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Sample records for gram-positive antibacterial activity

  1. Antibacterial activity of glutathione-coated silver nanoparticles against Gram positive and Gram negative bacteria.

    PubMed

    Taglietti, Angelo; Diaz Fernandez, Yuri A; Amato, Elvio; Cucca, Lucia; Dacarro, Giacomo; Grisoli, Pietro; Necchi, Vittorio; Pallavicini, Piersandro; Pasotti, Luca; Patrini, Maddalena

    2012-05-29

    In the present paper, we study the mechanism of antibacterial activity of glutathione (GSH) coated silver nanoparticles (Ag NPs) on model Gram negative and Gram positive bacterial strains. Interference in bacterial cell replication is observed for both cellular strains when exposed to GSH stabilized colloidal silver in solution, and microbicidal activity was studied when GSH coated Ag NPs are (i) dispersed in colloidal suspensions or (ii) grafted on thiol-functionalized glass surfaces. The obtained results confirm that the effect of dispersed GSH capped Ag NPs (GSH Ag NPs) on Escherichia coli is more intense because it can be associated with the penetration of the colloid into the cytoplasm, with the subsequent local interaction of silver with cell components causing damages to the cells. Conversely, for Staphylococcus aureus, since the thick peptidoglycan layer of the cell wall prevents the penetration of the NPs inside the cytoplasm, the antimicrobial effect is limited and seems related to the interaction with the bacterial surfaces. Experiments on GSH Ag NPs grafted on glass allowed us to elucidate more precisely the antibacterial mechanism, showing that the action is reduced because of GSH coating and the limitation of the translational freedom of NPs. PMID:22546237

  2. CHARACTERIZATION OF LEUKIN: AN ANTIBACTERIAL FACTOR FROM LEUCOCYTES ACTIVE AGAINST GRAM-POSITIVE PATHOGENS

    PubMed Central

    Skarnes, Robert C.; Watson, Dennis W.

    1956-01-01

    A method has been described for the preparation of a potent antibacterial factor from rabbit polymorphonuclear leucocytes. Upon characterization, the factor was found to possess many properties in common with basic proteins. The amino acid analysis revealed that it contained a relatively large amount of arginine (17 per cent) and small amounts of the other two basic amino acids. It has therefore been identified as a protamine or protamine derivative. The leucocyte factor was very active against all Gram-positive pathogens tested but exhibited little or no action against Gram-negative species. A possible explanation of this phenomenon has been discussed. The factor was very heat-stable at acid and neutral pH and its staphylococcidal activity was blocked by glutamyl polypeptide, hyaluronic acid, and desoxyribonudeic acid. Because of the apparent similarity of the product studied here to other poorly defined leucocyte factors which had been termed leukins in the early literature, it is suggested that the name leukin be retained for it. The possible significance of this leukin in natural immunity has been discussed. PMID:13376807

  3. Antibacterial Activity of Stenotrophomonas maltophilia Endolysin P28 against both Gram-positive and Gram-negative Bacteria

    PubMed Central

    Dong, Hongling; Zhu, Chaoyang; Chen, Jingyi; Ye, Xing; Huang, Yu-Ping

    2015-01-01

    Maltocin P28 is a phage-tail like bacteriocin produced by Stenotrophomonas maltophilia P28. The ORF8 of maltocin P28 gene cluster is predicted to encode an endolysin and we name it endolysin P28. Sequence analysis revealed that it contains the lysozyme_like superfamily conserved domain. Endolysin P28 has the four consensus motifs as that of Escherichia coli phage lambda gpR. In this study, endolysin P28 was expressed in E. coli BL21 (DE3) and purified with a C-terminal oligo-histidine tag. The antibacterial activity of endolysin P28 increased as the temperature rose from 25 to 45°C. Thermostability assays showed that endolysin P28 was stable up to 50°C, while its residual activity was reduced by 55% after treatment at 70°C for 30 min. Acidity and high salinity could enhance its antibacterial activity. Endolysin P28 exhibited a broad antibacterial activity against 14 out of 16 tested Gram-positive and Gram-negative bacteria besides S. maltophilia. Moreover, it could effectively lyse intact Gram-negative bacteria in the absence of ethylenediaminetetraacetic acid as an outer membrane permeabilizer. Therefore, the characteristics of endolysin P28 make it a potential therapeutic agent against multi-drug-resistant pathogens. PMID:26635765

  4. Indole trimers with antibacterial activity against Gram-positive organisms produced using combinatorial biocatalysis.

    PubMed

    McClay, Kevin; Mehboob, Shahila; Yu, Jerry; Santarsiero, Bernard D; Deng, Jiangping; Cook, James L; Jeong, Hyunyoung; Johnson, Michael E; Steffan, Robert J

    2015-12-01

    The I100V isoform of toluene-4-monooxygenase was used to catalyze the oxidative polymerization of anthranil and various indoles under mildly acidic conditions, favoring the production of trimers. Compounds produced in sufficient yield were purified and tested for their ability to inhibit the growth of B. anthracis, E. faecalis, L. monocytogenes, S. aureus, and in some cases, F. tularensis. 15 of the compounds displayed promising antibacterial activity (MIC < 5 µg/ml) against one or more of the strains tested, with the best MIC values being <0.8 µg/ml. All of these compounds had good selectivity, showing minimal cytotoxicity towards HepG2 cells. The structure was solved for six of the compounds that could be crystallized, revealing that minimally two classes of indole based trimers were produced. One compound class produced was a group of substituted derivatives of the natural product 2,2-bis(3-indolyl) indoxyl. The other group of compounds identified was classified as tryptanthrin-like compounds, all having multi-ring pendant groups attached at position 11 of tryptanthrin. One compound of particular interest, SAB-J85, had a structure that suggests that any compound, with a ring structure that can be activated by an oxygenase, might serve as a substrate for combinatorial biocatalysis. PMID:26112315

  5. Enhanced antibacterial and anti-biofilm activities of silver nanoparticles against Gram-negative and Gram-positive bacteria

    NASA Astrophysics Data System (ADS)

    Gurunathan, Sangiliyandi; Han, Jae Woong; Kwon, Deug-Nam; Kim, Jin-Hoi

    2014-07-01

    Silver nanoparticles (AgNPs) have been used as antibacterial, antifungal, antiviral, anti-inflammtory, and antiangiogenic due to its unique properties such as physical, chemical, and biological properties. The present study was aimed to investigate antibacterial and anti-biofilm activities of silver nanoparticles alone and in combination with conventional antibiotics against various human pathogenic bacteria. Here, we show that a simple, reliable, cost effective and green method for the synthesis of AgNPs by treating silver ions with leaf extract of Allophylus cobbe. The A. cobbe-mediated synthesis of AgNPs (AgNPs) was characterized by ultraviolet-visible absorption spectroscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), dynamic light scattering (DLS), and transmission electron microscopy (TEM). Furthermore, the antibacterial and anti-biofilm activity of antibiotics or AgNPs, or combinations of AgNPs with an antibiotic was evaluated using a series of assays: such as in vitro killing assay, disc diffusion assay, biofilm inhibition, and reactive oxygen species generation in Pseudomonas aeruginosa, Shigella flexneri, Staphylococcus aureus, and Streptococcus pneumonia. The results suggest that, in combination with antibiotics, there were significant antimicrobial and anti-biofilm effects at lowest concentration of AgNPs using a novel plant extract of A. cobbe, otherwise sublethal concentrations of the antibiotics. The significant enhancing effects were observed for ampicillin and vancomycin against Gram-negative and Gram-positive bacteria, respectively. These data suggest that combining antibiotics and biogenic AgNPs can be used therapeutically for the treatment of infectious diseases caused by bacteria. This study presented evidence of antibacterial and anti-biofilm effects of A. cobbe-mediated synthesis of AgNPs and their enhanced capacity against various human pathogenic bacteria. These results suggest that AgNPs could be used as an adjuvant for the treatment of infectious diseases.

  6. Enhanced antibacterial and anti-biofilm activities of silver nanoparticles against Gram-negative and Gram-positive bacteria

    PubMed Central

    2014-01-01

    Silver nanoparticles (AgNPs) have been used as antibacterial, antifungal, antiviral, anti-inflammtory, and antiangiogenic due to its unique properties such as physical, chemical, and biological properties. The present study was aimed to investigate antibacterial and anti-biofilm activities of silver nanoparticles alone and in combination with conventional antibiotics against various human pathogenic bacteria. Here, we show that a simple, reliable, cost effective and green method for the synthesis of AgNPs by treating silver ions with leaf extract of Allophylus cobbe. The A. cobbe-mediated synthesis of AgNPs (AgNPs) was characterized by ultraviolet-visible absorption spectroscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), dynamic light scattering (DLS), and transmission electron microscopy (TEM). Furthermore, the antibacterial and anti-biofilm activity of antibiotics or AgNPs, or combinations of AgNPs with an antibiotic was evaluated using a series of assays: such as in vitro killing assay, disc diffusion assay, biofilm inhibition, and reactive oxygen species generation in Pseudomonas aeruginosa, Shigella flexneri, Staphylococcus aureus, and Streptococcus pneumonia. The results suggest that, in combination with antibiotics, there were significant antimicrobial and anti-biofilm effects at lowest concentration of AgNPs using a novel plant extract of A. cobbe, otherwise sublethal concentrations of the antibiotics. The significant enhancing effects were observed for ampicillin and vancomycin against Gram-negative and Gram-positive bacteria, respectively. These data suggest that combining antibiotics and biogenic AgNPs can be used therapeutically for the treatment of infectious diseases caused by bacteria. This study presented evidence of antibacterial and anti-biofilm effects of A. cobbe-mediated synthesis of AgNPs and their enhanced capacity against various human pathogenic bacteria. These results suggest that AgNPs could be used as an adjuvant for the treatment of infectious diseases. PMID:25136281

  7. Efficient enzymatic systems for synthesis of novel ?-mangostin glycosides exhibiting antibacterial activity against Gram-positive bacteria.

    PubMed

    Le, Tuoi Thi; Pandey, Ramesh Prasad; Gurung, Rit Bahadur; Dhakal, Dipesh; Sohng, Jae Kyung

    2014-10-01

    Two enzymatic systems were developed for the efficient synthesis of glycoside products of ?-mangostin, a natural xanthonoid exhibiting anti-oxidant, antibacterial, anti-inflammatory, and anticancer activities. In these systems, one-pot reactions for the synthesis of UDP-?-D-glucose and UDP-?-D-2-deoxyglucose were modified and combined with a glycosyltransferase (GT) from Bacillus licheniformis DSM-13 to afford C-3 and C-6 position modified glucose and 2-deoxyglucose conjugated novel ?-mangostin derivatives. ?-Mangostin 3-O-?-D-glucopyranoside, ?-mangostin 6-O-?-D-glucopyranoside, ?-mangostin 3,6-di-O-?-D-glucopyranoside, ?-mangostin 3-O-?-D-2-deoxyglucopyranoside, ?-mangostin 6-O-?-D-2-deoxyglucopyranoside, and ?-mangostin 3,6-di-O-?-D-2-deoxyglucopyranoside were successfully produced in practical quantities and characterized by high-resolution quadruple time-of-flight electrospray ionization-mass spectrometry (HR-QTOF ESI/MS), (1)H and (13)C NMR analyses. In excess of the substrate, the maximum productions of three ?-mangostin glucopyranosides (4.8 mg/mL, 86.5 % overall conversion of ?-mangostin) and three ?-mangostin 2-deoxyglucopyronosides (4.0 mg/mL, 79 % overall conversion of ?-mangostin) were achieved at 4-h incubation period. All the ?-mangostin glycosides exhibited improved water solubility, and their antibacterial activity against three Gram-positive bacteria Micrococcus luteus, Bacillus subtilis, and Staphylococcus aureus was drastically enhanced by the glucosylation at C-3 position. In this study, diverse glycosylated ?-mangostin were produced in significant quantities by using inexpensive starting materials and recycling co-factors within a reaction vessel without use of expensive NDP-sugars in the glycosylation reactions. PMID:25038930

  8. Antibacterial activity of silver-doped hydroxyapatite nanoparticles against gram-positive and gram-negative bacteria

    NASA Astrophysics Data System (ADS)

    Ciobanu, Carmen Steluta; Iconaru, Simona Liliana; Le Coustumer, Phillippe; Constantin, Liliana Violeta; Predoi, Daniela

    2012-06-01

    Ag-doped nanocrystalline hydroxyapatite nanoparticles (Ag:HAp-NPs) (Ca10- x Ag x (PO4)6(OH)2, x Ag = 0.05, 0.2, and 0.3) with antibacterial properties are of great interest in the development of new products. Coprecipitation method is a promising route for obtaining nanocrystalline Ag:HAp with antibacterial properties. X-ray diffraction identified HAp as an unique crystalline phase in each sample. The calculated lattice constants of a = b = 9.435 Å, c = 6.876 Å for x Ag = 0.05, a = b = 9.443 Å, c = 6.875 Å for x Ag = 0.2, and a = b = 9.445 Å, c = 6.877 Å for x Ag = 0.3 are in good agreement with the standard of a = b = 9.418 Å, c = 6.884 Å (space group P63/m). The Fourier transform infrared and Raman spectra of the sintered HAp show the absorption bands characteristic to hydroxyapatite. The Ag:HAp nanoparticles are evaluated for their antibacterial activity against Staphylococcus aureus, Klebsiella pneumoniae, Providencia stuartii, Citrobacter freundii and Serratia marcescens. The results showed that the antibacterial activity of these materials, regardless of the sample types, was greatest against S. aureus, K. pneumoniae, P. stuartii, and C. freundii. The results of qualitative antibacterial tests revealed that the tested Ag:HAp-NPs had an important inhibitory activity on P. stuartii and C. freundii. The absorbance values measured at 490 nm of the P. stuartii and C. freundii in the presence of Ag:HAp-NPs decreased compared with those of organic solvent used (DMSO) for all the samples ( x Ag = 0.05, 0.2, and 0.3). Antibacterial activity increased with the increase of x Ag in the samples. The Ag:HAp-NP concentration had little influence on the bacterial growth ( P. stuartii).

  9. Antibacterial activity of silver-doped hydroxyapatite nanoparticles against gram-positive and gram-negative bacteria

    PubMed Central

    2012-01-01

    Ag-doped nanocrystalline hydroxyapatite nanoparticles (Ag:HAp-NPs) (Ca10-xAgx(PO4)6(OH)2, xAg?=?0.05, 0.2, and 0.3) with antibacterial properties are of great interest in the development of new products. Coprecipitation method is a promising route for obtaining nanocrystalline Ag:HAp with antibacterial properties. X-ray diffraction identified HAp as an unique crystalline phase in each sample. The calculated lattice constants of a?=?b?=?9.435 Å, c?=?6.876 Å for xAg?=?0.05, a?=?b?=?9.443 Å, c?=?6.875 Å for xAg?=?0.2, and a?=?b?=?9.445 Å, c?=?6.877 Å for xAg?=?0.3 are in good agreement with the standard of a?=?b?=?9.418 Å, c?=?6.884 Å (space group P63/m). The Fourier transform infrared and Raman spectra of the sintered HAp show the absorption bands characteristic to hydroxyapatite. The Ag:HAp nanoparticles are evaluated for their antibacterial activity against Staphylococcus aureus, Klebsiella pneumoniae, Providencia stuartii, Citrobacter freundii and Serratia marcescens. The results showed that the antibacterial activity of these materials, regardless of the sample types, was greatest against S. aureus, K. pneumoniae, P. stuartii, and C. freundii. The results of qualitative antibacterial tests revealed that the tested Ag:HAp-NPs had an important inhibitory activity on P. stuartii and C. freundii. The absorbance values measured at 490 nm of the P. stuartii and C. freundii in the presence of Ag:HAp-NPs decreased compared with those of organic solvent used (DMSO) for all the samples (xAg?=?0.05, 0.2, and 0.3). Antibacterial activity increased with the increase of xAg in the samples. The Ag:HAp-NP concentration had little influence on the bacterial growth (P. stuartii). PMID:22721352

  10. Synthesis, characterization and antibacterial activity against Gram positive and Gram negative bacteria of biomimetically coated silver nanoparticles.

    PubMed

    Amato, Elvio; Diaz-Fernandez, Yuri A; Taglietti, Angelo; Pallavicini, Piersandro; Pasotti, Luca; Cucca, Lucia; Milanese, Chiara; Grisoli, Pietro; Dacarro, Cesare; Fernandez-Hechavarria, Jose M; Necchi, Vittorio

    2011-08-01

    In the present work, we describe a simple procedure to produce biomimetically coated silver nanoparticles (Ag NPs), based on the postfunctionalization and purification of colloidal silver stabilized by citrate. Two biological capping agents have been used (cysteine Cys and glutathione GSH). The composition of the capped colloids has been ascertained by different techniques and antibacterial tests on GSH-capped Ag NPs have been conducted under physiological conditions, obtaining values of Minimum Inhibitory Concentration (MIC) of 180 and 15 ?g/mL for Staphylococcus aureus and Escherichia coli, respectively. The antibacterial activity of these GSH capped NPs can be ascribed to the direct action of metallic silver NPs, rather than to the bulk release of Ag(+). PMID:21736306

  11. Significance of postgrowth processing of ZnO nanostructures on antibacterial activity against gram-positive and gram-negative bacteria

    PubMed Central

    Mehmood, Shahid; Rehman, Malik A; Ismail, Hammad; Mirza, Bushra; Bhatti, Arshad S

    2015-01-01

    In this work, we highlighted the effect of surface modifications of one-dimensional (1D) ZnO nanostructures (NSs) grown by the vapor–solid mechanism on their antibacterial activity. Two sets of ZnO NSs were modified separately – one set was modified by annealing in an Ar environment, and the second set was modified in O2 plasma. Annealing in Ar below 800°C resulted in a compressed lattice, which was due to removal of Zn interstitials and increased O vacancies. Annealing above 1,000°C caused the formation of a new prominent phase, Zn2SiO4. Plasma oxidation of the ZnO NSs caused an expansion in the lattice due to the removal of O vacancies and incorporation of excess O. Photoluminescence (PL) spectroscopy was employed for the quantification of defects associated with Zn and O in the as-grown and processed ZnO NS. Two distinct bands were observed, one in the ultraviolet (UV) region, due to interband transitions, and other in the visible region, due to defects associated with Zn and O. PL confirmed the surface modification of ZnO NS, as substantial decrease in intensities of visible band was observed. Antibacterial activity of the modified ZnO NSs demonstrated that the surface modifications by Ar annealing limited the antibacterial characteristics of ZnO NS against Staphylococcus aureus. However, ZnO NSs annealed at 1,000°C or higher showed a remarkable antibacterial activity against Escherichia coli. O2 plasma–treated NS showed appreciable antibacterial activity against both E. coli and S. aureus. The minimum inhibition concentration was determined to be 0.5 mg/mL and 1 mg/mL for Ar-annealed and plasma-oxidized ZnO NS, respectively. It was thus proved that the O content at the surface of the ZnO NS was crucial to tune the antibacterial activity against both selected gram-negative (E. coli) and gram-positive (S. aureus) bacterial species. PMID:26213466

  12. In vitro antibacterial activity of AZD0914, a new spiropyrimidinetrione DNA gyrase/topoisomerase inhibitor with potent activity against Gram-positive, fastidious Gram-Negative, and atypical bacteria.

    PubMed

    Huband, Michael D; Bradford, Patricia A; Otterson, Linda G; Basarab, Gregory S; Kutschke, Amy C; Giacobbe, Robert A; Patey, Sara A; Alm, Richard A; Johnstone, Michele R; Potter, Marie E; Miller, Paul F; Mueller, John P

    2015-01-01

    AZD0914 is a new spiropyrimidinetrione bacterial DNA gyrase/topoisomerase inhibitor with potent in vitro antibacterial activity against key Gram-positive (Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pneumoniae, Streptococcus pyogenes, and Streptococcus agalactiae), fastidious Gram-negative (Haemophilus influenzae and Neisseria gonorrhoeae), atypical (Legionella pneumophila), and anaerobic (Clostridium difficile) bacterial species, including isolates with known resistance to fluoroquinolones. AZD0914 works via inhibition of DNA biosynthesis and accumulation of double-strand cleavages; this mechanism of inhibition differs from those of other marketed antibacterial compounds. AZD0914 stabilizes and arrests the cleaved covalent complex of gyrase with double-strand broken DNA under permissive conditions and thus blocks religation of the double-strand cleaved DNA to form fused circular DNA. Whereas this mechanism is similar to that seen with fluoroquinolones, it is mechanistically distinct. AZD0914 exhibited low frequencies of spontaneous resistance in S. aureus, and if mutants were obtained, the mutations mapped to gyrB. Additionally, no cross-resistance was observed for AZD0914 against recent bacterial clinical isolates demonstrating resistance to fluoroquinolones or other drug classes, including macrolides, ?-lactams, glycopeptides, and oxazolidinones. AZD0914 was bactericidal in both minimum bactericidal concentration and in vitro time-kill studies. In in vitro checkerboard/synergy testing with 17 comparator antibacterials, only additivity/indifference was observed. The potent in vitro antibacterial activity (including activity against fluoroquinolone-resistant isolates), low frequency of resistance, lack of cross-resistance, and bactericidal activity of AZD0914 support its continued development. PMID:25385112

  13. Non-Aqueous Glycerol Monolaurate Gel Exhibits Antibacterial and Anti-Biofilm Activity against Gram-Positive and Gram-Negative Pathogens

    PubMed Central

    Mueller, Elizabeth A.; Schlievert, Patrick M.

