99 ± 0.14 μM, when compared to the standard acarbose (IC 50  = 1.46 ± 0.26 μM). Limited SAR suggested that the variation in the inhibitory activities of the compounds are the result of different substitutions on aryl ring. In order to rationalize the binding interactions of most active compounds with the active site of α-amylase enzyme, in silico study was conducted. Copyright © 2018 Elsevier Masson SAS. All rights reserved.

HPLC based activity profiling for 5-lipoxygenase inhibitory activity in Isatis tinctoria leaf extracts.

PubMed

Oberthür, C; Jäggi, R; Hamburger, M

2005-06-01

In the pursuit of the anti-inflammatory constituents in lipophilic woad extracts, the 5-lipoxygenase (5-LOX) inhibitory activity was investigated by HPLC-based activity profiling. In a low-resolution profiling, two time windows with peaks of activity were found. The first coincided with tryptanthrin, a known dual inhibitor of cyclooxygenase-2 (COX-2) and 5-LOX, whereas the major inhibitory fraction was towards the end of the HPLC run. The active fractions were profiled in a peak-resolved manner, and the compounds analyzed by LC-MS, GC and TLC. The activity in the lipophilic fractions of the Isatis extract could be linked to an unsaturated fatty acid, alpha-linolenic acid.

Dose response of surfactants to attenuate gas embolism related platelet aggregation

NASA Astrophysics Data System (ADS)

Eckmann, David M.; Eckmann, Yonaton Y.; Tomczyk, Nancy

2014-03-01

Intravascular gas embolism promotes blood clot formation, cellular activation, and adhesion events, particularly with platelets. Populating the interface with surfactants is a chemical-based intervention to reduce injury from gas embolism. We studied platelet activation and platelet aggregation, prominent adverse responses to blood contact with bubbles. We examined dose-response relationships for two chemically distinct surfactants to attenuate the rise in platelet function stimulated by exposure to microbubbles. Significant reduction in platelet aggregation and platelet activation occurred with increasing concentration of the surfactants, indicating presence of a saturable system. A population balance model for platelet aggregation in the presence of embolism bubbles and surfactants was developed. Monte Carlo simulations for platelet aggregation were performed. Results agree qualitatively with experimental findings. Surfactant dose-dependent reductions in platelet activation and aggregation indicate inhibition of the gas/liquid interface's ability to stimulate cellular activation mechanically.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Salvucci, Michael

Research examined the thermal stability and propensity for aggregation of wild type and the C- and N-terminally modified forms of activase to determine if loss of activity under heat stress is dependent on protein aggregation. The results showed that 1) loss of activity at high temperature is independent of aggregation; 2) activase with both C- and N-terminal S-Tags are more susceptible to aggregation than wild type activase, 3) aggregation is highly dependent on the concentration of Mg2+ and 4) the ATP analog, ATPgammaS, protects against both thermal inactivation and aggregation.

NK cell activation: distinct stimulatory pathways counterbalancing inhibitory signals.

PubMed

Bakker, A B; Wu, J; Phillips, J H; Lanier, L L

2000-01-01

A delicate balance between positive and negative signals regulates NK cell effector function. Activation of NK cells may be initiated by the triggering of multiple adhesion or costimulatory molecules, and can be counterbalanced by inhibitory signals induced by receptors for MHC class I. A common pathway of inhibitory signaling is provided by immunoreceptor tyrosine-based inhibitory motifs (ITIMs) in the cytoplasmic domains of these receptors which mediate the recruitment of SH2 domain-bearing tyrosine phosphate-1 (SHP-1). In contrast to the extensive progress that has been made regarding the negative regulation of NK cell function, our knowledge of the signals that activate NK cells is still poor. Recent studies of the activating receptor complexes have shed new light on the induction of NK cell effector function. Several NK receptors using novel adaptors with immunoreceptor tyrosine-based activation motifs (ITAMs) and with PI 3-kinase recruiting motifs have been implicated in NK cell stimulation.

Chemometric profile, antioxidant and tyrosinase inhibitory activity of Camel's foot creeper leaves (Bauhinia vahlii).

PubMed

Panda, Pritipadma; Dash, Priyanka; Ghosh, Goutam

2018-03-01

The present study is the first effort to a comprehensive evaluation of antityrosinase activity and chemometric analysis of Bauhinia vahlii. The experimental results revealed that the methanol extract of Bauhinia vahlii (BVM) possesses higher polyphenolic compounds and total antioxidant activity than those reported elsewhere for other more conventionally and geographically different varieties. The BVM contain saturated fatty acids such as hexadecanoic acid (10.15%), octadecanoic acid (1.97%), oleic acid (0.61%) and cis-vaccenic acid (2.43%) along with vitamin E (12.71%), α-amyrin (9.84%), methyl salicylate (2.39%) and β-sitosterol (17.35%), which were mainly responsible for antioxidant as well as tyrosinase inhibitory activity. Tyrosinase inhibitory activity of this extract was comparable to that of Kojic acid. These findings suggested that the B. vahlii leaves could be exploited as potential source of natural antioxidant and tyrosinase inhibitory agent, as well.

Inhibitory Control of Memory Retrieval and Motor Processing Associated with the Right Lateral Prefrontal Cortex: Evidence from Deficits in Individuals with ADHD

ERIC Educational Resources Information Center

Depue, B. E.; Burgess, G. C.; Willcutt, E. G.; Ruzic, L.; Banich, M. T.

2010-01-01

Studies of inhibitory control have focused on inhibition of motor responses. Individuals with ADHD consistently show reductions in inhibitory control and exhibit reduced activity of rLPFC activity compared to controls when performing such tasks. Recently these same brain regions have been implicated in the inhibition of memory retrieval. The…

Novel magnetic cross-linked lipase aggregates for improving the resolution of (R, S)-2-octanol.

PubMed

Liu, Ying; Guo, Chen; Liu, Chun-Zhao

2015-03-01

Novel magnetic cross-linked lipase aggregates were fabricated by immobilizing the cross-linked lipase aggregates onto magnetic particles with a high number of -NH2 terminal groups using p-benzoquinone as the cross-linking agent. At the optimal fabrication conditions, 100% of immobilization efficiency and 139% of activity recovery of the magnetic cross-linked lipase aggregates were achieved. The magnetic cross-linked lipase aggregates were able to efficiently resolve (R, S)-2-octanol, and retained 100% activity and 100% enantioselectivity after 10 cycles of reuse, whereas the cross-linked lipase aggregates only retained about 50% activity and 70% enantioselectivity due to insufficient cross-linking. These results provide a great potential for industrial applications of the magnetic cross-linked lipase aggregates. © 2014 Wiley Periodicals, Inc.

Variations in organic carbon, aggregation, and enzyme activities of gangue-fly ash-reconstructed soils with sludge and arbuscular mycorrhizal fungi during 6-year reclamation.

PubMed

Yin, Ningning; Zhang, Zhen; Wang, Liping; Qian, Kuimei

2016-09-01

Mining activities can cause drastic disturbances in soil properties, which adversely affect the nutrient cycling and soil environment. As a result, many efforts have been made to explore suitable reclamation strategies that can be applied to accelerate ecology restoration. In this study, we reconstructed mine soils with fly ash, gangue, sludge, planted ryegrass, and inoculated arbuscular mycorrhizal fungi (AMF) in Pangzhuang mine of Xuzhou during 2009 to 2015. The soil aggregation process, enzyme activities (i.e., invertase, urease and acid phosphatase activities), soil organic carbon (SOC) as well as other soil nutrients such as nitrogen, phosphorus, and potassium contents of the reconstructed mine soils were monitored during 6-year reclamation. The integrated application of sludge and AMF led to a promising reclamation performance of mining areas, in which soil aggregate stability, enzyme activities, SOC, and ryegrass biomass were effectively enhanced. The micro-aggregates (< 0.25 mm) decreased with the increase of macro-aggregates (> 0.25 mm) during the reclamation, indicating that macro-aggregates were gradually formed from micro-aggregates during the pedogenesis of reconstructed mine soils. The correlation analysis shows that SOC contents in aggregate fraction of 0.25∼0.5 mm were correlated with aggregate distribution and enzyme activities. Enzyme activities, however, were not significantly correlated with aggregate distribution. The outcomes from the present study could enrich our understanding on soil property changes in pedogenesis process of reconstructed mine soils, and meanwhile, the employment of sludge combined with AMF is suggested to be an effective alternative for the mine soil reclamation.

Health-Beneficial Phenolic Aldehyde in Antigonon leptopus Tea

PubMed Central

Mulabagal, Vanisree; Alexander-Lindo, Ruby L.; DeWitt, David L.; Nair, Muraleedharan G.

2011-01-01

Tea prepared from the aerial parts of Antigonon leptopus is used as a remedy for cold and pain relief in many countries. In this study, A. leptopus tea, prepared from the dried aerial parts, was evaluated for lipid peroxidation (LPO) and cyclooxygenase (COX-1 and COX-2) enzyme inhibitory activities. The tea as a dried extract inhibited LPO, COX-1 and COX-2 enzymes by 78%, 38% and 89%, respectively, at 100 μg/mL. Bioassay-guided fractionation of the extract yielded a selective COX-2 enzyme inhibitory phenolic aldehyde, 2,3,4-trihydroxy benzaldehyde. Also, it showed LPO inhibitory activity by 68.3% at 6.25 μg/mL. Therefore, we have studied other hydroxy benzaldehydes and their methoxy analogs for LPO, COX-1 and COX-2 enzymes inhibitory activities and found that compound 1 gave the highest COX-2 enzyme inhibitory activity as indicated by a 50% inhibitory concentration (IC50) at 9.7 μg/mL. The analogs showed only marginal LPO activity at 6.25 μg/mL. The hydroxy analogs 6, 7 and 9 showed 55%, 61% and 43% of COX-2 inhibition at 100 μg/mL. However, hydroxy benzaldehydes 3 and 12 showed selective COX-1 inhibition while compounds 4 and 10 gave little or no COX-2 enzyme inhibition at 100 μg/mL. At the same concentration, compounds 14, 21 and 22 inhibited COX-1 by 83, 85 and 70%, respectively. Similarly, compounds 18, 19 and 23 inhibited COX-2 by 68%, 72% and 70%, at 100 μg/mL. This is the first report on the isolation of compound 1 from A. leptopus tea with selective COX-2 enzyme and LPO inhibitory activities. PMID:19454555

Pseudocatalytic Antiaggregation Activity of Antibodies: Immunoglobulins can Influence α-Synuclein Aggregation at Substoichiometric Concentrations.

PubMed

Breydo, Leonid; Morgan, Dave; Uversky, Vladimir N

2016-04-01

Protein aggregation is involved in a variety of diseases. Alteration of the aggregation pathway, either to produce less toxic structures or to increase aggregate clearance, is a promising therapeutic route. Both active and passive immunization has been used for this purpose. However, the mechanism of action of antibodies on protein aggregates is not completely clear especially given poor ability of antibodies to cross blood-brain barrier. Here, we have shown that antibodies can interfere with protein aggregation at substoichiometric concentrations (as low as 1:1000 antibody to protein ratio). This is an indication that antibodies interact with aggregation intermediates in chaperone-like manner altering the aggregation pathways at very low antibody levels. This observation supports earlier suggestions that antibodies can inhibit aggregation by interaction with low abundance aggregation intermediates.

Studying the Inhibitory Effect of Quercetin and Thymoquinone on Human Cytochrome P450 Enzyme Activities.

PubMed

Elbarbry, Fawzy; Ung, Aimy; Abdelkawy, Khaled

2018-01-01

Quercetin (QR) and thymoquinone (TQ) are herbal remedies that are currently extensively used by the general population to prevent and treat various chronic conditions. Therefore, investigating the potential of pharmacokinetic interactions caused by the concomitant use of these herbal remedies and conventional medicine is warranted to ensure patient safety. This study was conducted to determine the inhibitory effect of QR and TQ, two commonly used remedies, on the activities of selected cytochrome P450 (CYP) enzymes that play an important role in drug metabolism and/or toxicology. The in vitro studies were conducted using fluorescence-based high throughput assays using human c-DNA baculovirus expressed CYP enzymes. For measuring CYP2E1 activity, a validated High-performance liquid chromatography (HPLC) assay was utilized to measure the formation of 6-hydroxychlorzoxazone. The obtained half-maximum inhibitory concentration values with known positive control inhibitors of this study were comparable to the published values indicating accurate experimental techniques. Although QR did not show any significant effect on CYP1A2 and CYP2E1, it exhibited a strong inhibitory effect against CYP2D6 and a moderate effect against CYP2C19 and CYP3A4. On the other hand, TQ demonstrated a strong and a moderate inhibitory effect against CYP3A4 and CYP2C19, respectively. The findings of this study may indicate that consumption of QR or TQ, in the form of food or dietary supplements, with drugs that are metabolized by CYP2C19, CYP2D6, or CYP3A4 may cause significant herb-drug interactions. Neither QR nor TQ has any significant inhibitory effect on the activity of CYP1A2 or CYP2E1 enzymesBoth QR and TQ have a moderate to strong inhibitory effect on CYP3A4 activityQR has a moderate inhibitory effect on CYP2C19 and a strong inhibitory effect on CYP2D6Both QR and TQ are moderate inhibitors of the CYP2C9 activity. Abbreviations used: ABT: Aminobenztriazole, BZF: 7,8 Benzoflavone, CYP: Cytochrome P450, GB: Gingko Biloba, IC 50 : Half-maximum inhibitory concentration, KTZ: Ketoconazole, QND: Quinidine, QR: Quercetin, TCP: Tranylcypromine, TQ: Thymoquinone.

Bioavailability of angiotensin I-converting enzyme (ACE) inhibitory peptides derived from Virgibacillus halodenitrificans SK1-3-7 proteinases hydrolyzed tilapia muscle proteins.

PubMed

Toopcham, Tidarat; Mes, Jurriaan J; Wichers, Harry J; Roytrakul, Sittiruk; Yongsawatdigul, Jirawat

2017-04-01

The angiotensin I-converting enzyme (ACE) inhibitory activity of protein hydrolysates from tilapia muscle fractions, namely mince (M), washed mince (WM), and sarcoplasmic protein (SP), were investigated. Each fraction was hydrolyzed by Virgibacillus halodenitrificans SK1-3-7 proteinases for up to 24h. After 8h of hydrolysis, the M hydrolysate (48% degree of hydrolysis (DH)) showed the highest ACE inhibitory activity, with an IC 50 value of 0.54mg/ml, while the SP hydrolysate exhibited the lowest DH and ACE inhibition. In vitro gastrointestinal digestion reduced the ACE inhibitory activity of the M hydrolysate but enhanced its transport across Caco-2 cell monolayers. The transported peptides were found to contain 3-4 amino acid residues showing strong ACE inhibition. The novel ACE inhibitory peptide with the highest inhibition was found to be MCS, with an IC 50 value of 0.29μM. Therefore, tilapia mince hydrolyzed by V. halodenitrificans proteinases contained ACE inhibitory peptides that are potentially bioavailable. Copyright © 2016 Elsevier Ltd. All rights reserved.

Isolation of proanthocyanidins from red wine, and their inhibitory effects on melanin synthesis in vitro.

PubMed

Fujimaki, Takahiro; Mori, Shoko; Horikawa, Manabu; Fukui, Yuko

2018-05-15

The red wines made from Vitis vinifera were identified as skin-whitening effectors by using in vitro assays. OPCs in the wine were evaluated for tyrosinase activity and melanogenesis. Strong tyrosinase inhibitory activity was observed in fractions with high oligomeric proanthocyanidin (OPC) content. Among OPC dimers, a strong inhibitory effect on tyrosinase was observed with OPCs which contain (+)-catechin as an upper unit. Melanogenesis inhibitory effect was observed with OPCs which have (-)-epicatechin as upper units. Also, OPC trimers, upper and middle units joined with 4 → 8 bonds, showed stronger effects compared to trimers with 4 → 6 linkages. Interestingly, (-)-epicatechin-(4β → 8)-(-)-epicatechin 3-O-gallate, which is a unique component of grapes has potent inhibitory effects on both tyrosinase and melanogenesis. Our data provide structural information about such active compounds. These results suggest that red wines containing OPC, have high melanogenesis inhibitory effect and are supposed to have skin-whitening effect. Copyright © 2017 Elsevier Ltd. All rights reserved.

The Role of Inhibitory Control in Behavioral and Physiological Expressions of Toddler Executive Function

PubMed Central

Morasch, Katherine C.; Bell, Martha Ann

2010-01-01

Eighty-one toddlers (ranging from 24 to 27 months) participated in a biobehavioral investigation of inhibitory control. Maternal-report measures of inhibitory control were related to laboratory tasks assessing inhibitory abilities under conditions of conflict, delay, and compliance challenge as well as toddler verbal ability. Additionally, unique variance in inhibitory control was explained by task-related changes in brain electrical activity at lateral frontal scalp sites as well as concurrent inhibitory task performance. Implications regarding neural correlates of executive function in early development and a central, organizing role of inhibitory processing in toddlerhood are discussed. PMID:20719337

Antioxidative and antiplatelet effects of aqueous inflorescence Piper betle extract.

PubMed

Lei, Daniel; Chan, Chiu-Po; Wang, Ying-Jan; Wang, Tong-Mei; Lin, Bor-Ru; Huang, Chun-Hsun; Lee, Jang-Jaer; Chen, Hsin-Ming; Jeng, Jiiang-Huei; Chang, Mei-Chi

2003-03-26

Piper betle, belonging to the Piperaceae family, is a tropical plant, and its leaf and inflorescence are popularly consumed by betel quid (BQ) chewers in Taiwan and many other South and Southeast Asian countries. However, little is known about the biochemical properties of inflorescence Piper betle (IPB) toward reactive oxygen species (ROS) and platelet functions. In the present work, aqueous IPB extract was shown to be a scavenger of H(2)O(2), superoxide radical, and hydroxyl radical with a 50% inhibitory concentration (IC(50)) of about 80, 28, and 73 microg/mL, respectively. IPB extract also prevented the hydroxyl radical induced PUC18 plasmid DNA breaks at concentrations higher than 40 microg/mL. Since ROS are crucial for platelet aggregation, we further found that IPB extract also inhibited the arachidonic acid (AA) induced and collagen-induced platelet aggregation, with an IC(50) of 207 and 335 microg/mL, respectively. IPB extract also inhibited the AA-, collagen- (>100 microg/mL of IPB), and thrombin (>250 microg/mL of IPB)-induced thromboxane B(2) (TXB(2)) production by more than 90%. However, IPB extract showed little effect on thrombin-induced aggregation. These results indicated that aqueous components of IPB are potential ROS scavengers and may prevent the platelet aggregation possibly via scavenging ROS or inhibition of TXB(2) production.

Discovery of imidazopyridines containing isoindoline-1,3-dione framework as a new class of BACE1 inhibitors: Design, synthesis and SAR analysis.

PubMed

Azimi, Sara; Zonouzi, Afsaneh; Firuzi, Omidreza; Iraji, Aida; Saeedi, Mina; Mahdavi, Mohammad; Edraki, Najmeh

2017-09-29

Alzheimer's disease is characterized by chronic neurodegeneration leading to dementia. The main cause of neurodegeneration is considered to be the accumulation of amyloid-β. Inhibiting BACE1 is a well-studied approach to lower the burden of amyloid-β aggregates. We designed a series of imidazopyridines-based compounds bearing phthalimide moieties as inhibitors of BACE1. The compounds 8a-o were synthesized by the Groebke-Blackburn-Bienaymé three-component reaction of heteroaromatic amidines, aldehydes and isocyanides. Evaluating the BACE1 inhibitory effects of the synthesized compounds revealed that introducing an aminocyclohexyl moiety in the imidazopyridine core resulted in a significant improvement in its BACE1 inhibitory potential. In this regard, compound 8e was the most potent against BACE1 with an IC 50 value of 2.84 (±0.95) μM. Molecular docking revealed that the nitrogen atom of imidazopyridines and the oxygen atom of the phenoxypropyl linker were involved in hydrogen bound interactions with Asp228 and Asp32 of BACE1 active site, respectively. The phthalimide moiety oriented toward the flap pocket and interacted with phe108, lle110, Trp115, Ile118 through van der Waal's and hydrophobic interactions. These findings demonstrate that imidazopyridines-based compounds bearing phthalimide moiety have the potential to decrease amyloid-β levels and ameliorate the symptoms of Alzheimer's disease. Copyright © 2017. Published by Elsevier Masson SAS.

A novel antithrombotic effect of sulforaphane via activation of platelet adenylate cyclase: ex vivo and in vivo studies.

PubMed

Jayakumar, Thanasekaran; Chen, Wei-Fan; Lu, Wan-Jung; Chou, Duen-Suey; Hsiao, George; Hsu, Chung-Yi; Sheu, Joen-Rong; Hsieh, Cheng-Ying

2013-06-01

Sulforaphane is a naturally occurring isothiocyanate, which can be found in cruciferous vegetables such as broccoli and cabbage. Sulforaphane was found to have very potent inhibitory effects on tumor growth through regulation of diverse mechanisms. However, no data are available concerning the effects of sulforaphane on platelet activation and its relative issues. Activation of platelets caused by arterial thrombosis is relevant to a variety of cardiovascular diseases. Hence, the aim of this study was to examine the in vivo antithrombotic effects of sulforaphane and its possible mechanisms in platelet activation. Sulforaphane (0.125 and 0.25 mg/kg) was effective in reducing the mortality of ADP-induced acute pulmonary thromboembolism in mice. Other in vivo studies also revealed that sulforaphane (0.25 mg/kg) significantly prolonged platelet plug formation in mice. In addition, sulforaphane (15-75 μM) exhibited more-potent activity of inhibiting platelet aggregation stimulated by collagen. Sulforaphane inhibited platelet activation accompanied by inhibiting relative Ca(2+) mobilization; phosphorylation of phospholipase C (PLC)γ2, protein kinase C (PKC), mitogen-activated protein kinases (MAPKs) and Akt; and hydroxyl radical (OH(●)) formation. Sulforaphane markedly increased cyclic (c)AMP, but not cyclic (c)GMP levels, and stimulated vasodilator-stimulated phosphoprotein (VASP) phosphorylation. SQ22536, an inhibitor of adenylate cyclase, but not ODQ (1H-[1,2,4]Oxadiazolo[4,3-a]quinoxal in-1-one), an inhibitor of guanylate cyclase, obviously reversed the sulforaphane-mediated effects on platelet aggregation; PKC activation, p38 MAPK, Akt and VASP phosphorylation; and OH(●) formation. Furthermore, a PI3-kinase inhibitor (LY294002) and a p38 MAPK inhibitor (SB203580) both significantly diminished PKC activation and p38 MAPK and Akt phosphorylation; in contrast, a PKC inhibitor (RO318220) did not diminish p38 MAPK or Akt phosphorylation stimulated by collagen. This study demonstrates for the first time that in addition to it originally being considered as an agent for prevention of tumor growth, sulforaphane possesses potent antiplatelet activity which may initially activate adenylate cyclase/cAMP, followed by inhibiting intracellular signals (such as the PI3-kinase/Akt and PLCγ2-PKC-p47 cascades) and ultimately inhibiting platelet activation. Therefore, this novel role of sulforaphane may represent a high therapeutic potential for treatment or prevention of cardiovascular diseases. Copyright © 2013 Elsevier Inc. All rights reserved.

Influence of thermodynamic parameter in Lanosterol 14alpha-demethylase inhibitory activity as antifungal agents: a QSAR approach.

PubMed

Vasanthanathan, Poongavanam; Lakshmi, Manickavasagam; Arockia Babu, Marianesan; Kaskhedikar, Sathish Gopalrao

2006-06-01

A quantitative structure activity relationship, Hansch approach was applied on twenty compounds of chromene derivatives as Lanosterol 14alpha-demethylase inhibitory activity against eight fungal organisms. Various physicochemical descriptors and reported minimum inhibitory concentration values of different fungal organisms were used as independent variables and dependent variable respectively. The best models for eight different fungal organisms were first validated by leave-one-out cross validation procedure. It was revealed that thermodynamic parameters were found to have overall significant correlationship with anti fungal activity and these studies provide an insight to design new molecules.

Redox signaling via lipid raft clustering in homocysteine-induced injury of podocytes.

PubMed

Zhang, Chun; Hu, Jun-Jun; Xia, Min; Boini, Krishna M; Brimson, Christopher; Li, Pin-Lan

2010-04-01

Our recent studies have indicated that hyperhomocysteinemia (hHcys) may induce podocyte damage, resulting in glomerulosclerosis. However, the molecular mechanisms mediating hHcys-induced podocyte injury are still poorly understood. In the present study, we first demonstrated that an intact NADPH oxidase system is present in podocytes as shown by detection of its membrane subunit (gp91(phox)) and cytosolic subunit (p47(phox)). Then, confocal microscopy showed that gp91(phox) and p47(phox) could be aggregated in lipid raft (LR) clusters in podocytes treated with homocysteine (Hcys), which were illustrated by their colocalization with cholera toxin B, a common LR marker. Different mechanistic LR disruptors, either methyl-beta-cyclodextrin (MCD) or filipin abolished such Hcys-induced formation of LR-gp91(phox) or LR-p47(phox) transmembrane signaling complexes. By flotation of detergent-resistant membrane fractions we found that gp91(phox) and p47(phox) were enriched in LR fractions upon Hcys stimulation, and such enrichment of NADPH oxidase subunits and increase in its enzyme activity were blocked by MCD or filipin. Functionally, disruption of LR clustering significantly attenuated Hcys-induced podocyte injury, as shown by their inhibitory effects on Hcys-decreased expression of slit diaphragm molecules such as nephrin and podocin. Similarly, Hcys-increased expression of desmin was also reduced by disruption of LR clustering. In addition, inhibition of such LR-associated redox signaling prevented cytoskeleton disarrangement and apoptosis induced by Hcys. It is concluded that NADPH oxidase subunits aggregation and consequent activation of this enzyme through LR clustering is an important molecular mechanism triggering oxidative injury of podocytes induced by Hcys. 2009 Elsevier B.V. All rights reserved.

Redox signaling via lipid raft clustering in homocysteine-induced injury of podocytes

PubMed Central

Zhang, Chun; Hu, Jun-Jun; Xia, Min; Boini, Krishna M.; Brimson, Christopher; Li, Pin-Lan

2010-01-01

Our recent studies have indicated that hyperhomocysteinemia (hHcys) may induce podocyte damage, resulting in glomerulosclerosis. However, the molecular mechanisms mediating hHcys-induced podocyte injury are still poorly understood. In the present study, we first demonstrated that an intact NADPH oxidase system is present in podocytes as shown by detection of its membrane subunit (gp91phox) and cytosolic subunit (p47phox). Then, confocal microscopy showed that gp91phox and p47phox could be aggregated in lipid raft (LR) clusters in podocytes treated with homocysteine (Hcys), which were illustrated by their co-localization with cholera toxin B, a common LR marker. Different mechanistic LR disruptors, either methyl-β-cyclodextrin (MCD) or filipin abolished such Hcys-induced formation of LR-gp91phox or LR-p47phox transmembrane signaling complexes. By flotation of detergent-resistant membrane fractions we found that gp91phox and p47phox were enriched in LR fractions upon Hcys stimulation, and such enrichment of NADPH oxidase subunits and increase in its enzyme activity were blocked by MCD or filipin. Functionally, disruption of LR clustering significantly attenuated Hcys-induced podocyte injury, as shown by their inhibitory effects on Hcys-decreased expression of slit diaphragm molecules such as nephrin and podocin. Similarly, Hcys-increased expression of desmin was also reduced by disruption of LR clustering. In addition, inhibition of such LR-associated redox signaling prevented cytoskeleton disarrangement and apoptosis induced by Hcys. It is concluded that NADPH oxidase subunits aggregation and consequent activation of this enzyme through LR clustering is an important molecular mechanism triggering oxidative injury of podocytes induced by Hcys. PMID:20036696

Effects of Lys to Glu mutations in GsMTx4 on membrane binding, peptide orientation, and self-association propensity, as analyzed by molecular dynamics simulations.

PubMed

Nishizawa, Kazuhisa; Nishizawa, Manami; Gnanasambandam, Radhakrishnan; Sachs, Frederick; Sukharev, Sergei I; Suchyna, Thomas M

2015-11-01

GsMTx4, a gating modifier peptide acting on cationic mechanosensitive channels, has a positive charge (+5e) due to six Lys residues. The peptide does not have a stereospecific binding site on the channel but acts from the boundary lipids within a Debye length of the pore probably by changing local stress. To gain insight into how these Lys residues interact with membranes, we performed molecular dynamics simulations of Lys to Glu mutants in parallel with our experimental work. In silico, K15E had higher affinity for 1-palmitoyl-2-oleoyl-glycero-3-phosphocholine bilayers than wild-type (WT) peptide or any other mutant tested, and showed deeper penetration than WT, a finding consistent with the experimental data. Experimentally, the inhibitory activities of K15E and K25E were most compromised, whereas K8E and K28E inhibitory activities remained similar to WT peptide. Binding of WT in an interfacial mode did not influence membrane thickness. With interfacial binding, the direction of the dipole moments of K15E and K25E was predicted to differ from WT, whereas those of K8E and K28E oriented similarly to that of WT. These results support a model in which binding of GsMTx4 to the membrane acts like an immersible wedge that serves as a membrane expansion buffer reducing local stress and thus inhibiting channel activity. In simulations, membrane-bound WT attracted other WT peptides to form aggregates. This may account for the positive cooperativity observed in the ion channel experiments. The Lys residues seem to fine-tune the depth of membrane binding, the tilt angle, and the dipole moments. Copyright © 2015 Elsevier B.V. All rights reserved.

Is There Consistency between the Binding Affinity and Inhibitory Potential of Natural Polyphenols as α-amylase Inhibitors?

PubMed

Xu, Wei; Shao, Rong; Xiao, Jianbo

2016-07-26

The inhibitory potential of natural polyphenols for α-amylases has attracted great interests among researchers. The structure-affinity properties of natural polyphenols binding to α-amylase and the structure-activity relationship of dietary polyphenols inhibiting α-amylase were deeply investigated. There is a lack of consistency between the structure-affinity relationship and the structure-activity relationship of natural polyphenols as α-amylase inhibitors. Is it consistent between the binding affinity and inhibitory potential of natural polyphenols as with α-amylase inhibitors? It was found that the consistency between the binding affinity and inhibitory potential of natural polyphenols as with α-amylase inhibitors is not equivocal. For example, there is no consistency between the binding affinity and the inhibitory potential of quercetin and its glycosides as α-amylase inhibitors. However, catechins with higher α-amylase inhibitory potential exhibited higher affinity with α-amylase.

Expression patterns of lectin-like natural killer receptors, inhibitory CD94/NKG2A, and activating CD94/NKG2C on decidual CD56bright natural killer cells differ from those on peripheral CD56dim natural killer cells.

PubMed

Kusumi, Maki; Yamashita, Takahiro; Fujii, Tomoyuki; Nagamatsu, Takeshi; Kozuma, Shiro; Taketani, Yuji

2006-06-01

The balance of inhibitory and activating natural killer (NK) receptors on maternal decidual NK cells, most of which are CD56bright, is thought to be crucial for the proper growth of trophoblasts in placenta. A lectin-like NK receptor, CD94/NKG2, is the receptor for human leukocyte antigen (HLA)-E, which is expressed on trophoblasts. To clarify the mechanism regulating the activity of decidual NK cells during pregnancy, we investigated the expression patterns of inhibitory NK receptor, CD94/NKG2A, and activating receptor, CD94/NKG2C, on decidual NK cells in an early stage of normal pregnancy and compared them with those on peripheral NK cells, most of which are CD56dim. The rate of NKG2A-positive cells was significantly higher for decidual CD56bright NK cells than for peripheral CD56dim NK cells, but the rates of NKG2C-positive cells were comparable between the two cell types. Interestingly, peripheral CD56dim NK cells reciprocally expressed inhibitory NKG2A and activating NKG2C, but decidual CD56bright NK cells that expressed activating NKG2C simultaneously expressed inhibitory NKG2A. The co-expression of inhibitory and activating NKG2 receptors may fine-tune the immunoregulatory functions of the decidual NK cells to control the trophoblast invasion in constructing placenta.

Rofecoxib does not compromise platelet aggregation during anesthesia and surgery.

PubMed

Silverman, David G; Halaszynski, Thomas; Sinatra, Raymond; Luther, Martha; Rinder, Christine S

2003-12-01

This study was undertaken because, although there is evidence that cyclooxygenase type 2 (COX)-2 inhibitors do not compromise platelets in healthy volunteers, many clinicians remain hesitant to administer them perioperatively without definitive evidence of intact platelet function during anesthesia and surgery. In 20 patients scheduled for lower abdominal and pelvic surgery, 5 mL of blood were obtained for baseline platelet aggregometry. One hour prior to surgery, patients received an oral solution of either rofecoxib (ROF) 50 mg or placebo (PLAC) by randomized, double-blinded assignment. Approximately one hour after onset of anesthesia, an intraoperative blood sample was obtained. Baseline and postdrug samples were centrifuged to generate platelet-rich plasma, which was challenged with adenosine diphosphate (ADP) and arachidonic acid (AA). Aggregometry was performed with and without incubation with aspirin. The data in each subject were normalized to baseline aggregation in response to AA alone and ADP alone. Intergroup differences were assessed using paired t test; P < 0.05 was considered significant. Consistent with known effects of anesthesia on platelet function, both groups had approximately 25% intraoperative declines in aggregation in response to ADP (P = NS for PLAC vs ROF) and even greater declines in response to AA (P = NS for PLAC vs ROF). Aspirin eliminated aggregation in response to AA in both groups (P = NS), and it caused similar declines in PLAC and ROF groups during exposure to ADP (P = NS). This study provides strong evidence that ROF does not compromise platelet aggregation during anesthesia and surgery; nor does it interfere with the platelet inhibitory effect of aspirin.

Hsp105 reduces the protein aggregation and cytotoxicity by expanded-polyglutamine proteins through the induction of Hsp70

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yamagishi, Nobuyuki; Goto, Kazumasa; Nakagawa, Satomi

2010-09-10

Hsp105{alpha} and Hsp105{beta} are major heat shock proteins in mammalian cells and belong to the HSP105/110 family. Hsp105{alpha} is expressed constitutively in the cytoplasm of cells, while Hsp105{beta}, an alternatively spliced form of Hsp105{alpha}, is expressed specifically in the nucleus of cells during mild heat shock. Here, we show that not only Hsp105{beta} but also Hsp105{alpha} accumulated in the nucleus of cells following the expression of enhanced green fluorescent protein with a pathological length polyQ tract (EGFP-polyQ97) and suppressed the intranuclear aggregation of polyQ proteins and apoptosis induced by EGFP-polyQ97. Mutants of Hsp105{alpha} and Hsp105{beta} with changes in the nuclearmore » localization signal sequences, which localized exclusively in the cytoplasm with or without the expression of EGFP-polyQ97, did not suppress the intranuclear aggregation of polyQ proteins and apoptosis induced by EGFP-polyQ97. Furthermore, Hsp70 was induced by the co-expression of Hsp105{alpha} and EGFP-polyQ97, and the knockdown of Hsp70 reduced the inhibitory effect of Hsp105{alpha} and Hsp105{beta} on the intranuclear aggregation of polyQ proteins and apoptosis induced by EGFP-polyQ97. These observations suggested that Hsp105{alpha} and Hsp105{beta} suppressed the expanded polyQ tract-induced protein aggregation and apoptosis through the induction of Hsp70.« less

Inhibitory spectrum of alpha 2-plasmin inhibitor.

PubMed Central

Saito, H; Goldsmith, G H; Moroi, M; Aoki, N

1979-01-01

alpha 2-Plasmin inhibitor (alpha 2PI) has been recently characterized as a fast-reacting inhibitor of plasmin in human plasma and appears to play an important role in the regulation of fibrinolysis in vivo. We have studied the effect of purified alpha 2PI upon various proteases participating in human blood coagulation and kinin generation. At physiological concentration (50 microgram/ml), alpha 2PI inhibited the clot-promoting and prekallikrein-activating activity of Hageman factor fragments, the amidolytic, kininogenase, and clot-promoting activities of plasma kallikrein, and the clot-promoting properties of activated plasma thromboplastin antecedent (PTA, Factor XIa) and thrombin. alpha 2PI had minimal inhibitory effect on surface-bound activated PTA and activated Stuart factor (Factor Xa). alpha 2PI did not inhibit the activity of activated Christmas factor (Factor IXa) or urinary kallikrein. Heparin (1.5-2.0 units/ml) did not enhance the inhibitory function of alpha 2PI. These results suggest that, like other plasma protease inhibitors, alpha 2PI possesses a broad in vitro spectrum of inhibitory properties. PMID:156364

Pomegranate ellagitannins inhibit α-glucosidase activity in vitro and reduce starch digestibility under simulated gastro-intestinal conditions.

PubMed

Bellesia, Andrea; Verzelloni, Elena; Tagliazucchi, Davide

2015-02-01

Pomegranate extract was tested for its ability to inhibit α-amylase and α-glucosidase activity. Pomegranate extract strongly inhibited rat intestinal α-glucosidase in vitro whereas it was a weak inhibitor of porcine α-amylase. The inhibitory activity was recovered in an ellagitannins-enriched fraction and punicalagin, punicalin, and ellagic acid were identified as α-glucosidase inhibitors (IC(50) of 140.2, 191.4, and 380.9 μmol/L, respectively). Kinetic analysis suggested that the pomegranate extract and ellagitannins inhibited α-glucosidase activity in a mixed mode. The inhibitory activity was demonstrated using an in vitro digestion system, mimicking the physiological gastro-intestinal condition, and potatoes as food rich in starch. Pre-incubation between ellagitannins and α-glucosidase increased the inhibitory activity, suggesting that they acted by binding to α-glucosidase. During digestion punicalin and punicalagin concentration decreased. Despite this loss, the pomegranate extract retained high inhibitory activity. This study suggests that pomegranate ellagitannins may inhibit α-glucosidase activity in vitro possibly affecting in vivo starch digestion.

Piperazine derivatives inhibit PrP/PrP(res) propagation in vitro and in vivo.

PubMed

Leidel, Fabienne; Eiden, Martin; Geissen, Markus; Hirschberger, Thomas; Tavan, Paul; Giese, Armin; Kretzschmar, Hans A; Schätzl, Hermann; Groschup, Martin H

2014-02-28

Prion diseases are fatal neurodegenerative disorders, which are not curable and no effective treatment exists so far. The major neuropathological change in diseased brains is the conversion of the normal cellular form of the prion protein PrPc(C) into a disease-associated isoform PrP(Sc). PrP(Sc) accumulates into multimeres and fibrillar aggregates, which leads to the formation of amyloid plaques. Increasing evidence indicates a fundamental role of PrP(Sc) species and its aggregation in the pathogenesis of prion diseases, which initiates the pathological cascade and leads to neurodegeneration accompanied by spongiform changes. In search of compounds that have the potential to interfere with PrP(Sc) formation and propagation, we used a cell based assay for the screening of potential aggregation inhibitors. The assay deals with a permanently prion infected cell line that was adapted for a high-throughput screening of a compound library composed of 10,000 compounds (DIVERset 2, ChemBridge). We could detect six different classes of highly potent inhibitors of PrP(Sc) propagation in vitro and identified piperazine derivatives as a new inhibitory lead structure, which increased incubation time of scrapie infected mice. Copyright © 2014 Elsevier Inc. All rights reserved.

A-type dimeric epigallocatechin-3-gallate (EGCG) is a more potent inhibitor against the formation of insulin amyloid fibril than EGCG monomer.

PubMed

Nie, Rong-Zu; Zhu, Wei; Peng, Jin-Ming; Ge, Zhen-Zhen; Li, Chun-Mei

2016-06-01

Because fibrillary protein aggregates is regarded to be closely associated with many diseases such as Alzheimer's disease, diabetes, and Parkinson's disease, growing interest and researches have been focused on finding potential fibrillation inhibitors. In the present study, the inhibitory effects of epigallocatechin-3-gallate (EGCG) and A-type dimeric epigallocatechin-3-gallate (A-type EGCG dimer) on the formation of insulin fibrillation were compared by multi-dimensional approaches including thioflavin-T (ThT) fluorescence assay, 1-anilinonaphthalene-8-sulfonic (ANS) fluorescence assay, dynamic light scattering (DLS), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy and circular dichroism (CD) spectroscopy. Our results confirmed that A-type EGCG dimer is a more potent inhibitor against the formation of bovine insulin amyloid fibril than EGCG. In addition, A-type EGCG dimer could not only inhibit insulin amyloid fibril formation, but also change the aggregation pathway and induce bovine insulin into amorphous aggregates. The results of the present study may provide a new guide on finding novel anti-amyloidogenic agents. Copyright © 2016 Elsevier B.V. and Société française de biochimie et biologie Moléculaire (SFBBM). All rights reserved.

Impact of in Vitro Gastrointestinal Digestion and Transepithelial Transport on Antioxidant and ACE-Inhibitory Activities of Brewer's Spent Yeast Autolysate.

PubMed

Vieira, Elsa F; das Neves, José; Vitorino, Rui; Dias da Silva, Diana; Carmo, Helena; Ferreira, Isabel M P L V O

2016-10-05

Brewer's spent yeast (BSY) autolysates may have potential applications as food ingredients or nutraceuticals due to their antioxidant and ACE-inhibitory activities. The impact of simulated gastrointestinal (GI) digestion, the interaction with intracellular sources of oxidative stress, the intestinal cell permeability of BSY peptides, and the antioxidant and ACE-inhibitory activities of BSY permeates were assayed. Gastrointestinal digestion of BSY autolysates enhanced antioxidant and ACE-inhibitory activities as measured in vitro. No cytotoxic effects were observed on Caco-2 cells after exposure to the digested BSY autolysates within a concentration range of 0.5 to 3.0 mg of peptides/mL. A protective role to induced oxidative stress was observed. The transepithelial transport assays indicate high apparent permeability coefficient (P app ) values for BSY peptides across Caco-2/HT29-MTX cell monolayer (14.5-26.1 × 10 -6 cm/s) and for Caco-2 cell monolayer model (12.4-20.8 × 10 -6 cm/s), while the antioxidant and ACE-inhibitory activities found in flux material from the basolateral side suggest transepithelial absorption of bioactive compounds.

The reducing agent dithiothreitol (DTT) does not abolish the inhibitory nicotinic response recorded from rat dorsolateral septal neurons

NASA Technical Reports Server (NTRS)

Sorenson, E. M.; Gallagher, J. P.

1993-01-01

Previous intracellular recordings have demonstrated that dorsolateral septal nucleus (DLSN) neurons express a novel nicotinic receptor which produces a direct membrane hyperpolarization when activated by nicotinic agonists. Activation of the classical excitatory nicotinic receptors has been shown to require a disulfide bond involving the cysteines at positions 192 and 193 of the alpha subunits of the receptor. Reduction of this cystine bond with dithiothreitol (DTT) abolishes agonist activation of excitatory nicotinic receptors. We have now examined whether DTT treatment of the inhibitory nicotinic receptor on DLSN neurons also abolishes the inhibitory nicotinic response. We find that the inhibitory response persists after treatment of the neurons with 1 mM DTT, even if the reduction is followed by alkylation of the receptor with bromoacetylcholine to prevent possible reformation of disulfide bonds. This result suggests that the agonist binding site on the inhibitory nicotinic receptor does not require an intact disulfide bond, similar to the bond on the alpha subunit of the excitatory nicotinic receptor, for agonist activation of the receptor. Some of these results have been previously reported in abstract form.

Pancreatic lipase inhibitory activity of taraxacum officinale in vitro and in vivo

PubMed Central

Zhang, Jian; Kang, Min-Jung; Kim, Myung-Jin; Kim, Mi-Eun; Song, Ji-Hyun; Lee, Young-Min

2008-01-01

Obesity has become a worldwide health problem. Orlistat, an inhibitor of pancreatic lipase, is currently approved as an anti-obesity drug. However, gastrointestinal side effects caused by Orlistat may limit its use. In this study the inhibitory activities of dandelion (Taraxacum officinale) against pancreatic lipase in vitro and in vivo were measured to determine its possible use as a natural anti-obesity agent. The inhibitory activities of the 95% ethanol extract of T. officinale and Orlistat were measured using 4-methylumbelliferyl oleate (4-MU oleate) as a substrate at concentrations of 250, 125, 100, 25, 12.5 and 4 µg/ml. To determine pancreatic lipase inhibitory activity in vivo, mice (n=16) were orally administered with corn oil emulsion (5 ml/kg) alone or with the 95% ethanol extract of T. officinale (400 mg/kg) following an overnight fast. Plasma triglyceride levels were measured at 0, 90, 180, and 240 min after treatment and incremental areas under the response curves (AUC) were calculated. The 95% ethanol extract of T. officinale and Orlistat, inhibited, porcine pancreatic lipase activity by 86.3% and 95.7% at a concentration of 250 µg/ml, respectively. T. officinale extract showed dose-dependent inhibition with the IC50 of 78.2 µg/ml. A single oral dose of the extract significantly inhibited increases in plasma triglyceride levels at 90 and 180 min and reduced AUC of plasma triglyceride response curve (p<0.05). The results indicate that T. officinale exhibits inhibitory activities against pancreatic lipase in vitro and in vivo. Further studies to elucidate anti-obesity effects of chronic consumption of T. officinale and to identify the active components responsible for inhibitory activity against pancreatic lipase are necessary. PMID:20016719

Strategies for combating bacterial biofilms: A focus on anti-biofilm agents and their mechanisms of action

PubMed Central

Roy, Ranita; Tiwari, Monalisa; Donelli, Gianfranco; Tiwari, Vishvanath

2018-01-01

ABSTRACT Biofilm refers to the complex, sessile communities of microbes found either attached to a surface or buried firmly in an extracellular matrix as aggregates. The biofilm matrix surrounding bacteria makes them tolerant to harsh conditions and resistant to antibacterial treatments. Moreover, the biofilms are responsible for causing a broad range of chronic diseases and due to the emergence of antibiotic resistance in bacteria it has really become difficult to treat them with efficacy. Furthermore, the antibiotics available till date are ineffective for treating these biofilm related infections due to their higher values of minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC), which may result in in-vivo toxicity. Hence, it is critically important to design or screen anti-biofilm molecules that can effectively minimize and eradicate biofilm related infections. In the present article, we have highlighted the mechanism of biofilm formation with reference to different models and various methods used for biofilm detection. A major focus has been put on various anti-biofilm molecules discovered or tested till date which may include herbal active compounds, chelating agents, peptide antibiotics, lantibiotics and synthetic chemical compounds along with their structures, mechanism of action and their respective MICs, MBCs, minimum biofilm inhibitory concentrations (MBICs) as well as the half maximal inhibitory concentration (IC50) values available in the literature so far. Different mode of action of anti biofilm molecules addressed here are inhibition via interference in the quorum sensing pathways, adhesion mechanism, disruption of extracellular DNA, protein, lipopolysaccharides, exopolysaccharides and secondary messengers involved in various signaling pathways. From this study, we conclude that the molecules considered here might be used to treat biofilm-associated infections after significant structural modifications, thereby investigating its effective delivery in the host. It should also be ensured that minimum effective concentration of these molecules must be capable of eradicating biofilm infections with maximum potency without posing any adverse side effects on the host. PMID:28362216

Binding Modes of Phthalocyanines to Amyloid β Peptide and Their Effects on Amyloid Fibril Formation.

PubMed

Valiente-Gabioud, Ariel A; Riedel, Dietmar; Outeiro, Tiago F; Menacho-Márquez, Mauricio A; Griesinger, Christian; Fernández, Claudio O

2018-03-13

The inherent tendency of proteins to convert from their native states into amyloid aggregates is associated with a range of human disorders, including Alzheimer's and Parkinson's diseases. In that sense, the use of small molecules as probes for the structural and toxic mechanism related to amyloid aggregation has become an active area of research. Compared with other compounds, the structural and molecular basis behind the inhibitory interaction of phthalocyanine tetrasulfonate (PcTS) with proteins such as αS and tau has been well established, contributing to a better understanding of the amyloid aggregation process in these proteins. We present here the structural characterization of the binding of PcTS and its Cu(II) and Zn(II)-loaded forms to the amyloid β-peptide (Aβ) and the impact of these interactions on the peptide amyloid fibril assembly. Elucidation of the PcTS binding modes to Aβ 40 revealed the involvement of specific aromatic and hydrophobic interactions in the formation of the Aβ 40 -PcTS complex, ascribed to a binding mode in which the planarity and hydrophobicity of the aromatic ring system in the phthalocyanine act as main structural determinants for the interaction. Our results demonstrated that formation of the Aβ 40 -PcTS complex does not interfere with the progression of the peptide toward the formation of amyloid fibrils. On the other hand, conjugation of Zn(II) but not Cu(II) at the center of the PcTS macrocyclic ring modified substantially the binding profile of this phthalocyanine to Aβ 40 and became crucial to reverse the effects of metal-free PcTS on the fibril assembly of the peptide. Overall, our results provide a firm basis to understand the structural rules directing phthalocyanine-protein interactions and their implications on the amyloid fibril assembly of the target proteins; in particular, our results contradict the hypothesis that PcTS might have similar mechanisms of action in slowing the formation of a variety of pathological aggregates. Copyright © 2018 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Synthesis of potential radioprotective components from Chinese herb drug Rhizoma Chuanxiong (rhizome of Ligusticum chuanxiong Hort. , umbelliferae)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, X.

1993-01-01

The ethanolic extracts of some Chinese traditional herb drugs, reported by Hong-Fu Wang et al. in China, could inhibit platelet aggregation as well as protect against radiation damage in mice, rat and rabbits. The inhibitory effects of the extracts of five Chinese drugs on the rate of platelet aggregation were observed in both in vitro and in vivo tests, averaging 23--53% in vitro and 46--69% in vivo. Antiradiation tests on mice vs. 7.5--8.0 Gy of [gamma]-radiation, using the herb drug extracts as protective agents, showed increasing survival rates by 8--50%. Based on Hong-Fu Wang's report, a search for the activemore » constituents of these herb drugs in inhibiting platelet aggregation and protecting animals against radiation damage was started. In this research program, a Chinese traditional drug, Rhizoma Chuanxiong (rhizome of Ligusticum chuanxiong Hort.) was chosen. Three types of chemicals present in Rhizoma Chuanxiong, appeared promising for testing: 1-(5-hydroxymethyl-2-furyl)-9H-pyrido-(3,4-b)indole, 4-hydroxyl-3-butylidenephthalide and 5-hydroxyl-3-butylidenephthalide, and 4-hydroxyl-3-methoxycinnamyl 4-hydroxyl-3-methoxycinnamate. A total of 56 compounds of these derivatives has been synthesized and 30 were synthesized for the first time. The structure elucidation of these compounds was based on IR, [sup 1]H NMR and elemental analysis. From this research program, a very mild dehydrogenation method was developed. It was by using 2,3-dichloro-5,6-dicyanobenzoquinone in acetonitrile at ice bath temperature to dehydrogenate 1-(5-hydroxymethyl-2-furyl)-1,2,3,4-tetrahydro-9H-pyrido-(3,4-b)indole into 1-(5-hydroxymethyl-2-furyl)-9H-pyrido-(3,4-b)indole. This project showed for the first time that harmanoid alkaloids have the activity of inhibition of plate aggregation by 4 to 23 times that of aspirin. These results aid in establishing a relation between radiation protection in animals and prevention of platelet hyperaggregation.« less

Two new lignans from Saururus chinensis and their DGAT inhibitory activity.

PubMed

Li, Na; Tuo, Zhen-Dong; Qi, Shi-Zhou; Xing, Shan-Shan; Lee, Hyun-Sun; Chen, Jian-Guang; Cui, Long

2015-03-01

Two new lignans were isolated from Saururus chinensis, along with eight known compounds. Their structures were elucidated on the basis of spectroscopic and physico-chemical analyses. All the isolates were evaluated for in vitro inhibitory activity against DGAT1 and DGAT2. Among them, compounds 2, 3, 5 and 7 were found to exhibit selective inhibitory activity on DGAT1 with IC50 values ranging from 44.3±1.5 to 87.5±1.3μM. Copyright © 2014 Elsevier B.V. All rights reserved.

Design and synthesis of chalcone derivatives as potential non-purine xanthine oxidase inhibitors.

PubMed

Bui, Trung Huu; Nguyen, Nhan Trung; Dang, Phu Hoang; Nguyen, Hai Xuan; Nguyen, Mai Thanh Thi

2016-01-01

Based on some previous research, the chalcone derivatives exhibited potent xanthine oxidase inhibitory activity, e.g. sappanchalcone ( 7 ), with IC 50 value of 3.9 μM, was isolated from Caesalpinia sappan . Therefore, objectives of this research are design and synthesis of 7 and other chalcone derivatives by Claisen-Schmidt condensation and then evaluate their XO inhibitory activity. Fifteen chalcone derivatives were synthesized by Claisen-Schmidt condensation, and were evaluated for XO inhibitory activity. Nine out of 15 synthetic chalcones showed inhibitory activity ( 3 ; 5 - 8 ; 10 - 13 ). Sappanchalcone derivatives ( 11 ) (IC 50 , 2.5 μM) and a novel chalcone ( 13 ) (IC 50 , 2.4 μM) displayed strong xanthine oxidase inhibitory activity that is comparable to allopurinol (IC 50 , 2.5 μM). The structure-activity relationship of these chalcone derivatives was also presented. It is the first research on synthesis sappanchalcone ( 7 ) by Claisen-Schmidt condensation. The overall yield of this procedure was 6.6 %, higher than that of reported procedure (4 %). Design, synthesis, and evaluation of chalcone derivatives were carried out. This result suggests that the chalcone derivative can be used as potential non-purine XO inhibitors.Graphical abstractThe chalcone derivatives as potential non-purine xanthine oxidase inhibitors.

Single-molecule Analysis of Inhibitory Pausing States of V1-ATPase*

PubMed Central

Uner, Naciye Esma; Nishikawa, Yoshihiro; Okuno, Daichi; Nakano, Masahiro; Yokoyama, Ken; Noji, Hiroyuki

2012-01-01

V1-ATPase, the hydrophilic V-ATPase domain, is a rotary motor fueled by ATP hydrolysis. Here, we found that Thermus thermophilus V1-ATPase shows two types of inhibitory pauses interrupting continuous rotation: a short pause (SP, 4.2 s) that occurred frequently during rotation, and a long inhibitory pause (LP, >30 min) that terminated all active rotations. Both pauses occurred at the same angle for ATP binding and hydrolysis. Kinetic analysis revealed that the time constants of inactivation into and activation from the SP were too short to represent biochemically predicted ADP inhibition, suggesting that SP is a newly identified inhibitory state of V1-ATPase. The time constant of inactivation into LP was 17 min, consistent with one of the two time constants governing the inactivation process observed in bulk ATPase assay. When forcibly rotated in the forward direction, V1 in LP resumed active rotation. Solution ADP suppressed the probability of mechanical activation, suggesting that mechanical rotation enhanced inhibitory ADP release. These features were highly consistent with mechanical activation of ADP-inhibited F1, suggesting that LP represents the ADP-inhibited state of V1-ATPase. Mechanical activation largely depended on the direction and angular displacement of forced rotation, implying that V1-ATPase rotation modulates the off rate of ADP. PMID:22736762

Chemical constituents and their acetyl cholinesterase inhibitory and antioxidant activities from leaves of Acanthopanax henryi: potential complementary source against Alzheimer's disease.

PubMed

Zhang, Xiao Dan; Liu, Xiang Qian; Kim, Yang Hee; Whang, Wan Kyunn

2014-05-01

The aim of this study was to investigate chemical constituents of the leaves of Acanthopanax henryi, and their antioxidant, acetyl cholinesterase inhibitory activities. Caffeoyl quinic acid derivates and flavonoids were obtained from A. henry, through column chromatography technologies, and the content of major constituents was determined by the HPLC-UV method. Anti-oxidant activity of the isolated metabolites was evaluated by free radical scavenging (DPPH, ABTS radicals) and superoxide anion scavenging. The results showed that di-caffeoyl quinic acid derivates had stronger antioxidant activity than positive controls (ascorbic acid, trolox and allopurinol). Acetyl cholinesterase inhibitory activity was estimated on the constituents, among which, quercetin, 4-caffeoyl-quinic acid and 4,5-caffeoyl quinic acid were found to have strong acetyl cholinesterase inhibitory activity with IC50 values ranging from 62.6 to 121.9 μM. The present study showed that some of the tested constituents from the leaves of A. henryi exhibit strong antioxidant and acetyl cholinesterase inhibitory effects. This suggest that the leaves of A. henryi can be used as a new natural complementary source of acetyl cholinesterase inhibitors and anti-oxidant agents, thus being a promising potential complementary source against Alzheimer's disease.