    2015-01-01

    Background Skin and surgical infections due to Staphylococcus aureus, Pseudomonas aeruginosa, and Acinetobacter baumannii are causes of patient morbidity and increased healthcare costs. These organisms grow planktonically and as biofilms, and many strains exhibit antibiotic resistance. This study examines the antibacterial and anti-biofilm activity of glycerol monolaurate (GML), as solubilized in a non-aqueous vehicle (5% GML Gel), as a novel, broadly-active topical antimicrobial. The FDA has designated GML as generally recognized as safe for human use, and the compound is commonly used in the cosmetic and food industries. Methods In vitro, bacterial strains in broths and biofilms were exposed to GML Gel, and effects on bacterial colony-forming units (CFUs) were assessed. In vivo,subcutaneous incisions were made in New Zealand white rabbits; the incisions were closed with four sutures. Bacterial strains were painted onto the incision sites, and then GML Gel or placebo was liberally applied to cover the sites completely. Rabbits were allowed to awaken and were examined for CFUs as a function of exposure time. Results In vitro, GML Gel was bactericidal for all broth culture and biofilm organisms in <1 hour and <4 hour, respectively; no CFUs were detected after the entire 24 h test period. In vivo, GML Gel inhibited bacterial growth in the surgical incision sites, compared to no growth inhibition in controls. GML Gel significantly reduced inflammation, as viewed by lack of redness in and below the incision sites. Conclusions Our findings suggest that 5% GML Gel is useful as a potent topical antibacterial and anti-inflammatory agent for prevention of infections. PMID:25799455

  14. Three novel B-type mannose-specific lectins of Cynoglossus semilaevis possess varied antibacterial activities against Gram-negative and Gram-positive bacteria.

    PubMed

    Sun, Yuan-Yuan; Liu, Li; Li, Jun; Sun, Li

    2016-02-01

    Lectins are a group of sugar-binding proteins that are important factors of the innate immune system. In this study, we examined, in a comparative manner, the expression and function of three Bulb-type (B-type) mannose-specific lectins (named CsBML1, CsBML2, and CsBML3) from tongue sole. All three lectins possess three repeats of the conserved mannose binding motif QXDXNXVXY. Expression of CsBML1, CsBML2, and CsBML3 was most abundant in liver and upregulated by bacterial infection. Recombinant (r) CsBML1, CsBML2, and CsBML3 bound to a wide arrange of bacteria in a dose-dependent manner and with different affinities. All three lectins displayed mannose-specific and calcium-dependent agglutinating capacities but differed in agglutinating profiles. rCsBML1 and rCsBML2, but not rCsBML3, killed target bacteria in vitro and inhibited bacterial dissemination in fish tissues in vivo. These results indicate for the first time that in teleost, different members of B-type mannose-specific lectins likely play different roles in antibacterial immunity. PMID:26455466

  15. Antibacterial properties of biosurfactants against selected Gram-positive and -negative bacteria.

    PubMed

    Díaz De Rienzo, Mayri A; Stevenson, Paul; Marchant, Roger; Banat, Ibrahim M

    2016-01-01

    The antibacterial properties and ability to disrupt biofilms of biosurfactants (rhamnolipids, sophorolipids) and sodium dodecyl sulphate (SDS) in the presence and absence of selected organic acids were investigated. Pseudomonas aeruginosa PAO1 was inhibited by sophorolipids and SDS at concentrations >5% v/v, and the growth of Escherichia coli NCTC 10418 was also inhibited by sophorolipids and SDS at concentrations >5% and 0.1% v/v, respectively. Bacillus subtilis NCTC 10400 was inhibited by rhamnolipids, sophorolipids and SDS at concentrations >0.5% v/v of all three; the same effect was observed with Staphylococcus aureus ATCC 9144. The ability to attach to surfaces and biofilm formation of P. aeruginosa PAO1, E. coli NCTC 10418 and B. subtilis NCTC 10400 was inhibited by sophorolipids (1% v/v) in the presence of caprylic acid (0.8% v/v). In the case of S. aureus ATCC 9144, the best results were obtained using caprylic acid on its own. It was concluded that sophorolipids are promising compounds for the inhibition/disruption of biofilms formed by Gram-positive and Gram-negative microorganisms and this activity can be enhanced by the presence of booster compounds such as caprylic acid. PMID:26598715

  16. Lipoglycopeptide Antibacterial Agents in Gram-Positive Infections: A Comparative Review.

    PubMed

    Van Bambeke, Françoise

    2015-12-01

    Oritavancin, telavancin, and dalbavancin are recently marketed lipoglycopeptides that exhibit remarkable differences to conventional molecules. While dalbavancin inhibits the late stages of peptidoglycan synthesis by mainly impairing transglycosylase activity, oritavancin and telavancin anchor in the bacterial membrane by the lipophilic side chain linked to their disaccharidic moiety, disrupting membrane integrity and causing bacteriolysis. Oritavancin keeps activity against vancomycin-resistant enterocococci, being a stronger inhibitor of transpeptidase than of transglycosylase activity. These molecules have potent activity against Gram-positive organisms, most notably staphylococci (including methicillin-resistant Staphylococcus aureus and to some extent vancomycin-intermediate S. aureus), streptococci (including multidrug-resistant pneumococci), and Clostridia. All agents are indicated for the treatment of acute bacterial skin and skin structure infections, and telavancin, for hospital-acquired and ventilator-associated bacterial pneumonia. While telavancin is administered daily at 10 mg/kg, the remarkably long half-lives of oritavancin and dalbavancin allow for infrequent dosing (single dose of 1200 mg for oritavancin and 1000 mg at day 1 followed by 500 mg at day 8 for dalbavancin), which could be exploited in the future for outpatient therapy. Among possible safety issues evidenced during clinical development were an increased risk of developing osteomyelitis with oritavancin; taste disturbance, nephrotoxicity, and risk of corrected QT interval prolongation (especially in the presence of at-risk co-medications) with telavancin; and elevation of hepatic enzymes with dalbavancin. Interference with coagulation tests has been reported with oritavancin and telavancin. These drugs proved non-inferior to conventional treatments in clinical trials but their advantages may be better evidenced upon future evaluation in more severe infections. PMID:26603874

  17. Bactericidal Activity and Mechanism of Photoirradiated Polyphenols against Gram-Positive and -Negative Bacteria.

    PubMed

    Nakamura, Keisuke; Ishiyama, Kirika; Sheng, Hong; Ikai, Hiroyo; Kanno, Taro; Niwano, Yoshimi

    2015-09-01

    The bactericidal effect of various types of photoirradiated polyphenols against Gram-positive and -negative bacteria was evaluated in relation to the mode of action. Gram-positive bacteria (Enterococcus faecalis, Staphylococcus aureus, and Streptococcus mutans) and Gram-negative bacteria (Aggregatibacter actinomycetemcomitans, Escherichia coli, and Pseudomonas aeruginosa) suspended in a 1 mg/mL polyphenol aqueous solution (caffeic acid, gallic acid, chlorogenic acid, epigallocatechin, epigallocatechin gallate, and proanthocyanidin) were exposed to LED light (wavelength, 400 nm; irradiance, 260 mW/cm(2)) for 5 or 10 min. Caffeic acid and chlorogenic acid exerted the highest bactericidal activity followed by gallic acid and proanthocyanidin against both Gram-positive and -negative bacteria. It was also demonstrated that the disinfection treatment induced oxidative damage of bacterial DNA, which suggests that polyphenols are incorporated into bacterial cells. The present study suggests that blue light irradiation of polyphenols could be a novel disinfection treatment. PMID:25660393

  18. Antimicrobial activity of metal oxide nanoparticles against Gram-positive and Gram-negative bacteria: a comparative study

    PubMed Central

    Azam, Ameer; Ahmed, Arham S; Oves, Mohammad; Khan, Mohammad S; Habib, Sami S; Memic, Adnan

    2012-01-01

    Background Nanomaterials have unique properties compared to their bulk counterparts. For this reason, nanotechnology has attracted a great deal of attention from the scientific community. Metal oxide nanomaterials like ZnO and CuO have been used industrially for several purposes, including cosmetics, paints, plastics, and textiles. A common feature that these nanoparticles exhibit is their antimicrobial behavior against pathogenic bacteria. In this report, we demonstrate the antimicrobial activity of ZnO, CuO, and Fe2O3 nanoparticles against Gram-positive and Gram-negative bacteria. Methods and results Nanosized particles of three metal oxides (ZnO, CuO, and Fe2O3) were synthesized by a sol–gel combustion route and characterized by X-ray diffraction, Fourier-transform infrared spectroscopy, and transmission electron microscopy techniques. X-ray diffraction results confirmed the single-phase formation of all three nanomaterials. The particle sizes were observed to be 18, 22, and 28 nm for ZnO, CuO, and Fe2O3, respectively. We used these nanomaterials to evaluate their antibacterial activity against both Gram-negative (Escherichia coli and Pseudomonas aeruginosa) and Gram-positive (Staphylococcus aureus and Bacillus subtilis) bacteria. Conclusion Among the three metal oxide nanomaterials, ZnO showed greatest antimicrobial activity against both Gram-positive and Gram-negative bacteria used in this study. It was observed that ZnO nanoparticles have excellent bactericidal potential, while Fe2O3 nanoparticles exhibited the least bactericidal activity. The order of antibacterial activity was demonstrated to be the following: ZnO > CuO > Fe2O3. PMID:23233805

  19. New potent antibacterials against Gram-positive multiresistant pathogens: effects of side chain modification and chirality in linezolid-like 1,2,4-oxadiazoles.

    PubMed

    Fortuna, Cosimo G; Berardozzi, Roberto; Bonaccorso, Carmela; Caltabiano, Gianluigi; Di Bari, Lorenzo; Goracci, Laura; Guarcello, Annalisa; Pace, Andrea; Palumbo Piccionello, Antonio; Pescitelli, Gennaro; Pierro, Paola; Lonati, Elena; Bulbarelli, Alessandra; Cocuzza, Clementina E A; Musumarra, Giuseppe; Musumeci, Rosario

    2014-12-15

    The effects of side chain modification and chirality in linezolid-like 1,2,4-oxadiazoles have been studied to design new potent antibacterials against Gram-positive multidrug-resistant pathogens. The adopted strategy involved a molecular modelling approach, the synthesis and biological evaluation of new designed compounds, enantiomers separation and absolute configuration assignment. Experimental determination of the antibacterial activity of the designed (S)-1-((3-(4-(3-methyl-1,2,4-oxadiazol-5-yl)phenyl)-oxazolidin-2-one-5-yl)methyl)-3-methylthiourea and (S)-1-((3-(3-fluoro-4-(3-methyl-1,2,4-oxadiazol-5-yl)phenyl)-oxazolidin-2-one-5-yl)methyl)-3-methylthiourea against multidrug resistant linezolid bacterial strains was higher than that of linezolid. PMID:25464880

  20. Antimicrobial Activities of Leaf Extracts of Guava (Psidium guajava L.) on Two Gram-Negative and Gram-Positive Bacteria

    PubMed Central

    Biswas, Bipul; Rogers, Kimberly; McLaughlin, Fredrick; Yadav, Anand

    2013-01-01

    Aim. To determine the antimicrobial potential of guava (Psidium guajava) leaf extracts against two gram-negative bacteria (Escherichia coli and Salmonella enteritidis) and two gram-positive bacteria (Staphylococcus aureus and Bacillus cereus) which are some of foodborne and spoilage bacteria. The guava leaves were extracted in four different solvents of increasing polarities (hexane, methanol, ethanol, and water). The efficacy of these extracts was tested against those bacteria through a well-diffusion method employing 50??L leaf-extract solution per well. According to the findings of the antibacterial assay, the methanol and ethanol extracts of the guava leaves showed inhibitory activity against gram-positive bacteria, whereas the gram-negative bacteria were resistant to all the solvent extracts. The methanol extract had an antibacterial activity with mean zones of inhibition of 8.27 and 12.3?mm, and the ethanol extract had a mean zone of inhibition of 6.11 and 11.0?mm against B. cereus and S. aureus, respectively. On the basis of the present finding, guava leaf-extract might be a good candidate in the search for a natural antimicrobial agent. This study provides scientific understanding to further determine the antimicrobial values and investigate other pharmacological properties. PMID:24223039

  1. Silver nanoparticles synthesized by pulsed laser ablation: as a potent antibacterial agent for human enteropathogenic gram-positive and gram-negative bacterial strains.

    PubMed

    Pandey, Jitendra Kumar; Swarnkar, R K; Soumya, K K; Dwivedi, Priyanka; Singh, Manish Kumar; Sundaram, Shanthy; Gopal, R

    2014-10-01

    Present investigation deals with the study, to quantify the antibacterial property of silver nanoparticles (SNPs), synthesized by pulsed laser ablation (PLA) in aqueous media, on some human enteropathogenic gram-positive and gram-negative bacterial strains. Antibacterial property was studied by measuring the zone of inhibition using agar cup double-diffusion method, minimum inhibitory concentration by serial dilution method, and growth curve for 24 h. The results clearly show the potency of antibacterial property of PLA-synthesized SNPs and suggest that it can be used as an effective growth inhibitor against various pathogenic bacterial strains in various medical devices and antibacterial control systems. PMID:24801405

  2. Comparative in vitro activity profile of oritavancin against recent gram-positive clinical isolates.

    PubMed

    Arhin, Francis F; Draghi, Deborah C; Pillar, Chris M; Parr, Thomas R; Moeck, Gregory; Sahm, Daniel F

    2009-11-01

    Oritavancin activity was tested against 15,764 gram-positive isolates collected from 246 hospital centers in 25 countries between 2005 and 2008. Organisms were Staphylococcus aureus (n = 9,075), coagulase-negative staphylococci (n = 1,664), Enterococcus faecalis (n = 1,738), Enterococcus faecium (n = 819), Streptococcus pyogenes (n = 959), Streptococcus agalactiae (n = 415), group C, G, and F streptococci (n = 84), and Streptococcus pneumoniae (n = 1,010). Among the evaluated staphylococci, 56.7% were resistant to oxacillin. The vancomycin resistance rate among enterococci was 21.2%. Penicillin-resistant and -intermediate rates were 14.7% and 21.4%, respectively, among S. pneumoniae isolates. Among nonpneumococcal streptococci, 18.5% were nonsusceptible to erythromycin. Oritavancin showed substantial in vitro activity against all organisms tested, regardless of resistance profile. The maximum oritavancin MIC against all staphylococci tested (n = 10,739) was 4 microg/ml; the MIC(90) against S. aureus was 0.12 microg/ml. Against E. faecalis and E. faecium, oritavancin MIC(90)s were 0.06 and 0.12, respectively. Oritavancin was active against glycopeptide-resistant enterococci, including VanA strains (n = 486), with MIC(90)s of 0.25 and 1 microg/ml against VanA E. faecium and E. faecalis, respectively. Oritavancin showed potent activity against streptococci (n = 2,468); MIC(90)s for the different streptococcal species were between 0.008 and 1 microg/ml. These data are consistent with previous studies with respect to resistance rates of gram-positive isolates and demonstrate the spectrum and in vitro activity of oritavancin against a wide variety of contemporary gram-positive pathogens, regardless of resistance to currently used drugs. The data provide a foundation for interpreting oritavancin activity and potential changes in susceptibility over time once oritavancin enters into clinical use. PMID:19738026

  3. Comparative In Vitro Activity Profile of Oritavancin against Recent Gram-Positive Clinical Isolates?

    PubMed Central

    Arhin, Francis F.; Draghi, Deborah C.; Pillar, Chris M.; Parr, Thomas R.; Moeck, Gregory; Sahm, Daniel F.

    2009-01-01

    Oritavancin activity was tested against 15,764 gram-positive isolates collected from 246 hospital centers in 25 countries between 2005 and 2008. Organisms were Staphylococcus aureus (n = 9,075), coagulase-negative staphylococci (n = 1,664), Enterococcus faecalis (n = 1,738), Enterococcus faecium (n = 819), Streptococcus pyogenes (n = 959), Streptococcus agalactiae (n = 415), group C, G, and F streptococci (n = 84), and Streptococcus pneumoniae (n = 1,010). Among the evaluated staphylococci, 56.7% were resistant to oxacillin. The vancomycin resistance rate among enterococci was 21.2%. Penicillin-resistant and -intermediate rates were 14.7% and 21.4%, respectively, among S. pneumoniae isolates. Among nonpneumococcal streptococci, 18.5% were nonsusceptible to erythromycin. Oritavancin showed substantial in vitro activity against all organisms tested, regardless of resistance profile. The maximum oritavancin MIC against all staphylococci tested (n = 10,739) was 4 ?g/ml; the MIC90 against S. aureus was 0.12 ?g/ml. Against E. faecalis and E. faecium, oritavancin MIC90s were 0.06 and 0.12, respectively. Oritavancin was active against glycopeptide-resistant enterococci, including VanA strains (n = 486), with MIC90s of 0.25 and 1 ?g/ml against VanA E. faecium and E. faecalis, respectively. Oritavancin showed potent activity against streptococci (n = 2,468); MIC90s for the different streptococcal species were between 0.008 and 1 ?g/ml. These data are consistent with previous studies with respect to resistance rates of gram-positive isolates and demonstrate the spectrum and in vitro activity of oritavancin against a wide variety of contemporary gram-positive pathogens, regardless of resistance to currently used drugs. The data provide a foundation for interpreting oritavancin activity and potential changes in susceptibility over time once oritavancin enters into clinical use. PMID:19738026

  4. Two Active Forms of UDP-N-Acetylglucosamine Enolpyruvyl Transferase in Gram-Positive Bacteria

    PubMed Central

    Du, Wensheng; Brown, James R.; Sylvester, Daniel R.; Huang, Jianzhong; Chalker, Alison F.; So, Chi Y.; Holmes, David J.; Payne, David J.; Wallis, Nicola G.

    2000-01-01

    Gene sequences encoding the enzymes UDP-N-acetylglucosamine enolpyruvyl transferase (MurA) from many bacterial sources were analyzed. It was shown that whereas gram-negative bacteria have only one murA gene, gram-positive bacteria have two distinct genes encoding these enzymes which have possibly arisen from gene duplication. The two murA genes of the gram-positive organism Streptococcus pneumoniae were studied further. Each of the murA genes was individually inactivated by allelic replacement. In each case, the organism was viable despite losing one of its murA genes. However, when attempts were made to construct a double-deletion strain, no mutants were obtained. This indicates that both genes encode active enzymes that can substitute for each other, but that the presence of a MurA function is essential to the organism. The two genes were further cloned and overexpressed, and the enzymes they encode were purified. Both enzymes catalyzed the transfer of enolpyruvate from phosphoenolpyruvate to UDP-N-acetylglucosamine, confirming they are both active UDP-N-acetylglucosamine enolpyruvyl transferases. The catalytic parameters of the two enzymes were similar, and they were both inhibited by the antibiotic fosfomycin. PMID:10894720

  5. Tribolium castaneum defensins are primarily active against Gram-positive bacteria.

    PubMed

    Tonk, Miray; Knorr, Eileen; Cabezas-Cruz, Alejandro; Valdés, James J; Kollewe, Christian; Vilcinskas, Andreas

    2015-11-01

    The red flour beetle Tribolium castaneum is a destructive insect pest of stored food and feed products, and a model organism for development, evolutionary biology and immunity. The insect innate immune system includes antimicrobial peptides (AMPs) with a wide spectrum of targets including viruses, bacteria, fungi and parasites. Defensins are an evolutionarily-conserved class of AMPs and a potential new source of antimicrobial agents. In this context, we report the antimicrobial activity, phylogenetic and structural properties of three T. castaneum defensins (Def1, Def2 and Def3) and their relevance in the immunity of T. castaneum against bacterial pathogens. All three recombinant defensins showed bactericidal activity against Micrococcus luteus and Bacillus thuringiensis serovar tolworthi, but only Def1 and Def2 showed a bacteriostatic effect against Staphylococcus epidermidis. None of the defensins showed activity against the Gram-negative bacteria Escherichia coli and Pseudomonas entomophila or against the yeast Saccharomyces cerevisiae. All three defensins were transcriptionally upregulated following a bacterial challenge, suggesting a key role in the immunity of T. castaneum against bacterial pathogens. Phylogenetic analysis showed that defensins from T. castaneum, mealworms, Udo longhorn beetle and houseflies cluster within a well-defined clade of insect defensins. We conclude that T. castaneum defensins are primarily active against Gram-positive bacteria and that other AMPs may play a more prominent role against Gram-negative species. PMID:26522790

  6. Novel Imidazoline Antimicrobial Scaffold That Inhibits DNA Replication with Activity against Mycobacteria and Drug Resistant Gram-Positive Cocci

    PubMed Central

    2015-01-01

    Bacterial antimicrobial resistance is an escalating public health threat, yet the current antimicrobial pipeline remains alarmingly depleted, making the development of new antimicrobials an urgent need. Here, we identify a novel, potent, imidazoline antimicrobial compound, SKI-356313, with bactericidal activity against Mycobacterium tuberculosis and Gram-positive cocci, including vancomycin-resistant Enterococcus faecium (VRE) and methicillin-resistant Staphylococcus aureus (MRSA). SKI-356313 is active in murine models of Streptococcus pneumoniae and MRSA infection and is potently bactericidal for both replicating and nonreplicating M. tuberculosis. Using a combination of genetics, whole genome sequencing, and a novel target ID approach using real time imaging of core macromolecular biosynthesis, we show that SKI-356313 inhibits DNA replication and displaces the replisome from the bacterial nucleoid. These results identify a new antimicrobial scaffold with a novel mechanism of action and potential therapeutic utility against nonreplicating M. tuberculosis and antibiotic resistant Gram-positive cocci. PMID:25222597