Stabilized sulfur binding using activated fillers

DOEpatents

Kalb, Paul D.; Vagin, Vyacheslav P.; Vagin, Sergey P.

2015-07-21

A method of making a stable, sulfur binding composite comprising impregnating a solid aggregate with an organic modifier comprising unsaturated hydrocarbons with at least one double or triple covalent bond between adjacent carbon atoms to create a modifier-impregnated aggregate; heating and drying the modifier-impregnated aggregate to activate the surface of the modifier-impregnated aggregate for reaction with sulfur.

Lactoferricin B-derived peptides with inhibitory effects on ECE-dependent vasoconstriction.

PubMed

Fernández-Musoles, Ricardo; López-Díez, José Javier; Torregrosa, Germán; Vallés, Salvador; Alborch, Enrique; Manzanares, Paloma; Salom, Juan B

2010-10-01

Endothelin-converting enzyme (ECE), a key peptidase in the endothelin (ET) system, cleaves inactive big ET-1 to produce active ET-1, which binds to ET(A) receptors to exert its vasoconstrictor and pressor effects. ECE inhibition could be beneficial in the treatment of hypertension. In this study, a set of eight lactoferricin B (LfcinB)-derived peptides, previously characterized in our laboratory as angiotensin-converting enzyme (ACE) inhibitory peptides, was examined for their inhibitory effects on ECE. In vitro inhibitory effects on ECE activity were assessed using both the synthetic fluorogenic peptide substrate V (FPS V) and the natural substrate big ET-1. To study vasoactive effects, an ex vivo functional assay was developed using isolated rabbit carotid artery segments. With FPS V, only four LfcinB-derived peptides induced inhibition of ECE activity, whereas the eight peptides showed ECE inhibitory effects with big ET-1 as substrate. Regarding the ex vivo assays, six LfcinB-derived peptides showed inhibition of big ET-1-induced, ECE-dependent vasoconstriction. A positive correlation between the inhibitory effects of LfcinB-derived peptides on ECE activity when using big ET-1 and the inhibitory effects on ECE-dependent vasoconstriction was shown. ECE-independent vasoconstriction induced by ET-1 was not affected, thus discarding effects of LfcinB-derived peptides on ET(A) receptors or intracellular signal transduction mechanisms. In conclusion, a combined in vitro and ex vivo method to assess the effects of potentially antihypertensive peptides on the ET system has been developed and applied to show the inhibitory effects on ECE-dependent vasoconstriction of six LfcinB-derived peptides, five of which were dual vasopeptidase (ACE/ECE) inhibitors. Copyright © 2010 Elsevier Inc. All rights reserved.

ACE Inhibitory and Antioxidant Activities of Collagen Hydrolysates from the Ribbon Jellyfish (Chrysaora sp.)

PubMed Central

Latiff, Aishah Abd; Gan, Chee-Yuen; Abedin, Md. Zainul; Alias, Abd Karim

2014-01-01

Summary Collagen isolated from the ribbon jellyfish (Chrysaora sp.) was hydrolysed using three different proteases (i.e. trypsin, alcalase and Protamex) to obtain bioactive peptides. Angiotensin-I-converting enzyme (ACE) inhibitory activity and antioxidant activities (i.e. ferric reducing antioxidant power (FRAP) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity) of the peptides were measured and compared, and the effect of the duration of hydrolysis on the bioactivity (ACE inhibitory and antioxidant activities) of peptides was also evaluated. FRAP activity was the highest in Protamex-induced (25–27 mM) and trypsin-induced hydrolysates (24–26 mM) at 7 and 9 h, respectively. Conversely, hydrolysates produced by trypsin for 1 and 3 h showed the highest DPPH radical scavenging activities (94 and 92%, respectively). Trypsin-induced hydrolysates (at 3 h) also showed the highest ACE inhibitory activity (89%). The peptide sequences with the highest activities were identified using tandem mass spectrometry, and the results show that the hydrolysates had a high content of hydrophobic amino acids as well as unique amino acid sequences, which likely contribute to their biological activities. PMID:27904323

Bioactivity-guided isolation of polyacetylenes with inhibitory activity against NO production in LPS-activated RAW264.7 macrophages from the rhizomes of Atractylodes macrocephala.

PubMed

Yao, Chun-Mei; Yang, Xiu-Wei

2014-02-03

The rhizome of Atractylodes macrocephala (Compositae) is one of the most well-known traditional Chinese medicine in China, Japan and Korea, which has a long history of use for the treatment of splenic asthenia, edema, anorexia, and excessive perspiration, etc. As active compounds of anti-inflammatory activity of this medicinal plant have not been fully elucidated, the aim of this study was to isolate and identify the active constituents inhibiting nitric oxide (NO) production from the rhizomes of A. macrocephala. Inhibitory activity against NO production in lipopolysaccharide-activated RAW264.7 macrophages was evaluated by Griess reaction. Fifteen polyacetylenes were isolated from the active ethyl acetate extract using activity-guided screening. The structures of all compounds were elucidated by spectroscopic methods and comparison with published data. The compounds were further tested for their inhibitory activity against NO production. Seven new polyacetylenes, named atractylodemaynes A-G (1-7), along with eight known ones (8-15) were isolated. Compound 14 was isolated for the first time from the rhizomes of A. macrocephala. The study showed that the tested compounds exhibited inhibitory activity against NO production in a dose-dependent manner. Among them, compounds 10, 11 and 12 had relatively stronger inhibitory effect with IC50 values of 28, 23 and 19μM, respectively. The results demonstrated that the polyacetylenes might greatly contribute to the anti-inflammatory activity of the rhizomes of A. macrocephala. © 2013 Elsevier Ireland Ltd. All rights reserved.

Passive participation of fixed platelets in aggregation facilitated by covalently bound fibrinogen.

PubMed

Agam, G; Livne, A

1983-01-01

The role of fibrinogen in interplatelet recognition during aggregation was examined by combining two cell types: fresh platelets (in limiting density) activated by thrombin or A23187, and formaldehyde-fixed platelets, bearing cross-linked fibrinogen. The fixed platelets did not aggregate by themselves, nor with resting platelets, but were capable of interacting with activated platelets and of participating passively in aggregation. The participation, expressed by enhanced aggregation, was assayed by the conventional turbidometric traces and by cosedimentation of fixed 3H-platelets with aggregates of fresh platelets. Platelet suspensions, prepared without special means to avert spontaneous activation, retained plasma fibrinogen to the extent of 50 micrograms/ml of a suspension containing 10(8) platelets, and the derived fixed platelets participated in aggregation, independently of added fibrinogen. The capability of such fixed platelets to participate in aggregation was sensitive to proteolytic digestion and to massive acetylation. When platelet separation was aided by apyrase or aspirin, PGE1 and gel filtration, the residual plasma fibrinogen was limited to 0.4 micrograms/ml of 10(8) platelet suspension. The derived fixed platelets were incapable of participating in aggregation unless fibrinogen was added prior to fixation. The affixed fibrinogen could not be replaced by soluble fibrinogen or affixed albumin. It is concluded that fibrinogen, which binds to platelets upon activation or is linked to them covalently, is a recognition site for platelet-platelet interaction during aggregation.

Virus-cell fusion inhibitory activity of novel analogue peptides based on the HP (2-20) derived from N-terminus of Helicobacter pylori Ribosomal Protein L1.

PubMed

Woo, Eun-Rhan; Lee, Dong Gun; Chang, Young-Su; Park, Yoonkyung; Hahm, Kyung-Soo

2002-12-01

HP (2-20) (AKKVFKRLEKLFSKIQNDK) is the antibacterial sequence derived from N-terminus of Helicobacter pylori Ribosomal Protein L1 (RPL1). It has a broad-spectrum microbicidal activity in vitro that is thought to be related to the membrane-disruptive properties of the peptide. Based on the putative membrane-targeted mode of action, we postulated that HP (2-20) might be possessed virus-cell fusion inhibitory activity. To develop the novel virus-cell fusion inhibitory peptides, several analogues with amino acid substitution were designed to increase or decrease only net hydrophobic region. In particular, substitution of Gln and Asp for hydrophobic amino acid, Trp at position 17 and 19 of HP (2-20) (Anal 3) caused a dramatic increase in virus-cell fusion inhibitory activity without hemolytic effect.

Synthesis, crystal structures, fluorescence and xanthine oxidase inhibitory activity of pyrazole-based 1,3,4-oxadiazole derivatives

NASA Astrophysics Data System (ADS)

Qi, De-Qiang; Yu, Chuan-Ming; You, Jin-Zong; Yang, Guang-Hui; Wang, Xue-Jie; Zhang, Yi-Ping

2015-11-01

A series of pyrazole-based 1,3,4-oxadiazole derivatives were rationally designed and synthesized in good yields by following a convenient route. All the newly synthesized molecules were fully characterized by IR, 1H NMR and elemental analysis. Eight compounds were structurally determined by single crystal X-ray diffraction analysis. The fluorescence properties of all the compounds were investigated in dimethyl sulfoxide media. In addition, these newly synthesized compounds were evaluated for in vitro inhibitory activity against commercial enzyme xanthine oxidase (XO) by measuring the formation of uric acid from xanthine. Among the compounds synthesized and tested, 3d and 3e were found to be moderate inhibitory activity against commercial XO with IC50 = 72.4 μM and 75.6 μM. The studies gave a new insight in further optimization of pyrazole-based 1,3,4-oxadiazole derivatives with excellent fluorescence properties and XO inhibitory activity.

Antitubercular activity and inhibitory effect on Epstein-Barr virus activation of sterols and polyisoprenepolyols from an edible mushroom, Hypsizigus marmoreus.

PubMed

Akihisa, Toshihiro; Franzblau, Scott Gary; Tokuda, Harukuni; Tagata, Masaaki; Ukiya, Motohiko; Matsuzawa, Tsunetomo; Metori, Koichi; Kimura, Yumiko; Suzuki, Takashi; Yasukawa, Ken

2005-06-01

Seven sterols (1-7) and eight polyisoprenepolyols (8-15), isolated from the non-saponifiable lipid fraction of the dichloromethane extract of an edible mushroom, Hypsizigus marmoreus (Buna-shimeji), were tested for their antitubercular activity against Mycobacterium tuberculosis strain H37Rv using the Microplate Alamar Blue Assay (MABA). Six sterols (2-7) and two polyisoprenepolyols (8, 12) showed a minimum inhibitory concentration (MIC) in the range of 1-51 microg/ml, while the others (1, 9-11, 13-15) were inactive (MIC>128 microg/ml). The seven sterols (1-7) and three polyisoprenepolyols (8, 10, 12) were further evaluated for their inhibitory effects on Epstein-Barr virus early antigen (EBV-EA) activation induced by the tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA) in Raji cells. Sterols 6 and 7 showed potent inhibitory effects while preserving the high viability of Raji cells.

Ionic liquid mediated synthesis and molecular docking study of novel aromatic embedded Schiff bases as potent cholinesterase inhibitors.

PubMed

Abd Razik, Basma M; Osman, Hasnah; Basiri, Alireza; Salhin, Abdussalam; Kia, Yalda; Ezzat, Mohammed Oday; Murugaiyah, Vikneswaran

2014-12-01

Novel aromatic embedded Schiff bases have been synthesized in ionic liquid [bmim]Br and evaluated in vitro for their acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) enzymes inhibitory activities. Among the newly synthesized compounds, 5f, 5h and 7j displayed higher AChE enzyme inhibitory activities than standard drug, galanthamine, with IC50 values of 1.88, 2.05 and 2.03μM, respectively. Interestingly, all the compounds except for compound 5c displayed higher BChE inhibitories than standard with IC50 values ranging from 3.49 to 19.86μM. Molecular docking analysis for 5f and 7j possessing the most potent AChE and BChE inhibitory activities, disclosed their binding interaction templates to the active site of AChE and BChE enzymes, respectively. Copyright © 2014 Elsevier Inc. All rights reserved.

Dipeptidyl peptidase-IV inhibitory activity of dimeric dihydrochalcone glycosides from flowers of Helichrysum arenarium.

PubMed

Morikawa, Toshio; Ninomiya, Kiyofumi; Akaki, Junji; Kakihara, Namiko; Kuramoto, Hiroyuki; Matsumoto, Yurie; Hayakawa, Takao; Muraoka, Osamu; Wang, Li-Bo; Wu, Li-Jun; Nakamura, Seikou; Yoshikawa, Masayuki; Matsuda, Hisashi

2015-10-01

A methanol extract of everlasting flowers of Helichrysum arenarium L. Moench (Asteraceae) was found to inhibit the increase in blood glucose elevation in sucrose-loaded mice at 500 mg/kg p.o. The methanol extract also inhibited the enzymatic activity against dipeptidyl peptidase-IV (DPP-IV, IC50 = 41.2 μg/ml), but did not show intestinal α-glucosidase inhibitory activities. From the extract, three new dimeric dihydrochalcone glycosides, arenariumosides V-VII (2-4), were isolated, and the stereostructures were elucidated based on their spectroscopic properties and chemical evidence. Of the constituents, several flavonoid constituents, including 2-4, were isolated, and these isolated constituents were investigated for their DPP-IV inhibitory effects. Among them, chalconaringenin 2'-O-β-D-glucopyranoside (16, IC50 = 23.1 μM) and aureusidin 6-O-β-D-glucopyranoside (35, 24.3 μM) showed relatively strong inhibitory activities.

Influence of baking enzymes on antimicrobial activity of five bacteriocin-like inhibitory substances produced by lactic acid bacteria isolated from Lithuanian sourdoughs.

PubMed

Narbutaite, V; Fernandez, A; Horn, N; Juodeikiene, G; Narbad, A

2008-12-01

To evaluate the effect of four different baking enzymes on the inhibitory activity of five bacteriocin-like inhibitory substances (BLIS) produced by lactic acid bacteria (LAB) isolated from Lithuanian sourdoughs. The overlay assay and the Bioscreen methods revealed that the five BLIS exhibited an inhibitory effect against spore germination and vegetative outgrowth of Bacillus subtilis, the predominant species causing ropiness in bread. The possibility that the observed antibacterial activity of BLIS might be lost after treatment with enzymes used for baking purposes was also examined. The enzymes tested; hemicellulase, lipase, amyloglucosidase and amylase had little or no effect on the majority of the antimicrobial activities associated with the five BLIS studied. This study suggests a potential application in the sourdough baking industry for these antimicrobial producing LAB strains in the control of B. subtilis spore germination and vegetative outgrowth.

Partial purification and characterization of cysteine proteinase inhibitor from chicken plasma.

PubMed

Rawdkuen, Saroat; Benjakul, Soottawat; Visessanguan, Wonnop; Lanier, Tyre C

2006-08-01

A high-molecular-weight cysteine proteinase inhibitor (CPI) was purified from chicken (Gallus gallus) plasma using polyethylene glycol (PEG) fractionation and affinity chromatography on carboxymethyl-papain-Sepharose-4B. The CPI was purified 96.8-fold with a yield of 28.9%. Based on inhibitory activity staining for papain, CPI was shown to have an apparent molecular mass of 122 kDa. No inhibitory activity was obtained under reducing condition, indicating that CPI from chicken plasma was stabilized by disulfide bonds. CPI was stable in temperature ranges from 40 to 70 degrees C for 10 min; however, more than 50% of the inhibitory activity towards papain was lost within 30 min of heating at 90 degrees C. CPI was stable in the presence of salt up to 3%. The purified CPI exhibited the inhibitory activity toward autolysis of arrowtooth flounder (Atheresthes stomias) and Pacific whiting (Merluccius productus) natural actomyosin (NAM) in a concentration-dependent manner.

Cell Assembly Dynamics of Sparsely-Connected Inhibitory Networks: A Simple Model for the Collective Activity of Striatal Projection Neurons.

PubMed

Angulo-Garcia, David; Berke, Joshua D; Torcini, Alessandro

2016-02-01

Striatal projection neurons form a sparsely-connected inhibitory network, and this arrangement may be essential for the appropriate temporal organization of behavior. Here we show that a simplified, sparse inhibitory network of Leaky-Integrate-and-Fire neurons can reproduce some key features of striatal population activity, as observed in brain slices. In particular we develop a new metric to determine the conditions under which sparse inhibitory networks form anti-correlated cell assemblies with time-varying activity of individual cells. We find that under these conditions the network displays an input-specific sequence of cell assembly switching, that effectively discriminates similar inputs. Our results support the proposal that GABAergic connections between striatal projection neurons allow stimulus-selective, temporally-extended sequential activation of cell assemblies. Furthermore, we help to show how altered intrastriatal GABAergic signaling may produce aberrant network-level information processing in disorders such as Parkinson's and Huntington's diseases.

Cholinesterase inhibitory triterpenoids from the bark of Garcinia hombroniana.

PubMed

Jamila, Nargis; Khairuddean, Melati; Yeong, Khaw Kooi; Osman, Hasnah; Murugaiyah, Vikneswaran

2015-02-01

Context: Garcinia hombroniana Pierre, known as manggis hutan in Malaysia is a rich source of xanthones and benzophenones. This study was aimed to isolate and characterize potential cholinesterase inhibitors from the extracts of G. hombroniana bark and investigate their interactions with the enzymes. The dichloromethane extract afforded five triterpenoids which were characterized by NMR and mass spectral techniques. Cholinesterase inhibitory assay and molecular docking were performed to get insight of the inhibitory activity and molecular interactions of the compounds. The compounds were also tested for their antioxidant capacity. The isolated triterpenoids were identified as: 2β-hydroxy-3α-O-caffeoyltaraxar-14-en-28-oic acid (1), taraxerol (2), taraxerone (3), betulin (4) and betulinic acid (5). Compound 1 was the most active dual inhibitor of both AChE and BChE. Compound 1 also showed good antioxidant activities. Compound 1 had dual and moderate inhibitory activity on AChE and BChE worthy for further investigations.

Fear extinction causes target-specific remodeling of perisomatic inhibitory synapses

PubMed Central

Trouche, Stéphanie; Sasaki, Jennifer M.; Tu, Tiffany; Reijmers, Leon G.

2013-01-01

SUMMARY A more complete understanding of how fear extinction alters neuronal activity and connectivity within fear circuits may aid in the development of strategies to treat human fear disorders. Using a c-fos based transgenic mouse, we found that contextual fear extinction silenced basal amygdala (BA) excitatory neurons that had been previously activated during fear conditioning. We hypothesized that the silencing of BA fear neurons was caused by an action of extinction on BA inhibitory synapses. In support of this hypothesis, we found extinction-induced target-specific remodeling of BA perisomatic inhibitory synapses originating from parvalbumin and cholecystokinin-positive interneurons. Interestingly, the predicted changes in the balance of perisomatic inhibition matched the silent and active states of the target BA fear neurons. These observations suggest that target-specific changes in perisomatic inhibitory synapses represent a mechanism through which experience can sculpt the activation patterns within a neural circuit. PMID:24183705

Fear extinction causes target-specific remodeling of perisomatic inhibitory synapses.

PubMed

Trouche, Stéphanie; Sasaki, Jennifer M; Tu, Tiffany; Reijmers, Leon G

2013-11-20

A more complete understanding of how fear extinction alters neuronal activity and connectivity within fear circuits may aid in the development of strategies to treat human fear disorders. Using a c-fos-based transgenic mouse, we found that contextual fear extinction silenced basal amygdala (BA) excitatory neurons that had been previously activated during fear conditioning. We hypothesized that the silencing of BA fear neurons was caused by an action of extinction on BA inhibitory synapses. In support of this hypothesis, we found extinction-induced target-specific remodeling of BA perisomatic inhibitory synapses originating from parvalbumin and cholecystokinin-positive interneurons. Interestingly, the predicted changes in the balance of perisomatic inhibition matched the silent and active states of the target BA fear neurons. These observations suggest that target-specific changes in perisomatic inhibitory synapses represent a mechanism through which experience can sculpt the activation patterns within a neural circuit. Copyright © 2013 Elsevier Inc. All rights reserved.

Antibodies to Polymorphic Invasion-Inhibitory and Non-Inhibitory Epitopes of Plasmodium falciparum Apical Membrane Antigen 1 in Human Malaria

PubMed Central

Mugyenyi, Cleopatra K.; Elliott, Salenna R.; McCallum, Fiona J.; Anders, Robin F.; Marsh, Kevin; Beeson, James G.

2013-01-01

Background Antibodies to P. falciparum apical membrane protein 1 (AMA1) may contribute to protective immunity against clinical malaria by inhibiting blood stage growth of P. falciparum, and AMA1 is a leading malaria vaccine candidate. Currently, there is limited knowledge of the acquisition of strain-specific and cross-reactive antibodies to AMA1 in humans, or the acquisition of invasion-inhibitory antibodies to AMA1. Methodology/Findings We examined the acquisition of human antibodies to specific polymorphic invasion-inhibitory and non-inhibitory AMA1 epitopes, defined by the monoclonal antibodies 1F9 and 2C5, respectively. Naturally acquired antibodies were measured in cohorts of Kenyan children and adults. Antibodies to the invasion-inhibitory 1F9 epitope and non-inhibitory 2C5 epitope were measured indirectly by competition ELISA. Antibodies to the 1F9 and 2C5 epitopes were acquired by children and correlated with exposure, and higher antibody levels and prevalence were observed with increasing age and with active P. falciparum infection. Of note, the prevalence of antibodies to the inhibitory 1F9 epitope was lower than antibodies to AMA1 or the 2C5 epitope. Antibodies to AMA1 ectodomain, the 1F9 or 2C5 epitopes, or a combination of responses, showed some association with protection from P. falciparum malaria in a prospective longitudinal study. Furthermore, antibodies to the invasion-inhibitory 1F9 epitope were positively correlated with parasite growth-inhibitory activity of serum antibodies. Conclusions/Significance Individuals acquire antibodies to functional, polymorphic epitopes of AMA1 that may contribute to protective immunity, and these findings have implications for AMA1 vaccine development. Measuring antibodies to the 1F9 epitope by competition ELISA may be a valuable approach to assessing human antibodies with invasion-inhibitory activity in studies of acquired immunity and vaccine trials of AMA1. PMID:23861883

Effects of chlorpyrifos on soil carboxylesterase activity at an aggregate-size scale.

PubMed

Sanchez-Hernandez, Juan C; Sandoval, Marco

2017-08-01

The impact of pesticides on extracellular enzyme activity has been mostly studied on the bulk soil scale, and our understanding of the impact on an aggregate-size scale remains limited. Because microbial processes, and their extracellular enzyme production, are dependent on the size of soil aggregates, we hypothesized that the effect of pesticides on enzyme activities is aggregate-size specific. We performed three experiments using an Andisol to test the interaction between carboxylesterase (CbE) activity and the organophosphorus (OP) chlorpyrifos. First, we compared esterase activity among aggregates of different size spiked with chlorpyrifos (10mgkg -1 wet soil). Next, we examined the inhibition of CbE activity by chlorpyrifos and its metabolite chlorpyrifos-oxon in vitro to explore the aggregate size-dependent affinity of the pesticides for the active site of the enzyme. Lastly, we assessed the capability of CbEs to alleviate chlorpyrifos toxicity upon soil microorganisms. Our principal findings were: 1) CbE activity was significantly inhibited (30-67% of controls) in the microaggregates (<0.25mm size) and smallest macroaggregates (<1.0 - 0.25mm), but did not change in the largest macroaggregates (>1.0mm) compared with the corresponding controls (i.e., pesticide-free aggregates), 2) chlorpyrifos-oxon was a more potent CbE inhibitor than chlorpyrifos; however, no significant differences in the CbE inhibition were found between micro- and macroaggregates, and 3) dose-response relationships between CbE activity and chlorpyrifos concentrations revealed the capability of the enzyme to bind chlorpyrifos-oxon, which was dependent on the time of exposure. This chemical interaction resulted in a safeguarding mechanism against chlorpyrifos-oxon toxicity on soil microbial activity, as evidenced by the unchanged activity of dehydrogenase and related extracellular enzymes in the pesticide-treated aggregates. Taken together, these results suggest that environmental risk assessments of OP-polluted soils should consider the fractionation of soil in aggregates of different size to measure the CbE activity, and other potential soil enzyme activities. Copyright © 2017 Elsevier Inc. All rights reserved.

Structural investigation of protein kinase C inhibitors

NASA Technical Reports Server (NTRS)

Barak, D.; Shibata, M.; Rein, R.

1991-01-01

The phospholipid and Ca2+ dependent protein kinase (PKC) plays an essential role in a variety of cellular events. Inhibition of PKC was shown to arrest growth in tumor cell cultures making it a target for possible antitumor therapy. Calphostins are potent inhibitors of PKC with high affinity for the enzyme regulatory site. Structural characteristics of calphostins, which confer the inhibitory activity, are investigated by comparing their optimized structures with the existing models for PKC activation. The resulting model of inhibitory activity assumes interaction with two out of the three electrostatic interaction sites postulated for activators. The model shows two sites of hydrophobic interaction and enables the inhibitory activity of gossypol to be accounted for.

Inhibitory ryanodine prevents ryanodine receptor-mediated Ca²⁺ release without affecting endoplasmic reticulum Ca²⁺ content in primary hippocampal neurons.

PubMed

Adasme, Tatiana; Paula-Lima, Andrea; Hidalgo, Cecilia

2015-02-27

Ryanodine is a cell permeant plant alkaloid that binds selectively and with high affinity to ryanodine receptor (RyR) Ca(2+) release channels. Sub-micromolar ryanodine concentrations activate RyR channels while micromolar concentrations are inhibitory. Several reports indicate that neuronal synaptic plasticity, learning and memory require RyR-mediated Ca(2+)-release, which is essential for muscle contraction. The use of micromolar (inhibitory) ryanodine represents a common strategy to suppress RyR activity in neuronal cells: however, micromolar ryanodine promotes RyR-mediated Ca(2+) release and endoplasmic reticulum Ca(2+) depletion in muscle cells. Information is lacking in this regard in neuronal cells; hence, we examined here if addition of inhibitory ryanodine elicited Ca(2+) release in primary hippocampal neurons, and if prolonged incubation of primary hippocampal cultures with inhibitory ryanodine affected neuronal ER calcium content. Our results indicate that inhibitory ryanodine does not cause Ca(2+) release from the ER in primary hippocampal neurons, even though ryanodine diffusion should produce initially low intracellular concentrations, within the RyR activation range. Moreover, neurons treated for 1 h with inhibitory ryanodine had comparable Ca(2+) levels as control neurons. These combined findings imply that prolonged incubation with inhibitory ryanodine, which effectively abolishes RyR-mediated Ca(2+) release, preserves ER Ca(2+) levels and thus constitutes a sound strategy to suppress neuronal RyR function. Copyright © 2015 Elsevier Inc. All rights reserved.

Purification of angiotensin I-converting enzyme (ACE) inhibitory peptides from casein hydrolysate by IMAC-Ni2.

PubMed

Wu, Shanguang; Feng, Xuezhen; Lu, Yuan; Lu, Yuting; Liu, Saisai; Tian, Yuhong

2017-10-01

Casein proteins were hydrolyzed by papain to identify inhibitory peptides of angiotensin I-converting enzyme (ACE). The hydrolysate was fractionized by immobilized metal affinity chromatography (IMAC-Ni 2+ ). The fraction with high ACE inhibitory activity was enriched and further chromatographed on a reverse-phase column to yield four fractions. Among the fractions, the L4 fraction exhibited the highest ACE inhibitory activity and was identified by sequence analysis as Trp-Tyr-Leu-His-Tyr-Ala (WYLHYA), with IC 50 value of 16.22 ± 0.83 µM in vitro. This peptide was expected to be applied as an ingredient for preventing hypertension and IMAC-Ni 2+ may provide a simple method for purification of ACE inhibitory peptides.

Inhibitory potential of Grifola frondosa bioactive fractions on α-amylase and α-glucosidase for management of hyperglycemia.