  7. Bacteriocins of gram-positive bacteria.

    PubMed Central

    Jack, R W; Tagg, J R; Ray, B

    1995-01-01

    In recent years, a group of antibacterial proteins produced by gram-positive bacteria have attracted great interest in their potential use as food preservatives and as antibacterial agents to combat certain infections due to gram-positive pathogenic bacteria. They are ribosomally synthesized peptides of 30 to less than 60 amino acids, with a narrow to wide antibacterial spectrum against gram-positive bacteria; the antibacterial property is heat stable, and a producer strain displays a degree of specific self-protection against its own antibacterial peptide. In many respects, these proteins are quite different from the colicins and other bacteriocins produced by gram-negative bacteria, yet customarily they also are grouped as bacteriocins. Although a large number of these bacteriocins (or bacteriocin-like inhibitory substances) have been reported, only a few have been studied in detail for their mode of action, amino acid sequence, genetic characteristics, and biosynthesis mechanisms. Nevertheless, in general, they appear to be translated as inactive prepeptides containing an N-terminal leader sequence and a C-terminal propeptide component. During posttranslational modifications, the leader peptide is removed. In addition, depending on the particular type, some amino acids in the propeptide components may undergo either dehydration and thioether ring formation to produce lanthionine and beta-methyl lanthionine (as in lantibiotics) or thio ester ring formation to form cystine (as in thiolbiotics). Some of these steps, as well as the translocation of the molecules through the cytoplasmic membrane and producer self-protection against the homologous bacteriocin, are mediated through specific proteins (enzymes). Limited genetic studies have shown that the structural gene for such a bacteriocin and the genes encoding proteins associated with immunity, translocation, and processing are present in a cluster in either a plasmid, the chromosome, or a transposon. Following posttranslational modification and depending on the pH, the molecules may either be released into the environment or remain bound to the cell wall. The antibacterial action against a sensitive cell of a gram-positive strain is produced principally by destabilization of membrane functions. Under certain conditions, gram-negative bacterial cells can also be sensitive to some of these molecules. By application of site-specific mutagenesis, bacteriocin variants which may differ in their antimicrobial spectrum and physicochemical characteristics can be produced. Research activity in this field has grown remarkably but sometimes with an undisciplined regard for conformity in the definition, naming, and categorization of these molecules and their genetic effectors. Some suggestions for improved standardization of nomenclature are offered. PMID:7603408

  8. Isolation of Highly Active Monoclonal Antibodies against Multiresistant Gram-Positive Bacteria

    PubMed Central

    Rossmann, Friederike S.; Laverde, Diana; Kropec, Andrea; Romero-Saavedra, Felipe; Meyer-Buehn, Melanie; Huebner, Johannes

    2015-01-01

    Multiresistant nosocomial pathogens often cause life-threatening infections that are sometimes untreatable with currently available antibiotics. Staphylococci and enterococci are the predominant Gram-positive species associated with hospital-acquired infections. These infections often lead to extended hospital stay and excess mortality. In this study, a panel of fully human monoclonal antibodies was isolated from a healthy individual by selection of B-cells producing antibodies with high opsonic killing against E. faecalis 12030. Variable domains (VH and VL) of these immunoglobulin genes were amplified by PCR and cloned into an eukaryotic expression vector containing the constant domains of a human IgG1 molecule and the human lambda constant domain. These constructs were transfected into CHO cells and culture supernatants were collected and tested by opsonophagocytic assay against E. faecalis and S. aureus strains (including MRSA). At concentrations of 600 pg/ml, opsonic killing was between 40% and 70% against all strains tested. Monoclonal antibodies were also evaluated in a mouse sepsis model (using S. aureus LAC and E. faecium), a mouse peritonitis model (using S. aureus Newman and LAC) and a rat endocarditis model (using E. faecalis 12030) and were shown to provide protection in all models at a concentration of 4 ?g/kg per animal. Here we present a method to produce fully human IgG1 monoclonal antibodies that are opsonic in vitro and protective in vivo against several multiresistant Gram-positive bacteria. The monoclonal antibodies presented in this study are significantly more effective compared to another monoclonal antibody currently in clinical trials. PMID:25706415

  9. Production of a bacteriocin by a poultry derived Campylobacter jejuni isolate with antimicrobial activity against Clostridium perfringens and other Gram positive bacteria.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We have purified a bacteriocin peptide (termed CUV-3), produced by a poultry cecal isolate of Campylobacter jejuni (strain CUV-3) with inhibitory activity against Gram positive bacteria including Clostridium perfringens (38 strains), Staphylococcus aureus, Staphylococcus epidermidis and Listeria mon...

  10. Tryptophan-containing lipopeptide antibiotics derived from polymyxin B with activity against Gram positive and Gram negative bacteria.

    PubMed

    Grau-Campistany, Ariadna; Manresa, Ángeles; Pujol, Montserrat; Rabanal, Francesc; Cajal, Yolanda

    2016-02-01

    Resistance to all known antibiotics is a growing concern worldwide, and has renewed the interest in antimicrobial peptides, a structurally diverse class of amphipathic molecules that essentially act on the bacterial membrane. Propelled by the antimicrobial potential of this compound class, we have designed three new lipopeptides derived from polymyxin B, sp-34, sp-96 and sp-100, with potent antimicrobial activity against both Gram positive and Gram negative bacteria. The three peptides bind with high affinity to lipopolysaccharide as demonstrated by monolayer penetration and dansyl-displacement. The interaction with the cytoplasmic membrane has been elucidated by biophysical experiments with model membranes of POPG or POPE/POPG (6:4), mimicking the Gram positive and Gram negative bacterial membrane. Trp-based fluorescence experiments including steady-state, quenching, anisotropy and FRET, reveal selectivity for anionic phospholipids and deep insertion into the membrane. All three lipopeptides induce membrane fusion and leakage from anionic vesicles, a process that is favored by the presence of POPE. The molecules bind to zwitterionic POPC vesicles, a model of the eukaryotic membrane, but in a different way, with lower affinity, less penetration into the bilayer and no fusion or permeabilization of the membrane. Results in model membranes are consistent with flow cytometry experiments in Escherichia coli and Staphylococcus aureus using a membrane potential sensitive dye (bis-oxonol) and a nucleic acid dye (propidium iodide), suggesting that the mechanism of action is based on membrane binding and collapse of membrane integrity by depolarization and permeabilization. PMID:26607008

  11. Pyrrolidine bis-cyclic guanidines with antimicrobial activity against drug-resistant Gram-positive pathogens

    E-print Network

    Nizet, Victor

    Pyrrolidine bis-cyclic guanidines with antimicrobial activity against drug-resistant Gram chemical libraries amenable to high-throughput screening for antimicrobial activities. Here we report and bactericidal activities against the important human pathogen methicillin-resis- tant Staphylococcus aureus

  12. Daptomycin Activity against Uncommonly Isolated Streptococcal and Other Gram-Positive Species Groups

    PubMed Central

    Flamm, Robert K.; Farrell, David J.; Jones, Ronald N.

    2013-01-01

    A total of 1,356 clinical isolates were tested against daptomycin by broth microdilution methods. Daptomycin was active against seven groups of viridans group streptococci (MIC50 and MIC90 values ranging from ?0.06 and ?0.06 ?g/ml [Streptococcus bovis and Streptococcus dysgalactiae] to 0.5 and 1 ?g/ml [Streptococcus mitis, Streptococcus oralis, and Streptococcus parasanguinis], respectively), beta-hemolytic streptococci serogroups C, F, and G (MIC50 and MIC90, ?0.06 to 0.25 and 0.12 to 0.25 ?g/ml, respectively), Corynebacterium spp. (MIC50 and MIC90, ?0.06 and 0.12 ?g/ml, respectively), and Micrococcus spp. (MIC50 and MIC90, ?0.06 and 0.25 ?g/ml, respectively). Listeria monocytogenes exhibited higher daptomycin MICs (MIC50 and MIC90, 2 and 4 ?g/ml, respectively) than other tested organisms. PMID:24080651

  13. A poultry-intestinal isolate of Campylobacter jejuni produces a bacteriocin (CUV-3) active against a range of Gram positive bacterial pathogens including Clostridium perfringens

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A newly isolated bacteriocin, CUV-3, produced by a poultry cecal isolate of Campylobacter jejuni strain CUV-3 had inhibitory activity against several Gram positive bacteria including Clostridium perfringens (38 strains), Staphylococcus aureus, Staph.epidermidis and Listeria monocytogenes. The pept...

  14. Novel antibiotics targeting respiratory ATP synthesis in Gram-positive pathogenic bacteria.

    PubMed

    Balemans, Wendy; Vranckx, Luc; Lounis, Nacer; Pop, Ovidiu; Guillemont, Jérôme; Vergauwen, Karen; Mol, Selena; Gilissen, Ron; Motte, Magali; Lançois, David; De Bolle, Miguel; Bonroy, Kristien; Lill, Holger; Andries, Koen; Bald, Dirk; Koul, Anil

    2012-08-01

    Emergence of drug-resistant bacteria represents a high, unmet medical need, and discovery of new antibacterials acting on new bacterial targets is strongly needed. ATP synthase has been validated as an antibacterial target in Mycobacterium tuberculosis, where its activity can be specifically blocked by the diarylquinoline TMC207. However, potency of TMC207 is restricted to mycobacteria with little or no effect on the growth of other Gram-positive or Gram-negative bacteria. Here, we identify diarylquinolines with activity against key Gram-positive pathogens, significantly extending the antibacterial spectrum of the diarylquinoline class of drugs. These compounds inhibited growth of Staphylococcus aureus in planktonic state as well as in metabolically resting bacteria grown in a biofilm culture. Furthermore, time-kill experiments showed that the selected hits are rapidly bactericidal. Drug-resistant mutations were mapped to the ATP synthase enzyme, and biochemical analysis as well as drug-target interaction studies reveal ATP synthase as a target for these compounds. Moreover, knockdown of the ATP synthase expression strongly suppressed growth of S. aureus, revealing a crucial role of this target in bacterial growth and metabolism. Our data represent a proof of principle for using the diarylquinoline class of antibacterials in key Gram-positive pathogens. Our results suggest that broadening the antibacterial spectrum for this chemical class is possible without drifting off from the target. Development of the diarylquinolines class may represent a promising strategy for combating Gram-positive pathogens. PMID:22615276

  15. Lysis of gram-positive and gram-negative bacteria by antibacterial porous polymeric monolith formed in microfluidic biochips for sample preparation.

    PubMed

    Aly, Mohamed Aly Saad; Gauthier, Mario; Yeow, John

    2014-09-01

    Bacterial cell lysis is demonstrated using polymeric microfluidic biochips operating via a hybrid mechanical shearing/contact killing mechanism. These biochips are fabricated from a cross-linked poly(methyl methacrylate) (X-PMMA) substrate by well-controlled, high-throughput laser micromachining. The unreacted double bonds at the surface of X-PMMA provide covalent bonding for the formation of a porous polymeric monolith (PPM), thus contributing to the mechanical stability of the biochip and eliminating the need for surface treatment. The lysis efficiency of these biochips was tested for gram-positive (Enterococcus saccharolyticus and Bacillus subtilis) and gram-negative bacteria (Escherichia coli and Pseudomonas fluorescens) and confirmed by off-chip PCR without further purification. The influence of the flow rate when pumping the bacterial suspension through the PPM, and of the hydrophobic-hydrophilic balance on the cell lysis efficiency was investigated at a cell concentration of 10(5) CFU/mL. It was shown that the contribution of contact killing to cell lysis was more important than that of mechanical shearing in the PPM. The biochip showed better lysis efficiency than the off-chip chemical, mechanical, and thermal lysis techniques used in this work. The biochip also acts as a filter that isolates cell debris and allows PCR-amplifiable DNA to pass through. The system performs more efficient lysis for gram-negative than for gram-positive bacteria. The biochip does not require chemical/enzymatic reagents, power consumption, or complicated design and fabrication processes, which makes it an attractive on-chip lysis device that can be used in sample preparation for genetics and point-of-care diagnostics. The biochips were reused for 20 lysis cycles without any evidence of physical damage to the PPM, significant performance degradation, or DNA carryover when they were back-flushed between cycles. The biochips efficiently lysed both gram-positive and gram-negative bacteria in about 35 min per lysis and PPM regeneration cycle. PMID:25059724

  16. Antibacterial Activity of Glutathione-Coated Silver Nanoparticles against Gram Positive and Gram Negative Bacteria

    E-print Network

    Negative Bacteria Angelo Taglietti,*, Yuri A. Diaz Fernandez,*, Elvio Amato, Lucia Cucca, Giacomo Dacarro that the effect of dispersed GSH capped Ag NPs (GSH Ag NPs) on Escherichia coli is more intense because it can be considered an environmentally friendly antimicrobial, also considering the weak ability of bacteria

  17. New drugs for Gram-positive uropathogens.

    PubMed

    Wagenlehner, F M E; Naber, K G

    2004-09-01

    Complicated urinary tract infections (UTIs) are frequent nosocomial infections. The bacterial spectrum encompasses Gram-negative but also Gram-positive pathogens in up to 30-40%. The existing treatment for Gram-positive pathogens is not always optimal. Antimicrobials for the treatment of Gram-positive uropathogens comprise older agents, such as aminopenicillins with or without beta-lactamase inhibitors and vancomycin, as well as newer fluoroquinolones, such as levofloxacin or gatifloxacin. However, resistant bacteria such as vancomycin-resistant enterococci (VRE) or methicillin-resistant Staphylococcus aureus (MRSA) (except vancomycin-resistant) are generally also not susceptible to the fluoroquinolones. Therefore new agents need to be assessed in the treatment of UTI. Daptomycin and linezolid are new antimicrobial agents with good efficacy against Gram-positive uropathogens as shown by their minimal inhibitory concentrations. In a phase II study the urinary bactericidal activity of linezolid versus ciprofloxacin in volunteers showed comparable activity of both drugs against fluoroquinolone susceptible Gram-positive uropathogens, whereas linezolid was also as active against fluoroquinolone resistant ones. The pharmacokinetics and the mode of action of these two antibiotics are discussed together with some clinical data in the context of therapeutic use in patients with complicated UTIs. PMID:15364305

  18. The molecular switch that activates the cell wall anchoring step of pilus assembly in gram-positive bacteria

    PubMed Central

    Mandlik, Anjali; Das, Asis; Ton-That, Hung

    2008-01-01

    Cell surface pili in Gram-positive bacteria orchestrate the colonization of host tissues, evasion of immunity, and the development of biofilms. Recent work revealed that pilus assembly is a biphasic process wherein pilus polymerization is catalyzed by a pilus-specific sortase followed by cell wall anchoring of the pilus that is promoted by the housekeeping sortase. Here, we present molecular genetic and biochemical studies of a heterotrimeric pilus in Corynebacterium diphtheriae, uncovering the molecular switch that terminates pilus polymerization in favor of cell wall anchoring. The prototype pilus contains a major pilin (SpaA) forming the shaft, a tip pilin (SpaC), and another minor pilin (SpaB). Cells lacking SpaB form pilus fibers, but they are largely secreted in the medium, a phenotype also observed when cells lack the housekeeping sortase. Furthermore, the average pilus length is greatly increased in the absence of SpaB. Remarkably, a SpaB mutant that lacks the cell wall sorting signal but contains a critical lysine residue is incorporated in the pilus. However, the resulting pili fail to anchor to the cell wall. We propose that a specific minor pilin acts as the terminal subunit in pilus assembly. Cell wall anchoring ensues when the pilus polymer assembled on the pilus-specific sortase is transferred to the minor pilin presented by the housekeeping sortase via lysine-mediated transpeptidation. PMID:18779588

  19. The molecular switch that activates the cell wall anchoring step of pilus assembly in gram-positive bacteria.

    PubMed

    Mandlik, Anjali; Das, Asis; Ton-That, Hung

    2008-09-16

    Cell surface pili in gram-positive bacteria orchestrate the colonization of host tissues, evasion of immunity, and the development of biofilms. Recent work revealed that pilus assembly is a biphasic process wherein pilus polymerization is catalyzed by a pilus-specific sortase followed by cell wall anchoring of the pilus that is promoted by the housekeeping sortase. Here, we present molecular genetic and biochemical studies of a heterotrimeric pilus in Corynebacterium diphtheriae, uncovering the molecular switch that terminates pilus polymerization in favor of cell wall anchoring. The prototype pilus contains a major pilin (SpaA) forming the shaft, a tip pilin (SpaC), and another minor pilin (SpaB). Cells lacking SpaB form pilus fibers, but they are largely secreted in the medium, a phenotype also observed when cells lack the housekeeping sortase. Furthermore, the average pilus length is greatly increased in the absence of SpaB. Remarkably, a SpaB mutant that lacks the cell wall sorting signal but contains a critical lysine residue is incorporated in the pilus. However, the resulting pili fail to anchor to the cell wall. We propose that a specific minor pilin acts as the terminal subunit in pilus assembly. Cell wall anchoring ensues when the pilus polymer assembled on the pilus-specific sortase is transferred to the minor pilin presented by the housekeeping sortase via lysine-mediated transpeptidation. PMID:18779588

  20. ANTIBACTERIAL ACTIVITY OF BIOCONVERTED LINOLEIC ACID PRODUCED BY PSEUDOMONAS AERUGINOSA PR3

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Crude extract of bioconverted linoleic acid using Pseudomonas aeruginosa PR3 was evaluated for its antibacterial activity against food-borne pathogenic bacteria. Crude extract showed antibacterial activity against four Gram-positive bacteria, Staphylococcus aureus (ATCC 6538), S. aureus (KCTC 1916)...

  1. In Vitro Activity of AZD0914, a Novel Bacterial DNA Gyrase/Topoisomerase IV Inhibitor, against Clinically Relevant Gram-Positive and Fastidious Gram-Negative Pathogens.

    PubMed

    Biedenbach, Douglas J; Huband, Michael D; Hackel, Meredith; de Jonge, Boudewijn L M; Sahm, Daniel F; Bradford, Patricia A

    2015-10-01

    AZD0914, a new spiropyrimidinetrione bacterial DNA gyrase inhibitor with a novel mode of inhibition, has activity against bacterial species commonly cultured from patient infection specimens, including fluoroquinolone-resistant isolates. This study assessed the in vitro activity of AZD0914 against key Gram-positive and fastidious Gram-negative clinical isolates collected globally in 2013. AZD0914 demonstrated potent activity, with MIC90s for AZD0914 of 0.25 mg/liter against Staphylococcus aureus (n = 11,680), coagulase-negative staphylococci (n = 1,923), streptococci (n = 4,380), and Moraxella catarrhalis (n = 145), 0.5 mg/liter against Staphylococcus lugdunensis (n = 120) and Haemophilus influenzae (n = 352), 1 mg/liter against Enterococcus faecalis (n = 1,241), and 2 mg/liter against Haemophilus parainfluenzae (n = 70). The activity against Enterococcus faecium was more limited (MIC90, 8 mg/liter). The spectrum and potency of AZD0914 included fluoroquinolone-resistant isolates in each species group, including methicillin-resistant staphylococci, penicillin-resistant streptococci, vancomycin-resistant enterococci, ?-lactamase-producing Haemophilus spp., and M. catarrhalis. Based on these in vitro findings, AZD0914 warrants further investigation for its utility against a variety of Gram-positive and fastidious Gram-negative bacterial species. PMID:26195518

  2. Facile synthesis of gold nanoparticles on propylamine functionalized SBA-15 and effect of surface functionality of its enhanced bactericidal activity against gram positive bacteria

    NASA Astrophysics Data System (ADS)

    Bhuyan, Diganta; Gogoi, Animesh; Saikia, Mrinal; Saikia, Ratul; Saikia, Lakshi

    2015-07-01

    The facile synthesis of an SBA-15-pr-+NH3.Au0 nano-hybrid material by spontaneous autoreduction of aqueous chloroaurate anions on propylamine functionalized SBA-15 was successfully demonstrated. The as-synthesized SBA-15-pr-+NH3.Au0 nano-hybrid material was well characterized using low and wide angle x-ray diffraction (XRD), N2 adsorption-desorption isotherms, Fourier transform infrared (FTIR), transmission electron microscopy (TEM), scanning electron microscopy-energy dispersive x-ray spectroscopy (SEM-EDX), x-ray photoelectron spectroscopy (XPS), UV-Visible spectroscopy and atomic absorption spectroscopy (AAS). The activity of the nano-hybrid material as a potent bactericidal agent was successfully tested against Gram positive/negative bacteria viz. Bacillus subtilis, Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa. The colony killing percentage of Gram positive bacteria was found to be higher than Gram negative bacteria due to the stronger electrostatic interaction between the positively-charged amine functionality of SBA-15 and the negatively charged functionality of the bacterial cell wall.

  3. Alternating electric fields combined with activated carbon for disinfection of Gram negative and Gram positive bacteria in fluidized bed electrode system.

    PubMed

    Racyte, Justina; Bernard, Séverine; Paulitsch-Fuchs, Astrid H; Yntema, Doekle R; Bruning, Harry; Rijnaarts, Huub H M

    2013-10-15

    Strong electric fields for disinfection of wastewaters have been employed already for several decades. An innovative approach combining low strength (7 V/cm) alternating electric fields with a granular activated carbon fluidized bed electrode (FBE) for disinfection was presented recently. For disinfection performance of FBE several pure microbial cultures were tested: Bacillus subtilis, Bacillus subtilis subsp. subtilis, Enterococcus faecalis as representatives from Gram positive bacteria and Erwinia carotovora, Pseudomonas luteola, Pseudomonas fluorescens and Escherichia coli YMc10 as representatives from Gram negative bacteria. The alternating electric field amplitude and shape were kept constant. Only the effect of alternating electric field frequency on disinfection performance was investigated. From the bacteria tested, the Gram negative strains were more susceptible and the Gram positive microorganisms were more resistant to FBE disinfection. The collected data indicate that the efficiency of disinfection is frequency and strain dependent. During 6 h of disinfection, the decrease above 2 Log units was achieved with P. luteola and E. coli at 10 kHz and at dual frequency shift keying (FSK) modulated signal with frequencies of 10 kHz and 140 kHz. FBE technology appears to offer a new way for selective bacterial disinfection, however further optimizations are needed on treatment duration, and energy input, to improve effectiveness. PMID:24012021

  4. In Vitro Activities of Tedizolid and Linezolid against Gram-Positive Cocci Associated with Acute Bacterial Skin and Skin Structure Infections and Pneumonia.