PubMed

Su, Chun-Han; Lu, Tzy-Ming; Lai, Min-Nan; Ng, Lean-Teik

2013-01-01

This study examined the inhibitory effects of Grifola frondosa (GF), a medicinal mushroom popularly consumed in traditional medicine and health food, on digestive enzymes related to type 2 diabetes; chemical profiles and inhibitory kinetics of its bioactive fractions were also analyzed. Results showed that all GF extracts showed weak anti-α-amylase activity; however, strong anti-α-glucosidase activity was noted on GF n-hexane extract (GF-H). Further fractionation confirmed that compared with acarbose (a commercial α-glucosidase inhibitor), the nonpolar fraction of GF possessed a stronger anti-α-glucosidase activity but a weaker anti-α-amylase activity. These activities were not derived from ergosterol and ergosterol peroxide, two major compounds of this fraction. The inhibitory kinetics of GF-H on α-glucosidase was competitive inhibition. GF-H was as good as acarbose in inhibiting the starch digestion in vitro. Oleic acid and linoleic acid could be the major active constituents that have contributed to the potency of GF in inhibiting α-glucosidase activity. © 2013 International Union of Biochemistry and Molecular Biology, Inc.

Cytochrome P450-inhibitory activity of parabens and phthalates used in consumer products.

PubMed

Ozaki, Hitomi; Sugihara, Kazumi; Watanabe, Yoko; Ohta, Shigeru; Kitamura, Shigeyuki

2016-01-01

The in vitro cytochrome P450 (CYP)-inhibitory effects of 11 parabens and 7 phthalates used in consumer products, as well as their hydrolytic metabolites, were investigated, using rat liver microsomes as an enzyme source. The effects on individual CYP isozymes were evaluated by assaying inhibition of activities towards specific substrates, i.e., ethoxyresorufin O-dealkylase (EROD), methoxyresorufin O-dealkylase (MROD), pentoxyresorufin O-dealkylase (PROD), 7-benzyloxy-4-trifluoromethylcoumarin dealkylase (BFCD), 7-methoxy-4-trifluoromethylcoumarin dealkylase (MFCD) and 7-ethoxy-4-trifluoromethylcoumarin dealkylase (EFCD) activities. These activities were dose-dependently inhibited, most potently by medium-side-chain parabens (C6-9) and phthalates (C4-6), and less potently by shorter- and longer-side-chain esters. The hydrolytic product of parabens, 4-hydroxybenzoic acid, was not inhibitory, while those of phthalates, phthalic acid monoesters, showed lower inhibitory activity than the parent phthalates. Parabens showed relatively potent inhibition of MFCD activity, considered to be mainly due to CYP2C, and phthalates showed relatively potent inhibition of PROD activity, considered to be mainly due to CYP2B.

Inhibitory effect of burdock leaves on elastase and tyrosinase activity.

PubMed

Horng, Chi-Ting; Wu, Hsing-Chen; Chiang, Ni-Na; Lee, Chiu-Fang; Huang, Yu-Syuan; Wang, Hui-Yun; Yang, Jai-Sing; Chen, Fu-An

2017-10-01

Burdock ( Arctium lappa L.) leaves generate a considerable amount of waste following burdock root harvest in Taiwan. To increase the use of burdock leaves, the present study investigated the optimal methods for producing burdock leaf extract (BLE) with high antioxidant polyphenolic content, including drying methods and solvent extraction concentration. In addition, the elastase and tyrosinase inhibitory activity of BLE was examined. Burdock leaves were dried by four methods: Shadow drying, oven drying, sun drying and freeze-drying. The extract solution was then subjected to total polyphenol content analysis and the method that produced BLE with the highest amount of total antioxidant components was taken forward for further analysis. The 1,1-diphenyl-2-pycrylhydrazyl scavenging, antielastase and antityrosinase activity of the BLE were measured to enable the evaluation of the antioxidant and skin aging-associated enzyme inhibitory activities of BLE. The results indicated that the total polyphenolic content following extraction with ethanol (EtOH) was highest using the freeze-drying method, followed by the oven drying, shadow drying and sun drying methods. BLE yielded a higher polyphenol content and stronger antioxidant activity as the ratio of the aqueous content of the extraction solvent used increased. BLE possesses marked tyrosinase and elastase inhibitory activities, with its antielastase activity notably stronger compared with its antityrosinase activity. These results indicate that the concentration of the extraction solvent was associated with the antioxidant and skin aging-associated enzyme inhibitory activity of BLE. The reactive oxygen species scavenging theory of skin aging may explain the tyrosinase and elastase inhibitory activity of BLE. In conclusion, the optimal method for obtaining BLE with a high antioxidant polyphenolic content was freeze-drying followed by 30-50% EtOH extraction. In addition, the antielastase and antityrosinase activities of the BLE produced may be aid in the development of skincare products with antiwrinkle and skin-evening properties.

Inhibitory effect of burdock leaves on elastase and tyrosinase activity

PubMed Central

Horng, Chi-Ting; Wu, Hsing-Chen; Chiang, Ni-Na; Lee, Chiu-Fang; Huang, Yu-Syuan; Wang, Hui-Yun; Yang, Jai-Sing; Chen, Fu-An

2017-01-01

Burdock (Arctium lappa L.) leaves generate a considerable amount of waste following burdock root harvest in Taiwan. To increase the use of burdock leaves, the present study investigated the optimal methods for producing burdock leaf extract (BLE) with high antioxidant polyphenolic content, including drying methods and solvent extraction concentration. In addition, the elastase and tyrosinase inhibitory activity of BLE was examined. Burdock leaves were dried by four methods: Shadow drying, oven drying, sun drying and freeze-drying. The extract solution was then subjected to total polyphenol content analysis and the method that produced BLE with the highest amount of total antioxidant components was taken forward for further analysis. The 1,1-diphenyl-2-pycrylhydrazyl scavenging, antielastase and antityrosinase activity of the BLE were measured to enable the evaluation of the antioxidant and skin aging-associated enzyme inhibitory activities of BLE. The results indicated that the total polyphenolic content following extraction with ethanol (EtOH) was highest using the freeze-drying method, followed by the oven drying, shadow drying and sun drying methods. BLE yielded a higher polyphenol content and stronger antioxidant activity as the ratio of the aqueous content of the extraction solvent used increased. BLE possesses marked tyrosinase and elastase inhibitory activities, with its antielastase activity notably stronger compared with its antityrosinase activity. These results indicate that the concentration of the extraction solvent was associated with the antioxidant and skin aging-associated enzyme inhibitory activity of BLE. The reactive oxygen species scavenging theory of skin aging may explain the tyrosinase and elastase inhibitory activity of BLE. In conclusion, the optimal method for obtaining BLE with a high antioxidant polyphenolic content was freeze-drying followed by 30–50% EtOH extraction. In addition, the antielastase and antityrosinase activities of the BLE produced may be aid in the development of skincare products with antiwrinkle and skin-evening properties. PMID:28912875

An inhibitory gate for state transition in cortex

PubMed Central

Zucca, Stefano; D’Urso, Giulia; Pasquale, Valentina; Vecchia, Dania; Pica, Giuseppe; Bovetti, Serena; Moretti, Claudio; Varani, Stefano; Molano-Mazón, Manuel; Chiappalone, Michela; Panzeri, Stefano; Fellin, Tommaso

2017-01-01

Large scale transitions between active (up) and silent (down) states during quiet wakefulness or NREM sleep regulate fundamental cortical functions and are known to involve both excitatory and inhibitory cells. However, if and how inhibition regulates these activity transitions is unclear. Using fluorescence-targeted electrophysiological recording and cell-specific optogenetic manipulation in both anesthetized and non-anesthetized mice, we found that two major classes of interneurons, the parvalbumin and the somatostatin positive cells, tightly control both up-to-down and down-to-up state transitions. Inhibitory regulation of state transition was observed under both natural and optogenetically-evoked conditions. Moreover, perturbative optogenetic experiments revealed that the inhibitory control of state transition was interneuron-type specific. Finally, local manipulation of small ensembles of interneurons affected cortical populations millimetres away from the modulated region. Together, these results demonstrate that inhibition potently gates transitions between cortical activity states, and reveal the cellular mechanisms by which local inhibitory microcircuits regulate state transitions at the mesoscale. DOI: http://dx.doi.org/10.7554/eLife.26177.001 PMID:28509666

Structure activity relationship modelling of milk protein-derived peptides with dipeptidyl peptidase IV (DPP-IV) inhibitory activity.

PubMed

Nongonierma, Alice B; FitzGerald, Richard J

2016-05-01

Quantitative structure activity type models were developed in an attempt to predict the key features of peptide sequences having dipeptidyl peptidase IV (DPP-IV) inhibitory activity. The models were then employed to help predict the potential of peptides, which are currently reported in the literature to be present in the intestinal tract of humans following milk/dairy product ingestion, to act as inhibitors of DPP-IV. Two models (z- and v-scale) for short (2-5 amino acid residues) bovine milk peptides, behaving as competitive inhibitors of DPP-IV, were developed. The z- and the v-scale models (p<0.05, R(2) of 0.829 and 0.815, respectively) were then applied to 56 milk protein-derived peptides previously reported in the literature to be found in the intestinal tract of humans which possessed a structural feature of DPP-IV inhibitory peptides (P at the N2 position). Ten of these peptides were synthetized and tested for their in vitro DPP-IV inhibitory properties. There was no agreement between the predicted and experimentally determined DPP-IV half maximal inhibitory concentrations (IC50) for the competitive peptide inhibitors. However, the ranking for DPP-IV inhibitory potency of the competitive peptide inhibitors was conserved. Furthermore, potent in vitro DPP-IV inhibitory activity was observed with two peptides, LPVPQ (IC50=43.8±8.8μM) and IPM (IC50=69.5±8.7μM). Peptides present within the gastrointestinal tract of human may have promise for the development of natural DPP-IV inhibitors for the management of serum glucose. Copyright © 2016 Elsevier Inc. All rights reserved.

γ-Aminobutyric Acid (GABA) Production and Angiotensin-I Converting Enzyme (ACE) Inhibitory Activity of Fermented Soybean Containing Sea Tangle by the Co-Culture of Lactobacillus brevis with Aspergillus oryzae.

PubMed

Jang, Eun Kyeong; Kim, Nam Yeun; Ahn, Hyung Jin; Ji, Geun Eog

2015-08-01

To enhance the γ-aminobutyric acid (GABA) content, the optimized fermentation of soybean with added sea tangle extract was evaluated at 30°C and pH 5.0. The medium was first inoculated with Aspergillus oryzae strain FMB S46471 and fermented for 3 days, followed by the subsequent inoculation with Lactobacillus brevis GABA 100. After fermentation for 7 days, the fermented soybean showed approximately 1.9 g/kg GABA and exhibited higher ACE inhibitory activity than the traditional soybean product. Furthermore, several peptides in the fraction containing the highest ACE inhibitory activity were identified. The novel fermented soybean enriched with GABA and ACE inhibitory components has great pharmaceutical and functional food values.

Design, synthesis of novel tryptophan derivatives for antiplatelet aggregation activity based on tripeptide pENW (pGlu-Asn-Trp).

PubMed

Xie, Zhouling; Feng, Sen; Wang, Ying; Cao, Chen; Huang, Jing; Chen, Yahui; Kong, Yi; Li, Zhiyu

2015-09-18

pENW, a three mer peptide derived from Agkistrodon acutus Guenther venom, has been found to be an antagonist of the GPIIb/IIIa receptor and shows antiplatelet aggregation activity. Based on pENW and a GPIIb/IIIa inhibitor Tirofiban, a series of tryptophan derivatives were designed, synthesized and evaluated for their antiplatelet aggregation activity induced by ADP. The most potent compound 87 was also tested for the bleeding time and antithrombotic activity in vivo in comparison with Tirofiban. The results indicated that 87 shows similar antiplatelet aggregation activity as Tirofiban to the aggregation of platelet induced by all of the four agonists, but has lower bleeding risk than Tirofiban, representing a promising lead compound for further study. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

Opposing Effects of Platelet-Activating Factor and Lyso-Platelet-Activating Factor on Neutrophil and Platelet ActivationS⃞

PubMed Central

Welch, Emily J.; Naikawadi, Ram P.; Li, Zhenyu; Lin, Phoebe; Ishii, Satoshi; Shimizu, Takao; Tiruppathi, Chinnaswamy; Du, Xiaoping; Subbaiah, Papasani V.; Ye, Richard D.

2009-01-01

Platelet-activating factor (PAF) is a potent, bioactive phospholipid that acts on multiple cells and tissues through its G protein-coupled receptor (GPCR). PAF is not stored but is rapidly generated via enzymatic acetylation of the precursor 1-O-hexadecyl-2-hydroxy-sn-glycero-3-phosphocholine (lysoPAF). The bioactivity of PAF is effectively and tightly regulated by PAF acetylhydrolases, which convert PAF back to lysoPAF. Previous studies report that lysoPAF is an inactive precursor and metabolite of PAF. However, lysoPAF has not been carefully studied in its own context. Here we report that lysoPAF has an opposing effect of PAF in the activation of neutrophils and platelets. Whereas PAF potentiates neutrophil NADPH oxidase activation, lysoPAF dose-dependently inhibits this function. Inhibition by lysoPAF is not affected by the use of a PAF receptor antagonist or genetic deletion of the PAF receptor gene. The mechanism of lysoPAF-mediated inhibition of neutrophils involves an elevation in the intracellular cAMP level, and pharmacological blockade of adenylyl cyclase completely reverses the inhibitory effect of lysoPAF. In addition, lysoPAF increases intracellular cAMP levels in platelets and inhibits thrombin-induced platelet aggregation, which can be reversed by inhibition of protein kinase A. These findings identify lysoPAF as a bioactive lipid with opposing functions of PAF and suggest a novel and intrinsic regulatory mechanism for balance of the potent activity of PAF. PMID:18931035

Determining the probiotic potential of cholesterol-reducing Lactobacillus and Weissella strains isolated from gherkins (fermented cucumber) and south Indian fermented koozh.

PubMed

Anandharaj, Marimuthu; Sivasankari, Balayogan; Santhanakaruppu, Rajendran; Manimaran, Muthusamy; Rani, Rizwana Parveen; Sivakumar, Subramaniyan

2015-06-01

This study sought to evaluate the probiotic potential of lactic acid bacteria (LAB) isolated from traditionally fermented south Indian koozh and gherkin (cucumber). A total of 51 LAB strains were isolated, among which four were identified as Lactobacillus spp. and three as Weissella spp. The strains were screened for their probiotic potential. All isolated Lactobacillus and Weissella strains were capable of surviving under low pH and bile salt conditions. GI9 and FKI21 were able to survive at pH 2.0 and 0.50% bile salt for 3 h without losing their viability. All LAB strains exhibited inhibitory activity against tested pathogens and were able to deconjugate bile salt. Higher deconjugation was observed in the presence of sodium glycocholate (P < 0.05). Strain FKI21 showed maximum auto-aggregation (79%) and co-aggregation with Escherichia coli MTCC 1089 (68%). Exopolysaccharide production of LAB strains ranged from 68.39 to 127.12 mg/L (P < 0.05). Moreover, GI9 (58.08 μg/ml) and FKI21 (56.25 μg/ml) exhibited maximum cholesterol reduction with bile salts. 16S rRNA sequencing confirmed GI9 and FKI21 as Lactobacillus crispatus and Weissella koreensis, respectively. This is the first study to report isolation of W. koreensis FKI21 from fermented koozh and demonstrates its cholesterol-reducing potential. Copyright © 2015 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

Do piperacillin/tazobactam and other antibiotics with inhibitory activity against Clostridium difficile reduce the risk for acquisition of C. difficile colonization?

PubMed

Kundrapu, Sirisha; Sunkesula, Venkata C K; Jury, Lucy A; Cadnum, Jennifer L; Nerandzic, Michelle M; Musuuza, Jackson S; Sethi, Ajay K; Donskey, Curtis J

2016-04-18

Systemic antibiotics vary widely in in vitro activity against Clostridium difficile. Some agents with activity against C. difficile (e.g., piperacillin/tazobactam) inhibit establishment of colonization in mice. We tested the hypothesis that piperacillin/tazobactam and other agents with activity against C. difficile achieve sufficient concentrations in the intestinal tract to inhibit colonization in patients. Point-prevalence culture surveys were conducted to compare the frequency of asymptomatic rectal carriage of toxigenic C. difficile among patients receiving piperacillin/tazobactam or other inhibitory antibiotics (e.g. ampicillin, linezolid, carbapenems) versus antibiotics lacking activity against C. difficile (e.g., cephalosporins, ciprofloxacin). For a subset of patients, in vitro inhibition of C. difficile (defined as a reduction in concentration after inoculation of vegetative C. difficile into fresh stool suspensions) was compared among antibiotic treatment groups. Of 250 patients, 32 (13 %) were asymptomatic carriers of C. difficile. In comparison to patients receiving non-inhibitory antibiotics or prior antibiotics within 90 days, patients currently receiving piperacillin/tazobactam were less likely to be asymptomatic carriers (1/36, 3 versus 7/36, 19 and 15/69, 22 %, respectively; P = 0.024) and more likely to have fecal suspensions with in vitro inhibitory activity against C. difficile (20/28, 71 versus 3/11, 27 and 4/26, 15 %; P = 0.03). Patients receiving other inhibitory antibiotics were not less likely to be asymptomatic carriers than those receiving non-inhibitory antibiotics. Our findings suggest that piperacillin/tazobactam achieves sufficient concentrations in the intestinal tract to inhibit C. difficile colonization during therapy.

Novel synthetic kojic acid-methimazole derivatives inhibit mushroom tyrosinase and melanogenesis.

PubMed

Chen, Ming-Jen; Hung, Chih-Chuan; Chen, Yan-Ru; Lai, Shih-Ting; Chan, Chin-Feng

2016-12-01

In this study, two kojic acid-methimazole (2-mercapto-1-methylimidazole, MMI, 1) derivatives, 5-hydroxy-2-{[(1-methyl-1H-imidazol-2-yl)thio]methyl}-4H-pyran-4-one (compound 4) and 5-methoxy-2-{[(1-methyl-1H-imidazol-2-yl)thio]methyl}-4H-pyran-4-one (compound 5), were synthesized to examine their inhibitory kinetics on mushroom tyrosinase. Compound 4 exhibited a potent inhibitory effect on monophenolase activity in a dose-dependent manner, with an IC 50 value of 0.03 mM. On diphenolase activity, compound 4 exhibited a less inhibitory effect (IC 50  = 1.29 mM) but was stronger than kojic acid (IC 50  = 1.80 mM). Kinetic analysis indicated that compound 4 was both as a noncompetitive monophenolase and diphenolase inhibitor. By contrast, compound 5 exhibited no inhibitory effects on mushroom tyrosinase activity. The IC 50 value of compound 4 for the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity was 4.09 mM, being much higher than the IC 50 of compound 4 for inhibiting the tyrosinase activity. The results indicated that the antioxidant activity of compound 4 may be partly related to the potent inhibitory effect on mushroom tyrosinase. Compound 4 also exerted a potent inhibitory effect on intracellular melanin formation in B16/F10 murine melanoma cells, and caused no cytotoxicity. Furthermore, compound 4 induced no adverse effects on the Hen's egg test-chorioallantoic membrane (HET-CAM). Copyright © 2016 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Selective functional interactions between excitatory and inhibitory cortical neurons and differential contribution to persistent activity of the slow oscillation.

PubMed

Tahvildari, Babak; Wölfel, Markus; Duque, Alvaro; McCormick, David A

2012-08-29

The neocortex depends upon a relative balance of recurrent excitation and inhibition for its operation. During spontaneous Up states, cortical pyramidal cells receive proportional barrages of excitatory and inhibitory synaptic potentials. Many of these synaptic potentials arise from the activity of nearby neurons, although the identity of these cells is relatively unknown, especially for those underlying the generation of inhibitory synaptic events. To address these fundamental questions, we developed an in vitro submerged slice preparation of the mouse entorhinal cortex that generates robust and regular spontaneous recurrent network activity in the form of the slow oscillation. By performing whole-cell recordings from multiple cell types identified with green fluorescent protein expression and electrophysiological and/or morphological properties, we show that distinct functional subpopulations of neurons exist in the entorhinal cortex, with large variations in contribution to the generation of balanced excitation and inhibition during the slow oscillation. The most active neurons during the slow oscillation are excitatory pyramidal and inhibitory fast spiking interneurons, receiving robust barrages of both excitatory and inhibitory synaptic potentials. Weak action potential activity was observed in stellate excitatory neurons and somatostatin-containing interneurons. In contrast, interneurons containing neuropeptide Y, vasoactive intestinal peptide, or the 5-hydroxytryptamine (serotonin) 3a receptor, were silent. Our data demonstrate remarkable functional specificity in the interactions between different excitatory and inhibitory cortical neuronal subtypes, and suggest that it is the large recurrent interaction between pyramidal neurons and fast spiking interneurons that is responsible for the generation of persistent activity that characterizes the depolarized states of the cortex.

Antioxidant and ACE Inhibitory Bioactive Peptides Purified from Egg Yolk Proteins

PubMed Central

Yousr, Marwa; Howell, Nazlin

2015-01-01

Protein by-products from the extraction of lecithin from egg yolk can be converted into value-added products, such as bioactive hydrolysates and peptides that have potential health enhancing antioxidant, and antihypertensive properties. In this study, the antioxidant and angiotensin converting enzyme (ACE) inhibitory activities of peptides isolated and purified from egg yolk protein were investigated. Defatted egg yolk was hydrolyzed using pepsin and pancreatin and sequentially fractionated by ultrafiltration, followed by gel filtration to produce egg yolk gel filtration fractions (EYGF). Of these, two fractions, EYGF-23 and EYGF-33, effectively inhibited the peroxides and thiobarbituric acid reactive substance (TBARS) in an oxidizing linoleic acid model system. The antioxidant mechanism involved superoxide anion and hydroxyl radicals scavenging and ferrous chelation. The presence of hydrophobic amino acids such as tyrosine (Y) and tryptophan (W), in sequences identified by LC-MS as WYGPD (EYGF-23) and KLSDW (EYGF-33), contributed to the antioxidant activity and were not significantly different from the synthetic BHA antioxidant. A third fraction (EYGF-56) was also purified from egg yolk protein by gel filtration and exhibited high ACE inhibitory activity (69%) and IC50 value (3.35 mg/mL). The SDNRNQGY peptide (10 mg/mL) had ACE inhibitory activity, which was not significantly different from that of the positive control captopril (0.5 mg/mL). In addition, YPSPV in (EYGF-33) (10 mg/mL) had higher ACE inhibitory activity compared with captopril. These findings indicated a substantial potential for producing valuable peptides with antioxidant and ACE inhibitory activity from egg yolk. PMID:26690134

Antioxidant and ACE Inhibitory Bioactive Peptides Purified from Egg Yolk Proteins.

PubMed

Yousr, Marwa; Howell, Nazlin

2015-12-07

Protein by-products from the extraction of lecithin from egg yolk can be converted into value-added products, such as bioactive hydrolysates and peptides that have potential health enhancing antioxidant, and antihypertensive properties. In this study, the antioxidant and angiotensin converting enzyme (ACE) inhibitory activities of peptides isolated and purified from egg yolk protein were investigated. Defatted egg yolk was hydrolyzed using pepsin and pancreatin and sequentially fractionated by ultrafiltration, followed by gel filtration to produce egg yolk gel filtration fractions (EYGF). Of these, two fractions, EYGF-23 and EYGF-33, effectively inhibited the peroxides and thiobarbituric acid reactive substance (TBARS) in an oxidizing linoleic acid model system. The antioxidant mechanism involved superoxide anion and hydroxyl radicals scavenging and ferrous chelation. The presence of hydrophobic amino acids such as tyrosine (Y) and tryptophan (W), in sequences identified by LC-MS as WYGPD (EYGF-23) and KLSDW (EYGF-33), contributed to the antioxidant activity and were not significantly different from the synthetic BHA antioxidant. A third fraction (EYGF-56) was also purified from egg yolk protein by gel filtration and exhibited high ACE inhibitory activity (69%) and IC50 value (3.35 mg/mL). The SDNRNQGY peptide (10 mg/mL) had ACE inhibitory activity, which was not significantly different from that of the positive control captopril (0.5 mg/mL). In addition, YPSPV in (EYGF-33) (10 mg/mL) had higher ACE inhibitory activity compared with captopril. These findings indicated a substantial potential for producing valuable peptides with antioxidant and ACE inhibitory activity from egg yolk.

Cultural influences on neural basis of inhibitory control.

PubMed

Pornpattananangkul, Narun; Hariri, Ahmad R; Harada, Tokiko; Mano, Yoko; Komeda, Hidetsugu; Parrish, Todd B; Sadato, Norihiro; Iidaka, Tetsuya; Chiao, Joan Y

2016-10-01

Research on neural basis of inhibitory control has been extensively conducted in various parts of the world. It is often implicitly assumed that neural basis of inhibitory control is universally similar across cultures. Here, we investigated the extent to which culture modulated inhibitory-control brain activity at both cultural-group and cultural-value levels of analysis. During fMRI scanning, participants from different cultural groups (including Caucasian-Americans and Japanese-Americans living in the United States and native Japanese living in Japan) performed a Go/No-Go task. They also completed behavioral surveys assessing cultural values of behavioral consistency, or the extent to which one's behaviors in daily life are consistent across situations. Across participants, the Go/No-Go task elicited stronger neural activity in several inhibitory-control areas, such as the inferior frontal gyrus (IFG) and anterior cingulate cortex (ACC). Importantly, at the cultural-group level, we found variation in left IFG (L-IFG) activity that was explained by a cultural region where participants lived in (as opposed to race). Specifically, L-IFG activity was stronger for native Japanese compared to Caucasian- and Japanese-Americans, while there was no systematic difference in L-IFG activity between Japanese- and Caucasian-Americans. At the cultural-value level, we found that participants who valued being "themselves" across situations (i.e., having high endorsement of behavioral consistency) elicited stronger rostral ACC activity during the Go/No-Go task. Altogether, our findings provide novel insight into how culture modulates the neural basis of inhibitory control. Copyright © 2016 Elsevier Inc. All rights reserved.

Chromanyl-isoxazolidines as Antibacterial agents: Synthesis, Biological Evaluation, Quantitative Structure Activity Relationship, and Molecular Docking Studies.

PubMed

Singh, Gagandeep; Sharma, Anuradha; Kaur, Harpreet; Ishar, Mohan Paul S

2016-02-01

Regio- and stereoselective 1,3-dipolar cycloadditions of C-(chrom-4-one-3-yl)-N-phenylnitrones (N) with different mono-substituted, disubstituted, and cyclic dipolarophiles were carried out to obtain substituted N-phenyl-3'-(chrom-4-one-3-yl)-isoxazolidines (1-40). All the synthesized compounds were assayed for their in vitro antibacterial activity and display significant inhibitory potential; in particular, compound 32 exhibited good inhibitory activity against Salmonella typhymurium-1 & Salmonella typhymurium-2 with minimum inhibitory concentration value of 1.56 μg/mL and also showed good potential against methicillin-resistant Staphylococcus aureus with minimum inhibitory concentration 3.12 μg/mL. Quantitative structure activity relationship investigations with stepwise multiple linear regression analysis and docking simulation studies have been performed for validation of the observed antibacterial potential of the investigated compounds for determination of the most important parameters regulating antibacterial activities. © 2015 John Wiley & Sons A/S.

Synthesis, crystal structures, molecular docking, and in vitro biological activities evaluation of transition metal complexes with 4-(3,4-dichlorophenyl) piperazine-1-carboxylic acid

NASA Astrophysics Data System (ADS)

Chen, Zhi-Jian; Chen, Ya-Na; Xu, Chun-Na; Zhao, Shan-Shan; Cao, Qi-Yue; Qian, Shao-Song; Qin, Jie; Zhu, Hai-Liang

2016-08-01

Three novel mononuclear complexes, [MⅡ(L)2·2H2O], (M = Cu, Ni or Cd; HL = 4-(3,4-dichlorophenyl)piperazine-1-carboxylic acid)were synthesized and structurally determined by single-crystal X-ray diffraction. Molecular docking study preliminarily revealed that complex 1 had potential urease inhibitory activity. In accordance with the result of calculation, in vitro tests of the inhibitory activities of complexes 1-3 against jack bean urease showed complex 1 (IC50 = 8.17 ± 0.91 μM) had better inhibitory activities than the positive reference acetohydroxamic acid (AHA) (IC50 = 26.99 ± 1.43 μM), while complexes 2 and 3 showed no inhibitory activities., kinetics study was carried out to explore the mechanism of the inhibiting of the enzyme, and the result indicated that complex 1 was a competitive inhibitor of urease. Albumin binding experiment and in vitro toxicity evaluation of complex 1 were implemented to explore its Pharmacological properties.

Amino group of salicylic acid exhibits enhanced inhibitory potential against insulin amyloid fibrillation with protective aptitude toward amyloid induced cytotoxicity.

PubMed

Zaman, Masihuz; Khan, Mohsin Vahid; Zakariya, Syed Mohammad; Nusrat, Saima; Meeran, Syed Mustapha; Alam, Parvez; Ajmal, Mohammad Rehan; Wahiduzzaman, Wahiduzzaman; Shahein, Yasser E; Abouelella, Amira M; Khan, Rizwan Hasan

2018-05-01

Protein misfolding and aggregation lead to amyloid generation that in turn may induce cell membrane disruption and leads to cell apoptosis. In an effort to prevent or treat amyloidogenesis, large number of studies has been paying attention on breakthrough of amyloid inhibitors. In the present work, we aim to access the effect of two drugs, that is, acetylsalicylic acid and 5-amino salicylic acid on insulin amyloids by using various biophysical, imaging, cell viability assay, and computational approaches. We established that both drugs reduce the turbidity, light scattering and fluorescence intensity of amyloid indicator dye thioflavin T. Premixing of drugs with insulin inhibited the nucleation phase and inhibitory potential was boosted by increasing the concentration of the drug. Moreover, addition of drugs at the studied concentrations attenuated the insulin fibril induced cytotoxicity in breast cancer cell line MDA-MB-231. Our results highlight the amino group of salicylic acid exhibited enhanced inhibitory effects on insulin fibrillation in comparison to acetyl group. It may be due to presence of amino group that helps it to prolong the nucleation phase with strong binding as well as disruption of aromatic and hydrophobic stacking that plays a key role in amyloid progression. © 2017 Wiley Periodicals, Inc.

Green synthesis of silk sericin-capped silver nanoparticles and their potent anti-bacterial activity

NASA Astrophysics Data System (ADS)

Aramwit, Pornanong; Bang, Nipaporn; Ratanavaraporn, Juthamas; Ekgasit, Sanong

2014-02-01

In this study, a `green chemistry' approach was introduced to synthesize silk sericin (SS)-capped silver nanoparticles (AgNPs) under an alkaline condition (pH 11) using SS as a reducing and stabilizing agent instead of toxic chemicals. The SS-capped AgNPs were successfully synthesized at various concentrations of SS and AgNO3, but the yields were different. A higher yield of SS-capped AgNPs was obtained when the concentrations of SS and AgNO3 were increased. The SS-capped AgNPs showed a round shape and uniform size with diameter at around 48 to 117 nm. The Fourier transform infrared (FT-IR) spectroscopy result proved that the carboxylate groups obtained from alkaline degradation of SS would be a reducing agent for the generation of AgNPs while COO- and NH2 + groups stabilized the AgNPs and prevented their precipitation or aggregation. Furthermore, the SS-capped AgNPs showed potent anti-bacterial activity against various gram-positive bacteria (minimal inhibitory concentration (MIC) 0.008 mM) and gram-negative bacteria (MIC ranging from 0.001 to 0.004 mM). Therefore, the SS-capped AgNPs would be a safe candidate for anti-bacterial applications.

Selfish prion of Rnq1 mutant in yeast.

PubMed

Kurahashi, Hiroshi; Shibata, Shoichiro; Ishiwata, Masao; Nakamura, Yoshikazu

2009-05-01

[PIN(+)] is a prion form of Rnq1 in Saccharomyces cerevisiae and is necessary for the de novo induction of a second prion, [PSI(+)]. We previously isolated a truncated form of Rnq1, named Rnq1Delta100, as a [PSI(+)]-eliminating factor in S. cerevisiae. Rnq1Delta100 deletes the N-terminal non-prion domain of Rnq1, and eliminates [PSI(+)] in [PIN(+)] yeast. Here we found that [PIN(+)] is transmissible to Rnq1Delta100 in the absence of full-length Rnq1, forming a novel prion variant [RNQ1Delta100(+)]. [RNQ1Delta100(+)] has similar [PIN(+)] properties as it stimulates the de novo induction of [PSI(+)] and is eliminated by the null hsp104Delta mutation, but not by Hsp104 overproduction. In contrast, [RNQ1Delta100(+)] inherits the inhibitory activity and hampers the maintenance of [PSI(+)] though less efficiently than [PIN(+)] made of Rnq1-Rnq1Delta100 co-aggregates. Interestingly, [RNQ1Delta100(+)] prion was eliminated by de novo [PSI(+)] induction. Thus, the [RNQ1Delta100(+)] prion demonstrates selfish activity to eliminate a heterologous prion in S. cerevisiae, showing the first instance of a selfish prion variant in living organisms.

Intrinsically-generated fluctuating activity in excitatory-inhibitory networks.

PubMed

Mastrogiuseppe, Francesca; Ostojic, Srdjan

2017-04-01

Recurrent networks of non-linear units display a variety of dynamical regimes depending on the structure of their synaptic connectivity. A particularly remarkable phenomenon is the appearance of strongly fluctuating, chaotic activity in networks of deterministic, but randomly connected rate units. How this type of intrinsically generated fluctuations appears in more realistic networks of spiking neurons has been a long standing question. To ease the comparison between rate and spiking networks, recent works investigated the dynamical regimes of randomly-connected rate networks with segregated excitatory and inhibitory populations, and firing rates constrained to be positive. These works derived general dynamical mean field (DMF) equations describing the fluctuating dynamics, but solved these equations only in the case of purely inhibitory networks. Using a simplified excitatory-inhibitory architecture in which DMF equations are more easily tractable, here we show that the presence of excitation qualitatively modifies the fluctuating activity compared to purely inhibitory networks. In presence of excitation, intrinsically generated fluctuations induce a strong increase in mean firing rates, a phenomenon that is much weaker in purely inhibitory networks. Excitation moreover induces two different fluctuating regimes: for moderate overall coupling, recurrent inhibition is sufficient to stabilize fluctuations; for strong coupling, firing rates are stabilized solely by the upper bound imposed on activity, even if inhibition is stronger than excitation. These results extend to more general network architectures, and to rate networks receiving noisy inputs mimicking spiking activity. Finally, we show that signatures of the second dynamical regime appear in networks of integrate-and-fire neurons.

In vitro antifungal efficacy of ciclopirox olamine alone and associated with zinc pyrithione compared to ketoconazole against Malassezia globosa and Malassezia restricta reference strains.

PubMed

Roques, Christine; Brousse, Sabine; Panizzutti, Cédric

2006-12-01

The aim of this study was to determine the in vitro fungicidal and growth inhibitory activity of ciclopirox olamine alone (1% and 1.5%) or in association with 1% zinc pyrithione compared to 2% ketoconazole, against Malassezia species particularly involved in the pathogenesis of seborrheic dermatitis. Experiments were performed on Malassezia globosa IP 2387.96 and M. restricta IP 2392.96 strains. Growth inhibitory activity of the active compounds in solution was evaluated by measuring minimal inhibitory concentrations using a broth micro-method and their fungicidal activity by a filtration method after contact times between solutions and yeasts ranging from 3-5 to 30 min. Concerning the determination of minimal inhibitory concentration of ciclopirox olamine/zinc pyrithione, it revealed the marked synergistic inhibitory effect of the association, leading to a higher efficacy compared to ketoconazole. As to the fungicidal activity of ciclopirox olamine, it significantly increased with the contact time. After 15-30 min of contact between 1.5% ciclopirox olamine and Malassezia strains, a 2-log reduction of Malassezia counts was observed. The 1.5% ciclopirox olamine/1% zinc pyrithione association was characterized by a steady fungicidal efficacy whereas the 2% ketoconazole solution did not express any fungicidal effect. In conclusion, this study demonstrates the in vitro inhibitory and fungicidal efficacy of the ciclopirox olamine/zinc pyrithione association against Malassezia species and underscores its potential interest in the treatment of seborrheic dermatitis.

Effect of Jatropha curcas Peptide Fractions on the Angiotensin I-Converting Enzyme Inhibitory Activity

PubMed Central

Segura-Campos, Maira R.; Peralta-González, Fanny; Castellanos-Ruelas, Arturo; Chel-Guerrero, Luis A.; Betancur-Ancona, David A.

2013-01-01

Hypertension is one of the most common worldwide diseases in humans. Angiotensin I-converting enzyme (ACE) plays an important role in regulating blood pressure and hypertension. An evaluation was done on the effect of Alcalase hydrolysis of defatted Jatropha curcas kernel meal on ACE inhibitory activity in the resulting hydrolysate and its purified fractions. Alcalase exhibited broad specificity and produced a protein hydrolysate with a 21.35% degree of hydrolysis and 34.87% ACE inhibition. Ultrafiltration of the hydrolysate produced peptide fractions with increased biological activity (24.46–61.41%). Hydrophobic residues contributed substantially to the peptides' inhibitory potency. The 5–10 and <1 kDa fractions were selected for further fractionation by gel filtration chromatography. ACE inhibitory activity (%) ranged from 22.66 to 45.96% with the 5–10 kDa ultrafiltered fraction and from 36.91 to 55.83% with the <1 kDa ultrafiltered fraction. The highest ACE inhibitory activity was observed in F2 (IC50 = 6.7 μg/mL) from the 5–10 kDa fraction and F1 (IC50 = 4.78 μg/mL) from the <1 kDa fraction. ACE inhibitory fractions from Jatropha kernel have potential applications in alternative hypertension therapies, adding a new application for the Jatropha plant protein fraction and improving the financial viability and sustainability of a Jatropha-based biodiesel industry. PMID:24224169

Two Novel Bioactive Peptides from Antarctic Krill with Dual Angiotensin Converting Enzyme and Dipeptidyl Peptidase IV Inhibitory Activities.

PubMed

Ji, Wei; Zhang, Chaohua; Ji, Hongwu

2017-07-01

Inhibition of dipeptidyl peptidase IV (DPP-IV) and angiotensin converting enzyme (ACE) are considered useful in managing 2 often associated conditions: diabetes and hypertension. In this study, corolase PP was used to hydrolyze Antarctic krill protein. The hydrolysate (AKH) was isolated by ultrafiltration and purified by size-exclusion chromatography, ion exchange chromatography and reversed-phase high-performance liquid chromatography (RP-HPLC) sequentially. The in vitro inhibitory activities of all AKHs and several fractions obtained against ACE and DPP-IV were assessed. Two peptides, purified with dual-strength inhibitory activity against ACE and DPP-IV, were identified by TOF-MS/MS. Results indicated that not all fractions exhibited dual inhibitory activities of ACE and DPP-IV. The purified peptide Lys-Val-Glu-Pro-Leu-Pro had half-maximal inhibitory concentrations (IC 50 ) of 0.93±0.05 and 0.73±0.04 mg/mL against ACE and DPP-IV, respectively. The other peptide Pro-Ala-Leu had IC 50 values of 0.64±0.05 and 0.88±0.03 mg/mL against ACE and DPP-IV, respectively. This study firstly reported the sequences of dual bioactive peptides from Antarctic krill proteins, further provided new insights into the bioactive peptides responsible for the ACE and DPP-IV inhibitory activities from the Antarctic krill protein hydrolysate to manage hypertension and diabetes. © 2017 Institute of Food Technologists®.

Frontal and limbic activation during inhibitory control predicts treatment response in major depressive disorder.

PubMed

Langenecker, Scott A; Kennedy, Susan E; Guidotti, Leslie M; Briceno, Emily M; Own, Lawrence S; Hooven, Thomas; Young, Elizabeth A; Akil, Huda; Noll, Douglas C; Zubieta, Jon-Kar

2007-12-01

Inhibitory control or regulatory difficulties have been explored in major depressive disorder (MDD) but typically in the context of affectively salient information. Inhibitory control is addressed specifically by using a task devoid of affectively-laden stimuli, to disentangle the effects of altered affect and altered inhibitory processes in MDD. Twenty MDD and 22 control volunteer participants matched by age and gender completed a contextual inhibitory control task, the Parametric Go/No-go (PGNG) task during functional magnetic resonance imaging. The PGNG includes three levels of difficulty, a typical continuous performance task and two progressively more difficult versions including Go/No-go hit and rejection trials. After this test, 15 of 20 MDD patients completed a full 10-week treatment with s-citalopram. There was a significant interaction among response time (control subjects better), hits (control subjects better), and rejections (patients better). The MDD participants had greater activation compared with the control group in frontal and anterior temporal areas during correct rejections (inhibition). Activation during successful inhibitory events in bilateral inferior frontal and left amygdala, insula, and nucleus accumbens and during unsuccessful inhibition (commission errors) in rostral anterior cingulate predicted post-treatment improvement in depression symptoms. The imaging findings suggest that in MDD subjects, greater neural activation in frontal, limbic, and temporal regions during correct rejection of lures is necessary to achieve behavioral performance equivalent to control subjects. Greater activation in similar regions was further predictive of better treatment response in MDD.

Intrinsically-generated fluctuating activity in excitatory-inhibitory networks

PubMed Central

Mastrogiuseppe, Francesca; Ostojic, Srdjan

2017-01-01

Recurrent networks of non-linear units display a variety of dynamical regimes depending on the structure of their synaptic connectivity. A particularly remarkable phenomenon is the appearance of strongly fluctuating, chaotic activity in networks of deterministic, but randomly connected rate units. How this type of intrinsically generated fluctuations appears in more realistic networks of spiking neurons has been a long standing question. To ease the comparison between rate and spiking networks, recent works investigated the dynamical regimes of randomly-connected rate networks with segregated excitatory and inhibitory populations, and firing rates constrained to be positive. These works derived general dynamical mean field (DMF) equations describing the fluctuating dynamics, but solved these equations only in the case of purely inhibitory networks. Using a simplified excitatory-inhibitory architecture in which DMF equations are more easily tractable, here we show that the presence of excitation qualitatively modifies the fluctuating activity compared to purely inhibitory networks. In presence of excitation, intrinsically generated fluctuations induce a strong increase in mean firing rates, a phenomenon that is much weaker in purely inhibitory networks. Excitation moreover induces two different fluctuating regimes: for moderate overall coupling, recurrent inhibition is sufficient to stabilize fluctuations; for strong coupling, firing rates are stabilized solely by the upper bound imposed on activity, even if inhibition is stronger than excitation. These results extend to more general network architectures, and to rate networks receiving noisy inputs mimicking spiking activity. Finally, we show that signatures of the second dynamical regime appear in networks of integrate-and-fire neurons. PMID:28437436

Associative plasticity in intracortical inhibitory circuits in human motor cortex.

PubMed

Russmann, Heike; Lamy, Jean-Charles; Shamim, Ejaz A; Meunier, Sabine; Hallett, Mark

2009-06-01

Paired associative stimulation (PAS) is a transcranial magnetic stimulation technique inducing Hebbian-like synaptic plasticity in the human motor cortex (M1). PAS is produced by repetitive pairing of a peripheral nerve shock and a transcranial magnetic stimulus (TMS). Its effect is assessed by a change in size of a motor evoked response (MEP). MEP size results from excitatory and inhibitory influences exerted on cortical pyramidal cells, but no robust effects on inhibitory networks have been demonstrated so far. In 38 healthy volunteers, we assessed whether a PAS intervention influences three intracortical inhibitory circuits: short (SICI) and long (LICI) intracortical inhibitions reflecting activity of GABA(A) and GABA(B) interneurons, respectively, and long afferent inhibition (LAI) reflecting activity of somatosensory inputs. After PAS, MEP sizes, LICI and LAI levels were significantly changed while changes of SICI were inconsistent. The changes in LICI and LAI lasted 45 min after PAS. Their direction depended on the delay between the arrival time of the afferent volley at the cortex and the TMS-induced cortical activation during the PAS. PAS influences inhibitory circuits in M1. PAS paradigms can demonstrate Hebbian-like plasticity at selected inhibitory networks as well as excitatory networks.

Effective degradation of primary color direct azo dyes using Fe0 aggregates-activated persulfate process.

PubMed

Liu, Na; Ding, Feng; Weng, Chih-Huang; Hwang, Chi-Chin; Lin, Yao-Tung

2018-01-15

The present study examined the oxidation power of a Fe 0 aggregates/persulfate (PS/Fe 0 ) system for the degradation of the wastewater containing mixed primary direct dyes (i.e., Sirius ® Gelb S-2G, Sirius ® Red F3B, and Sirius ® Turkis GL01). Results indicated that decolorization efficiency was determined by operating parameters of the PS/Fe 0 system and the structural complexity of dye molecules. System efficiency increased with increasing persulfate and Fe 0 dosages. Faster decolorization was observed in experiments conducted at pH < 10. The process obeyed a first-order kinetics. Slow heterogeneous reactions were observed at high initial pH (>10.5) and low PS concentration (<2 × 10 -3  M). Inhibitory effect occurred in systems containing salts Na 2 SO 4 , NaCl, Na 2 CO 3 , and Na 2 HPO 4 at 1 × 10 -2  M. The effect was suppressed when reaction temperature was raised to 55 °C. Heat enhanced not only decolorization efficiency, but also COD removal. Complete decolorization of a mixed dye containing ADMI (the American Dye Manufacture Institute) 15105 was achieved within10 min in the PS/Fe 0 /55 °C system with an initial pH of 6.0 and dosages of 5 × 10 -3  M Na 2 S 2 O 8 and 0.5 g/L Fe 0 . Low molecular weight intermediates including organic acids were identified. Due to a relatively low activation energy (4.68 kcaL/mol), the PS/Fe 0 system exhibited higher efficiency at higher temperature. This study demonstrated that Fe 0 -activated PS is a promising process for the treatment of textile wastewaters containing mixed azo direct dyes. Copyright © 2017 Elsevier Ltd. All rights reserved.

Neuroforecasting Aggregate Choice

PubMed Central

Knutson, Brian; Genevsky, Alexander

2018-01-01

Advances in brain-imaging design and analysis have allowed investigators to use neural activity to predict individual choice, while emerging Internet markets have opened up new opportunities for forecasting aggregate choice. Here, we review emerging research that bridges these levels of analysis by attempting to use group neural activity to forecast aggregate choice. A survey of initial findings suggests that components of group neural activity might forecast aggregate choice, in some cases even beyond traditional behavioral measures. In addition to demonstrating the plausibility of neuroforecasting, these findings raise the possibility that not all neural processes that predict individual choice forecast aggregate choice to the same degree. We propose that although integrative choice components may confer more consistency within individuals, affective choice components may generalize more broadly across individuals to forecast aggregate choice. PMID:29706726

Prolyl endopeptidase and thrombin inhibitory diterpenoids from the bark of Xylopia aethiopica.

PubMed

Diderot, Noungoue Tchamo; Silvere, Ngouela; Yasin, Amsha; Zareen, Seema; Fabien, Zelefack; Etienne, Tsamo; Choudhary, M Iqbal; Atta-Ur-Rahman

2005-09-01

The inhibitory effects of seven diterpenes, belonging to three different structural classes and isolated from the bark of Xylopia aethiopica, were investigated against the enzymes prolyl endopeptidase (PEP) and alpha-thrombin. Five compounds exhibited inhibitory activity against them.

Xanthine oxidase inhibitory activities of extracts and flavonoids of the leaves of Blumea balsamifera.

PubMed

Nessa, Fazilatun; Ismail, Zhari; Mohamed, Nornisah

2010-12-01

Blumea balsamifera DC (Compositae) leaves have been recommended for use as a folk medicine in the treatment of various diseases related to urolithiasis in southeast Asia. Phytochemical studies of this plant revealed it contains four classes of flavonoids (e.g., flavonols, flavones, flavanones, and dihydroflavonol derivatives). In view of the broad pharmacological activity of flavonoids, this study was carried out to determine the xanthine oxidase (XO) inhibitory and enzymatically produced superoxide radical scavenging activity of different organic extracts and that of the isolated flavonoids from B. balsamifera leaves. The inhibitory activity of XO was assayed spectrophotometrically at 295 nm. The superoxide radicals scavenging activity was assessed by NBT reduction method, spectrophotometrically at 560 nm. A dose response curve was plotted for determining IC₅₀ values. The methanol extract (IC₅₀ = 0.111 mg/mL) showed higher XO inhibitory activity than the chloroform (0.138 mg/mL) and pet-ether extracts (0.516 mg/mL). IC₅₀ values of scavenging of superoxide radicals for extracts decreased in the order of: methanol (0.063 mg/mL) > chloroform (0.092 mg/mL) > pet-ether (0.321 mg/mL). The XO inhibitory activity of the isolated flavonoids and reference compounds tested decreased in the order of: allopurinol > luteolin > quercetin > tamarixetin > 5,7,3',5'-tetrahydroxyflavanone > rhamnetin > luteolin-7-methyl ether > blumeatin > dihydroquercetin-4'-methyl ether > dihydroquercetin-7,4'-dimethyl ether > L-ascorbic acid. The results indicated that the flavone derivatives were more active than the flavonol derivatives. The flavanone derivatives were moderately active and the dihydroflavonol derivatives were the least. The higher flavonoid content of extracts contributed to their higher XO inhibitory activity.

Quantification of Anti-Aggregation Activity of Chaperones: A Test-System Based on Dithiothreitol-Induced Aggregation of Bovine Serum Albumin

PubMed Central

Borzova, Vera A.; Markossian, Kira A.; Kara, Dmitriy A.; Chebotareva, Natalia A.; Makeeva, Valentina F.; Poliansky, Nikolay B.; Muranov, Konstantin O.; Kurganov, Boris I.

2013-01-01

The methodology for quantification of the anti-aggregation activity of protein and chemical chaperones has been elaborated. The applicability of this methodology was demonstrated using a test-system based on dithiothreitol-induced aggregation of bovine serum albumin at 45°C as an example. Methods for calculating the initial rate of bovine serum albumin aggregation (v agg) have been discussed. The comparison of the dependences of v agg on concentrations of intact and cross-linked α-crystallin allowed us to make a conclusion that a non-linear character of the dependence of v agg on concentration of intact α-crystallin was due to the dynamic mobility of the quaternary structure of α-crystallin and polydispersity of the α-crystallin–target protein complexes. To characterize the anti-aggregation activity of the chemical chaperones (arginine, arginine ethyl ester, arginine amide and proline), the semi-saturation concentration [L]0.5 was used. Among the chemical chaperones studied, arginine ethyl ester and arginine amide reveal the highest anti-aggregation activity ([L]0.5 = 53 and 58 mM, respectively). PMID:24058554

Inhibitory activities of the alkaloids from Coptidis Rhizoma against aldose reductase.

PubMed

Jung, Hyun Ah; Yoon, Na Young; Bae, Hyun Ju; Min, Byung-Sun; Choi, Jae Sue

2008-11-01

As part of our ongoing search of natural sources for therapeutic and preventive agents for diabetic complications, the rat lens aldose reductase (RLAR) inhibitory effect of Coptidis Rhizoma (the rhizome of Coptis chinensis Franch) was evaluated. Its extract and fractions exhibited broad and moderate RLAR inhibitory activities of 38.9 approximately 67.5 microg/mL. In an attempt to identify bioactive components, six quaternary protoberberine-type alkaloids (berberine, palmatine, jateorrhizine, epiberberine, coptisine, and groenlandicine) and one quaternary aporphine-type alkaloid (magnoflorine) were isolated from the most active n-BuOH fraction, and the chemical structures therein were elucidated on the basis of spectroscopic evidence and comparison with published data. The anti-diabetic complications capacities of seven C. chinensis-derived alkaloids were evaluated via RLAR and human recombinant AR (HRAR) inhibitory assays. Although berberine and palmatine were previously reported as prime contributors to AR inhibition, these two major components exhibited no AR inhibitory effects at a higher concentration of 50 microg/ml in the present study. Conversely, epiberberine, coptisine, and groenlandicine exhibited moderate inhibitory effects with IC(50) values of 100.1, 118.4, 140.1 microM for RLAR and 168.1, 187.3, 154.2 microM for HRAR. The results clearly indicated that the presence of the dioxymethylene group in the D ring and the oxidized form of the dioxymethylene group in the A ring were partly responsible for the AR inhibitory activities of protoberberine-type alkaloids. Therefore, Coptidis Rhizoma, and the alkaloids contained therein, would clearly have beneficial uses in the development of therapeutic and preventive agents for diabetic complications and diabetes mellitus.

Incorporation of liposomes containing squid tunic ACE-inhibitory peptides into fish gelatin.

PubMed

Mosquera, Mauricio; Giménez, Begoña; Montero, Pilar; Gómez-Guillén, Maria Carmen

2016-02-01

Hydrolysates from collagen of jumbo squid (Dosidicus gigas) tunics have shown excellent angiotensin I-converting enzyme (ACE)-inhibitory activity. However, peptides directly included in food systems may suffer a decrease in activity, which could be minimized by loading them into nanoliposomes. A fraction of peptides with molecular weights <1 kDa obtained from hydrolyzed squid tunics, with reasonably high ACE-inhibitory activity (half-maximal inhibitory concentration IC50 = 0.096 g L(-1)), was encapsulated in phosphatidylcholine nanoliposomes. The peptide concentration affected the encapsulation efficiency and the stability of the resulting liposomes, which remained with a high zeta potential value (-54.3 mV) for at least 1 week at the most suitable peptide concentration. The optimal peptide concentration was established as 1.75 g L(-1). Liposomes obtained with this peptide concentration showed an encapsulation efficiency of 53%, a zeta potential of -59 mV, an average diameter of 70.3 nm and proved to be stable in the pH range 3-7 at 4 °C. Liposomes containing ACE-inhibitory peptides were incorporated in fish gelatin without detriment to the rheological properties and thermal stability of the resulting cold-induced gel. The ACE-inhibitory activity of the peptide fraction, which was not affected by the encapsulation process, conferred the bioactive potential to the nanoliposome-containing gelatin gel. © 2015 Society of Chemical Industry.

The Dictyostelium MAP kinase kinase DdMEK1 regulates chemotaxis and is essential for chemoattractant-mediated activation of guanylyl cyclase.

PubMed Central

Ma, H; Gamper, M; Parent, C; Firtel, R A

1997-01-01

We have identified a MAP kinase kinase (DdMEK1) that is required for proper aggregation in Dictyostelium. Null mutations produce extremely small aggregate sizes, resulting in the formation of slugs and terminal fruiting bodies that are significantly smaller than those of wild-type cells. Time-lapse video microscopy and in vitro assays indicate that the cells are able to produce cAMP waves that move through the aggregation domains. However, these cells are unable to undergo chemotaxis properly during aggregation in response to the chemoattractant cAMP or activate guanylyl cyclase, a known regulator of chemotaxis in Dictyostelium. The activation of guanylyl cyclase in response to osmotic stress is, however, normal. Expression of putative constitutively active forms of DdMEK1 in a ddmek1 null background is capable, at least partially, of complementing the small aggregate size defect and the ability to activate guanylyl cyclase. However, this does not result in constitutive activation of guanylyl cyclase, suggesting that DdMEK1 activity is necessary, but not sufficient, for cAMP activation of guanylyl cyclase. Analysis of a temperature-sensitive DdMEK1 mutant suggests that DdMEK1 activity is required throughout aggregation at the time of guanylyl cyclase activation, but is not essential for proper morphogenesis during the later multicellular stages. The activation of the MAP kinase ERK2, which is essential for chemoattractant activation of adenylyl cyclase, is not affected in ddmek1 null strains, indicating that DdMEK1 does not regulate ERK2 and suggesting that at least two independent MAP kinase cascades control aggregation in Dictyostelium. PMID:9250676

Cyclooxygenase-2 inhibitory and antioxidant compounds from the truffle Elaphomyces granulatus

Treesearch

Rita Stanikunaite; Shabana I. Khan; James M. Trappe; Samir A. Ross

2009-01-01

The ethanol extract of fruiting bodies of Elaphomyces granulatus, a truffle-like fungus, was evaluated for cyclooxygenase-2 (COX-2) enzyme inhibitory and antioxidant activities. Inhibition of COX-2 activity was evaluated in mouse macrophages (RAW 264.7). The extract of E. granulatus caused a 68% inhibition of COX-2 activity at...