    PubMed

    Chen, Ko-Hung; Huang, Yu-Tsung; Liao, Chun-Hsing; Sheng, Wang-Hui; Hsueh, Po-Ren

    2015-10-01

    Tedizolid is a novel, expanded-spectrum oxazolidinone with potent activity against a wide range of Gram-positive pathogens. A total of 425 isolates of Gram-positive bacteria were obtained consecutively from patients with acute bacterial skin and skin structure infections (ABSSSIs) or pneumonia. These isolates included methicillin-susceptible Staphylococcus aureus (MSSA) (n = 100), methicillin-resistant Staphylococcus aureus (MRSA) (n = 100), Streptococcus pyogenes (n = 50), Streptococcus agalactiae (n = 50), Streptococcus anginosus group (n = 75), Enterococcus faecalis (n = 50), and vancomycin-resistant enterococci (VRE) (Enterococcus faecium) (n = 50). The MICs of tedizolid and linezolid were determined by the agar dilution method. Tedizolid exhibited better in vitro activities than linezolid against MSSA (MIC90s, 0.5 versus 2 ?g/ml), MRSA (MIC90s, 0.5 versus 2 ?g/ml), S. pyogenes (MIC90s, 0.5 versus 2 ?g/ml), S. agalactiae (MIC90s, 0.5 versus 2 ?g/ml), Streptococcus anginosus group (MIC90s, 0.5 versus 2 ?g/ml), E. faecalis (MIC90s, 0.5 versus 2 ?g/ml), and VRE (MIC90s, 0.5 versus 2 ?g/ml). The tedizolid MICs against E. faecalis (n = 3) and VRE (n = 2) intermediate to linezolid (MICs, 4 ?g/ml) were 1 ?g/ml and 0.5 ?g/ml, respectively. The tedizolid MIC90s against S. anginosus, S. constellatus, and S. intermedius were 0.5, 1, and 0.5 ?g/ml, respectively, and the rates of susceptibility based on the U.S. FDA MIC interpretive breakpoints to the isolates were 16%, 28%, and 72%, respectively. Tedizolid exhibited 2- to 4-fold better in vitro activities than linezolid against a variety of Gram-positive cocci associated with ABSSSIs and pneumonia. The lower susceptibilities of tedizolid against isolates of S. anginosus and S. constellatus than against those of S. intermedius in Taiwan were noted. PMID:26248355

  5. An antimicrobial modified silicone peritoneal catheter with activity against both Gram-positive and Gram-negative bacteria.

    PubMed

    Bayston, Roger; Fisher, Leanne E; Weber, Klaus

    2009-06-01

    Peritonitis, exit site and tunnel infections are serious complications of peritoneal dialysis (CAPD), which may lead to catheter loss, despite measures taken to reduce the infection rate. Catheters coated with antimicrobials have shown only short-term activity. We have developed a process for conferring broad-spectrum, long-duration antimicrobial activity on CAPD catheters while reducing the risk of resistance. Catheters were processed using an impregnation method. Three agents were used: rifampicin, triclosan and trimethoprim. Tests included establishing the duration of activity before test bacteria became resistant, the ability to kill 100% of attached bacteria in a predetermined time (tK100), and ability to withstand multiple high-count challenges until failure in a flow model. Antimicrobial activity continued until it was stopped at 280 days and the agents prevented the emergence of resistant strains. tK100 results showed a >99.9% reduction of attached bacteria. The flow model showed no colonization when repeatedly challenged with high loads of meticillin-resistant Staphylococcus aureus or Escherichia coli for approximately 90 days. The antimicrobial catheter material showed prolonged activity against common CAPD pathogens and promises to reduce clinical CAPD infection. PMID:19289248

  6. Design and synthesis of novel antimicrobials with activity against Gram-positive bacteria and mycobacterial species, including M. tuberculosis

    PubMed Central

    Tiruveedhula, V.V.N. Phani Babu; Witzigmann, Christopher M.; Verma, Ranjit; Kabir, M. Shahjahan; Rott, Marc; Schwan, William R.; Medina-Bielski, Sara; Lane, Michelle; Close, William; Polanowski, Rebecca L.; Sherman, David; Monte, Aaron; Deschamps, Jeffrey R.; Cook, James M.

    2013-01-01

    The alarming increase in bacterial resistance over the last decade along with a dramatic decrease in new treatments for infections has led to problems in the healthcare industry. Tuberculosis (TB) is caused mainly by Mycobacterium tuberculosis which is responsible for 1.4 million deaths per year. A world-wide threat with HIV co-infected with multi and extensively drug-resistant strains of TB has emerged. In this regard, herein, novel acrylic acid ethyl ester derivatives were synthesized in simple, efficient routes and evaluated as potential agents against several Mycobacterium species. These were synthesized via a stereospecific process for structure activity relationship (SAR) studies. Minimum inhibitory concentration (MIC) assays indicated that esters 12, 13, and 20 exhibited greater in vitro activity against Mycobacterium smegmatis than rifampin, one of the current, first-line anti-mycobacterial chemotherapeutic agents. Based on these studies the acrylic ester 20 has been developed as a potential lead compound which was found to have an MIC value of 0.4 ?g/mL against Mycobacterium tuberculosis. The SAR and biological activity of this series is presented; a Michael – acceptor mechanism appears to be important for potent activity of this series of analogs. PMID:24200931

  7. Characterization of a Novel Small Molecule That Potentiates ?-Lactam Activity against Gram-Positive and Gram-Negative Pathogens

    PubMed Central

    Nair, Dhanalakshmi R.; Monteiro, João M.; Memmi, Guido; Thanassi, Jane; Pucci, Michael; Schwartzman, Joseph; Pinho, Mariana G.

    2015-01-01

    In a loss-of-viability screen using small molecules against methicillin-resistant Staphylococcus aureus (MRSA) strain USA300 with a sub-MIC of a ?-lactam, we found a small molecule, designated DNAC-1, which potentiated the effect of oxacillin (i.e., the MIC of oxacillin decreased from 64 to 0.25 ?g/ml). Fluorescence microscopy indicated a disruption in the membrane structures within 15 min of exposure to DNAC-1 at 2× MIC. This permeabilization was accompanied by a rapid loss of membrane potential, as monitored by use of the DiOC2 (3,3?-diethyloxacarbocyanine iodide) dye. Macromolecular analysis showed the inhibition of staphylococcal cell wall synthesis by DNAC-1. Transmission electron microscopy of treated MRSA USA300 cells revealed a slightly thicker cell wall, together with mesosome-like projections into the cytosol. The exposure of USA300 cells to DNAC-1 was associated with the mislocalization of FtsZ accompanied by the localization of penicillin-binding protein 2 (PBP2) and PBP4 away from the septum, as well as mild activation of the vraRS-mediated cell wall stress response. However, DNAC-1 does not have any generalized toxicity toward mammalian host cells. DNAC-1 in combination with ceftriaxone is also effective against an assortment of Gram-negative pathogens. Using a murine subcutaneous coinjection model with 108 CFU of USA300 as a challenge inoculum, DNAC-1 alone or DNAC-1 with a sub-MIC of oxacillin resulted in a 6-log reduction in bacterial load and decreased abscess formation compared to the untreated control. We propose that DNAC-1, by exerting a bimodal effect on the cell membrane and cell wall, is a viable candidate in the development of combination therapy against many common bacterial pathogens. PMID:25583731

  8. In vitro activity of ceftazidime, ceftaroline and aztreonam alone and in combination with avibactam against European Gram-negative and Gram-positive clinical isolates.

    PubMed

    Testa, Raymond; Cantón, Rafael; Giani, Tommaso; Morosini, María-Isabel; Nichols, Wright W; Seifert, Harald; Stefanik, Danuta; Rossolini, Gian Maria; Nordmann, Patrice

    2015-06-01

    Recent clinical isolates of key Gram-negative and Gram-positive bacteria were collected in 2012 from hospitalised patients in medical centres in four European countries (France, Germany, Italy and Spain) and were tested using standard broth microdilution methodology to assess the impact of 4 mg/L avibactam on the in vitro activities of ceftazidime, ceftaroline and aztreonam. Against Enterobacteriaceae, addition of avibactam significantly enhanced the level of activity of these antimicrobials. MIC(90) values (minimum inhibitory concentration that inhibits 90% of the isolates) of ceftazidime, ceftaroline and aztreonam for Escherichia coli, Klebsiella pneumoniae, Enterobacter cloacae, Enterobacter aerogenes, Citrobacter freundii and Morganella morganii were reduced up to 128-fold or greater when combined with avibactam. A two-fold reduction in the MIC(90) of ceftazidime to 8 mg/L was noted in Pseudomonas aeruginosa isolates when combined with avibactam, whereas little effect of avibactam was noted on the MIC values of the test compounds when tested against Acinetobacter baumannii isolates. Avibactam had little effect on the excellent activity of ceftazidime, ceftaroline and aztreonam against Haemophilus influenzae. It had no impact on the in vitro activity of ceftazidime and ceftaroline against staphylococci and streptococci. This study demonstrates that addition of avibactam enhances the activities of ceftazidime, ceftaroline and aztreonam against Enterobacteriaceae and P. aeruginosa but not against A. baumannii. PMID:25748553

  9. Potential antibacterial activity of coumarin and coumarin-3-acetic acid derivatives.

    PubMed

    Chattha, Fauzia Anjum; Munawar, Munawar Ali; Nisa, Mehrun; Ashraf, Mohammad; Kousar, Samina; Arshad, Shafia

    2015-05-01

    Coumarin and coumarin-3-acetic acid derivatives were synthesized by reacting phenols with malic acid, ethyl acetoacetate and ethyl acetylsuccinate in appropriate reaction conditions. All synthesized compounds were subjected to test for their antimicrobial activities against variety of gram positive (Bacillus subtilis, Staphylococcus aureus) and gram negative bacterial stains (Shigella sonnei, Escherichia coli) by agar dilution method. Several of them exhibited appreciable good antibacterial activity against the different strains of gram positive and gram negative bacteria. These findings suggest a great potential of these compounds for screening and use as antibacterial agents for further studies with a battery of bacteria. PMID:26004713

  10. Developing of a novel antibacterial agent by functionalization of graphene oxide with guanidine polymer with enhanced antibacterial activity

    NASA Astrophysics Data System (ADS)

    Li, Ping; Sun, Shiyu; Dong, Alideertu; Hao, Yanping; Shi, Shuangqiang; Sun, Zijia; Gao, Ge; Chen, Yuxin

    2015-11-01

    New materials with excellent antibacterial activity attract numerous research interests. Herein, a facile synthetic method of polyethylene glycol (PEG) and polyhexamethylene guanidine hydrochloride (PHGC) dual-polymer-functionalized graphene oxide (GO) (GO-PEG-PHGC), a novel antibacterial material, was reported. The as-prepared products were characterized by scanning electron microscopy (SEM), Fourier transform infrared (FTIR), thermogravimetric analysis (TGA), X-ray pattern (XRD) and elemental analysis. The antibacterial effect on the bacterial strain was investigated by incubating both Gram-negative bacteria (Escherichia coli) and Gram-positive bacteria (Staphylococcus aureus). The results show that GO-PEG-PHGC has enhanced antibacterial activity when compared to GO, GO-PEG or GO-PHGC alone. The improved antibacterial activity was described to be related to a better dispersion of GO-PEG-PHGC in the presence of PEG. This better dispersion leads to a greater contact between the bacteria membrane and nanomaterials, therefore leading to greater cell damage. Not only Gram-negative bacteria but also Gram-positive bacteria are greatly inhibited by this antibacterial agent. With the powerful antibacterial activity as well as its low cost and facile preparation, the GO-PEG-PHGC as a novel antibacterial agent can find potential application in the areas of healthcare and environmental engineering.

  11. A metal-repressed promoter from gram-positive Bacillus subtilis is highly active and metal-induced in gram-negative Cupriavidus metallidurans.

    PubMed

    Ribeiro-dos-Santos, Gabriela; Biondo, Ronaldo; Quadros, Oeber de Freitas; Vicente, Elisabete José; Schenberg, Ana Clara Guerrini

    2010-10-15

    A synthetic version of the metal-regulated gene A (mrgA) promoter from Bacillus subtilis, which in this Gram-positive bacterium is negatively regulated by manganese, iron, cobalt, or copper turned out to promote high level of basal gene expression that is further enhanced by Co(II), Cd(II), Mn(II), Zn(II), Cu(II), or Ni(II), when cloned in the Gram-negative bacterium Cupriavidus metallidurans. Promoter activity was monitored by expression of the reporter gene coding for the enhanced green fluorescent protein (EGFP), and cellular intensity fluorescence was quantified by flow cytometry. Expression levels in C. metallidurans driven by the heterologous promoter, here called pan, ranged from 20- to 53-fold the expression level driven by the Escherichia coli lac promoter (which is constitutively expressed in C. metallidurans), whether in the absence or presence of metal ions, respectively. The pan promoter did also function in E. coli in a constitutive pattern, regardless of the presence of Mn(II) or Fe(II). In conclusion, the pan promoter proved to be a powerful tool to express heterologous proteins in Gram-negative bacteria, especially in C. metallidurans grown upon high levels of toxic metals, with potential applications in bioremediation. PMID:20517979

  12. Classification of a bacterial isolate, from pozol, exhibiting antimicrobial activity against several gram-positive and gram-negative bacteria, yeasts, and molds.

    PubMed

    Ray, P; Sanchez, C; O'Sullivan, D J; McKay, L L

    2000-08-01

    A bacterial isolate, designated CS93, capable of producing a broad-spectrum antimicrobial compound(s) effective against gram-positive and gram-negative bacteria, yeasts, and molds was isolated from pozol, a fermented maize product. This strain was phenotypically similar to another pozol isolate that was previously designated as Agrobacterium azotophilium by other investigators. By using biochemical, phenotypic, and 16S rRNA sequence analysis, both pozol isolates were identified as members of the genus Bacillus, possibly a variant of Bacillus subtilis. While the antimicrobial compound(s) was initially produced only on a solid medium, parameters were identified for production in broth. The compound(s) was heat stable (121 degrees C for 15 min), exhibited activity over a wide pH range (pH 3 to pH 11), and was inactivated by pronase E. The antimicrobial compound(s) was bactericidal and bacteriolytic against Escherichia coli V517, bacteriostatic against Micrococcus luteus, and fungistatic against Saccharomyces cerevisiae. The inhibitory compound(s) could possibly serve as a food biopreservative. PMID:10945591

  13. Antibacterial activity of lichen Usnea rubrotincta, Ramalina dumeticola, and Cladonia verticillata

    NASA Astrophysics Data System (ADS)

    Gunasekaran, Saranyapiriya; Rajan, Vinoshene Pillai; Samsudin, Mohd. Wahid; Din, Laily; Ramanathan, Surash; Murugaiyah, Vikneswaran

    2015-09-01

    The present study was carried out to evaluate the antibacterial activity of extract and chemical constituents of Usnea rubrotincta, Ramalina dumeticola and Cladonia verticillata. Extracts of U. rubrotincta and R. dumeticola showed promising antibacterial activity against gram positive bacteria Staphylococcus aureus and Bacillus subtilis. The lowest value of MIC (15.63 ?g/mL) was observed for the acetone extract of U. rubrotincta against B. subtilis. While extract of C. verticillata was neither active against gram positive nor gram negative bacteria at the highest tested concentration of 500 ?g/m. This is the first evaluation of antibacterial activity of lichens found in Malaysia and to our knowledge, this is the first report of antibacterial

  14. Bacillus subtilis subsp. subtilis CBMDC3f with antimicrobial activity against Gram-positive foodborne pathogenic bacteria: UV-MALDI-TOF MS analysis of its bioactive compounds.

    PubMed

    Torres, M J; Petroselli, G; Daz, M; Erra-Balsells, R; Audisio, M C

    2015-06-01

    In this work a new Bacillus sp. strain, isolated from honey, was characterized phylogenetically. Its antibacterial activity against three relevant foodborne pathogenic bacteria was studied; the main bioactive metabolites were analyzed using ultraviolet matrix assisted laser desorption-ionization mass spectrometry (UV-MALDI MS). Bacillus CBMDC3f was phylogenetically characterized as Bacillus subtilis subsp. subtilis after rRNA analysis of the 16S subunit and the gyrA gene (access codes Genbank JX120508 and JX120516, respectively). Its antibacterial potential was evaluated against Listeria monocytogenes (9 strains), B. cereus (3 strains) and Staphylococcus aureus ATCC29213. Its cell suspension and cell-free supernatant (CFS) exerted significant anti-Listeria and anti-S. aureus activities, while the lipopeptides fraction (LF) also showed anti-B. cereus effect. The UV-MALDI-MS analysis revealed surfactin, iturin and fengycin in the CFS, whereas surfactin predominated in the LF. The CFS from CBMDC3f contained surfactin, iturin and fengycin with four, two and four homologues per family, respectively, whereas four surfactin, one iturin and one fengycin homologues were identified in the LF. For some surfactin homologues, their UV-MALDI-TOF/TOF (MS/MS; Laser Induced Decomposition method, LID) spectra were also obtained. Mass spectrometry analysis contributed with relevant information about the type of lipopeptides that Bacillus strains can synthesize. From our results, surfactin would be the main metabolite responsible for the antibacterial effect. PMID:25820813

  15. Gram-Positive Anaerobic Cocci

    PubMed Central

    Murdoch, D. A.

    1998-01-01

    Gram-positive anaerobic cocci (GPAC) are a heterogeneous group of organisms defined by their morphological appearance and their inability to grow in the presence of oxygen; most clinical isolates are identified to species in the genus Peptostreptococcus. GPAC are part of the normal flora of all mucocutaneous surfaces and are often isolated from infections such as deep organ abscesses, obstetric and gynecological sepsis, and intraoral infections. They have been little studied for several reasons, which include an inadequate classification, difficulties with laboratory identification, and the mixed nature of the infections from which they are usually isolated. Nucleic acid studies indicate that the classification is in need of radical revision at the genus level. Several species of Peptostreptococcus have recently been described, but others still await formal recognition. Identification has been based on carbohydrate fermentation tests, but most GPAC are asaccharolytic and use the products of protein degradation for their metabolism; the introduction of commercially available preformed enzyme kits affords a physiologically more appropriate method of identification, which is simple and relatively rapid and can be used in routine diagnostic laboratories. Recent reports have documented the isolation in pure culture of several species, notably Peptostreptococcus magnus, from serious infections. Studies of P. magnus have elucidated several virulence factors which correlate with the site of infection, and reveal some similarities to Staphylococcus aureus. P. micros is a strongly proteolytic species; it is increasingly recognized as an important pathogen in intraoral infections, particularly periodontitis, and mixed anaerobic deep-organ abscesses. Comparison of antibiotic susceptibility patterns reveals major differences between species. Penicillins are the antibiotics of choice, although some strains of P. anaerobius show broad-spectrum ?-lactam resistance. PMID:9457430

  16. Transformation of gram positive bacteria by sonoporation

    DOEpatents

    Yang, Yunfeng; Li, Yongchao

    2014-03-11

    The present invention provides a sonoporation-based method that can be universally applied for delivery of compounds into Gram positive bacteria. Gram positive bacteria which can be transformed by sonoporation include, for example, Bacillus, Streptococcus, Acetobacterium, and Clostridium. Compounds which can be delivered into Gram positive bacteria via sonoporation include nucleic acids (DNA or RNA), proteins, lipids, carbohydrates, viruses, small organic and inorganic molecules, and nano-particles.

  17. Bifunctionalized mesoporous silica-supported gold nanoparticles: intrinsic oxidase and peroxidase catalytic activities for antibacterial applications.

    PubMed

    Tao, Yu; Ju, Enguo; Ren, Jinsong; Qu, Xiaogang

    2015-02-11

    Bifunctionalized mesoporous silica-supported gold nanoparticles as oxidase and peroxidase mimics for antibacterial applications are demonstrated. For the first time, these mesoporous silica-supported gold nanoparticles are applied as oxidase and peroxidase mimics. Taking advantage of their prominent enzyme activities, the MSN-AuNPs show excellent antibacterial properties against both Gram-negative and Gram-positive bacteria. Furthermore, MSN-AuNPs also exhibit outstanding performance in biofilm elimination . PMID:25655182

  18. Trans-generational Immune Priming Protects the Eggs Only against Gram-Positive Bacteria in the Mealworm Beetle

    PubMed Central

    Dubuffet, Aurore; Zanchi, Caroline; Boutet, Gwendoline; Moreau, Jérôme; Teixeira, Maria; Moret, Yannick

    2015-01-01

    In many vertebrates and invertebrates, offspring whose mothers have been exposed to pathogens can exhibit increased levels of immune activity and/or increased survival to infection. Such phenomena, called “Trans-generational immune priming” (TGIP) are expected to provide immune protection to the offspring. As the offspring and their mother may share the same environment, and consequently similar microbial threats, we expect the immune molecules present in the progeny to be specific to the microbes that immune challenged the mother. We provide evidence in the mealworm beetle Tenebrio molitor that the antimicrobial activity found in the eggs is only active against Gram-positive bacteria, even when females were exposed to Gram-negative bacteria or fungi. Fungi were weak inducers of TGIP while we obtained similar levels of anti-Gram-positive activity using different bacteria for the maternal challenge. Furthermore, we have identified an antibacterial peptide from the defensin family, the tenecin 1, which spectrum of activity is exclusively directed toward Gram-positive bacteria as potential contributor to this antimicrobial activity. We conclude that maternal transfer of antimicrobial activity in the eggs of T. molitor might have evolved from persistent Gram-positive bacterial pathogens between insect generations. PMID:26430786

  19. Identification of proteins capable of metal reduction from the proteome of the Gram-positive bacterium Desulfotomaculum reducens MI-1 using an NADH-based activity assay

    SciTech Connect

    Otwell, Annie E.; Sherwood, Roberts; Zhang, Sheng; Nelson, Ornella D.; Li, Zhi; Lin, Hening; Callister, Stephen J.; Richardson, Ruth E.

    2015-01-01

    Metal reduction capability has been found in numerous species of environmentally abundant Gram-positive bacteria. However, understanding of microbial metal reduction is based almost solely on studies of Gram-negative organisms. In this study, we focus on Desulfotomaculum reducens MI-1, a Gram-positive metal reducer whose genome lacks genes with similarity to any characterized metal reductase. D. reducens has been shown to reduce not only Fe(III), but also the environmentally important contaminants U(VI) and Cr(VI). By extracting, separating, and analyzing the functional proteome of D. reducens, using a ferrozine-based assay in order to screen for chelated Fe(III)-NTA reduction with NADH as electron donor, we have identified proteins not previously characterized as iron reductases. Their function was confirmed by heterologous expression in E. coli. These are the protein NADH:flavin oxidoreductase (Dred_2421) and a protein complex composed of oxidoreductase FAD/NAD(P)-binding subunit (Dred_1685) and dihydroorotate dehydrogenase 1B (Dred_1686). Dred_2421 was identified in the soluble proteome and is predicted to be a cytoplasmic protein. Dred_1685 and Dred_1686 were identified in both the soluble as well as the insoluble (presumably membrane) protein fraction, suggesting a type of membrane-association, although PSORTb predicts both proteins are cytoplasmic. Furthermore, we show that these proteins have the capability to reduce soluble Cr(VI) and U(VI) with NADH as electron donor. This study is the first functional proteomic analysis of D. reducens, and one of the first analyses of metal and radionuclide reduction in an environmentally relevant Gram-positive bacterium.

  20. Screening of Ethanol, Petroleum Ether and Chloroform Extracts of Medicinal Plants, Lawsonia inermis L. and Mimosa pudica L. for Antibacterial Activity

    PubMed Central

    Akter, A.; Neela, F. A.; Khan, M. S. I.; Islam, M. S.; Alam, M. F.

    2010-01-01

    Organic extracts (ethanol, petroleum ether and chloroform) of two medicinal plants Lawsonia inermis L. and Mimosa pudica L. were proven for antibacterial properties against 15 Gram-positive and Gram-negative human pathogenic bacteria. Among the three types of extracts tested, ethanol extract was found to possess maximum antibacterial activity. The diameter of the zone of inhibition of bacterial growth showed that Gram-negative bacteria are more sensitive than Gram-positive bacteria to plant extracts. Between the two plants species studied, Lawsonia inermis extract showed more antibacterial activity compared to Mimosa pudica extract. PMID:21188055

  1. Screening of solvent dependent antibacterial activity of Prunus domestica.

    PubMed

    Yaqeen, Zahra; Naqvi, Naim-ul-Hasan; Sohail, Tehmina; Rehman, Zakir-ur; Fatima, Nudrat; Imran, Hina; Rehman, Atiqur

    2013-03-01

    Fruit of Prunus domestica was extracted in ethanol. The ethanol extract was further extracted with two solvents ethyl acetate and chloroform. The crude ethanol extract and two fractions (ethyl acetate and chloroform) were screened for their antibacterial activity using the agar well diffusion method .They were tested against nine bacteria; five Gram positive bacteria (Staphylococcus aureus, Streptococcuc intermedius, Bacillus cereus, Bacillus pumilus) and four Gram negative bacteria (Eschrichia coli, Proteus mirabilis Shigella flexneri, Salmonella typhi and Klebsiela pneumoniae). The susceptibility of microorganisms to all three fractions was compared with each other and with standard antibiotic (Ampicillin) Among all fractions ethyl acetate exhibited highest antibacterial activity (average zone of inhibition 34.57mm ± 1.3) while ethyl alcohol exhibited least antibacterial activity (average zone of inhibition 17.42mm ± 3.3). Minimum inhibitory concentration of ethanol, ethyl acetate and chloroform fractions was found in the range of 78 ? g/ml to 2500 ? gl/ml against gram positive and gram negative bacteria. PMID:23455215

  2. Screening of Yemeni medicinal plants for antibacterial and cytotoxic activities.

    PubMed

    Ali, N A; Jülich, W D; Kusnick, C; Lindequist, U

    2001-02-01

    Ethanolic extracts of 20 selected plant species used by Yemeni traditional healers to treat infectious diseases were screened for their antibacterial activity against both Gram-positive and Gram-negative bacteria, as well as for cytotoxic activity. Fourteen of the ethanolic extracts showed variable degrees of antibacterial activity. The active ethanolic extracts were partitioned between ethyl acetate and water for a first separation. The ethyl acetate extract of Lawsonia inermis was found to be the most active one against all bacteria in the test system. Other promising results could be obtained from extracts of Aloe perryi, Indigofera oblongifolia, Meriandra benghalensis and Ziziphus spina christi. Additionally, the ethanolic extracts of the 20 plants under investigation were tested for their cytotoxic effects on FL-cells using the neutral red assay. Extracts of Calotropis procera, Chenopodium murale, Pulicaria orientalis, Tribulus terrestris and Withania somniferum displayed a remarkable activity. PMID:11167035

  3. Synthesis and in vitro antibacterial activity of (2S)-N-(substitutedphenyl)-1-[(2R)-2-[(formylhydroxyamino)methyl]-1-oxohexyl]-2-pyrrolidinecarboxamides as potential peptide deformylase inhibitors.

    PubMed

    Wang, Zhenyu; Zhou, Weicheng

    2009-01-01

    Gram-positive organisms have re-emerged as the major hospital pathogens, which make the unmet medical needs for antibacterial therapy even worse. In searching for potent agents against Gram-positive pathogens, novel (2S)-N-(substitutedphenyl)-1-[(2R)-2-[(formylhydroxyamino)methyl]-1-oxohexyl]-2-pyrrolidinecarboxamides, analogues of peptide deformylase inhibitor LBM-415 were designed, synthesized and evaluated for their antibacterial activities in vitro. Many of these compounds exhibited high potency against Gram-positive organisms compared with reference agent: LBM-415. PMID:19152643

  4. Suicin 90-1330 from a Nonvirulent Strain of Streptococcus suis: a Nisin-Related Lantibiotic Active on Gram-Positive Swine Pathogens

    PubMed Central

    LeBel, Geneviève; Vaillancourt, Katy; Frenette, Michel; Gottschalk, Marcelo

    2014-01-01

    Streptococcus suis serotype 2 is known to cause severe infections (meningitis, endocarditis, and septicemia) in pigs and is considered an emerging zoonotic agent. Antibiotics have long been used in the swine industry for disease treatment/prevention and growth promoters. This pattern of utilization resulted in the spread of antibiotic resistance in S. suis worldwide. Interestingly, pigs may harbor S. suis in their tonsils without developing diseases, while North American strains belonging to the sequence type 28 (ST28) are nonvirulent in animal models. Consequently, the aim of this study was to purify and characterize a bacteriocin produced by a nonvirulent strain of S. suis serotype 2, with a view to a potential therapeutic and preventive application. S. suis 90-1330 belonging to ST28 and previously shown to be nonvirulent in an animal model exhibited antibacterial activity toward all S. suis pathogenic isolates tested. The bacteriocin produced by this strain was purified to homogeneity by cationic exchange and reversed-phase fast protein liquid chromatography. Given its properties (molecular mass of <4 kDa, heat, pH and protease stability, and the presence of modified amino acids), the bacteriocin, named suicin 90-1330, belongs to the lantibiotic class. Using a DNA-binding fluorophore, the bacteriocin was found to possess a membrane permeabilization activity. When tested on other swine pathogens, the suicin showed activity against Staphylococcus hyicus and Staphylococcus aureus, whereas it was inactive against all Gram-negative bacteria tested. Amino acid sequencing of the purified bacteriocin showed homology (90.9% identity) with nisin U produced by Streptococcus uberis. The putative gene cluster involved in suicin production was amplified by PCR and sequence analysis revealed the presence of 11 open reading frames, including the structural gene and those required for the modification of amino acids, export, regulation, and immunity. Further studies will evaluate the ability of suicin 90-1330 or the producing strain to prevent experimental S. suis infections in pigs. PMID:24973067

  5. Suicin 90-1330 from a nonvirulent strain of Streptococcus suis: a nisin-related lantibiotic active on gram-positive swine pathogens.

    PubMed

    LeBel, Geneviève; Vaillancourt, Katy; Frenette, Michel; Gottschalk, Marcelo; Grenier, Daniel

    2014-09-01

    Streptococcus suis serotype 2 is known to cause severe infections (meningitis, endocarditis, and septicemia) in pigs and is considered an emerging zoonotic agent. Antibiotics have long been used in the swine industry for disease treatment/prevention and growth promoters. This pattern of utilization resulted in the spread of antibiotic resistance in S. suis worldwide. Interestingly, pigs may harbor S. suis in their tonsils without developing diseases, while North American strains belonging to the sequence type 28 (ST28) are nonvirulent in animal models. Consequently, the aim of this study was to purify and characterize a bacteriocin produced by a nonvirulent strain of S. suis serotype 2, with a view to a potential therapeutic and preventive application. S. suis 90-1330 belonging to ST28 and previously shown to be nonvirulent in an animal model exhibited antibacterial activity toward all S. suis pathogenic isolates tested. The bacteriocin produced by this strain was purified to homogeneity by cationic exchange and reversed-phase fast protein liquid chromatography. Given its properties (molecular mass of <4 kDa, heat, pH and protease stability, and the presence of modified amino acids), the bacteriocin, named suicin 90-1330, belongs to the lantibiotic class. Using a DNA-binding fluorophore, the bacteriocin was found to possess a membrane permeabilization activity. When tested on other swine pathogens, the suicin showed activity against Staphylococcus hyicus and Staphylococcus aureus, whereas it was inactive against all Gram-negative bacteria tested. Amino acid sequencing of the purified bacteriocin showed homology (90.9% identity) with nisin U produced by Streptococcus uberis. The putative gene cluster involved in suicin production was amplified by PCR and sequence analysis revealed the presence of 11 open reading frames, including the structural gene and those required for the modification of amino acids, export, regulation, and immunity. Further studies will evaluate the ability of suicin 90-1330 or the producing strain to prevent experimental S. suis infections in pigs. PMID:24973067

  6. Synthesis and antibacterial activity of sulfonamides. SAR and DFT studies

    NASA Astrophysics Data System (ADS)

    Boufas, Wahida; Dupont, Nathalie; Berredjem, Malika; Berrezag, Kamel; Becheker, Imène; Berredjem, Hajira; Aouf, Nour-Eddine

    2014-09-01

    A series of substituted sulfonamide derivatives were synthesized from chlorosulfonyl isocyanate (CSI) in tree steps (carbamoylation, sulfamoylation and deprotection). Antibacterial activity in vitro of some newly formed compounds investigated against clinical strains Gram-positive and Gram-negative: Escherichia coli and Staphylococcus aureus applying the method of dilution and minimal inhibition concentration (MIC) methods. These compounds have significant bacteriostatic activity with totalities of bacterial strains used. DFT calculations with B3LYP/6-31G(d) level have been used to analyze the electronic and geometric characteristics deduced for the stable structure of three compounds presenting conjugation between a nitrogen atom N through its lone pair and an aromatic ring next to it. The principal quantum chemical descriptors have been correlated with the antibacterial activity.

  7. In Vitro Activity and Microbiological Efficacy of Tedizolid (TR-700) against Gram-Positive Clinical Isolates from a Phase 2 Study of Oral Tedizolid Phosphate (TR-701) in Patients with Complicated Skin and Skin Structure Infections

    PubMed Central

    Prokocimer, Philippe; Bien, Paul; DeAnda, Carisa; Pillar, Chris M.

    2012-01-01

    Tedizolid (TR-700, formerly torezolid) is the active moiety of the prodrug tedizolid phosphate (TR-701), a next-generation oxazolidinone, with high potency against Gram-positive species, including methicillin-resistant Staphylococcus aureus (MRSA). A recently completed randomized, double-blind phase 2 trial evaluated 200, 300, or 400 mg of oral tedizolid phosphate once daily for 5 to 7 days in patients with complicated skin and skin structure infections. This report examines the in vitro activity of tedizolid and Zyvox (linezolid) against Gram-positive pathogens isolated at baseline and describes the microbiological and clinical efficacy of tedizolid. Of 196 isolates tested, 81.6% were S. aureus, and of these, 76% were MRSA. The MIC50 and MIC90 of tedizolid against both methicillin-susceptible S. aureus (MSSA) and MRSA were 0.25 ?g/ml, compared with a MIC50 of 1 ?g/ml and MIC90 of 2 ?g/ml for linezolid. For coagulase-negative staphylococci (n = 7), viridans group streptococci (n = 15), and beta-hemolytic streptococci (n = 3), the MICs ranged from 0.03 to 0.25 ?g/ml for tedizolid and from 0.12 to 1 ?g/ml for linezolid. The microbiological eradication rates at the test-of-cure visit (7 to 14 days posttreatment) in the microbiologically evaluable population (n = 133) were similar in all treatment groups, with overall eradication rates of 97.7% for all pathogens, 97.9% for MRSA, and 95.7% for MSSA. The clinical cure rates for MRSA and MSSA infections were 96.9% and 95.7%, respectively, across all dose groups. This study confirms the potent in vitro activity of tedizolid against pathogenic Gram-positive cocci, including MRSA, and its 4-fold-greater potency in comparison with linezolid. All dosages of tedizolid phosphate showed excellent microbiological and clinical efficacy against MRSA and MSSA. PMID:22687509

  8. In vitro antibacterial activity in seed extracts of Manilkara zapota, Anona squamosa, and Tamarindus indica.

    PubMed

    Kothari, Vijay; Seshadri, Sriram

    2010-01-01

    Extracts prepared from seeds of Manilkara zapota, Anona squamosa, and Tamarindus indica were screened for their antibacterial activity by disc diffusion and broth dilution methods. Acetone and methanol extracts of T. indica seeds were found active against both gram-positive and gram-negative organisms. MIC values of potent extracts against susceptible organisms ranged from 53-380 ?g/mL. Methanol extract of T. indica and acetone extract of M. zapota seeds were found to be bactericidal. PMID:21031260

  9. Synthesis of isoindole and benzoisoindole derivatives of teicoplanin pseudoaglycon with remarkable antibacterial and antiviral activities.

    PubMed

    Sipos, Attila; Török, Zsolt; R?th, Erzsébet; Kiss-Szikszai, Attila; Batta, Gyula; Bereczki, Ilona; Fejes, Zsolt; Borbás, Anikó; Ostorházi, Eszter; Rozgonyi, Ferenc; Naesens, Lieve; Herczegh, Pál

    2012-12-01

    The primary amino function of teicoplanin pseudoaglycon has been transformed into arylthioisoindole or benzoisoindole and glycosylthioisoindole derivatives, in a reaction with o-phthalaldehyde or naphtalene-2,3-dicarbaldehyde and various thiols. All of the obtained semisynthetic antibiotics exhibited potent antibacterial activities against Gram-positive bacteria in the ng per ml concentration range. A few of them showed antiviral activity, in particular against influenza virus. PMID:23099097

  10. Ethanol production in Gram-positive microbes

    DOEpatents

    Ingram, L.O.; Barbosa-Alleyne, M.D.F.

    1996-01-09

    The subject invention concerns the transformation of Gram-positive bacteria with heterologous genes which confer upon these microbes the ability to produce ethanol as a fermentation product. Specifically exemplified is the transformation of bacteria with genes, obtainable from Zymomonas mobilis, which encode pyruvate decarboxylase and alcohol dehydrogenase. 2 figs.

  11. Ethanol production in Gram-positive microbes

    DOEpatents

    Ingram, Lonnie O'Neal (Gainesville, FL); Barbosa-Alleyne, Maria D. F. (Gainesville, FL)

    1996-01-01

    The subject invention concerns the transformation of Gram-positive bacteria with heterologous genes which confer upon these microbes the ability to produce ethanol as a fermentation product. Specifically exemplified is the transformation of bacteria with genes, obtainable from Zymomonas mobilis, which encode pyruvate decarboxylase and alcohol dehydrogenase.

  12. Ethanol production in gram-positive microbes

    DOEpatents

    Ingram, Lonnie O'Neal (Gainesville, FL); Barbosa-Alleyne, Maria D. F. (Gainesville, FL)

    1999-01-01

    The subject invention concerns the transformation of Gram-positive bacteria with heterologous genes which confer upon these microbes the ability to produce ethanol as a fermentation product. Specifically exemplified is the transformation of bacteria with genes, obtainable from Zymomonas mobilis, which encode pyruvate decarboxylase and alcohol dehydrogenase.

  13. Ethanol production in Gram-positive microbes

    DOEpatents

    Ingram, L.O.; Barbosa-Alleyne, M.D.F.

    1999-06-29

    The subject invention concerns the transformation of Gram-positive bacteria with heterologous genes which confer upon these microbes the ability to produce ethanol as a fermentation product. Specifically exemplified is the transformation of bacteria with genes, obtainable from Zymomonas mobilis, which encode pyruvate decarboxylase and alcohol dehydrogenase. 2 figs.

  14. Accentuate the (Gram) positive Victor Nizet

    E-print Network

    Nizet, Victor

    research. Streptococcus pneumoniae (SPN) is a leading agent of pneumonia, meningitis and sepsis throughout January 2010 # Springer-Verlag 2010 Keywords Gram-positive bacteria . Streptococcus . Special issue [7]. The mechanisms of SPN invasion to produce lower respiratory tract, pneumonia, and meningitis

  15. Protamine-induced permeabilization of cell envelopes of gram-positive and gram-negative bacteria.

    PubMed Central

    Johansen, C; Verheul, A; Gram, L; Gill, T; Abee, T

    1997-01-01

    The inhibitory effect of the cationic peptide protamine on Listeria monocytogenes, Escherichia coli, and Shewanella putrefaciens has been studied in detail. The addition of protamine (10 to 1,000 micrograms/ml) resulted in inhibition of oxygen consumption after less than 1 min and loss of intracellular carboxyfluorescein and ATP after 2 to 5 min. Maximum antibacterial activity was reached at alkaline pH and in the absence of divalent cations. The efficient permeabilization of cell envelopes of both gram-positive and gram-negative bacteria suggests that protamine causes a general disruption of the cell envelope, leading to a rapid and nonspecific efflux of low- and high-molecular-weight compounds. PMID:9055431

  16. Antibacterial Activity of Myristica fragrans against Oral Pathogens.

    PubMed

    Shafiei, Zaleha; Shuhairi, Nadia Najwa; Md Fazly Shah Yap, Nordiyana; Harry Sibungkil, Carrie-Anne; Latip, Jalifah

    2012-01-01

    Myristica fragrans Houtt is mostly cultivated for spices in Penang Island, Malaysia. The ethyl acetate and ethanol extracts of flesh, mace and seed of Myristica fragrans was evaluated the bactericidal potential against three Gram-positive cariogenic bacteria (Streptococcus mutans ATCC 25175, Streptococcus mitis ATCC 6249, and Streptococcus salivarius ATCC 13419) and three Gram-negative periodontopathic bacteria (Aggregatibacter actinomycetemcomitans ATCC 29522, Porphyromonas gingivalis ATCC 33277, and Fusobacterium nucleatum ATCC 25586). Antibacterial activities of the extracts was determined by twofold serial microdilution, with minimum inhibitory concentrations (MIC) ranging from 1.25 to 640?mg/mL and 0.075 to 40?mg/mL. The minimum bactericidal concentration (MBC) was obtained by subculturing method. Among all extracts tested, ethyl acetate extract of flesh has the highest significant inhibitory effects against Gram-positive and Gram-negative bacteria with mean MIC value ranging from 0.625 to 1.25 ± 0.00 (SD) mg/mL; P = 0.017) and highest bactericidal effects at mean MBC value ranging from 0.625?mg/mL to 20 ± 0.00 (SD) mg/mL. While for seed and mace of Myristica fragrans, their ethanol extracts exhibited good antibacterial activity against both groups of test pathogens compared to its ethyl acetate extracts. All of the extracts of Myristica fragrans did not show any antibacterial activities against Fusobacterium nucleatum ATCC 25586. Thus, our study showed the potential effect of ethyl acetate and ethanol extracts from flesh, seed and mace of Myristica fragrans to be new natural agent that can be incorporated in oral care products. PMID:23049613

  17. Antibacterial Activity of Myristica fragrans against Oral Pathogens

    PubMed Central

    Shafiei, Zaleha; Shuhairi, Nadia Najwa; Md Fazly Shah Yap, Nordiyana; Harry Sibungkil, Carrie-Anne; Latip, Jalifah

    2012-01-01

    Myristica fragrans Houtt is mostly cultivated for spices in Penang Island, Malaysia. The ethyl acetate and ethanol extracts of flesh, mace and seed of Myristica fragrans was evaluated the bactericidal potential against three Gram-positive cariogenic bacteria (Streptococcus mutans ATCC 25175, Streptococcus mitis ATCC 6249, and Streptococcus salivarius ATCC 13419) and three Gram-negative periodontopathic bacteria (Aggregatibacter actinomycetemcomitans ATCC 29522, Porphyromonas gingivalis ATCC 33277, and Fusobacterium nucleatum ATCC 25586). Antibacterial activities of the extracts was determined by twofold serial microdilution, with minimum inhibitory concentrations (MIC) ranging from 1.25 to 640?mg/mL and 0.075 to 40?mg/mL. The minimum bactericidal concentration (MBC) was obtained by subculturing method. Among all extracts tested, ethyl acetate extract of flesh has the highest significant inhibitory effects against Gram-positive and Gram-negative bacteria with mean MIC value ranging from 0.625 to 1.25 ± 0.00 (SD) mg/mL; P = 0.017) and highest bactericidal effects at mean MBC value ranging from 0.625?mg/mL to 20 ± 0.00 (SD) mg/mL. While for seed and mace of Myristica fragrans, their ethanol extracts exhibited good antibacterial activity against both groups of test pathogens compared to its ethyl acetate extracts. All of the extracts of Myristica fragrans did not show any antibacterial activities against Fusobacterium nucleatum ATCC 25586. Thus, our study showed the potential effect of ethyl acetate and ethanol extracts from flesh, seed and mace of Myristica fragrans to be new natural agent that can be incorporated in oral care products. PMID:23049613

  18. Antibacterial and antitumour activities of some plants grown in Turkey

    PubMed Central

    Usta, Canan; Yildirim, Arzu Birinci; Turker, Arzu Ucar

    2014-01-01

    Screening of antibacterial and antitumour activities of 33 different extracts prepared with three types of solvents (water, ethanol and methanol) was conducted. The extracts were obtained from 11 different plant species grown in Turkey: Eryngium campestre L., Alchemilla mollis (Buser) Rothm., Dorycnium pentaphyllum Scop., Coronilla varia L., Onobrychis oxyodonta Boiss., Fritillaria pontica Wahlenb., Asarum europaeum L., Rhinanthus angustifolius C. C. Gmelin, Doronicum orientale Hoffm., Campanula glomerata L. and Campanula olympica Boiss. Antibacterial activity against six bacteria was evaluated: Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, Streptococcus pyogenes, Staphylococcus aureus and Staphylococcus epidermidis by using disc diffusion and well diffusion methods. S. aureus and S. epidermidis were most sensitive to the methanolic extract from A. europaeum. S. pyogenes was vulnerable to all used extracts of D. orientale. In addition, ethanolic or methanolic extracts of E. campestre, A. mollis, D. pentaphyllum, C. varia, R. angustifolius, C. glomerata and C. olympica displayed strong antibacterial activity against at least one of the tested gram-negative bacteria. The methanolic extract from R. angustifolius showed a broad-spectrum activity against both gram-positive and gram-negative bacteria. Antitumour activity was evaluated with Agrobacterium-tumefaciens-induced potato disc tumour assay. Best antitumour activity was obtained with the aqueous extract from A. europaeum and methanolic extract from E. campestre (100% and 86% tumour inhibition, respectively).