Antioxidant and cholinesterase inhibitory activity of a new peptide from Ziziphus jujuba fruits.

PubMed

Zare-Zardini, Hadi; Tolueinia, Behnaz; Hashemi, Azam; Ebrahimi, Leila; Fesahat, Farzaneh

2013-11-01

Antioxidant agents and cholinesterase inhibitors are the foremost drugs for the treatment of Alzheimer's disease (AD). In this study, a new peptide from Ziziphus jujuba fruits was investigated for its inhibitory activity against acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) enzymes as well as antioxidant activity. This peptide was introduced as a new peptide and named Snakin-Z. The Snakin-Z displayed considerable cholinesterase inhibition against AChE and BChE. The half maximal inhibitory concentration (IC50) values of Snakin-Z against AChE and BChE are 0.58 ± 0.08 and 0.72 ± 0.085 mg/mL, respectively. This peptide has 80% enzyme inhibitory activity on AChE and BChE at 1.5 mg/mL. The Snakin-Z also had the high antioxidant activity (IC50 = 0.75 ± 0.09 mg/mL). Thus, it is suggested that Snakin-Z may be beneficial in the treatment of AD. However, more detailed researches are still required as in vivo testing its anticholinesterase and antioxidant activities.

Discrete Fourier Transform-Based Multivariate Image Analysis: Application to Modeling of Aromatase Inhibitory Activity.

PubMed

Barigye, Stephen J; Freitas, Matheus P; Ausina, Priscila; Zancan, Patricia; Sola-Penna, Mauro; Castillo-Garit, Juan A

2018-02-12

We recently generalized the formerly alignment-dependent multivariate image analysis applied to quantitative structure-activity relationships (MIA-QSAR) method through the application of the discrete Fourier transform (DFT), allowing for its application to noncongruent and structurally diverse chemical compound data sets. Here we report the first practical application of this method in the screening of molecular entities of therapeutic interest, with human aromatase inhibitory activity as the case study. We developed an ensemble classification model based on the two-dimensional (2D) DFT MIA-QSAR descriptors, with which we screened the NCI Diversity Set V (1593 compounds) and obtained 34 chemical compounds with possible aromatase inhibitory activity. These compounds were docked into the aromatase active site, and the 10 most promising compounds were selected for in vitro experimental validation. Of these compounds, 7419 (nonsteroidal) and 89 201 (steroidal) demonstrated satisfactory antiproliferative and aromatase inhibitory activities. The obtained results suggest that the 2D-DFT MIA-QSAR method may be useful in ligand-based virtual screening of new molecular entities of therapeutic utility.

Macrophage triggering by aggregated immunoglobulins. II. Comparison of IgE and IgG aggregates or immune complexes.

PubMed Central

Pestel, J; Dessaint, J P; Joseph, M; Bazin, H; Capron, A

1984-01-01

Macrophages incubated with complexed or aggregated IgE released beta-glucuronidase (beta-G) within 30 min. In contrast in the presence of aggregated or complexed IgG, macrophages liberated equivalent amount of beta-G only after 6 h incubation. In addition the rapid macrophage stimulation induced by aggregated IgE was also followed by a faster 3H-glucosamine incorporation when compared to the delayed activation caused by aggregated IgG. However, macrophages stimulated either by IgG or by IgE oligomers produced the same percentage of plasminogen activator at 24 h. In contrast, while the interaction between macrophages and aggregated IgE was only followed by a peak of cyclic GMP and a beta-G release during the first 30 min of incubation, the interaction between macrophages and IgG oligomers was accompanied by a simultaneous increase of cyclic GMP and AMP nucleotides and by an absence of beta-G exocytosis. Moreover, the beta-G release induced by aggregated IgE was increased when macrophages were preincubated with aggregated IgG. This additive effect was not observed in the reverse situation. Finally macrophages activated by IgG oligomers were demonstrated to exert a cytotoxic effect on tumour cells and to kill schistosomula in the presence of a low level of complement. Taken together these results underline the peculiar ability of aggregated or complexed IgE to trigger rapidly the macrophage activation compared to aggregated IgG and can explain the important role of complexed IgE in some macrophage dependent cytotoxicity mechanisms (i.e. in parasitic diseases). PMID:6088135

Synthesis, biological evaluation, and metabolic stability of chlorogenic acid derivatives possessing thiazole as potent inhibitors of α-MSH-stimulated melanogenesis.

PubMed

Jo, Hyeju; Zhou, Yuanyuan; Viji, Mayavan; Choi, Minho; Lim, Jae Young; Sim, Jaeuk; Rhee, Jeongtae; Kim, Youngsoo; Seo, Seung-Yong; Kim, Wun-Jae; Hong, Jin Tae; Lee, Heesoon; Lee, Kiho; Jung, Jae-Kyung

2017-11-01

A series of catechol and dioxolane analogs containing thiazole CGA derivatives have been synthesized and evaluated for their inhibitory activity against α-MSH. The inhibitory activity was improved by replacing an α,β-unsaturated carbonyl of previously reported caffeamides with thiazole motif. Surprisingly, compound 7d, one of the derivatives of dioxolane analogs, displayed the most potent inhibitory activity with an IC 50 of 0.90μM. Further studies on metabolic stability and bioactivation potential were also accomplished. Copyright © 2017 Elsevier Ltd. All rights reserved.

Constituents of PG201 (Layla(®)), a multi-component phytopharmaceutical, with inhibitory activity on LPS-induced nitric oxide and prostaglandin E2 productions in macrophages.

PubMed

Kim, Hyun Ji; Kim, Hye Mi; Ryu, Byeol; Lee, Woo-Seok; Shin, Ji-Sun; Lee, Kyung-Tae; Jang, Dae Sik

2016-02-01

Fourteen compounds, coumarin (1), demethylsuberosin (2), xanthotoxin (3), psoralen (4), decursinol (5), decursin (6), decursinol angelate (7), chikusetsusaponin IVa (8), chikusetsusaponin IVa methyl ester (9), ethyl caffeate (10), syringaresinol (11), cnidilide (12), farnesol (13), and linoleic acid (14), were isolated from phytopharmaceutical PG201 (Layla(®)) by activity-guided fractionation utilizing inhibitory activity on nitric oxide (NO) production in vitro. The isolates 1-14 were evaluated for their inhibitory activity on LPS-induced NO and prostaglandin E2 (PGE2) productions in RAW 264.7 cells. All the compounds except 14 displayed suppressive effects on LPS-induced NO and PGE2 production with IC50 values ranging from 8 to 60 μM. Among these, compound 10 showed the most potent inhibitory effect on NO production from RAW 264.7 cells with an IC50 value of 8.25 μM. Compounds 2, 9, and 10 exhibited high inhibitory effects on PGE2 production with the IC50 values of 9.42, 7.51, and 6.49 μM, respectively. These findings suggest that compounds 2, 9, and 10 are the potential anti-inflammatory active constituents of PG201 and further study may be needed to explain their mechanism of action.

Proteolytic and ACE-inhibitory activities of probiotic yogurt containing non-viable bacteria as affected by different levels of fat, inulin and starter culture.

PubMed

Shakerian, Mansour; Razavi, Seyed Hadi; Ziai, Seyed Ali; Khodaiyan, Faramarz; Yarmand, Mohammad Saeid; Moayedi, Ali

2015-04-01

In this study, the effects of fat (0.5 %, 3.2 % and 5.0 %), inulin (0.0 and 1.0 %) and starter culture (0.0 %, 0.5 %, 1.0 % and 1.5 %) on the angiotensin converting enzyme (ACE)-inhibitory activity of probiotic yogurt containing non-viable bacteria were assessed. Proteolytic activities of bacteria were also investigated. Yogurts were prepared either using a sole yogurt commercial culture including Streptococcus thermophilus and Lactobacillus delbrueckii subs. bulgaricus or bifidobacterium animalis BB-12 and Lactobacillus acidophilus La5 in addition to yogurt culture. Relative degrees of proteolysis were found to be considerably higher in yogurt samples than UHT milk as the control. Both regular and probiotic yogurts showed considerable ACE-inhibitory activities. Results showed that degree of proteolysis was not influenced by different fat contents, while was increased by high concentration of starter culture (1.5 % w/w) and reduced by inulin (1 % w/w). ACE-inhibitory activities of yogurt were also negatively affected by the presence of inulin and high levels of fat (5 % w/w). Moreover, yogurt containing probiotic bacteria showed higher inhibitory against ACE in comparison to the yogurt prepared with non-probiotic strains.

Cholinesterase inhibitory effects of Rhizophora lamarckii, Avicennia officinalis, Sesuvium portulacastrum and Suaeda monica: Mangroves inhabiting an Indian coastal area (Vellar Estuary).

PubMed

Suganthy, Natarajan; Pandian, Shanmugiahthevar Karutha; Devi, Kasi Pandima

2009-06-01

Alzheimer's disease is a progressive neurodegenerative illness accounting for approximately 50% of all types of dementia in elderly people. The only symptomatic treatment proven effective to date is the use of cholinesterase inhibitors to augment surviving cholinergic activity. The purpose of this study is to investigate cholinesterase inhibitory activity of mangroves as an alternative medicine for the treatment of Alzheimer's disease. About nine mangrove plants, which were used as folk medicine in tropical countries, were collected from Parangipettai, Vellar estuary, Tamilnadu, India. Nile Tilapia muscle homogenate was used as source of enzyme. Inhibitory effect of methanolic leaf extract was assessed under in vitro condition by incubating various concentration of the extract with total cholinesterase and butyryl cholinesterase and assessing their residual activities by Ellman's colorimetric method. The results showed that of the nine plants screened Rhizophora lamarckii, Suaeda monica, Avicennia officinalis and Sesuvium portulacastrum showed 50% inhibitory activity to both TChE and BChE at concentrations less than 2 mg/mL when compared to other plant extracts, which was comparable to the standard drug Donepezil. Phytochemical analysis showed the presence of alkaloids in high concentration which might be correlated to its cholinesterase inhibitory activity.

Identification of flavonoids and flavonoid rhamnosides from Rhododendron mucronulatum for. albiflorum and their inhibitory activities against aldose reductase.

PubMed

Mok, So-Youn; Lee, Sanghyun

2013-01-15

To investigate the therapeutic potential of compounds from natural sources, Rhododendron mucronulatum for. albiflorum flowers (RMAF) and R. mucronulatum flowers (RMF) were tested for inhibition of aldose reductase (AR). The methanol extracts of RMAF and RMF exhibited AR inhibitory activities (IC(50) values 1.07 and 1.29 μg/mL, respectively). The stepwise polarity fractions of RMAF were tested for in vitro inhibition of AR from rat lenses. Of these, the ethyl acetate (EtOAc) fraction exhibited AR inhibitory activity (IC(50) 0.15 μg/mL). A chromatography of the active EtOAc fraction of RMAF led to the isolation of six flavonoids, which were identified by spectroscopic analysis as kaempferol (1), afzelin (2), quercetin (3), quercitrin (4), myricetin (5) and myricitrin (6). Compounds 1-6 exhibited high AR inhibitory activity, with IC(50) values of 0.79, 0.31, 0.48, 0.13, 11.92 and 2.67 μg/mL, respectively. HPLC/UV analysis revealed that the major flavonoids of RMAF and RMF are quercitrin (4) and myricitrin (6). Our results suggest that RMAF containing these six flavonoids could be a useful natural source in the development of a novel AR inhibitory agent against diabetic complications. Copyright © 2012 Elsevier Ltd. All rights reserved.

Trypsin inhibitory activity and gel-enhancing effect of sarcoplasmic proteins from common carp.

PubMed

Siriangkanakun, Siriphon; Yongsawatdigul, Jirawat

2012-10-01

Proteinase inhibitory activity of sarcoplasmic protein (SP) extracted from common carp (Cyprinus carpio) muscle and its gel-improving ability were investigated. SPs displayed 89% and 54% inhibitory activity toward trypsin at 40 and 65 °C, respectively. Protein bands with molecular mass of 69, 50, 44, 41, and 35 kDa appeared on trypsin inhibitory activity staining under nonreducing condition when incubated at 40 °C, while 2 protein bands at 54 and 35 kDa were observed at 65 °C. Addition of SP at 0.18 g protein/100 g increased textural properties of threadfin bream surimi gel. However, when SP was added in combination with various CaCl(2) concentrations (0.1% to 0.5%) it did not further improve textural properties as compared to the addition of SP alone. Retention of myosin heavy chain of threadfin bream surimi was greater with the addition of SP. These results indicated that the gel-enhancing effect of common carp SP was due to the inhibitory activity toward endogenous trypsin-like proteinases in threadfin bream surimi. Sarcoplasmic protein from common carp muscle could be used as a functional protein ingredient that minimizes muscle proteolysis and improves textural properties of surimi containing trypsin-like endogenous proteinases. © 2012 Institute of Food Technologists®

The role of cardiac vagal tone and inhibitory control in pre-schoolers' listening comprehension.

PubMed

Scrimin, Sara; Patron, Elisabetta; Florit, Elena; Palomba, Daniela; Mason, Lucia

2017-12-01

This study investigated the role of basal cardiac activity and inhibitory control at the beginning of the school year in predicting oral comprehension at the end of the year in pre-schoolers. Forty-three, 4-year-olds participated in the study. At the beginning of the school year children's electrocardiogram at rest was registered followed by the assessment of inhibitory control as well as verbal working memory and verbal ability. At the end of the year all children were administered a listening comprehension ability measure. A stepwise regression showed a significant effect of basal cardiac vagal tone in predicting listening comprehension together with inhibitory control and verbal ability. These results are among the first to show the predictive role of basal cardiac vagal tone and inhibitory control in pre-schoolers' oral text comprehension, and offer new insight into the association between autonomic regulation of the heart, inhibitory control, and cognitive activity at a young age. © 2017 Wiley Periodicals, Inc.

Evaluation of in vitro aldose reductase inhibitory potential of alkaloidal fractions of Piper nigrum, Murraya koenigii, Argemone mexicana, and Nelumbo nucifera.

PubMed

Gupta, Sakshi; Singh, Nirmal; Jaggi, Amteshwar Singh

2014-05-01

Aldose reductase is primarily involved in development of long-term diabetic complications due to increased polyol pathway activity. The synthetic aldose reductase inhibitors are not very successful clinically. Therefore, the natural sources may be exploited for safer and effective aldose reductase inhibitors. In the present study, the aldose reductase inhibitory potential of hydroalcoholic and alkaloidal extracts of Piper nigrum, Murraya koenigii, Argemone mexicana, and Nelumbo nucifera was evaluated. The hydroalcoholic and alkaloidal extracts of the selected plants were prepared. The different concentrations of hydroalcoholic and alkaloidal extracts of these plants were evaluated for their goat lens aldose reductase inhibitory activity using dl-glyceraldehyde as substrate. The aldose reductase inhibitory potential of extracts was assessed in terms of their IC50 value. Amongst the hydroalcoholic extracts, the highest aldose reductase inhibitory activity was shown by P. nigrum (IC50 value 35.64±2.7 μg/mL) followed by M. koenigii (IC50 value 45.67±2.57 μg/mL), A. mexicana (IC50 value 56.66±1.30 μg/mL), and N. nucifera (IC50 value 59.78±1.32 μg/mL). Among the alkaloidal extracts, highest inhibitory activity was shown by A. mexicana (IC50 value 25.67±1.25 μg/mL), followed by N. nucifera (IC50 value 28.82±1.85 μg/mL), P. nigrum (IC50 value 30.21±1.63 μg/mL), and M. koenigii (IC50 value 35.66±1.64 μg/mL). It may be concluded that the alkaloidal extracts of these plants possess potent aldose reductase inhibitory activity and may be therapeutically exploited in diabetes-related complications associated with increased activity of aldose reductase.

Astrocyte transforming growth factor beta 1 promotes inhibitory synapse formation via CaM kinase II signaling.

PubMed

Diniz, Luan Pereira; Tortelli, Vanessa; Garcia, Matheus Nunes; Araújo, Ana Paula Bérgamo; Melo, Helen M; Silva, Gisele S Seixas da; Felice, Fernanda G De; Alves-Leon, Soniza Vieira; Souza, Jorge Marcondes de; Romão, Luciana Ferreira; Castro, Newton Gonçalves; Gomes, Flávia Carvalho Alcantara

2014-12-01

The balance between excitatory and inhibitory synaptic inputs is critical for the control of brain function. Astrocytes play important role in the development and maintenance of neuronal circuitry. Whereas astrocytes-derived molecules involved in excitatory synapses are recognized, molecules and molecular mechanisms underlying astrocyte-induced inhibitory synapses remain unknown. Here, we identified transforming growth factor beta 1 (TGF-β1), derived from human and murine astrocytes, as regulator of inhibitory synapse in vitro and in vivo. Conditioned media derived from human and murine astrocytes induce inhibitory synapse formation in cerebral cortex neurons, an event inhibited by pharmacologic and genetic manipulation of the TGF-β pathway. TGF-β1-induction of inhibitory synapse depends on glutamatergic activity and activation of CaM kinase II, which thus induces localization and cluster formation of the synaptic adhesion protein, Neuroligin 2, in inhibitory postsynaptic terminals. Additionally, intraventricular injection of TGF-β1 enhanced inhibitory synapse number in the cerebral cortex. Our results identify TGF-β1/CaMKII pathway as a novel molecular mechanism underlying astrocyte control of inhibitory synapse formation. We propose here that the balance between excitatory and inhibitory inputs might be provided by astrocyte signals, at least partly achieved via TGF-β1 downstream pathways. Our work contributes to the understanding of the GABAergic synapse formation and may be of relevance to further the current knowledge on the mechanisms underlying the development of various neurological disorders, which commonly involve impairment of inhibitory synapse transmission. © 2014 Wiley Periodicals, Inc.

Cholinesterases and cell proliferation in "nonstratified" and "stratified" cell aggregates from chicken retina and tectum.

PubMed

Vollmer, G; Layer, P G

1987-12-01

Dissociated single cells from chicken retina or tectum kept in rotation-mediated cell culture aggregate, proliferate and establish a certain degree of histotypical cell-to-cell relationships ("sorting out"), but these systems never form highly laminated aggregates ("nonstratified" R- and T-aggregates). In contrast, a mixture of retinal plus pigment epithelial cells forms highly "stratified" aggregates ("RPE-aggregates", see Vollmer et al. 1984). The present comparative study of "stratified" and "nonstratified" aggregates enables us to investigate the process of cell proliferation uncoupled from that of tissue stratification. Here we try to relate these two basic neurogenetic processes with patterns of expression of cholinesterases (AChE, BChE) during formation of both types of aggregates. During early aggregate formation, in both "stratified" and "nonstratified" aggregates an increased butyrylcholinesterase activity is observed close to mitotically active cells. Quantitatively both phenomena show their maxima after 2-3 days in culture. In contrast, AChE-expression in all systems increases with incubation time. In nonproliferative areas, in the center of RPE-aggregates, the formation of plexiform layers is characterized initially by weak BChE- and then strong AChE-activity. These areas correspond with the inner (IPL) and outer (OPL) plexiform layers of the retina in vivo. Although by sucrose gradient centrifugation we find that the 6S- and the fiber-associated 11S-molecules of AChE are present in all types of aggregates, during the culture period the ratio of 11S/6S-forms increases only in RPE-aggregates, which again indicates the advanced degree of differentiation within these aggregates.(ABSTRACT TRUNCATED AT 250 WORDS)

Lack of inhibitory effect of acetylsalicylic acid and meloxicam on whole blood platelet aggregation in cats.

PubMed

Cathcart, Curtis J; Brainard, Benjamin M; Reynolds, Lisa R; Al-Nadaf, Sami; Budsberg, Steven C

2012-02-01

To determine the effects of acetylsalicylic acid (ASA) and meloxicam on feline platelet aggregation and associated platelet thromboxane production and serotonin release. Prospective interventional study. University research facility. Eight healthy male castrated domestic short hair cats from a research colony. Oral medications were administered to 8 cats for 14 days in a randomized, placebo-controlled, crossover design. Treatment groups included: aspirin (ASA) (5 mg/kg q 48 h), meloxicam (0.05 mg/kg q 24 h), and placebo (0.5 mL of water q 24 h). Thromboxane assays (TXB(2) ) and whole blood (impedance) aggregometry (WBA) were performed on samples collected before drug administration, and on days 7, 15, and 17, using adenosine diphosphate (ADP; 10 μM) and collagen (5 μg/mL) as agonists for WBA. Serotonin release was assayed on postaggregation plasma. Oral mucosal bleeding time (OMBT) and complete blood cell counts were measured on days 0 and 15. Neither medication affected WBA at any time point. OMBT decreased in the ASA group relative to baseline. No differences were detected in WBA and OMBT baseline between any groups. No difference was detected in serotonin secretion at any time point. TXB(2) was significantly decreased in the ASA group at all times after initiation of treatment but no change was noted in the meloxicam or placebo groups. At the doses studied, neither meloxicam nor ASA had an inhibitory effect on WBA or OMBT in cats. Thromboxane concentrations were significantly decreased with ASA treatment. © Veterinary Emergency and Critical Care Society 2011.

Transepithelial transport across Caco-2 cell monolayers of angiotensin converting enzyme (ACE) inhibitory peptides derived from simulated in vitro gastrointestinal digestion of cooked chicken muscles.

PubMed

Sangsawad, Papungkorn; Roytrakul, Sittiruk; Choowongkomon, Kiattawee; Kitts, David D; Chen, Xiu-Min; Meng, Guangtao; Li-Chan, Eunice C Y; Yongsawatdigul, Jirawat

2018-06-15

Korat-chicken breast and thigh were subjected to heating at 70, 100 or 121 °C for 30 min and simulated in vitro gastrointestinal digestion. At 70 or 100 °C heating, digests of breast possessed higher ACE inhibitory activity than those of thigh. The highest ACE inhibitory activity was found in the digest of breast cooked at 70 °C (B/H-70), whereas breast heated at 121 °C (B/H-121) exhibited the lowest. The 1-kDa permeate of the B/H-70 digest revealed higher permeability through colorectal adenocarcinoma monolayers and ACE inhibitory activity than did B/H-121. Among nine transported peptides, APP derived from myosin showed the highest ACE inhibition, with a non-competitive characteristic (K i 0.93 μM). Molecular docking showed that APP interacts with ACE via hydrogen bonds, electrostatic and van der Waals interactions. In conclusion, mild thermal treatment of chicken breast resulted in a higher amount of transported peptides, exerting higher ACE inhibitory activity, which could lead to potential health benefits. Copyright © 2018 Elsevier Ltd. All rights reserved.

Improving the acetylcholinesterase inhibitory effect of Illigera henryi by solid-state fermentation with Clonostachys rogersoniana.

PubMed

Li, Xue-Jiao; Dong, Jian-Wei; Cai, Le; Mei, Rui-Feng; Ding, Zhong-Tao

2017-11-01

Illigera henryi, an endemic traditional Chinese medicine, contains abundant aporphine alkaloids that possess various bioactivities. In the present study, tubers of I. henryi were fermented by several fungi, and the acetylcholinesterase (AChE) inhibitory activities of non-fermented and fermented I. henryi were measured. The results showed that the fermentation of I. henryi with Clonostachys rogersoniana 828H2 is effective for improving the AChE inhibitory activity. A key biotransformation was found during the C. rogersoniana fermentation for clarifying the improvement of the AChE inhibitory activity of I. henryi: (S)-actinodaphnine (1) was converted to a new 4-hydroxyaporphine alkaloid (4R,6aS)-4-hydroxyactinodaphnine (2) that possessed a stronger AChE inhibitory activity, with an IC 50 value of 17.66±0.06 μM. This paper is the first to report that the pure strain fermentation processing of I. henryi and indicated C. rogersoniana fermentation might be a potential processing method for I. henryi. Copyright © 2017 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

[Based on Curing Age of Calcined Coal Gangue Fine Aggregate Mortar of X-Ray Diffraction and Scanning Electron Microscopy Analysis].

PubMed

Dong, Zuo-chao; Xia, Jun-wu; Duan, Xiao-mu; Cao, Ji-chang

2016-03-01

By using X-ray diffraction (XRD) and environmental scanning electron microscope (SEM) analysis method, we stud- ied the activity of coal gangue fine aggregate under different calcination temperature. In view of the activity of the highest-700 degrees C high temperature calcined coal gangue fine aggregate mortar of hydration products, microstructure and strength were discussed in this paper, and the change laws of mortar strength with curing age (3, 7, 14, 28, 60 and 90 d) growth were analyzed. Test results showed that coal gangue fine aggregate with the increase of calcination temperature, the active gradually increases. When the calcination temperature reaches 700 degrees C, the activity of coal gangue fine aggregate is the highest. When calcining temperature continues to rise, activity falls. After 700 degrees C high temperature calcined coal gangue fine aggregate has obvious ash activity, the active components of SiO2 and Al2 O3 can be with cement hydration products in a certain degree of secondary hydration reaction. Through on the top of the activity of different curing age 700 degrees C high temperature calcined coal gangue fine aggregate mortar, XRD and SEM analysis showed that with the increase of curing age, secondary hydration reaction will be more fully, and the amount of hydration products also gradually increases. Compared with the early ages of the cement mortar, the products are more stable hydration products filling in mortar microscopic pore, which can further improve the microstructure of mortar, strengthen the interface performance of the mortar. The mortar internal structure is more uniform, calcined coal gangue fine aggregate and cement mortar are more of a strong continuous whole, which increase the later strength of hardened cement mortar, 700 degrees C high temperature calcined coal gangue fine aggregate pozzolanic effect is obvious.

Aqueous extracts of Roselle (Hibiscus sabdariffa Linn.) varieties inhibit α-amylase and α-glucosidase activities in vitro.

PubMed

Ademiluyi, Adedayo O; Oboh, Ganiyu

2013-01-01

This study sought to investigate the inhibitory effect of aqueous extracts of two varieties (red and white) of Hibiscus sabdariffa (Roselle) calyces on carbohydrate hydrolyzing enzymes (α-amylase and α-glucosidase), with the aim of providing the possible mechanism for their antidiabetes properties. Aqueous extracts were prepared (1:100 w/v) and the supernatant used for the analysis. The extracts caused inhibition of α-amylase and α-glucosidase activities in vitro.The IC(50) revealed that the red variety (25.2 μg/mL) exhibited higher α-glucosidase inhibitory activity than the white variety (47.4 μg/mL), while the white variety (90.5 μg/mL) exhibited higher α-amylase inhibitory activity than the red variety (187.9 μg/mL). However, the α-glucosidase inhibitory activities of both calyces were higher than that of their α-amylase. In addition, the red variety possessed higher antioxidant capacity as exemplified by the (•)OH scavenging abilities, Fe(2+) chelating ability, and inhibition of Fe(2+)-induced pancreatic lipid peroxidation in vitro. The enzyme inhibitory activities and antioxidant properties of the roselle extracts agreed with their phenolic content. Hence, inhibition of α-amylase and α-glucosidase, coupled with strong antioxidant properties could be the possible underlying mechanism for the antidiabetes properties of H. sabdariffa calyces; however, the red variety appeared to be more potent.

Variation in Phenolics, Flavanoids, Antioxidant and Tyrosinase Inhibitory Activity of Peach Blossoms at Different Developmental Stages.

PubMed

Liu, Jie-Chao; Jiao, Zhong-Gao; Yang, Wen-Bo; Zhang, Chun-Ling; Liu, Hui; Lv, Zhen-Zhen

2015-11-18

Peach blossoms were harvested and classified into six developmental stages: (I) bud emerging stage; (II) middle bud stage; (III) large bud stage; (IV) initial-flowering stage; (V) full-flowering stage; and (VI) end-flowering stage. The contents of total phenolics, flavanoids, individual phenolic compounds as well as antioxidant and tyrosinase inhibitory activity of peach blossoms at different developmental stages were investigated. The total phenolic contents varied from 149.80 to 74.80 mg chlorogenic acid equivalents/g dry weight (DW), and the total flavanoid contents ranged from 93.03 to 44.06 mg rutin equivalents/g DW. Both the contents of total phenolics and flavanoids decreased during blossom development. Chlorogenic acid was the predominant component, accounting for 62.08%-71.09% of the total amount of identified phenolic compounds in peach blossom. The antioxidant capacities determined by different assays and tyrosinase inhibitory activity also showed descending patterns during blossom development. Significant correlations were observed between antioxidant capacities with contents of total phenolics and total flavanoids as well as chlorogenic acid, cinnamic acid and kaempferol-3-O-galactoside, while the tyrosinase inhibitory activity had lower correlations with total phenolics and total flavanoids as well as chlorogenic acid, quercetin-3-O-rhamnoside, kaempferol-3-O-galactoside and cinnamic acid. The antioxidant activities of peach blossom seemed to be more dependent on the phenolic compounds than tyrosinase inhibitory activity.