  19. In vitro activity of nadifloxacin against several Gram-positive bacteria and analysis of the possible evolution of resistance after 2 years of use in Germany.

    PubMed

    Alba, Veronica; Urban, Edit; Angeles Dominguez, M; Nagy, Elisabeth; Nord, Carl-Erik; Palacín, Celia; Vila, Jordi

    2009-03-01

    Nadifloxacin has good activity against Propionibacterium acnes as well as against both meticillin-susceptible and -resistant Staphylococcus aureus (MSSA and MRSA, respectively) and Staphylococcus epidermidis. The aim of this study was to evaluate the activity of this fluoroquinolone against the abovementioned microorganisms, comparing isolates collected in 2007 in Germany, a country where nadifloxacin has been used for the last 2 years, with isolates collected from 2006-2007 in Spain where nadifloxacin has not been used. A collection of P. acnes from Hungary (strains collected during 2005-2006) and a collection of P. acnes from different countries in Europe (collected during 2002) were also included. The activity of nadifloxacin was compared with ciprofloxacin, erythromycin and clindamycin. Susceptibility testing of P. acnes was performed by agar dilution, whereas the susceptibility of the different staphylococci was determined by microdilution. Although the isolates were collected from three different countries (Spain, Hungary and Germany) where the use of quinolones can produce a different effect, no significant differences in the percentages of resistance to nadifloxacin were observed in P. acnes, MSSA, MRSA and S. epidermidis. Therefore, topical antibiotics such as nadifloxacin do not have an additional effect on resistance. Moreover, nadifloxacin presented much better activity than the comparator drugs used in this study against the studied microorganisms. PMID:19095414

  20. Draft Genome Sequence Analysis of a Pseudomonas putida W15Oct28 Strain with Antagonistic Activity to Gram-Positive and Pseudomonas sp. Pathogens

    PubMed Central

    Ye, Lumeng; Hildebrand, Falk; Dingemans, Jozef; Ballet, Steven; Laus, George; Matthijs, Sandra; Berendsen, Roeland; Cornelis, Pierre

    2014-01-01

    Pseudomonas putida is a member of the fluorescent pseudomonads known to produce the yellow-green fluorescent pyoverdine siderophore. P. putida W15Oct28, isolated from a stream in Brussels, was found to produce compound(s) with antimicrobial activity against the opportunistic pathogens Staphylococcus aureus, Pseudomonas aeruginosa, and the plant pathogen Pseudomonas syringae, an unusual characteristic for P. putida. The active compound production only occurred in media with low iron content and without organic nitrogen sources. Transposon mutants which lost their antimicrobial activity had the majority of insertions in genes involved in the biosynthesis of pyoverdine, although purified pyoverdine was not responsible for the antagonism. Separation of compounds present in culture supernatants revealed the presence of two fractions containing highly hydrophobic molecules active against P. aeruginosa. Analysis of the draft genome confirmed the presence of putisolvin biosynthesis genes and the corresponding lipopeptides were found to contribute to the antimicrobial activity. One cluster of ten genes was detected, comprising a NAD-dependent epimerase, an acetylornithine aminotransferase, an acyl CoA dehydrogenase, a short chain dehydrogenase, a fatty acid desaturase and three genes for a RND efflux pump. P. putida W15Oct28 genome also contains 56 genes encoding TonB-dependent receptors, conferring a high capacity to utilize pyoverdines from other pseudomonads. One unique feature of W15Oct28 is also the presence of different secretion systems including a full set of genes for type IV secretion, and several genes for type VI secretion and their VgrG effectors. PMID:25369289

  1. Screening of some Kenyan medicinal plants for antibacterial activity.

    PubMed

    Wagate, Cyrus G; Mbaria, James M; Gakuya, Daniel W; Nanyingi, Mark O; Kareru, P G; Njuguna, Anne; Gitahi, Nduhiu; Macharia, James K; Njonge, Francis K

    2010-01-01

    Eleven medicinal plants used by traditional healers in Machakos and Kitui District were screened, namely: Ajuga remota Benth, Aloe secundiflora Engl, Amaranthus hybridus L, Cassia didymobotrya Fes, Croton macrostachyus Del, Entada leptostachya Harms, Erythrina abyssinica DC, Harrisonia abyssinica Oliv, Schkuhria pinnata O. Ktze, Terminalia kilimandscharica Engl and Ziziphus abyssinica Hochst for potential antibacterial activity against four medically important bacterial strains, namely: Bacillus cereus ATCC 11778, Escherichia coli ATCC 25922, Micrococcus lutea ATCC 9341 and Pseudomonas aeruginosa ATCC 27853. The antibacterial activity of methanol extracts was determined as the minimum inhibitory concentration (MIC). The plant extracts were more active against Gram-positive (G+) than Gram-negative (G-) bacteria. The positive controls were streptomycin and benzylpenicillin for G- and G+ bacteria, respectively, both had a significant MIC at <1 mg/mL. The most susceptible bacteria were B. cereus, followed by M. lutea, while the most resistant bacteria were Ps. aeruginosa, followed by E. coli. The present study supports the use of these plants by the herbalists in the management of bacterial ailments. H. abyssinica and T. kilimandscharica showed the best antibacterial activity; hence these plants can be further subjected to phytochemical and pharmacological evaluation. PMID:19548257

  2. In Vitro Study to Evaluate Antibacterial and Non-haemolytic Activities of Four Iranian Medicinal Plants

    PubMed Central

    Sepahi, S; Ghorani-Azam, A; Sepahi, S; Asoodeh, A; Rostami, S

    2014-01-01

    Objective: Aqueous extracts of four medicinal plants including Ferula gummosa, Echinophora orientalis, Nasturtium microphyllum and Verbascum thapsus were used to determine their antibacterial activities and minimum inhibitory concentration (MIC). The aim of this study was to assess antibacterial activity of extracts of four medicinal plants against a Gram-positive and a Gram-negative bacteria (Staphylococcus aureus PTCC1431, and Escherichia coli HP101BA 7601c). Methods: Radial diffusion assay was used to assess the antibacterial activity of extracted samples. Haemolysis assay was also used to examine their nontoxic effects on human red blood cells. Results: This study showed that all the mentioned plants have satisfactory antibacterial effects against both Gram-positive and Gram-negative bacteria. Minimum inhibitory concentration values of these samples were less than 750 ?g/mL. In addition, no significant haemolytic activity was observed at their MIC values. Conclusion: The results of this study showed that all these studied plants have good potential for further studies for drug discovery. PMID:25429470

  3. Antibacterial Activity of Rhizome of Curcuma aromatica and Partial Purification of Active Compounds

    PubMed Central

    Revathi, S.; Malathy, N. S.

    2013-01-01

    The hexane extract of Curcuma aromatica, a plant belonging to the family Zingiberaceae was tested on 10 bacterial strains (clinical isolates and standard strains). Agar diffusion method was adopted for determining the antibacterial activity of the extract. The hexane extract was found to be active against all Gram-positive strains tested, but inactive against Gram-negative strains. The minimum inhibitory concentration and minimum bactericidal concentration were determined and found to be 539 ?g/ml. The phytochemical analysis of hexane extract by gas chromatography mass spectrometry revealed the presence of 13 compounds. The crude hexane extract was partially purified by thin layer chromatography. The zone showing good antibacterial activity was analysed further by gas chromatography mass spectrometry, UV/Vis spectrophotometry and Fourier transform infrared spectroscopy, which indicated the probable presence of germacrone. PMID:24591751

  4. Antibacterial Activity of Rhizome of Curcuma aromatica and Partial Purification of Active Compounds.

    PubMed

    Revathi, S; Malathy, N S

    2013-11-01

    The hexane extract of Curcuma aromatica, a plant belonging to the family Zingiberaceae was tested on 10 bacterial strains (clinical isolates and standard strains). Agar diffusion method was adopted for determining the antibacterial activity of the extract. The hexane extract was found to be active against all Gram-positive strains tested, but inactive against Gram-negative strains. The minimum inhibitory concentration and minimum bactericidal concentration were determined and found to be 539 ?g/ml. The phytochemical analysis of hexane extract by gas chromatography mass spectrometry revealed the presence of 13 compounds. The crude hexane extract was partially purified by thin layer chromatography. The zone showing good antibacterial activity was analysed further by gas chromatography mass spectrometry, UV/Vis spectrophotometry and Fourier transform infrared spectroscopy, which indicated the probable presence of germacrone. PMID:24591751

  5. Rose Bengal-decorated silica nanoparticles as photosensitizers for inactivation of gram-positive bacteria

    NASA Astrophysics Data System (ADS)

    Guo, Yanyan; Rogelj, Snezna; Zhang, Peng

    2010-02-01

    A new type of photosensitizer, made from Rose Bengal (RB)-decorated silica (SiO2-NH2-RB) nanoparticles, was developed to inactivate gram-positive bacteria, including Methicillin-resistant Staphylococcus aureus (MRSA), with high efficiency through photodynamic action. The nanoparticles were characterized microscopically and spectroscopically to confirm their structures. The characterization of singlet oxygen generated by RB, both free and immobilized on a nanoparticle surface, was performed in the presence of anthracene-9,10-dipropionic acid. The capability of SiO2-NH2-RB nanoparticles to inactivate bacteria was tested in vitro on both gram-positive and gram-negative bacteria. The results showed that RB-decorated silica nanoparticles can inactivate MRSA and Staphylococcus epidermidis (both gram-positive) very effectively (up to eight-orders-of-magnitude reduction). Photosensitizers of such design should have good potential as antibacterial agents through a photodynamic mechanism.

  6. Anti-bacterial Studies of Silver Nanoparticles

    E-print Network

    T. Theivasanthi; M. Alagar

    2011-01-01

    We discuss about the antibacterial activities of Silver nanoparticles and compare them on both Gram negative and Gram positive bacteria in this investigation. The activities of Silver nanoparticles synthesized by electrolysis method are more in Gram (-) than Gram (+) bacteria. First time, we increase its antibacterial activities by using electrical power while on electrolysis synthesis and it is confirmed from its more antibacterial activities (For Escherichia coli bacteria). We investigate the changes of inner unit cell Lattice constant of Silver nanoparticles prepared in two different methods and its effects on antibacterial activities. We note that slight change of the lattice constant results in the enhancement of its antibacterial activities.

  7. Unveiling the Mode of Action of Two Antibacterial Tanshinone Derivatives

    PubMed Central

    Wang, Dongdong; Zhang, Wuxia; Wang, Tingting; Li, Na; Mu, Haibo; Zhang, Jiwen; Duan, Jinyou

    2015-01-01

    In this study, 2-(N-pyrrolidine-alkyl) tanshinones bearing pyrrolidine groups were synthesized and the antibacterial mechanism was explored. These derivatives selectively elicited antibacterial activity against Gram-positive bacteria. Moreover, their antibacterial activities were time-, concentration-dependent and persistent. It appeared that Fenton-mediated hydroxyl radicals were involved, and the disruption of cell membranes was observed. This study indicates that 2-(N-pyrrolidine-alkyl) tanshinones might be potential candidates as antibacterial agents. PMID:26263982

  8. Synthesis of novel bisindolylmethane Schiff bases and their antibacterial activity.

    PubMed

    Imran, Syahrul; Taha, Muhammad; Ismail, Nor Hadiani; Khan, Khalid Mohammed; Naz, Farzana; Hussain, Memona; Tauseef, Saima

    2014-01-01

    In an effort to develop new antibacterial drugs, some novel bisindolylmethane derivatives containing Schiff base moieties were prepared and screened for their antibacterial activity. The synthesis of the bisindolylmethane Schiff base derivatives 3-26 was carried out in three steps. First, the nitro group of 3,3'-((4-nitrophenyl)-methylene)bis(1H-indole) (1) was reduced to give the amino substituted bisindolylmethane 2 without affecting the unsaturation of the bisindolylmethane moiety using nickel boride in situ generated. Reduction of compound 1 using various catalysts showed that combination of sodium borohydride and nickel acetate provides the highest yield for compound 2. Bisindolylmethane Schiff base derivatives were synthesized by coupling various benzaldehydes with amino substituted bisindolylmethane 2. All synthesized compounds were characterized by various spectroscopic methods. The bisindolylmethane Schiff base derivatives were evaluated against selected Gram-positive and Gram-negative bacterial strains. Derivatives having halogen and nitro substituent display weak to moderate antibacterial activity against Salmonella typhi, S. paratyphi A and S. paratyphi B. PMID:25102118

  9. Antibacterial activity of leaves extracts of Trifolium alexandrinum Linn. against pathogenic bacteria causing tropical diseases

    PubMed Central

    Khan, Abdul Viqar; Ahmed, Qamar Uddin; Shukla, Indu; Khan, Athar Ali

    2012-01-01

    Objective To investigate antibacterial potential of Trifolium alexandrinum (T. alexandrinum) Linn. against seven gram positive and eleven gram negative hospital isolated human pathogenic bacterial strains responsible for many tropical diseases. Methods Non-polar and polar extracts of the leaves of T. alexandrinum i.e., hexane, dichloromethane (DCM), ethyl acetate (EtOAc), methanol (MeOH) and aqueous (AQ) extracts at five different concentrations (1, 2, 5, 10 and 15 mg/mL) were prepared to evaluate their antibacterial value. NCCL standards were strictly followed to perform antimicrobial disc susceptibility test using disc diffusion method. Results Polar extracts demonstrated significant antibacterial activity against tested pathogens. EtOAc and MeOH extracts showed maximum antibacterial activity with higher inhibition zone and were found effective against seventeen of the tested pathogens. While AQ plant extract inhibited the growth of sixteen of the test strains. EtOAc and MeOH plant extracts inhibited the growth of all seven gram positive and ten of the gram negative bacterial strains. Conclusions The present study strongly confirms the effectiveness of crude leaves extracts against tested human pathogenic bacterial strains causing several tropical diseases. Since Egyptian clover is used as a fodder plant, it could be helpful in controlling various infectious diseases associated with cattle as well. PMID:23569896

  10. Microwave-assisted synthesis of CdO-ZnO nanocomposite and its antibacterial activity against human pathogens

    NASA Astrophysics Data System (ADS)

    Karthik, K.; Dhanuskodi, S.; Gobinath, C.; Sivaramakrishnan, S.

    2015-03-01

    CdO-ZnO nanocomposite was prepared by microwave-assisted method and characterized by X-ray crystallography (XRD), Scanning Electron Microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FT-IR). It exhibits hexagonal cubic structure with an average crystallite size of 27 nm. From the UV-Vis spectra, the bandgap is estimated as 2.92 eV. The fluorescence spectrum shows a near band edge emission at 422 nm. In addition the antibacterial activity of CdO-ZnO nanocomposite was carried out in-vitro against two kinds of bacteria: gram negative bacteria (G -ve) i.e. Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae and gram positive bacteria (G +ve): Staphylococcus aureus, Proteus vulgaris and Bacillus spp. This study indicates the zone of inhibition of 40 mm has high antibacterial activity towards the gram positive bacterium S. aureus.

  11. Microwave-assisted synthesis of CdO-ZnO nanocomposite and its antibacterial activity against human pathogens.

    PubMed

    Karthik, K; Dhanuskodi, S; Gobinath, C; Sivaramakrishnan, S

    2015-03-15

    CdO-ZnO nanocomposite was prepared by microwave-assisted method and characterized by X-ray crystallography (XRD), Scanning Electron Microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FT-IR). It exhibits hexagonal cubic structure with an average crystallite size of 27 nm. From the UV-Vis spectra, the bandgap is estimated as 2.92 eV. The fluorescence spectrum shows a near band edge emission at 422 nm. In addition the antibacterial activity of CdO-ZnO nanocomposite was carried out in-vitro against two kinds of bacteria: gram negative bacteria (G -ve) i.e. Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae and gram positive bacteria (G +ve): Staphylococcus aureus, Proteus vulgaris and Bacillus spp. This study indicates the zone of inhibition of 40 mm has high antibacterial activity towards the gram positive bacterium S. aureus. PMID:25546491

  12. Synthesis and antibacterial activity of novel phosphonium salts on the basis of pyridoxine.

    PubMed

    Pugachev, Mikhail V; Shtyrlin, Nikita V; Sysoeva, Lubov P; Nikitina, Elena V; Abdullin, Timur I; Iksanova, Alfiya G; Ilaeva, Alina A; Musin, Rashid Z; Berdnikov, Eugeny A; Shtyrlin, Yurii G

    2013-07-15

    A series of 13 phosphonium salts on the basis of pyridoxine derivatives were synthesized and their antibacterial activity against clinically relevant strains was tested in vitro. All compounds were almost inactive against gram-negative bacteria and exhibited structure-dependent activity against gram-positive bacteria. A crucial role of ketal protection group in phosphonium salts for their antibacterial properties was demonstrated. Among synthesized compounds 5,6-bis[triphenylphosphonio(methyl)]-2,2,8-trimethyl-4H-[1,3]dioxino[4,5-c]pyridine dichloride (compound 20) was found to be the most effective towards Staphylococcus aureus and Staphylococcus epidermidis strains (MIC 5?g/ml). The mechanism of antibacterial activity of this compound probably involves cell penetration and interaction with genomic and plasmid DNA. PMID:23683836

  13. New polymeric biocides: synthesis and antibacterial activities of polycations with pendant biguanide groups.

    PubMed Central

    Ikeda, T; Yamaguchi, H; Tazuke, S

    1984-01-01

    Acrylate monomers with pendant biguanide groups were successfully synthesized, and their homopolymers and copolymers were prepared with acrylamide. These cationic disinfectants of polymeric forms exhibited high antibacterial activity against gram-positive bacteria, whereas they were less active against gram-negative bacteria. It was found that the activity of the polymeric disinfectants was much higher than that of the monomeric species, and the difference in activity between the polymers and the monomers was discussed on the basis of their contributions to each elementary process of the lethal action. PMID:6385836

  14. Isolation, purification and partial characterization of antibacterial activities produced by a newly isolated Streptomyces sp. US24 strain.

    PubMed

    Mellouli, Lotfi; Ben Ameur-Mehdi, Raoudha; Sioud, Samiha; Salem, Mansour; Bejar, Samir

    2003-06-01

    A new actinomycete strain designated US24 producing antibacterial activities against Gram-positive and Gram-negative bacteria was isolated from Tunisian soil. Culture characteristic studies strongly suggested that the US24 strain belonged to the genus Streptomyces. Analysis of the nucleotide sequence of the 16S rRNA gene of the Streptomyces sp. US24 strain showed high similarity (98%) with the 16S rRNA gene of Streptomyces caelestis which produces two antibiotics, niddamycin and celesticetin. Study of the influence of different nutritional compounds on antibiotic biosynthesis showed that the highest antibacterial activities were obtained when starch at 1% (w/v) was used as sole carbon source in the presence of traces of mineral oligoelements. Application to the supernatant culture of the Streptomyces sp. US24 strain of various separation steps led to isolation of two pure active molecules having a retention time of 34 and 37.26 min, respectively. P(34 min) possessed antibacterial activity against Gram-positive and Gram-negative bacteria, whereas P(37.26 min) inhibited only Gram-positive bacteria. Partial characterization of the P(34 min) molecule using spectroscopic studies showed that this active molecule is different from the two antibiotics produced by the S. caelestis strain. PMID:12837510

  15. Antioxidant and antibacterial activity of Rhoeo spathacea (Swartz) Stearn leaves.

    PubMed

    Tan, Joash Ban Lee; Lim, Yau Yan; Lee, Sui Mae

    2015-04-01

    The decoction and infusion of Rhoeo spathacea (Swartz) Stearn leaves have been recognized as a functional food particularly in South America, but has not yet gained international popularity as a beverage. The primary aim of this study was to establish the viability of R. spathacea aqueous leaf extracts as a beverage, in terms of its antioxidant activity and antibacterial activity. The antioxidant contents of aqueous and methanol leaf extracts were evaluated by the total phenolic content (TPC) and total flavonoid content (TFC) assays. The antioxidant activities measured were DPPH radical scavenging activity (FRS), ferric reducing power (FRP) and ferrous ion chelating (FIC) activity. The aqueous leaf extracts in the forms of decoction and infusion, were found to have comparable TPC and antioxidant activity with other herbal teas previously reported by our research group. Both decoction and infusion also exhibited antibacterial activity against six species of Gram positive and four species of Gram negative bacteria, notably methicillin-resistant Staphylococcus aureus and Neisseria gonorrhoeae. A total of four different known phenolic compounds were identified by HPLC and MS, three of which have not been previously reported to be found in this plant. Both the decoction and infusion of the leaves R. spathacea have potential to be popularized into a common beverage. PMID:25829624

  16. Antibacterial activity of cotton coated with ZnO and ZnO-CNT composites.

    PubMed

    Yazhini, K Bharathi; Prabu, H Gurumallesh

    2015-01-01

    With the growing public health awareness of the pathogenic effects and strain formations caused by microorganisms, there is an increasing need for antibacterial materials in many applications. Zinc oxide (ZnO)-1,2,3,4-butanetetracarboxylic acid (BTCA) and ZnO-BTCA-carbon nanotube (CNT) composites were synthesized by simple stirring method. The synthesized materials were coated on cotton fabric by pad-dry-cure method separately. The coated fabrics were characterized by FT-IR analysis that revealed the cross-linking in the composites. The fabrics were screened for antibacterial activity by agar well diffusion method against gram positive Staphylococcus aureus and gram negative Escherichia coli. The results showed that the ZnO-BTCA-CNT-coated fabric has improved antibacterial activity when compared with the ZnO-BTCA-coated fabric. PMID:25240851

  17. Enhanced antibacterial activity of silver/polyrhodanine-composite-decorated silica nanoparticles.

    PubMed

    Song, Jooyoung; Kim, Hyunyoung; Jang, Yoonsun; Jang, Jyongsik

    2013-11-27

    This work describes the synthesis of silver/polyrhodanine-composite-decorated silica nanoparticles and their antibacterial activity. Polymerization of polyrhodanine proceeded preferentially on the surface of the silica nanoparticles where Ag(+) ions were located. In addition, the embedded Ag(+) ions were reduced to form metallic Ag nanoparticles; consequently, silver/polyrhodanine-composite nanoparticles (approximately 7 nm in diameter) were formed on the surface of the silica nanoparticles. The resulting nanostructure was investigated using electron microscopy, Fourier-transform infrared spectroscopy, ultraviolet-visible spectroscopy, and X-ray photoelectron spectroscopy. The silver/polyrhodanine-nanocomposite-decorated silica nanoparticles exhibited excellent antimicrobial activity toward gram-negative Escherichia coli and gram-positive Staphylococcus aureus because of the antibacterial effects of the silver nanoparticles and the polyrhodanine. The silver/polyrhodanine-composite nanoparticles may therefore have potential for use as a long-term antibacterial agent. PMID:24156562

  18. In vitro antibacterial activities and mechanism of sugar fatty acid esters against five food-related bacteria.

    PubMed

    Zhao, Lei; Zhang, Heyan; Hao, Tianyang; Li, Siran

    2015-11-15

    The objective of this study was to evaluate the antibacterial activities of sugar fatty acid esters, with different fatty acid and saccharide moieties, against five food-related bacteria including Bacillus cereus, Bacillus subtilis, Staphylococcus aureus, Escherichia coli and Salmonella typhimurium. Sucrose monocaprate showed the strongest antibacterial activity against all tested bacteria, especially Gram-positive bacteria. The minimum inhibitory concentrations (MICs) for Gram-positive bacteria and Gram-negative bacteria were 2.5 and 10 mM, respectively. The minimum bactericidal concentrations (MBCs) for Gram-positive bacteria were 10 mM. Time-kill assay also showed that sucrose monocaprate significantly inhibit the growth of tested bacteria. The permeability of the cell membrane and intracellular proteins were both changed by sucrose monocaprate according to cell constituents' leakage, SDS-PAGE and scanning electron microscope assays. It is suggested that sucrose monocaprate, with both emulsifying and antibacterial activities, have a potential to serve as a safe multifunctional food additive in food industries. PMID:25977039

  19. Antibacterial Activity of Pseudonocardia sp. JB05, a Rare Salty Soil Actinomycete against Staphylococcus aureus

    PubMed Central

    Jafari, Nesa; Behroozi, Reza; Farajzadeh, Davoud; Farsi, Mohammad; Akbari-Noghabi, Kambiz

    2014-01-01

    Staphylococcus aureus is a Gram-positive bacterium that causes many harmful and life-threatening diseases. Some strains of this bacterium are resistant to available antibiotics. This study was designed to evaluate the ability of indigenous actinomycetes to produce antibacterial compounds against S. aureus and characterize the structure of the resultant antibacterial compounds. Therefore, a slightly modified agar well diffusion method was used to determine the antibacterial activity of actinomycete isolates against the test microorganisms. The bacterial extracts with antibacterial activity were fractionated by silica gel and G-25 sephadex column chromatography. Also, the active fractions were analyzed by thin layer chromatography. Finally, the partial structure of the resultant antibacterial compound was characterized by Fourier transform infrared spectroscopy. One of the isolates, which had a broad spectrum and high antibacterial activity, was designated as Pseudonocardia sp. JB05, based on the results of biochemical and 16S rDNA gene sequence analysis. Minimum inhibitory concentration for this bacterium was 40?AU?mL?1 against S. aureus. The antibacterial activity of this bacterium was stable after autoclaving, 10% SDS, boiling, and proteinase K. Thin layer chromatography, using anthrone reagent, showed the presence of carbohydrates in the purified antibacterial compound. Finally, FT-IR spectrum of the active compound illustrated hydroxyl groups, hydrocarbon skeleton, and double bond of polygenic compounds in its structure. To the best of our knowledge, this is the first report describing the efficient antibacterial activity by a local strain of Pseudonocardia. The results presented in this work, although at the initial stage in bioactive product characterization, will possibly contribute toward the Pseudonocardia scale-up for the production and identification of the antibacterial compounds. PMID:25202705

  20. Microcins from Enterobacteria: On the Edge Between Gram-Positive Bacteriocins and Colicins

    NASA Astrophysics Data System (ADS)

    Rebuffat, Sylvie

    Most bacteria and archaea produce gene-encoded antimicrobial peptides/proteins called bacteriocins, which are secreted by the producing bacteria to compete against other microorganisms in a given niche. They are considered important mediators of intra- and interspecies interactions and therefore a factor in ­maintaining the microbial diversity and stability. They are ribosomally synthesized, and most of them are produced as inactive precursor proteins, which in some cases are further enzymatically modified. Bacteriocins generally exert potent antibacterial activities directed against bacterial species closely related to the producing bacteria. Bacteriocins are abundant and diverse in Gram-negative and Gram-positive bacteria. This chapter focuses on colicins and microcins from enterobacteria (mainly Escherichia coli) and on bacteriocins from lactic acid bacteria (LAB). Microcins are the lower-molecular-mass bacteriocins produced by Gram-negative bacteria with a repertoire of only 14 representatives. They form a very restricted family of bacteriocins, compared to the huge family of LAB bacteriocins that is constituted of several hundreds of peptides, with which microcins share common characteristics. Nevertheless, microcins also show similarities, particularly in their uptake mechanisms, with the higher-molecular-mass colicins, also produced by E. coli strains. On the edge between LAB bacteriocins and colicins, microcins appear to combine highly efficient strategies developed by both Gram-positive and Gram-negative bacteria at different levels, including uptake, translocation, killing of target cells, and immunity of the producing bacteria, making them important actors of bacterial competitions and fascinating models for novel concepts toward antimicrobial strategies and against resistance mechanisms.

  1. Synthesis and antibacterial activities of acylide derivatives bearing an aryl-tetrazolyl chain

    PubMed Central

    Shan, Ling-Xing; Sun, Ping-Hua; Guo, Bao-Qin; Xu, Xing-Jun; Li, Zhi-Qiang; Sun, Jia-Zhi; Zhou, Shu-Feng; Chen, Wei-Min

    2014-01-01

    Seventeen acylides bearing an aryl-tetrazolyl alkyl-substituted side chain were synthesized, starting from clarithromycin, via several reactions including hydrolysis, acetylating, esterification, carbamylation, and Michael addition. The structures of all new compounds were confirmed by 1H nuclear magnetic resonance spectroscopy, 13C nuclear magnetic resonance spectroscopy, and mass spectrometry. All these synthesized acylides were evaluated for in vitro antimicrobial activities against gram-positive pathogens (Staphylococcus aureus, Staphylococcus epidermidis) and gram-negative pathogens (Pseudomonas aeruginosa, Escherichia coli), using the broth microdilution method. Results showed that compounds 10e, 10f, 10g, 10 h, 10o have good antibacterial activities. PMID:25284984

  2. Acquired inducible antimicrobial resistance in Gram-positive bacteria

    PubMed Central

    Chancey, Scott T; Zähner, Dorothea; Stephens, David S

    2012-01-01

    A major contributor to the emergence of antibiotic resistance in Gram-positive bacterial pathogens is the expansion of acquired, inducible genetic elements. Although acquired, inducible antibiotic resistance is not new, the interest in its molecular basis has been accelerated by the widening distribution and often ‘silent’ spread of the elements responsible, the diagnostic challenges of such resistance and the mounting limitations of available agents to treat Gram-positive infections. Acquired, inducible antibiotic resistance elements belong to the accessory genome of a species and are horizontally acquired by transformation/recombination or through the transfer of mobile DNA elements. The two key, but mechanistically very different, induction mechanisms are: ribosome-sensed induction, characteristic of the macrolide–lincosamide–streptogramin B antibiotics and tetracycline resistance, leading to ribosomal modifications or efflux pump activation; and resistance by cell surface-associated sensing of ?-lactams (e.g., oxacillin), glycopeptides (e.g., vancomycin) and the polypeptide bacitracin, leading to drug inactivation or resistance due to cell wall alterations. PMID:22913355

  3. Apolipophorin III from honeybees (Apis cerana) exhibits antibacterial activity.

    PubMed

    Kim, Bo Yeon; Jin, Byung Rae

    2015-04-01

    Apolipophorin III (apoLp-III) is involved in lipid transport and innate immunity in insects. In this study, an apoLp-III protein that exhibits antibacterial activity was identified in honeybees (Apis cerana). A. cerana apoLp-III cDNA encodes a 193 amino acid sequence that shares high identity with other members of the hymenopteran insect apoLp-III family. A. cerana apoLp-III is expressed constitutively in the fat body, epidermis, and venom gland and is detected as a 23-kDa protein. A. cerana apoLp-III expression is induced in the fat body after injection with Escherichia coli, Bacillus thuringiensis, or Beauveria bassiana. However, recombinant A. cerana apoLp-III (expressed in baculovirus-infected insect cells) binds directly to E. coli and B. thuringiensis but not to B. bassiana. Consistent with these findings, A. cerana apoLp-III exhibited antibacterial activity against both Gram-negative and Gram-positive bacteria. These results provide insight into the role of A. cerana apoLp-III during the innate immune response following bacterial infection. PMID:25483322

  4. Methods for targetted mutagenesis in gram-positive bacteria

    DOEpatents

    Yang, Yunfeng

    2014-05-27

    The present invention provides a method of targeted mutagenesis in Gram-positive bacteria. In particular, the present invention provides a method that effectively integrates a suicide integrative vector into a target gene in the chromosome of a Gram-positive bacterium, resulting in inactivation of the target gene.

  5. Cytotoxicity of Ultrasmall Gold Nanoparticles on Planktonic and Biofilm Encapsulated Gram-Positive Staphylococci.

    PubMed

    Boda, Sunil Kumar; Broda, Janine; Schiefer, Frank; Weber-Heynemann, Josefine; Hoss, Mareike; Simon, Ulrich; Basu, Bikramjit; Jahnen-Dechent, Willi

    2015-07-01

    The emergence of multidrug resistant bacteria, especially biofilm-associated Staphylococci, urgently requires novel antimicrobial agents. The antibacterial activity of ultrasmall gold nanoparticles (AuNPs) is tested against two gram positive: S. aureus and S. epidermidis and two gram negative: Escherichia coli and Pseudomonas aeruginosa strains. Ultrasmall AuNPs with core diameters of 0.8 and 1.4 nm and a triphenylphosphine-monosulfonate shell (Au0.8MS and Au1.4MS) both have minimum inhibitory concentration (MIC) and minimum bactericidal concentration of 25 × 10(-6) m [Au]. Disc agar diffusion test demonstrates greater bactericidal activity of the Au0.8MS nanoparticles over Au1.4MS. In contrast, thiol-stabilized AuNPs with a diameter of 1.9 nm (AuroVist) cause no significant toxicity in any of the bacterial strains. Ultrasmall AuNPs cause a near 5 log bacterial growth reduction in the first 5 h of exposure, and incomplete recovery after 21 h. Bacteria show marked membrane blebbing and lysis in biofilm-associated bacteria treated with ultrasmall AuNP. Importantly, a twofold MIC dosage of Au0.8MS and Au1.4MS each cause around 80%-90% reduction in the viability of Staphylococci enveloped in biofilms. Altogether, this study demonstrates potential therapeutic activity of ultrasmall AuNPs as an effective treatment option against staphylococcal infections. PMID:25712910

  6. Antibacterial Activity of a Novel Peptide-Modified Lysin Against Acinetobacter baumannii and Pseudomonas aeruginosa

    PubMed Central

    Yang, Hang; Wang, Mengyue; Yu, Junping; Wei, Hongping

    2015-01-01

    The global emergence of multidrug-resistant (MDR) bacteria is a growing threat to public health worldwide. Natural bacteriophage lysins are promising alternatives in the treatment of infections caused by Gram-positive pathogens, but not Gram-negative ones, like Acinetobacter baumannii and Pseudomonas aeruginosa, due to the barriers posed by their outer membranes. Recently, modifying a natural lysin with an antimicrobial peptide was found able to break the barriers, and to kill Gram-negative pathogens. Herein, a new peptide-modified lysin (PlyA) was constructed by fusing the cecropin A peptide residues 1–8 (KWKLFKKI) with the OBPgp279 lysin and its antibacterial activity was studied. PlyA showed good and broad antibacterial activities against logarithmic phase A. baumannii and P. aeruginosa, but much reduced activities against the cells in stationary phase. Addition of outer membrane permeabilizers (EDTA and citric acid) could enhance the antibacterial activity of PlyA against stationary phase cells. Finally, no antibacterial activity of PlyA could be observed in some bio-matrices, such as culture media, milk, and sera. In conclusion, we reported here a novel peptide-modified lysin with significant antibacterial activity against both logarithmic (without OMPs) and stationary phase (with OMPs) A. baumannii and P. aeruginosa cells in buffer, but further optimization is needed to achieve broad activity in diverse bio-matrices.

  7. Nanostructured Ag4O4 films with enhanced antibacterial activity

    NASA Astrophysics Data System (ADS)

    Dellasega, D.; Facibeni, A.; Di Fonzo, F.; Bogana, M.; Polissi, A.; Conti, C.; Ducati, C.; Casari, C. S.; Bassi, A. Li; Bottani, C. E.

    2008-11-01

    Ag4O4 (i.e. silver(I)-silver(III) oxide) thin films with tailored structure and morphology at the nanoscale have been grown by reactive pulsed laser deposition (PLD) in an oxygen-containing atmosphere and they are shown to exhibit a very strong antibacterial activity towards Gram-negative bacteria (E. coli) and to completely inhibit the growth of Gram-positive bacteria (S. aureus). The formation of this particular high-valence silver oxide is explained in terms of the reactions occurring during the expansion of the ablated species in the reactive atmosphere, leading to the formation of low-stability Ag-O dimers and atomic oxygen, providing reactive species at the substrate where the film grows. PLD is shown to allow control of the structure (i.e. crystallinity and grain size) and of the morphology of the films, from compact and columnar to foam-like, thus allowing the deposition of nanocrystalline films with increased porosity and surface area. The antibacterial action towards E. coli is demonstrated and is shown to be superior to that of nanostructured Ag-based medical products. This can be related to the release of Ag ions with high oxidation number, which are known to be very reactive towards bacteria, and to the peculiar morphology at the nanoscale resulting in a large effective surface area.

  8. Facile Preparation of Ag/NiO Composite Nanosheets and Their Antibacterial Activity

    NASA Astrophysics Data System (ADS)

    Shi, Cui-E.; Pan, Lu; Wang, Cheng-Run; He, Yi; Wu, Yong-Feng; Xue, Sai-Sai

    2015-08-01

    Sheet-like precursors of NiO and Ag/NiO with different Ag contents were synthesized by a facile and easily controlled hydrothermal method. The NiO and Ag/NiO composite nanosheets were prepared by calcination of the corresponding precursors at 400°C for 3 h. The as-synthesized samples were characterized by thermogravimetric analysis, x-ray diffraction, transmission electron microscopy, and scanning electron microscopy. The antibacterial activity of NiO and Ag/NiO composites to several gram-positive and gram-negative bacteria was examined. Results showed that NiO nanosheets hardly exhibited antibacterial activity; however, Ag/NiO composites displayed higher activity even with low Ag content.

  9. Phenolic Content, Antioxidant Activity, Antibacterial Activity and Phytochemical Composition of Garcinia lancifolia

    PubMed Central

    Policegoudra, R. S.; Saikia, S.; Das, J.; Chattopadhyay, P.; Singh, L.; Veer, V.

    2012-01-01

    Garcinia lancifolia (Clusiaceae) is an unexplored medicinal plant used as stomachic, diuretic and its fruit is used to cure dysentery and diarrhoea. The acidic fruits are used to prepare juice, pickle and curries. The phytochemical analysis of different extracts of G. lancifolia leaf, stem and fruit revealed the presence of tannins, saponins, flavonoids, terpenoids, alkaloids and cardiac glycosides. The high phenolic content was observed in the methanol extract of leaf followed by methanol extract of stem and dichloromethane extract of leaf. The G. lancifolia fruit juice exhibited high antibacterial activity against Pseudomonas aeruginosa, Escherichia coli, Micrococcus luteus, Streptococcus mutans, Bacillus mycoides and Bacillus subtilis. The methanol extract of fruit pulp was also very effective against Gram-positive bacteria when compared with Gram-negative bacteria. The radical scavenging activity of 1,1-diphenyl-2-picrylhydrazyl was highest in fruit juice followed by methanol extract of leaf and stem. All extracts showed concentration-dependent increase in the antioxidant activity. PMID:23439879

  10. Y-doped zinc oxide (YZO) nanoflowers, microstructural analysis and test their antibacterial activity.

    PubMed

    Sharma, Sanjeev Kumar; Sudheer Pamidimarri, D V N; Kim, Deuk Young; Na, Jeong-Geol

    2015-08-01

    Self-assembled 3D flower-like yttrium-doped zinc oxide (YZO) microstructures composed of nanorods were prepared by hydrothermal-precipitation, and tested their antibacterial activity. The morphological, structural, and compositional properties of YZO nanoflowers were characterized by various techniques, which confirmed a well-crystallized wurtzite hexagonal phase. X-ray photoelectron spectroscopy (XPS) of YZO nanopowder showed the 3d core level spectra of yttrium (Y), which formed by two components at about 158.2 eV (3d5/2) and 160.4 eV (3d3/2). The antibacterial activity of YZO nanoflowers were investigated using both gram-positive and gram-negative microorganisms. Enhancement in antibacterial activity was observed by the incorporation of yttrium (Y: 2 at.%) of nanorod-based-flowers because of increased surface area. The prepared YZO nanocomposite showed potential as an antibacterial agent with applications in controlling the spread of infections and also the ability of fast antibacterial activity which can hinder the re-emergence of infection. PMID:26042696

  11. Antibacterial and antifungal activities of acetonic extract from Paullinia cupana Mart. seeds.

    PubMed

    Basile, Adriana; Rigano, Daniela; Conte, Barbara; Bruno, Maurizio; Rosselli, Sergio; Sorbo, Sergio

    2013-01-01

    The antibacterial and antifungal activities of the acetone extract from Paullinia cupana var. sorbilis Mart. (Sapindaceae) seeds, commonly called guarana, were assessed against selected bacterial and fungal strains. We tested the extract against both standard American Type Culture Collection (ATCC) and clinically isolated (CI) bacterial strains and three fungal strains. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values for bacteria and MIC and minimum fungicidal concentration for fungi were determined. The extract showed an activity against the nine bacterial strains tested, both CI and ATCC strains (MIC comprised between 32 and 128 ?m/mL and MBC between 128 and 512 ?m/mL), showing a significant antibacterial effect against both Gram-negative and Gram-positive bacteria. Also, the tested fungi were sensitive to the extract (MIC between 125 and 250 ?m/mL). The contemporaneous presence of different bioactivities in the extract from guarana suggests this plant as a source of bioactive substances. PMID:23672664

  12. Antibacterial activity of magnetic iron oxide nanoparticles synthesized by laser ablation in liquid.

    PubMed

    Ismail, Raid A; Sulaiman, Ghassan M; Abdulrahman, Safa A; Marzoog, Thorria R

    2015-08-01

    In this study, (50-110 nm) magnetic iron oxide (?-Fe2O3) nanoparticles were synthesized by pulsed laser ablation of iron target in dimethylformamide (DMF) and sodium dodecyl sulfate (SDS) solutions. The structural properties of the synthesized nanoparticles were investigated by using Fourier Transform Infrared (FT-IR) spectroscopy, UV-VIS absorption, scanning electron microscopy (SEM), atomic force microscopy (AFM), and X-ray diffraction (XRD). The effect of laser fluence on the characteristics of these nanoparticles was studied. Antibacterial activities of iron oxide nanoparticles were tested against Gram-positive; Staphylococcus aureus and Gram-negative; Escherichia coli, Pseudomonas aeruginosa and Serratia marcescens. The results showed a noteworthy inhibition on both bacterial strains. The preparation conditions were found to affect significantly the antibacterial activity of these nanoparticles. The synthesized magnetic nanoparticles were used to capture rapidly S. aureus bacteria under the magnetic field effect. PMID:26042717

  13. Decoction, infusion and hydroalcoholic extract of cultivated thyme: antioxidant and antibacterial activities, and phenolic characterisation.