Two antibacterial C-type lectins from crustacean, Eriocheir sinensis, stimulated cellular encapsulation in vitro.

PubMed

Jin, Xing-Kun; Li, Shuang; Guo, Xiao-Nv; Cheng, Lin; Wu, Min-Hao; Tan, Shang-Jian; Zhu, You-Ting; Yu, Ai-Qing; Li, Wei-Wei; Wang, Qun

2013-12-01

The first step of host fighting against pathogens is that pattern recognition receptors recognized pathogen-associated molecular patterns. However, the specificity of recognition within the innate immune molecular of invertebrates remains largely unknown. In the present study, we investigated how invertebrate pattern recognition receptor (PRR) C-type lectins might be involved in the antimicrobial response in crustacean. Based on our previously obtained completed coding regions of EsLecA and EsLecG in Eriocheir sinensis, the recombinant EsLectin proteins were produced via prokaryotic expression system and affinity chromatography. Subsequently, both rEsLecA and rEsLecG were discovered to have wide spectrum binding activities towards microorganisms, and their microbial-binding was calcium-independent. Moreover, the binding activities of both rEsLecA and rEsLecG induced the aggregation against microbial pathogens. Both microorganism growth inhibitory activities assays and antibacterial activities assays revealed their capabilities of suppressing microorganisms growth and directly killing microorganisms respectively. Furthermore, the encapsulation assays signified that both rEsLecA and rEsLecG could stimulate the cellular encapsulation in vitro. Collectively, data presented here demonstrated the successful expression and purification of two C-type lectins proteins in the Chinese mitten crab, and their critical role in the innate immune system of an invertebrate. Copyright © 2013 Elsevier Ltd. All rights reserved.

Sensory Regulation of Network Components Underlying Ciliary Locomotion in Hermissenda

PubMed Central

Crow, Terry; Tian, Lian-Ming

2008-01-01

Ciliary locomotion in the nudibranch mollusk Hermissenda is modulated by the visual and graviceptive systems. Components of the neural network mediating ciliary locomotion have been identified including aggregates of polysensory interneurons that receive monosynaptic input from identified photoreceptors and efferent neurons that activate cilia. Illumination produces an inhibition of type Ii (off-cell) spike activity, excitation of type Ie (on-cell) spike activity, decreased spike activity in type IIIi inhibitory interneurons, and increased spike activity of ciliary efferent neurons. Here we show that pairs of type Ii interneurons and pairs of type Ie interneurons are electrically coupled. Neither electrical coupling or synaptic connections were observed between Ie and Ii interneurons. Coupling is effective in synchronizing dark-adapted spontaneous firing between pairs of Ie and pairs of Ii interneurons. Out-of-phase burst activity, occasionally observed in dark-adapted and light-adapted pairs of Ie and Ii interneurons, suggests that they receive synaptic input from a common presynaptic source or sources. Rhythmic activity is typically not a characteristic of dark-adapted, light-adapted, or light-evoked firing of type I interneurons. However, burst activity in Ie and Ii interneurons may be elicited by electrical stimulation of pedal nerves or generated at the offset of light. Our results indicate that type I interneurons can support the generation of both rhythmic activity and changes in tonic firing depending on sensory input. This suggests that the neural network supporting ciliary locomotion may be multifunctional. However, consistent with the nonmuscular and nonrhythmic characteristics of visually modulated ciliary locomotion, type I interneurons exhibit changes in tonic activity evoked by illumination. PMID:18768639

Effects of temperature and medium composition on inhibitory activities of gossypol-related compounds against aflatoxigenic fungi.

PubMed

Mellon, J E; Dowd, M K; Beltz, S B

2013-07-01

To investigate the effects of temperature and medium composition on growth/aflatoxin inhibitory activities of terpenoids gossypol, gossypolone and apogossypolone against Aspergillus flavus and A. parasiticus. The compounds were tested at a concentration of 100 μg ml(-1) in a Czapek Dox (Czapek) agar medium at 25, 31 and 37°C. Increased incubation temperature marginally increased growth inhibition caused by these compounds, but reduced the aflatoxin inhibition effected by gossypol. Gossypolone and apogossypolone retained good aflatoxin inhibitory activity against A. flavus and A. parasiticus at higher incubation temperatures. However, increased temperature also significantly reduced aflatoxin production in control cultures. The effects of the terpenoids on fungal growth and aflatoxin production against the same fungi were also determined in Czapek, Czapek with a protein/amino acid addendum and yeast extract sucrose (YES) media. Growth of these fungi in the protein-supplemented Czapek medium or in the YES medium greatly reduced the growth inhibition effects of the terpenoids. Apogossypolone displayed strong anti-aflatoxigenic activity in the Czapek medium, but this activity was significantly reduced in the protein-amended Czapek and YES media. Gossypol, which displayed little to no aflatoxin inhibitory activity in the Czapek medium, did yield significant anti-aflatoxigenic activity in the YES medium. Incubation temperature and media composition are important parameters involved in the regulation of aflatoxin production in A. flavus and A. parasiticus. These parameters also affect the potency of growth and aflatoxin inhibitory activities of these gossypol-related compounds against aflatoxigenic fungi. Studies utilizing gossypol-related compounds as inhibitory agents of biological activities should be interpreted with caution due to compound interaction with multiple components of the test system, especially serum proteins. Published [2013]. This article is a U.S. Government work and is in the public domain in the USA.

NPP4 is a procoagulant enzyme on the surface of vascular endothelium

PubMed Central

Albright, Ronald A.; Chang, William C.; Robert, Donna; Ornstein, Deborah L.; Cao, Wenxiang; Liu, Lynn; Redick, Meredith E.; Young, J. Isaac; De La Cruz, Enrique M.

2012-01-01

Ap3A is a platelet-dense granule component released into the extracellular space during the second wave of platelet aggregation on activation. Here, we identify an uncharacterized enzyme, nucleotide pyrophosphatase/phosphodiesterase-4 (NPP4), as a potent hydrolase of Ap3A capable of stimulating platelet aggregation and secretion. We demonstrate that NPP4 is present on the surface of vascular endothelium, where it hydrolyzes Ap3A into AMP and ADP, and Ap4A into AMP and ATP. Platelet aggregation assays with citrated platelet-rich plasma reveal that the primary and secondary waves of aggregation and dense granule release are strongly induced by nanomolar NPP4 in a concentration-dependent manner in the presence of Ap3A, while Ap3A alone initiates a primary wave of aggregation followed by rapid disaggregation. NPP2 and an active site NPP4 mutant, neither of which appreciably hydrolyzes Ap3A, have no effect on platelet aggregation and secretion. Finally, by using ADP receptor blockade we confirm that NPP4 mediates platelet aggregation via release of ADP from Ap3A and activation of ADP receptors. Collectively, these studies define the biologic and enzymatic basis for NPP4 and Ap3A activity in platelet aggregation in vitro and suggest that NPP4 promotes hemostasis in vivo by augmenting ADP-mediated platelet aggregation at the site of vascular injury. PMID:22995898

Spice phenolics inhibit human PMNL 5-lipoxygenase.

PubMed

Prasad, N Satya; Raghavendra, R; Lokesh, B R; Naidu, K Akhilender

2004-06-01

A wide variety of phenolic compounds and flavonoids present in spices possess potent antioxidant, antimutagenic and anticarcinogenic activities. We examined whether 5-lipoxygenase (5-LO), the key enzyme involved in biosynthesis of leukotrienes is a possible target for the spices. Effect of aqueous extracts of turmeric, cloves, pepper, chili, cinnamon, onion and also their respective active principles viz., curcumin, eugenol, piperine, capsaicin, cinnamaldehyde, quercetin, and allyl sulfide were tested on human PMNL 5-LO activity by spectrophotomeric and HPLC methods. The formation of 5-LO product 5-HETE was significantly inhibited in a concentration-dependent manner with IC(50) values of 0.122-1.44 mg for aqueous extracts of spices and 25-83 microM for active principles, respectively. The order of inhibitory activity was of quercetin>eugenol>curcumin>cinnamaldehyde>piperine>capsaicin>allyl sulfide. Quercetin, eugenol and curcumin with one or more phenolic ring and methoxy groups in their structure showed high inhibitory effect, while the non-phenolic spice principle allyl sulfide showed least inhibitory effect on 5-LO. The inhibitory effect of quercetin, curcumin and eugenol was similar to that of synthetic 5-LO inhibitors-phenidone and NDGA. Moreover, the inhibitory potency of aqueous extracts of spice correlated with the active principles of their respective spices. The synergistic or antagonistic effect of mixtures of spice active principles and spice extracts were investigated and all the combinations of spice active principles/extracts exerted synergistic effect in inhibiting 5-LO activity. These findings clearly suggest that phenolic compounds present in spices might have physiological role in modulating 5-LO pathway.

Inhibitory control and adaptive behaviour in children with mild intellectual disability.

PubMed

Gligorović, M; Buha Ðurović, N

2014-03-01

Inhibitory control, as one of the basic mechanisms of executive functions, is extremely important for adaptive behaviour. The relation between inhibitory control and adaptive behaviour is the most obvious in cases of behavioural disorders and psychopathology. Considering the lack of studies on this relation in children with disabilities, the aim of our research is to determine the relation between inhibitory control and adaptive behaviour in children with mild intellectual disability. The sample consists of 53 children with mild intellectual disability. Selection criteria were: IQ between 50 and 70, age between 10 and 14, absence of bilingualism, and with no medical history of neurological impairment, genetic and/or emotional problems. Modified Day-Night version of the Stroop task, and Go-no-Go Tapping task were used for the assessment of inhibitory control. Data on adaptive behaviour were obtained by applying the first part of AAMR (American Association on Mental Retardation) Adaptive Behaviour Scale-School, Second Edition (ABS-S:2). Significant relationships were determined between some aspects of inhibitory control and the most of assessed domains of adaptive behaviour. Inhibitory control measures, as a unitary inhibition model, significantly predict results on Independent Functioning, Economic Activity, Speech and Language Development, and Number and Times domains of the ABS-S:2. Inhibitory control, assessed by second part of the Stroop task, proved to be a significant factor in practical (Independent Functioning) and conceptual (Economic Activity, Speech and Language Development, and Numbers and Time) adaptive skills. The first part of the Stroop task, as a measure of selective attention, proved to be a significant factor in language and numerical demands, along with second one. Inhibitory control through motor responses proved to be a significant factor in independent functioning, economic activities, language and self-direction skills. We can conclude that inhibitory control represents a significant developmental factor of different adaptive behaviour domains in children with mild intellectual disability. © 2012 The Authors. Journal of Intellectual Disability Research © 2012 John Wiley & Sons Ltd, MENCAP & IASSIDD.

Compounds from the aerial parts of Piper bavinum and their anti-cholinesterase activity.

PubMed

Dung, Hoang Viet; Cuong, To Dao; Chinh, Nguyen Minh; Quyen, Do; Kim, Jeong Ah; Byeon, Jeong Su; Woo, Mi Hee; Choi, Jae Sui; Min, Byung Sun

2015-01-01

A new alkenylphenol, bavinol A (1), together with six known compounds (2-7) were isolated from the aerial parts of Piper bavinum (Piperaceae). The chemical structures of these compounds were determined by spectroscopic analyses including 2D NMR spectroscopy. The anti-Alzheimer effects of compounds 1-7 were evaluated from acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitory activity assays. Bavinol A (1), ampelopsin (3), and violanthin (4) exhibited AChE inhibitory activities with IC50 values of 29.80, 59.47 and 79.80 μM. Compound 1 also showed the most potent BChE inhibitory activity with an IC50 value of 19.25 μM.

Triterpenoid saponins from the rhizomes of Anemone flaccida and their inhibitory activities on LPS-induced NO production in macrophage RAW264.7 cells.

PubMed

Huang, Xiao-Jun; Tang, Jing-Qun; Li, Man-Mei; Liu, Qing; Li, Yao-Lan; Fan, Chun-Lin; Pei, Hong; Zhao, Hui-Nan; Wang, Ying; Ye, Wen-Cai

2014-01-01

A new ursane-type triterpenoid saponin, flaccidoside IV (1), and three new oleanane-type triterpenoid saponins, flaccidosides V-VII (2-4), along with 17 known saponins (5-21), were isolated from the rhizomes of Anemone flaccida. The structures of the new triterpenoid saponins were determined based on spectroscopic analyses and chemical methods. All the isolated saponins were tested for their inhibitory activities on lipopolysaccharide-induced nitric oxide production in RAW264.7 macrophages, and several bisdesmosidic oleanane-type triterpenoid saponins (2, 7, and 10) showed significant inhibitory activities, which indicated they had potential anti-inflammatory activities under their noncytotoxic concentrations in vitro.

Biological evaluation and 3D-QSAR studies of curcumin analogues as aldehyde dehydrogenase 1 inhibitors.

PubMed

Wang, Hui; Du, Zhiyun; Zhang, Changyuan; Tang, Zhikai; He, Yan; Zhang, Qiuyan; Zhao, Jun; Zheng, Xi

2014-05-16

Aldehyde dehydrogenase 1 (ALDH1) is reported as a biomarker for identifying some cancer stem cells, and down-regulation or inhibition of the enzyme can be effective in anti-drug resistance and a potent therapeutic for some tumours. In this paper, the inhibitory activity, mechanism mode, molecular docking and 3D-QSAR (three-dimensional quantitative structure activity relationship) of curcumin analogues (CAs) against ALDH1 were studied. Results demonstrated that curcumin and CAs possessed potent inhibitory activity against ALDH1, and the CAs compound with ortho di-hydroxyl groups showed the most potent inhibitory activity. This study indicates that CAs may represent a new class of ALDH1 inhibitor.

Lysosomal enzyme cathepsin B enhances the aggregate forming activity of exogenous α-synuclein fibrils.

PubMed

Tsujimura, Atsushi; Taguchi, Katsutoshi; Watanabe, Yoshihisa; Tatebe, Harutsugu; Tokuda, Takahiko; Mizuno, Toshiki; Tanaka, Masaki

2015-01-01

The formation of intracellular aggregates containing α-synuclein (α-Syn) is one of the key steps in the progression of Parkinson's disease and dementia with Lewy bodies. Recently, it was reported that pathological α-Syn fibrils can undergo cell-to-cell transmission and form Lewy body-like aggregates. However, little is known about how they form α-Syn aggregates from fibril seeds. Here, we developed an assay to study the process of aggregate formation using fluorescent protein-tagged α-Syn-expressing cells and examined the aggregate forming activity of exogenous α-Syn fibrils. α-Syn fibril-induced formation of intracellular aggregates was suppressed by a cathepsin B specific inhibitor, but not by a cathepsin D inhibitor. α-Syn fibrils pretreated with cathepsin B in vitro enhanced seeding activity in cells. Knockdown of cathepsin B also reduced fibril-induced aggregate formation. Moreover, using LAMP-1 immunocytochemistry and live-cell imaging, we observed that these aggregates initially occurred in the lysosome. They then rapidly grew larger and moved outside the boundary of the lysosome within one day. These results suggest that the lysosomal protease cathepsin B is involved in triggering intracellular aggregate formation by α-Syn fibrils. Copyright © 2015. Published by Elsevier Inc.

Soil aggregate mediates the impacts of land uses on organic carbon, total nitrogen, and microbial activity in a Karst ecosystem

NASA Astrophysics Data System (ADS)

Xiao, Shuangshuang; Zhang, Wei; Ye, Yingying; Zhao, Jie; Wang, Kelin

2017-02-01

Understanding the effect of land use on soil carbon, nitrogen, and microbial activity associated with aggregates is critical for thorough comprehension of the C and N dynamics of karst landscapes/ecosystems. We monitored soil organic carbon (SOC), total nitrogen (TN), microbial biomass carbon (MBC), and Cmic: Corg ratio in large macro- (>2 mm), small macro- (0.25-2 mm), and micro- (0.053-0.25 mm) aggregates to determine the changes in soil properties under different land uses in the karst area of Southwest China. Five common land-use types—enclosure land (natural system, control), prescribed-burning land, fuel-wood shrubland, pasture and maize fields—were selected. Results showed that pasture and maize fields remarkably decreased the SOC and TN concentrations in aggregates. Conversion of natural system to other land uses decreased MBC (except for prescribed-burning) and increased Cmic: Corg ratios in aggregates. The extent of the response to land uses of SOC and TN concentrations was similar whereas that of MBC and Cmic: Corg ratios differed across the three aggregate sizes. Further, the SOC concentrations were significantly higher in macro-aggregates than micro-aggregates; the MBC and Cmic: Corg ratios were highest in small macro-aggregates. Therefore, small macro-aggregates might have more active C dynamics.

Correlation Between Monoamine Oxidase Inhibitors and Anticonvulsants

PubMed Central

Dwivedi, Chandradhar; Misra, Radhey S.; Chaudhari, Anshumali; Parmar, Surendra S.

1980-01-01

Monoamine oxidase inhibitory and anticonvulsant properties of 2-substituted styryl-6-bromo-3-(4-ethylbenzoate/4 benzhydrazide)-4-quinazoles are studied. All styryl quinazolone esters except compound number 9 exhibited monoamine oxidase inhibitory properties during oxidative deamination of kynuramine. Corresponding hydrazides were found to have relatively higher activity. All these quinazolones were able to protect against pentylenetetrazol induced seizures. These observations in general do not prove that monoamine oxidase inhibitory properties represent the biochemical basis for the anticonvulsant activity of these compounds. PMID:7420438

Identification of crypto- and neochlorogenic lactones as potent xanthine oxidase inhibitors in roasted coffee beans.

PubMed

Honda, Sari; Miura, Yukari; Masuda, Akiko; Masuda, Toshiya

2014-01-01

Xanthine oxidase (XO) inhibitory activity has been found in boiling water extracts from roasted coffee beans. Therefore, assay-guided purification of the extracts was performed using size-exclusion column chromatography, and subsequently with reversed phase HPLC to afford lactone derivatives of chlorogenic acids. Among the tested lactones, crypto- and neochlorogenic lactones showed potent XO inhibitory activities compared with three major chlorogenic acids found in coffee beans. These XO inhibitory lactones may ameliorate gout and hyperuricemia in humans who drink coffee.

Prefrontal Cortex Activation and Young Driver Behaviour: A fNIRS Study

PubMed Central

Foy, Hannah J.; Runham, Patrick; Chapman, Peter

2016-01-01

Road traffic accidents consistently show a significant over-representation for young, novice and particularly male drivers. This research examines the prefrontal cortex activation of young drivers and the changes in activation associated with manipulations of mental workload and inhibitory control. It also considers the explanation that a lack of prefrontal cortex maturation is a contributing factor to the higher accident risk in this young driver population. The prefrontal cortex is associated with a number of factors including mental workload and inhibitory control, both of which are also related to road traffic accidents. This experiment used functional near infrared spectroscopy to measure prefrontal cortex activity during five simulated driving tasks: one following task and four overtaking tasks at varying traffic densities which aimed to dissociate workload and inhibitory control. Age, experience and gender were controlled for throughout the experiment. The results showed that younger drivers had reduced prefrontal cortex activity compared to older drivers. When both mental workload and inhibitory control increased prefrontal cortex activity also increased, however when inhibitory control alone increased there were no changes in activity. Along with an increase in activity during overtaking manoeuvres, these results suggest that prefrontal cortex activation is more indicative of workload in the current task. There were no differences in the number of overtakes completed by younger and older drivers but males overtook significantly more than females. We conclude that prefrontal cortex activity is associated with the mental workload required for overtaking. We additionally suggest that the reduced activation in younger drivers may be related to a lack of prefrontal maturation which could contribute to the increased crash risk seen in this population. PMID:27227990

Microbial community dynamics in soil aggregates shape biogeochemical gas fluxes from soil profiles - upscaling an aggregate biophysical model.

PubMed

Ebrahimi, Ali; Or, Dani

2016-09-01

Microbial communities inhabiting soil aggregates dynamically adjust their activity and composition in response to variations in hydration and other external conditions. These rapid dynamics shape signatures of biogeochemical activity and gas fluxes emitted from soil profiles. Recent mechanistic models of microbial processes in unsaturated aggregate-like pore networks revealed a highly dynamic interplay between oxic and anoxic microsites jointly shaped by hydration conditions and by aerobic and anaerobic microbial community abundance and self-organization. The spatial extent of anoxic niches (hotspots) flicker in time (hot moments) and support substantial anaerobic microbial activity even in aerated soil profiles. We employed an individual-based model for microbial community life in soil aggregate assemblies represented by 3D angular pore networks. Model aggregates of different sizes were subjected to variable water, carbon and oxygen contents that varied with soil depth as boundary conditions. The study integrates microbial activity within aggregates of different sizes and soil depth to obtain estimates of biogeochemical fluxes from the soil profile. The results quantify impacts of dynamic shifts in microbial community composition on CO2 and N2 O production rates in soil profiles in good agreement with experimental data. Aggregate size distribution and the shape of resource profiles in a soil determine how hydration dynamics shape denitrification and carbon utilization rates. Results from the mechanistic model for microbial activity in aggregates of different sizes were used to derive parameters for analytical representation of soil biogeochemical processes across large scales of practical interest for hydrological and climate models. © 2016 John Wiley & Sons Ltd.

Plant-mediated effects on extracellular enzyme activities in distinct soil aggregate size classes in field

NASA Astrophysics Data System (ADS)

Kumar, Amit; Dorodnikov, Maxim; Splettstößer, Thomas; Kuzyakov, Yakov; Pausch, Johanna

2017-04-01

Soil aggregation and microbial activities within the aggregates are important factors regulating soil carbon (C) turnover. A reliable and sensitive proxy for microbial activity is activity of extracellular enzymes (EEA). In the present study, effects of soil aggregates on EEA were investigated under three maize plant densities (Low, Normal, and High). Bulk soil was fractionated into three aggregate size classes (>2000 µm large macroaggregates; 2000-250 µm small macroaggregates; <250 µm microaggregates) by optimal-moisture sieving. Microbial biomass and EEA (β-1,4-glucosidase (BG), β-1,4-N-acetylglucosaminidase (NAG), L-leucine aminopeptidase (LAP) and acid phosphatase (acP)) catalyzing soil organic matter (SOM) decomposition were measured in rooted soil of maize and soil from bare fallow. Microbial biomass C (Cmic) decreased with decreasing aggregate size classes. Potential and specific EEA (per unit of Cmic) increased from macro- to microaggregates. In comparison with bare fallow soil, specific EEA of microaggregates in rooted soil was higher by up to 73%, 31%, 26%, and 92% for BG, NAG, acP and LAP, respectively. Moreover, high plant density decreased macroaggregates by 9% compared to bare fallow. Enhanced EEA in three aggregate size classes demonstrated activation of microorganisms by roots. Strong EEA in microaggregates can be explained by microaggregates' localization within the soil. Originally adhering to surfaces of macroaggregates, microaggregates were preferentially exposed to C substrates and nutrients, thereby promoting microbial activity.

Dieckol, a phlorotannin isolated from a brown seaweed, Ecklonia cava, inhibits adipogenesis through AMP-activated protein kinase (AMPK) activation in 3T3-L1 preadipocytes.

PubMed

Ko, Seok-Chun; Lee, Myoungsook; Lee, Ji-Hyeok; Lee, Seung-Hong; Lim, Yunsook; Jeon, You-Jin

2013-11-01

In this study, we assessed the potential inhibitory effect of 5 species of brown seaweeds on adipogenesis the differentiation of 3T3-L1 preadipocytes into mature adipocytes by measuring Oil-Red O staining. The Ecklonia cava extract tested herein evidenced profound adipogenesis inhibitory effect, compared to that exhibited by the other four brown seaweed extracts. Thus, E. cava was selected for isolation of active compounds and finally the three polyphenol compounds of phlorotannins were obtained and their inhibitory effect on adipogenesis was observed. Among the phlorotannins, dieckol exhibited greatest potential adipogenesis inhibition and down-regulated the expression of peroxisome proliferator-activated receptor-γ (PPARγ), CCAAT/enhancer-binding proteins (C/EBPα), sterol regulatory element-binding protein 1 (SREBP1) and fatty acid binding protein 4 (FABP4) in a dose-dependent manner. The specific mechanism mediating the effects of dieckol was confirmed by AMP-activated protein kinase (AMPK) activation. These results demonstrate inhibitory effect of dieckol compound on adipogenesis through the activation of the AMPK signal pathway. Copyright © 2013 Elsevier B.V. All rights reserved.

Three cyanobacteriochromes work together to form a light color-sensitive input system for c-di-GMP signaling of cell aggregation.

PubMed

Enomoto, Gen; Ni-Ni-Win; Narikawa, Rei; Ikeuchi, Masahiko

2015-06-30

Cyanobacteriochromes (CBCRs) are cyanobacterial photoreceptors that have diverse spectral properties and domain compositions. Although large numbers of CBCR genes exist in cyanobacterial genomes, no studies have assessed whether multiple CBCRs work together. We recently showed that the diguanylate cyclase (DGC) activity of the CBCR SesA from Thermosynechococcus elongatus is activated by blue-light irradiation and that, when irradiated, SesA, via its product cyclic dimeric GMP (c-di-GMP), induces aggregation of Thermosynechococcus vulcanus cells at a temperature that is suboptimum for single-cell viability. For this report, we first characterize the photobiochemical properties of two additional CBCRs, SesB and SesC. Blue/teal light-responsive SesB has only c-di-GMP phosphodiesterase (PDE) activity, which is up-regulated by teal light and GTP. Blue/green light-responsive SesC has DGC and PDE activities. Its DGC activity is enhanced by blue light, whereas its PDE activity is enhanced by green light. A ΔsesB mutant cannot suppress cell aggregation under teal-green light. A ΔsesC mutant shows a less sensitive cell-aggregation response to ambient light. ΔsesA/ΔsesB/ΔsesC shows partial cell aggregation, which is accompanied by the loss of color dependency, implying that a nonphotoresponsive DGC(s) producing c-di-GMP can also induce the aggregation. The results suggest that SesB enhances the light color dependency of cell aggregation by degrading c-di-GMP, is particularly effective under teal light, and, therefore, seems to counteract the induction of cell aggregation by SesA. In addition, SesC seems to improve signaling specificity as an auxiliary backup to SesA/SesB activities. The coordinated action of these three CBCRs highlights why so many different CBCRs exist.

Feedbacks Between Soil Structure and Microbial Activities in Soil

NASA Astrophysics Data System (ADS)

Bailey, V. L.; Smith, A. P.; Fansler, S.; Varga, T.; Kemner, K. M.; McCue, L. A.

2017-12-01

Soil structure provides the physical framework for soil microbial habitats. The connectivity and size distribution of soil pores controls the microbial access to nutrient resources for growth and metabolism. Thus, a crucial component of soil research is how a soil's three-dimensional structure and organization influences its biological potential on a multitude of spatial and temporal scales. In an effort to understand microbial processes at scale more consistent with a microbial community, we have used soil aggregates as discrete units of soil microbial habitats. Our research has shown that mean pore diameter (x-ray computed tomography) of soil aggregates varies with the aggregate diameter itself. Analyzing both the bacterial composition (16S) and enzyme activities of individual aggregates showed significant differences in the relative abundances of key members the microbial communities associated with high enzyme activities compared to those with low activities, even though we observed no differences in the size of the biomass, nor in the overall richness or diversity of these communities. We hypothesize that resources and substrates have stimulated key populations in the aggregates identified as highly active, and as such, we conducted further research that explored how such key populations (i.e. fungal or bacterial dominated populations) alter pathways of C accumulation in aggregate size domains and microbial C utilization. Fungi support and stabilize soil structure through both physical and chemical effects of their hyphal networks. In contrast, bacterial-dominated communities are purported to facilitate micro- and fine aggregate stabilization. Here we quantify the direct effects fungal versus bacterial dominated communities on aggregate formation (both the rate of aggregation and the quality, quantity and distribution of SOC contained within aggregates). A quantitative understanding of the different mechanisms through which fungi or bacteria shape aggregate formation could alter how we currently treat our predictions of soil biogeochemistry. Current predictions are largely site- or biome-specific; quantitative mechanisms could underpin "rules" that operate at the pore-scale leading to more robust, mechanistic models.

Antidiabetic and Antioxidant Effects and Phytochemicals of Mulberry Fruit (Morus alba L.) Polyphenol Enhanced Extract

PubMed Central

Wang, Yihai; Xiang, Limin; Wang, Chunhua; Tang, Chao; He, Xiangjiu

2013-01-01

The antidiabetic and antioxidant activities of the ethyl acetate-soluble extract (MFE) of mulberry fruit (Morus alba L.) were investigated. In vitro, MFE showed potent α-glucosidase inhibitory activity and radical-scavenging activities against DPPH and superoxide anion radicals. In vivo, MFE could significantly decrease fasting blood glucose (FBG) and glycosylated serum protein (GSP), and increase antioxidant enzymatic activities (SOD, CAT, GSH-Px) in streptozotocin (STZ)-induced diabetic mice. Bioactivity-guided fractionation of the MFE led to the isolation of 25 phenolic compounds, and their structures were identified on the basis of MS and NMR data. All the 25 compounds were isolated from mulberry fruit for the first time. Also, the α-glucosidase inhibitory activity and antioxidant activity of the phenolics were evaluated. Potent α-glucosidase inhibitory and radical-scavenging activities of these phenolics suggested that they may be partially responsible for the antidiabetic and antioxidant activities of mulberry fruit. PMID:23936259

Antidiabetic and antioxidant effects and phytochemicals of mulberry fruit (Morus alba L.) polyphenol enhanced extract.

PubMed

Wang, Yihai; Xiang, Limin; Wang, Chunhua; Tang, Chao; He, Xiangjiu

2013-01-01

The antidiabetic and antioxidant activities of the ethyl acetate-soluble extract (MFE) of mulberry fruit (Morus alba L.) were investigated. In vitro, MFE showed potent α-glucosidase inhibitory activity and radical-scavenging activities against DPPH and superoxide anion radicals. In vivo, MFE could significantly decrease fasting blood glucose (FBG) and glycosylated serum protein (GSP), and increase antioxidant enzymatic activities (SOD, CAT, GSH-Px) in streptozotocin (STZ)-induced diabetic mice. Bioactivity-guided fractionation of the MFE led to the isolation of 25 phenolic compounds, and their structures were identified on the basis of MS and NMR data. All the 25 compounds were isolated from mulberry fruit for the first time. Also, the α-glucosidase inhibitory activity and antioxidant activity of the phenolics were evaluated. Potent α-glucosidase inhibitory and radical-scavenging activities of these phenolics suggested that they may be partially responsible for the antidiabetic and antioxidant activities of mulberry fruit.

QSAR Analysis of 2-Amino or 2-Methyl-1-Substituted Benzimidazoles Against Pseudomonas aeruginosa

PubMed Central

Podunavac-Kuzmanović, Sanja O.; Cvetković, Dragoljub D.; Barna, Dijana J.

2009-01-01

A set of benzimidazole derivatives were tested for their inhibitory activities against the Gram-negative bacterium Pseudomonas aeruginosa and minimum inhibitory concentrations were determined for all the compounds. Quantitative structure activity relationship (QSAR) analysis was applied to fourteen of the abovementioned derivatives using a combination of various physicochemical, steric, electronic, and structural molecular descriptors. A multiple linear regression (MLR) procedure was used to model the relationships between molecular descriptors and the antibacterial activity of the benzimidazole derivatives. The stepwise regression method was used to derive the most significant models as a calibration model for predicting the inhibitory activity of this class of molecules. The best QSAR models were further validated by a leave one out technique as well as by the calculation of statistical parameters for the established theoretical models. To confirm the predictive power of the models, an external set of molecules was used. High agreement between experimental and predicted inhibitory values, obtained in the validation procedure, indicated the good quality of the derived QSAR models. PMID:19468332

Synthesis and biological evaluation of 1,3-diaryl pyrazole derivatives as potential antibacterial and anti-inflammatory agents.

PubMed

Li, Ya-Ru; Li, Chao; Liu, Jia-Chun; Guo, Meng; Zhang, Tian-Yi; Sun, Liang-Peng; Zheng, Chang-Ji; Piao, Hu-Ri

2015-11-15

Three series of 1,3-diaryl pyrazole derivatives bearing aminoguanidine or furan-2-carbohydrazide moieties have been synthesized, characterized and evaluated for antibacterial and anti-inflammatory activities. Most of the synthesized compounds showed potent inhibition of several Gram-positive bacterial strains (including multidrug-resistant clinical isolates) and Gram-negative bacterial strains with minimum inhibitory concentration values in the range of 1-64 μg/mL. Compounds 6g, 6l and 7l presented the most potent inhibitory activity against Gram-positive bacteria (e.g. Staphylococcus aureus 4220), Gram-negative bacteria (e.g. Escherichia coli 1924) and the fungus, Candida albicans 7535, with minimum inhibitory concentration values of 1 or 2 μg/mL. Compared with previous studies, these compounds exhibited a broad spectrum of inhibitory activity. Furthermore, compound 7l showed the greatest anti-inflammatory activity (93.59% inhibition, 30 min after intraperitoneal administration), which was more potent than the reference drugs ibuprofen and indomethacin. Copyright © 2015 Elsevier Ltd. All rights reserved.

Antioxidant and α-glucosidase inhibitory ingredients identified from Jerusalem artichoke flowers.

PubMed

Wang, Yan-Ming; Zhao, Jian-Qiang; Yang, Jun-Li; Idong, Pema Tsering; Mei, Li-Juan; Tao, Yan-Duo; Shi, Yan-Ping

2017-11-09

Jerusalem artichoke (JA, Helianthus tuberosus L.) has been researched extensively due to its wide range of uses, but there are limited studies on its flowers. In this study, we report the first detailed phytochemical study on JA flowers, which yielded 21 compounds. Compound 4 was identified as a major water-soluble yellow pigment of JA flowers. In addition, the methanol extract of JA flowers and the isolates were evaluated for their antioxidant and α-glucosidase inhibitory activities. Among the tested compounds, compound 13 showed the strongest ABTS + free radical scavenging activity with SC 50 value of 2.30 ± 0.13 μg/mL, and compound 6 showed most potent α-glucosidase inhibitory activity with inhibition rate of 60.0% ± 10.3% at a concentration of 250 μg/mL. Results showed that methanol extract of JA flowers exhibited antioxidant and α-glucosidase inhibitory activities which could be attributed to its phenolic ingredients including chlorogenic acid derivatives, flavonoids and phenols.

Decomposing decision components in the Stop-signal task: A model-based approach to individual differences in inhibitory control

PubMed Central

White, Corey N.; Congdon, Eliza; Mumford, Jeanette A.; Karlsgodt, Katherine H.; Sabb, Fred W.; Freimer, Nelson B.; London, Edythe D.; Cannon, Tyrone D.; Bilder, Robert M.; Poldrack, Russell A.

2014-01-01

The Stop-signal task (SST), in which participants must inhibit prepotent responses, has been used to identify neural systems that vary with individual differences in inhibitory control. To explore how these differences relate to other aspects of decision-making, a drift diffusion model of simple decisions was fitted to SST data from Go trials to extract measures of caution, motor execution time, and stimulus processing speed for each of 123 participants. These values were used to probe fMRI data to explore individual differences in neural activation. Faster processing of the Go stimulus correlated with greater activation in the right frontal pole for both Go and Stop trials. On Stop trials stimulus processing speed also correlated with regions implicated in inhibitory control, including the right inferior frontal gyrus, medial frontal gyrus, and basal ganglia. Individual differences in motor execution time correlated with activation of the right parietal cortex. These findings suggest a robust relationship between the speed of stimulus processing and inhibitory processing at the neural level. This model-based approach provides novel insight into the interrelationships among decision components involved in inhibitory control, and raises interesting questions about strategic adjustments in performance and inhibitory deficits associated with psychopathology. PMID:24405185

Production of antioxidant and ACE-inhibitory peptides from Kluyveromyces marxianus protein hydrolysates: Purification and molecular docking.

PubMed

Mirzaei, Mahta; Mirdamadi, Saeed; Ehsani, Mohamad Reza; Aminlari, Mahmoud

2018-04-01

Kluyveromyces marxianus protein hydrolysates were prepared by two different sonicated-enzymatic (trypsin and chymotrypsin) hydrolysis treatments to obtain antioxidant and ACE-inhibitory peptides. Trypsin and chymotrypsin hydrolysates obtained by 5 h, exhibited the highest antioxidant and ACE-inhibitory activities. After fractionation using ultrafiltration and reverse phase high performance liquid chromatography (RP-HPLC) techniques, two new peptides were identified. One fragment (LL-9, MW = 1180 Da) with the amino acid sequence of Leu-Pro-Glu-Ser-Val-His-Leu-Asp-Lys showed significant ACE inhibitory activity (IC 50  = 22.88 μM) while another peptide fragment (VL-9, MW = 1118 Da) with the amino acid sequence of Val-Leu-Ser-Thr-Ser-Phe-Pro-Pro-Lys showed the highest antioxidant and ACE inhibitory properties (IC 50  = 15.20 μM, 5568 μM TE/mg protein). The molecular docking studies revealed that the ACE inhibitory activities of VL-9 is due to interaction with the S2 (His513, His353, Glu281) and S'1 (Glu162) pockets of ACE and LL-9 can fit perfectly into the S1 (Thr345) and S2 (Tyr520, Lys511, Gln281) pockets of ACE. Copyright © 2017. Published by Elsevier B.V.

Behavioral and Neural Inhibitory Control Moderates the Effects of Reward Sensitivity on Adolescent Substance Use

PubMed Central

Kim-Spoon, Jungmeen; Deater-Deckard, Kirby; Holmes, Christopher; Lee, Jacob; Chiu, Pearl; King-Casas, Brooks

2016-01-01

The developmental period of adolescence is characterized by increasing incidence of health risk behaviors, including experimenting with drugs and alcohol. We examined how inhibitory control interacts with reward and punishment sensitivity to predict substance use severity and age of onset among early adolescents. The sample was comprised of 157 early adolescents (13-14 years of age, 52% male). Composite scores for behavioral activation system (BAS), behavioral inhibition system (BIS), and substance use severity and onset were computed using adolescents’ questionnaire data, and inhibitory control was assessed based on adolescents’ behavioral performance and brain imaging during the Multiple Source Interference Task (MSIT). Structural equation modeling analyses indicated that for both behavioral performance and neural activity indicators of inhibitory control, high levels of BAS predicted earlier onset of substance use among adolescents with low inhibitory control—but not among adolescents with high inhibitory control. BIS was not related to substance use severity and onset among adolescents. The results support the theoretically hypothesized moderating role of inhibitory control and its associated frontal cortex functioning, and offer new insights into the identification of adolescents with neurobehavioral vulnerabilities to developing maladaptive substance use behaviors. PMID:27580969

Activation of 5-HT1A receptors in the rat dorsomedial hypothalamus inhibits stress-induced activation of the hypothalamic-pituitary-adrenal axis.

PubMed

Stamper, Christopher E; Hassell, James E; Kapitz, Adam J; Renner, Kenneth J; Orchinik, Miles; Lowry, Christopher A

2017-03-01

Acute activation of the hypothalamic-pituitary-adrenal (HPA) axis, leading to the release of corticosteroid hormones into the circulation, is an adaptive response to perceived threats. Persistent activation of the HPA axis can lead to impaired physiological or behavioral function with maladaptive consequences. Thus, efficient control and termination of stress responses is essential for well-being. However, inhibitory control mechanisms governing the HPA axis are poorly understood. Previous studies suggest that serotonergic systems, acting within the medial hypothalamus, play an important role in inhibitory control of stress-induced HPA axis activity. To test this hypothesis, we surgically implanted chronic jugular cannulae in adult male rats and conducted bilateral microinjection of vehicle or the 5-HT 1A receptor agonist, 8-hydroxy-2-(di-n-propylamino) tetralin hydrobromide (8-OH-DPAT; 8 nmol, 0.2 μL, 0.1 μL/min, per side) into the dorsomedial hypothalamus (DMH) immediately prior to a 40 min period of restraint stress. Repeated blood sampling was conducted using an automated blood sampling system and plasma corticosterone concentrations were determined using enzyme-linked immunosorbent assay. Bilateral intra-DMH microinjections of 8-OH-DPAT suppressed stress-induced increases in plasma corticosterone within 10 min of the onset of handling prior to restraint and, as measured by area-under-the-curve analysis of plasma corticosterone concentrations, during the 40 min period of restraint. These data support an inhibitory role for serotonergic systems, acting within the DMH, on stress-induced activation of the HPA axis. Lay summary: Inhibitory control of the hypothalamic-pituitary-adrenal (HPA) stress hormone response is important for well-being. One neurochemical implicated in inhibitory control of the HPA axis is serotonin. In this study we show that activation of serotonin receptors, specifically inhibitory 5-HT 1A receptors in the dorsomedial hypothalamus, is sufficient to inhibit stress-induced HPA axis activity in rats.

Identification by GeLC-MS/MS of trypsin inhibitor in sarcoplasmic proteins of three tropical fish and characterization of their inhibitory properties.

PubMed

Siriangkanakun, Siriphon; Li-Chan, Eunice C Y; Yongsawadigul, Jirawat

2014-07-01

Sarcoplasmic proteins from 3 fish species were fractionated by 50% to 70% ammonium sulfate precipitation. Lyophilized fractionated sarcoplasmic proteins of threadfin bream (TB-SP), bigeye snapper (BS-SP), and yellow croaker (YC-SP) showed 80% to 92% trypsin inhibitory activity. Trypsin inhibitory activity staining gel electrophoresis revealed bands at 32, 33, 37, 45, 48, and 50 kDa for the 3 species, and a band at 95 kDa was observed for TB-SP and YC-SP. Alpha-1-antitrypsin with molecular mass of 45 to 50 kDa was identified in YC-SP by gel-based liquid chromatography-tandem mass spectrometry (GeLC-MS/MS). Other major protein bands appeared on trypsin activity staining included phosphorylase, glyceraldehyde-3-phosphate dehydrogenase, and creatine kinase with molecular mass of 95 and 35 to 40 kDa, respectively. But, these 3 proteins did not show true trypsin inhibitory activity. Trypsin inhibitory activity of fractionated sarcoplasmic proteins showed good stability, with >80% activity retained at 60 °C and up to 0.6 M NaCl. TB-SP showed the highest inhibitory activity against autolysis of washed threadfin bream mince at 65 °C. Addition of 0.5% or 1% TB-SP improved textural properties of threadfin bream surimi gels preincubated at 37 or 65 °C followed by heating at 90 °C. Therefore, TB-SP could be a promising protein ingredient for enhancing surimi gel texture. Threadfin bream, bigeye snapper, and yellow croaker are the main species used as raw material for tropical surimi production. Sarcoplasmic proteins from 3 species contain trypsin inhibitor(s) that can minimize proteolytic activity and improve gel texture of proteinase-laden fish muscle. Therefore, sarcoplasmic proteins that are byproducts from surimi processing of these species could be recovered, fractionated, and utilized as a functional protein ingredient. © 2014 Institute of Food Technologists®

Quantitative structure activity relationship studies of sulfamide derivatives as carbonic anhydrase inhibitor: as antiglaucoma agents.

PubMed

Kumar, Surendra; Singh, Vineet; Tiwari, Meena

2007-07-01

Selective inhibition of ciliary process enzyme i.e. Carbonic Anhydrase-II is an excellent approach in reducing elevated intraocular pressure, thus treating glaucoma. Due to characteristic physicochemical properties of sulphonamide (Inhibition of Carbonic Anhydrase), they are clinically effective against glaucoma. But the non-specificity of sulphonamide derivatives to isozyme, leads to a range of side effects. Presently, the absence of comparative studies related to the binding of the sulphonamides as inhibitors to CA isozymes limits their use. In this paper we have represented "Three Dimensional Quantitative Structure Activity Relationship" study to characterize structural features of Sulfamide derivative [RR'NSO(2)NH(2)] as inhibitors, that are required for selective binding of carbonic anhydrase isozymes (CAI and CAII). In the analysis, stepwise multiple linear regression was performed using physiochemical parameters as independent variable and CA-I and CA-II inhibitory activity as dependent variable, respectively. The best multiparametric QSAR model obtained for CA-I inhibitory activity shows good statistical significance (r= 0.9714) and predictability (Q(2)=0.8921), involving the Electronic descriptors viz. Highest Occupied Molecular Orbital, Lowest Unoccupied Molecular Orbital and Steric descriptors viz. Principal moment of Inertia at X axis. Similarly, CA-II inhibitory activity also shows good statistical significance (r=0.9644) and predictability (Q(2)=0.8699) involving aforementioned descriptors. The predictive power of the model was successfully tested externally using a set of six compounds as test set for CA-I inhibitory activity and a set of seven compounds in case of CA-II inhibitory activity with good predictive squared correlation coefficient, r(2)(pred)=0.6016 and 0.7662, respectively. Overview of analysis favours substituents with high electronegativity and less bulk at R and R' positions of the parent nucleus, provides a basis to design new Sulfamide derivatives possessing potent and selective carbonic anhydrase-II inhibitory activity.

Bacteriocin-like inhibitory activities of seven Lactobacillus delbrueckii subsp. bulgaricus strains against antibiotic susceptible and resistant Helicobacter pylori strains.

PubMed

Boyanova, L; Gergova, G; Markovska, R; Yordanov, D; Mitov, I

2017-12-01

The aim of the study was to detect anti-Helicobacter pylori activity of seven Lactobacillus delbrueckii subsp. bulgaricus (GLB) strains by four cell-free supernatant (CFS) types. Activity of non-neutralized and non-heat-treated (CFSs1), non-neutralized and heat-treated (CFSs2), pH neutralized, catalase-treated and non-heat-treated (CFSs3), or neutralized, catalase- and heat-treated (CFSs4) CFSs against 18 H. pylori strains (11 of which with antibiotic resistance) was evaluated. All GLB strains produced bacteriocin-like inhibitory substances (BLISs), the neutralized CFSs of two GLB strains inhibited >81% of test strains and those of four GLB strains were active against >71% of antibiotic resistant strains. Two H. pylori strains were BLIS resistant. The heating did not reduce the CFS activity. Briefly, all GLB strains evaluated produced heat-stable BLISs, although GLB and H. pylori strain susceptibility patterns exhibited differences. Bacteriocin-like inhibitory substance activity can be an advantage for the probiotic choice for H. pylori infection control. In this study, anti-Helicobacter pylori activity of seven Lactobacillus delbrueckii subsp. bulgaricus (GLB) strains was evaluated by four cell-free supernatant (CFS) types. The GLB strains produced heat-stable bacteriocin-like inhibitory substances (BLISs) with a strong anti-H. pylori activity and some neutralized, catalase- and heat-treated CFSs inhibited >83% of the test strains. Bacteriocin-like inhibitory substance production of GLB strains can render them valuable probiotics in the control of H. pylori infection. © 2017 The Society for Applied Microbiology.

Synthesis and biological evaluation of N-(carbobenzyloxy)-l-phenylalanine and N-(carbobenzyloxy)-l-aspartic acid-β-benzyl ester derivatives as potent topoisomerase IIα inhibitors.

PubMed

Han, Xiaoyan; Zhong, Yifan; Zhou, Guan; Qi, Hui; Li, Shengbin; Ding, Qiang; Liu, Zhenming; Song, Yali; Qiao, Xiaoqiang

2017-06-15

A new series of thirteen N-(carbobenzyloxy)-l-phenylalanine and N-(carbobenzyloxy)-l-aspartic acid-β-benzyl ester compounds were synthesized and evaluated for antiproliferative activity against four different human cancer cell lines: cervical cancer (HeLa), lung cancer (A549), gastric cancer (MGC-803) and breast cancer (MCF-7) as well as topoisomerase I and IIα inhibitory activity. Compounds (5a, 5b, 5e, 8a, 8b) showed significant antiproliferative activity with low IC 50 values against the four cancer cell lines. Equally, compounds 5a, 5b, 5e, 5f, 8a, 8d, 8e and 8f showed topoisomerase IIα inhibitory activity at 100μM with 5b, 5e, 8f exhibiting potential topoisomerase IIα inhibitory activity compared to positive control at 100μM and 20μM, respectively. Conversely compounds 5e, 5f, 5g and 8a showed weaker topoisomerase I inhibitory activity compared to positive control at 100μM. Compound 5b exhibited the most potent topoisomerase IIα inhibitory activity at low concentration and better antiproliferative activity against the four human cancer cell lines. The molecular interactions between compounds 5a-5g, 8a-8f and the topoisomerase IIα (PDB ID: 1ZXM) were further investigated through molecular docking. The results indicated that these compounds could serve as promising leads for further optimization as novel antitumor agents. Copyright © 2017 Elsevier Ltd. All rights reserved.

Spontaneous pre-stimulus fluctuations in the activity of right fronto-parietal areas influence inhibitory control performance

PubMed Central

Chavan, Camille F.; Manuel, Aurelie L.; Mouthon, Michael; Spierer, Lucas

2013-01-01

Inhibitory control refers to the ability to suppress planned or ongoing cognitive or motor processes. Electrophysiological indices of inhibitory control failure have been found to manifest even before the presentation of the stimuli triggering the inhibition, suggesting that pre-stimulus brain-states modulate inhibition performance. However, previous electrophysiological investigations on the state-dependency of inhibitory control were based on averaged event-related potentials (ERPs), a method eliminating the variability in the ongoing brain activity not time-locked to the event of interest. These studies thus left unresolved whether spontaneous variations in the brain-state immediately preceding unpredictable inhibition-triggering stimuli also influence inhibitory control performance. To address this question, we applied single-trial EEG topographic analyses on the time interval immediately preceding NoGo stimuli in conditions where the responses to NoGo trials were correctly inhibited [correct rejection (CR)] vs. committed [false alarms (FAs)] during an auditory spatial Go/NoGo task. We found a specific configuration of the EEG voltage field manifesting more frequently before correctly inhibited responses to NoGo stimuli than before FAs. There was no evidence for an EEG topography occurring more frequently before FAs than before CR. The visualization of distributed electrical source estimations of the EEG topography preceding successful response inhibition suggested that it resulted from the activity of a right fronto-parietal brain network. Our results suggest that the fluctuations in the ongoing brain activity immediately preceding stimulus presentation contribute to the behavioral outcomes during an inhibitory control task. Our results further suggest that the state-dependency of sensory-cognitive processing might not only concern perceptual processes, but also high-order, top-down inhibitory control mechanisms. PMID:23761747

Alpha-synuclein aggregates activate calcium pump SERCA leading to calcium dysregulation.

PubMed

Betzer, Cristine; Lassen, Louise Berkhoudt; Olsen, Anders; Kofoed, Rikke Hahn; Reimer, Lasse; Gregersen, Emil; Zheng, Jin; Calì, Tito; Gai, Wei-Ping; Chen, Tong; Moeller, Arne; Brini, Marisa; Fu, Yuhong; Halliday, Glenda; Brudek, Tomasz; Aznar, Susana; Pakkenberg, Bente; Andersen, Jens Peter; Jensen, Poul Henning

2018-05-01

Aggregation of α-synuclein is a hallmark of Parkinson's disease and dementia with Lewy bodies. We here investigate the relationship between cytosolic Ca 2+ and α-synuclein aggregation. Analyses of cell lines and primary culture models of α-synuclein cytopathology reveal an early phase with reduced cytosolic Ca 2+ levels followed by a later Ca 2+ increase. Aggregated but not monomeric α-synuclein binds to and activates SERCA in vitro , and proximity ligation assays confirm this interaction in cells. The SERCA inhibitor cyclopiazonic acid (CPA) normalises both the initial reduction and the later increase in cytosolic Ca 2+ CPA protects the cells against α-synuclein-aggregate stress and improves viability in cell models and in Caenorhabditis elegans in vivo Proximity ligation assays also reveal an increased interaction between α-synuclein aggregates and SERCA in human brains affected by dementia with Lewy bodies. We conclude that α-synuclein aggregates bind SERCA and stimulate its activity. Reducing SERCA activity is neuroprotective, indicating that SERCA and down-stream processes may be therapeutic targets for treating α-synucleinopathies. © 2018 The Authors. Published under the terms of the CC BY NC ND 4.0 license.

Porcine Pancreatic Lipase Inhibitory Agent Isolated from Medicinal Herb and Inhibition Kinetics of Extracts from Eleusine indica (L.) Gaertner

PubMed Central

Ong, Siew Ling

2016-01-01

Eleusine indica (Linnaeus) Gaertner is a traditional herb known to be depurative, febrifuge, and diuretic and has been reported with the highest inhibitory activity against porcine pancreatic lipase (PPL) among thirty two plants screened in an earlier study. This study aims to isolate and identify the active components that may possess high potential as an antiobesity agent. Of the screened solvent fractions of E. indica, hexane fraction showed the highest inhibitory activity of 27.01 ± 5.68% at 100 μg/mL. Bioactivity-guided isolation afforded three compounds from the hexane fraction of E. indica, namely, β-sitosterol, stigmasterol, and lutein. The structures of these compounds were elucidated using spectral techniques. Lutein showed an outstanding inhibitory activity against PPL (55.98 ± 1.04%), with activity 60% higher than that of the reference drug Orlistat. The other compounds isolated and identified were β-sitosterol (2.99 ± 0.80%) and stigmasterol (2.68 ± 0.38%). The enzyme kinetics of E. indica crude methanolic extract on PPL showed mixed inhibition mechanism. PMID:27872792

Porcine Pancreatic Lipase Inhibitory Agent Isolated from Medicinal Herb and Inhibition Kinetics of Extracts from Eleusine indica (L.) Gaertner.

PubMed

Ong, Siew Ling; Mah, Siau Hui; Lai, How Yee

2016-01-01

Eleusine indica (Linnaeus) Gaertner is a traditional herb known to be depurative, febrifuge, and diuretic and has been reported with the highest inhibitory activity against porcine pancreatic lipase (PPL) among thirty two plants screened in an earlier study. This study aims to isolate and identify the active components that may possess high potential as an antiobesity agent. Of the screened solvent fractions of E. indica , hexane fraction showed the highest inhibitory activity of 27.01 ± 5.68% at 100  μ g/mL. Bioactivity-guided isolation afforded three compounds from the hexane fraction of E. indica , namely,  β -sitosterol, stigmasterol, and lutein. The structures of these compounds were elucidated using spectral techniques. Lutein showed an outstanding inhibitory activity against PPL (55.98 ± 1.04%), with activity 60% higher than that of the reference drug Orlistat. The other compounds isolated and identified were  β -sitosterol (2.99 ± 0.80%) and stigmasterol (2.68 ± 0.38%). The enzyme kinetics of E. indica crude methanolic extract on PPL showed mixed inhibition mechanism.

Antiproliferative activity of novel imidazopyridine derivatives on castration-resistant human prostate cancer cells.

PubMed

Muniyan, Sakthivel; Chou, Yu-Wei; Ingersoll, Matthew A; Devine, Alexus; Morris, Marisha; Odero-Marah, Valerie A; Khan, Shafiq A; Chaney, William G; Bu, Xiu R; Lin, Ming-Fong

2014-10-10

Metastatic prostate cancer (mPCa) relapses after a short period of androgen deprivation therapy and becomes the castration-resistant prostate cancer (CR PCa); to which the treatment is limited. Hence, it is imperative to identify novel therapeutic agents towards this patient population. In the present study, antiproliferative activities of novel imidazopyridines were compared. Among three derivatives, PHE, AMD and AMN, examined, AMD showed the highest inhibitory activity on LNCaP C-81 cell proliferation, following dose- and time-dependent manner. Additionally, AMD exhibited significant antiproliferative effect against a panel of PCa cells, but not normal prostate epithelial cells. Further, when compared to AMD, its derivative DME showed higher inhibitory activities on PCa cell proliferation, clonogenic potential and in vitro tumorigenicity. The inhibitory activity was apparently in part due to the induction of apoptosis. Mechanistic studies indicate that AMD and DME treatments inhibited both AR and PI3K/Akt signaling. The results suggest that better understanding of inhibitory mechanisms of AMD and DME could help design novel therapeutic agents for improving the treatment of CR PCa. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.