    PubMed

    Martins, Natália; Barros, Lillian; Santos-Buelga, Celestino; Silva, Sónia; Henriques, Mariana; Ferreira, Isabel C F R

    2015-01-15

    Bioactivity of thyme has been described, but mostly related to its essential oils, while studies with aqueous extracts are scarce. Herein, the antioxidant and antibacterial properties of decoction, infusion and hydroalcoholic extract, as also their phenolic compounds, were evaluated and compared. Decoction showed the highest concentration of phenolic compounds (either phenolic acids or flavonoids), followed by infusion and hydroalcoholic extract. In general, the samples were effective against gram-positive (Staphylococcus aureus and Staphylococcus epidermidis) and gram-negative (Escherichia coli, Klebsiella spp., Pseudomonas aeruginosa, Enterococcus aerogenes, Proteus vulgaris and Enterobacter sakazakii) bacteria, with decoction presenting the most pronounced effect. This sample also displayed the highest radical scavenging activity and reducing power. Data obtained support the idea that compounds with strong antioxidant and antibacterial activities are also water-soluble. Furthermore, the use of thyme infusion and decoction, by both internal and external use, at recommended doses, is safe and no adverse reactions have been described. PMID:25148969

  14. In vitro effects on biofilm viability and antibacterial and antiadherent activities of silymarin.

    PubMed

    Evren, Ebru; Yurtcu, Erkan

    2015-07-01

    Limited treatment options in infectious diseases caused by resistant microorganisms created the need to search new approaches. Several herbal extracts are studied for their enormous therapeutic potential. Silymarin extract, from Silybum marianum (milk thistle), is an old and a new remedy for this goal. The purpose of this study is to evaluate the antibacterial and antiadherent effects of silymarin besides biofilm viability activity on standard bacterial strains. Minimal inhibitory concentration (MIC), minimal bactericidal concentration (MBC), antiadherent/antibiofilm activity, and effects on biofilm viability of silymarin were evaluated against standard bacterial strains. MIC values were observed between 60 and >241 ?g/mL (0.25->1 mmol/L). Gram-positive bacteria were inhibited at concentrations between 60 and 120 ?g/mL. Gram-negative bacteria were not inhibited by the silymarin concentrations included in this study. MBC values for Gram-positive bacteria were greater than 241 ?g/mL. Adherence/biofilm formations were decreased to 15 ?g/mL silymarin concentration when compared with silymarin-untreated group. Silymarin reduced the biofilm viabilities to 13 and 46 % at 1 and 0.5 mmol/L concentrations, respectively. We demonstrated that silymarin shows antibacterial and antiadherent/antibiofilm activity against certain standard bacterial strains which may be beneficial when used as a dietary supplement or a drug. PMID:25937395

  15. Triaminotriazine DNA helicase inhibitors with antibacterial activity.

    PubMed

    McKay, Geoffrey A; Reddy, Ranga; Arhin, Francis; Belley, Adam; Lehoux, Dario; Moeck, Greg; Sarmiento, Ingrid; Parr, Thomas R; Gros, Philippe; Pelletier, Jerry; Far, Adel Rafai

    2006-03-01

    Screening of a chemical library in a DNA helicase assay involving the Pseudomonas aeruginosa DnaB helicase provided a triaminotriazine inhibitor with good antibacterial activity but associated cytotoxicity toward mammalian cells. Synthesis of analogs provided a few inhibitors that retained antibacterial activity and demonstrated a significant reduction in cytotoxicity. The impact of serum and initial investigations toward a mode of action highlight several features of this class of compounds as antibacterials. PMID:16343901

  16. Clinical update on linezolid in the treatment of Gram-positive bacterial infections

    PubMed Central

    Ager, Sally; Gould, Kate

    2012-01-01

    Gram-positive pathogens are a significant cause of morbidity and mortality in both community and health care settings. Glycopeptides have traditionally been the antibiotics of choice for multiresistant Gram-positive pathogens but there are problems with their use, including the emergence of glycopeptide-resistant strains, tissue penetration, and achieving and monitoring adequate serum levels. Newer antibiotics such as linezolid, a synthetic oxazolidinone, are available for the treatment of resistant Gram-positive bacteria. Linezolid is active against a wide range of Gram-positive bacteria and has been generally available for the treatment of Gram-positive infections since 2000. There are potential problems with linezolid use, including its bacteriostatic action and the relatively high incidence of reported adverse effects, particularly with long-term use. Long-term use may also be complicated by the development of resistance. However, linezolid has been shown to be clinically useful in the treatment of several serious infections where traditionally bacteriocidal agents have been required and many of its adverse effects are reversible on cessation. It has also been shown to be a cost-effective treatment option in several studies, with its high oral bioavailability allowing an early change from intravenous to oral formulations with consequent earlier patient discharge and lower inpatient costs. PMID:22787406

  17. Optical control of antibacterial activity

    NASA Astrophysics Data System (ADS)

    Velema, Willem A.; van der Berg, Jan Pieter; Hansen, Mickel J.; Szymanski, Wiktor; Driessen, Arnold J. M.; Feringa, Ben L.

    2013-11-01

    Bacterial resistance is a major problem in the modern world, stemming in part from the build-up of antibiotics in the environment. Novel molecular approaches that enable an externally triggered increase in antibiotic activity with high spatiotemporal resolution and auto-inactivation are highly desirable. Here we report a responsive, broad-spectrum, antibacterial agent that can be temporally activated with light, whereupon it auto-inactivates on the scale of hours. The use of such a ‘smart’ antibiotic might prevent the build-up of active antimicrobial material in the environment. Reversible optical control over active drug concentration enables us to obtain pharmacodynamic information. Precisely localized control of activity is achieved, allowing the growth of bacteria to be confined to defined patterns, which has potential for the development of treatments that avoid interference with the endogenous microbial population in other parts of the organism.

  18. Aqueous synthesis of silver nanoparticle embedded cationic polymer nanofibers and their antibacterial activity.

    PubMed

    Song, Jooyoung; Kang, Haeyoung; Lee, Choonghyeon; Hwang, Sun Hye; Jang, Jyongsik

    2012-01-01

    This paper describes the one-pot, aqueous synthesis of cationic polymer nanofibers with embedded silver nanoparticles. Poly[2-(tert-butylaminoethyl) methacrylate] (PTBAM) was used as a cationic polymer substrate to reinforce the antimicrobial activity of the embedded silver nanoparticles. Electron microscope analyses revealed that the as-synthesized nanofibers had diameters of approximately 40 nm and lengths up to about 10 ?m. Additionally, silver nanoparticles of approximately 8 nm in diameter were finely embedded into the prepared nanofibers. The embedded silver nanoparticles had a lower tendency to agglomerate than colloidal silver nanoparticles of comparable size. In addition, the nanofibers with embedded silver nanoparticles exhibited excellent antibacterial performance against Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus. Interestingly, the prepared nanofibers exhibited enhanced bactericidal performance compared with the silver-embedded poly(methyl methacrylate) (PMMA) nanofibers, presumably because of the antibacterial properties of the PTBAM substrate. PMID:22181053

  19. Assessment of Tamarindus indica extracts for antibacterial activity.

    PubMed

    Nwodo, Uchechukwu U; Obiiyeke, Grace E; Chigor, Vincent N; Okoh, Anthony I

    2011-01-01

    Ethanolic and aqueous (hot and cold) extracts of the fruit pulp, stem bark and leaves of Tamarindus indica were evaluated for antibacterial activity, in vitro, against 13 Gram negative and 5 Gram positive bacterial strains using agar well diffusion and macro broth dilution techniques, simultaneously. The fruit pulp extracts exhibited a wide spectrum of activity; the cold water extract against 95.5% of the test bacterial strains; and the hot water and ethanolic extracts against 90.9% and 86.4%, respectively. In contrast the cold water extract of the leaves and stem bark, each was active against 16.7%; while the ethanolic extract of each was active against 75% of the test strains. The minimum inhibitory concentrations (MIC) ranged from 7.81 mg/mL against Bacillus subtilis ATCC 6051 to 31.25 mg/mL against Escherichia coli ATCC 11775; and the minimum bactericidal concentration (MBC) ranged from 125 mg/mL against Pseudomonas aeruginosa ATCC 10145 to 250 mg/mL against Bacillus subtilis ATCC 6051. PMID:22072893

  20. Human odontoblast-like cells produce nitric oxide with antibacterial activity upon TLR2 activation

    PubMed Central

    Farges, Jean-Christophe; Bellanger, Aurélie; Ducret, Maxime; Aubert-Foucher, Elisabeth; Richard, Béatrice; Alliot-Licht, Brigitte; Bleicher, Françoise; Carrouel, Florence

    2015-01-01

    The penetration of cariogenic oral bacteria into enamel and dentin during the caries process triggers an immune/inflammatory response in the underlying pulp tissue, the reduction of which is considered a prerequisite to dentinogenesis-based pulp regeneration. If the role of odontoblasts in dentin formation is well known, their involvement in the antibacterial response of the dental pulp to cariogenic microorganisms has yet to be elucidated. Our aim here was to determine if odontoblasts produce nitric oxide (NO) with antibacterial activity upon activation of Toll-like receptor-2 (TLR2), a cell membrane receptor involved in the recognition of cariogenic Gram-positive bacteria. Human odontoblast-like cells differentiated from dental pulp explants were stimulated with the TLR2 synthetic agonist Pam2CSK4. We found that NOS1, NOS2, and NOS3 gene expression was increased in Pam2CSK4-stimulated odontoblast-like cells compared to unstimulated ones. NOS2 was the most up-regulated gene. NOS1 and NOS3 proteins were not detected in Pam2CSK4-stimulated or control cultures. NOS2 protein synthesis, NOS activity and NO extracellular release were all augmented in stimulated samples. Pam2CSK4-stimulated cell supernatants reduced Streptococcus mutans growth, an effect counteracted by the NOS inhibitor L-NAME. In vivo, the NOS2 gene was up-regulated in the inflamed pulp of carious teeth compared with healthy ones. NOS2 protein was immunolocalized in odontoblasts situated beneath the caries lesion but not in pulp cells from healthy teeth. These results suggest that odontoblasts may participate to the antimicrobial pulp response to dentin-invading Gram-positive bacteria through NOS2-mediated NO production. They might in this manner pave the way for accurate dental pulp healing and regeneration. PMID:26157393

  1. Human odontoblast-like cells produce nitric oxide with antibacterial activity upon TLR2 activation.

    PubMed

    Farges, Jean-Christophe; Bellanger, Aurélie; Ducret, Maxime; Aubert-Foucher, Elisabeth; Richard, Béatrice; Alliot-Licht, Brigitte; Bleicher, Françoise; Carrouel, Florence

    2015-01-01

    The penetration of cariogenic oral bacteria into enamel and dentin during the caries process triggers an immune/inflammatory response in the underlying pulp tissue, the reduction of which is considered a prerequisite to dentinogenesis-based pulp regeneration. If the role of odontoblasts in dentin formation is well known, their involvement in the antibacterial response of the dental pulp to cariogenic microorganisms has yet to be elucidated. Our aim here was to determine if odontoblasts produce nitric oxide (NO) with antibacterial activity upon activation of Toll-like receptor-2 (TLR2), a cell membrane receptor involved in the recognition of cariogenic Gram-positive bacteria. Human odontoblast-like cells differentiated from dental pulp explants were stimulated with the TLR2 synthetic agonist Pam2CSK4. We found that NOS1, NOS2, and NOS3 gene expression was increased in Pam2CSK4-stimulated odontoblast-like cells compared to unstimulated ones. NOS2 was the most up-regulated gene. NOS1 and NOS3 proteins were not detected in Pam2CSK4-stimulated or control cultures. NOS2 protein synthesis, NOS activity and NO extracellular release were all augmented in stimulated samples. Pam2CSK4-stimulated cell supernatants reduced Streptococcus mutans growth, an effect counteracted by the NOS inhibitor L-NAME. In vivo, the NOS2 gene was up-regulated in the inflamed pulp of carious teeth compared with healthy ones. NOS2 protein was immunolocalized in odontoblasts situated beneath the caries lesion but not in pulp cells from healthy teeth. These results suggest that odontoblasts may participate to the antimicrobial pulp response to dentin-invading Gram-positive bacteria through NOS2-mediated NO production. They might in this manner pave the way for accurate dental pulp healing and regeneration. PMID:26157393

  2. ?ECF factors of gram-positive bacteria

    PubMed Central

    Souza, Bianca Mendes; Castro, Thiago Luiz de Paula; Carvalho, Rodrigo Dias de Oliveira; Seyffert, Nubia; Silva, Artur; Miyoshi, Anderson; Azevedo, Vasco

    2014-01-01

    The survival of bacteria to different environmental conditions depends on the activation of adaptive mechanisms, which are intricately driven through gene regulation. Because transcriptional initiation is considered to be the major step in the control of bacterial genes, we discuss the characteristics and roles of the sigma factors, addressing (1) their structural, functional and phylogenetic classification; (2) how their activity is regulated; and (3) the promoters recognized by these factors. Finally, we focus on a specific group of alternative sigma factors, the so-called ?ECF factors, in Bacillus subtilis and some of the main species that comprise the CMNR group, providing information on the roles they play in the microorganisms’ physiology and indicating some of the genes whose transcription they regulate. PMID:24921931

  3. Antifungal and antibacterial activity of marine microorganisms.

    PubMed

    El Amraoui, B; El Amraoui, M; Cohen, N; Fassouane, A

    2014-03-01

    In order to explore marine microorganisms with pharmaceutical potential, marine bacteria, collected from different coastal areas of the Moroccan Atlantic Ocean, were previously isolated from seawater, sediment, marine invertebrates and seaweeds. The antimicrobial activities of these microorganisms were investigated against the pathogens involved in human pathologies. Whole cultures of 34 marine microorganisms were screened for antimicrobial activities using the method of agar diffusion against three Gram-positive bacteria, two Gram-negative bacteria, and against yeast. The results showed that among the 34 isolates studied, 28 (82%) strains have antimicrobial activity against at least one pathogen studied, 11 (32%) strains have antifungal activity and 24 (76%) strains are active against Gram-positive bacteria, while 21 (62%) strains are active against Gram-negative bacteria. Among isolates having antimicrobial activity, 14 were identified and were assigned to the genera Acinetobacter, Aeromonas, Alcaligenes, Bacillus, Chromobacterium, Enterococcus, Pantoea and Pseudomonas. Due to a competitive role for space and nutrient, the marine microorganisms can produce antibiotic substance; therefore, these marine microorganisms were expected to be potential resources of natural antibiotic products. PMID:24630312

  4. Antibacterial activity in bovine lactoferrin-derived peptides.

    PubMed Central

    Hoek, K S; Milne, J M; Grieve, P A; Dionysius, D A; Smith, R

    1997-01-01

    Several peptides sharing high sequence homology with lactoferricin B (Lf-cin B) were generated from bovine lactoferrin (Lf) with recombinant chymosin. Two peptides were copurified, one identical to Lf-cin B and another differing from Lf-cin B by the inclusion of a C-terminal alanine (lactoferricin). Two other peptides were copurified from chymosin-hydrolyzed Lf, one differing from Lf-cin B by the inclusion of C-terminal alanyl-leucine and the other being a heterodimer linked by a disulfide bond. These peptides were isolated in a single step from chymosin-hydrolyzed Lf by membrane ion-exchange chromatography and were purified by reverse-phase high-pressure liquid chromatography (HPLC). They were characterized by N-terminal Edman sequencing, mass spectrometry, and antibacterial activity determination. Pure lactoferricin, prepared from pepsin-hydrolyzed Lf, was purified by standard chromatography techniques. This peptide was analyzed against a number of gram-positive and gram-negative bacteria before and after reduction of its disulfide bond or cleavage after its single methionine residue and was found to inhibit the growth of all the test bacteria at a concentration of 8 microM or less. Subfragments of lactoferricin were isolated from reduced and cleaved peptide by reverse-phase HPLC. Subfragment 1 (residues 1 to 10) was active against most of the test microorganisms at concentrations of 10 to 50 microM. Subfragment 2 (residues 11 to 26) was active against only a few microorganisms at concentrations up to 100 microM. These antibacterial studies indicate that the activity of lactoferricin is mainly, but not wholly, due to its N-terminal region. PMID:8980754

  5. Preparation and antibacterial activity of Fe3O4@Ag nanoparticles

    NASA Astrophysics Data System (ADS)

    Gong, Ping; Li, Huimin; He, Xiaoxiao; Wang, Kemin; Hu, Jianbing; Tan, Weihong; Zhang, Shouchun; Yang, Xiaohai

    2007-07-01

    Bifunctional Fe3O4@Ag nanoparticles with both superparamagnetic and antibacterial properties were prepared by reducing silver nitrate on the surface of Fe3O4 nanoparticles using the water-in-oil microemulsion method. Formation of well-dispersed nanoparticles with sizes of 60 ± 20 nm was confirmed by transmission electron microscopy and dynamic light scattering. X-ray diffraction patterns and UV-visible spectroscopy indicated that both Fe3O4 and silver are present in the same particle. The superparamagnetism of Fe3O4@Ag nanoparticles was confirmed with a vibrating sample magnetometer. Their antibacterial activity was evaluated by means of minimum inhibitory concentration value, flow cytometry, and antibacterial rate assays. The results showed that Fe3O4@Ag nanoparticles presented good antibacterial performance against Escherichia coli (gram-negative bacteria), Staphylococcus epidermidis (gram-positive bacteria) and Bacillus subtilis (spore bacteria). Furthermore, Fe3O4@Ag nanoparticles can be easily removed from water by using a magnetic field to avoid contamination of surroundings. Reclaimed Fe3O4@Ag nanoparticles can still have antibacterial capability and can be reused.

  6. Resistance to bacteriocins produced by Gram-positive bacteria.

    PubMed

    Bastos, Maria do Carmo de Freire; Coelho, Marcus Lívio Varella; Santos, Olinda Cabral da Silva

    2015-04-01

    Bacteriocins are prokaryotic proteins or peptides with antimicrobial activity. Most of them exhibit a broad spectrum of activity, inhibiting micro-organisms belonging to different genera and species, including many bacterial pathogens which cause human, animal or plant infections. Therefore, these substances have potential biotechnological applications in either food preservation or prevention and control of bacterial infectious diseases. However, there is concern that continuous exposure of bacteria to bacteriocins may select cells resistant to them, as observed for conventional antimicrobials. Based on the models already investigated, bacteriocin resistance may be either innate or acquired and seems to be a complex phenomenon, arising at different frequencies (generally from 10(-9) to 10(-2)) and by different mechanisms, even amongst strains of the same bacterial species. In the present review, we discuss the prevalence, development and molecular mechanisms involved in resistance to bacteriocins produced by Gram-positive bacteria. These mechanisms generally involve changes in the bacterial cell envelope, which result in (i) reduction or loss of bacteriocin binding or insertion, (ii) bacteriocin sequestering, (iii) bacteriocin efflux pumping (export) and (iv) bacteriocin degradation, amongst others. Strategies that can be used to overcome this resistance are also addressed. PMID:25406453

  7. Purification, characterization and antibacterial activity of L-amino acid oxidase from Cerastes cerastes.

    PubMed

    Hanane-Fadila, Ziad-Meziane; Fatima, Laraba-Djebari

    2014-08-01

    Antibiotic resistance presents a real problem in which new antibacterial molecules from natural secretions could be beneficial in the development of new drugs. In this study, Cerastes cerastes venom was investigated for its antibacterial activity against Gram-positive and Gram-negative bacteria. The antibacterial activity was evaluated by measuring the halo inhibition and minimum inhibitory concentration (MIC). An L-amino acid oxidase (CcLAAO) was purified from this venom using three chromatographic steps; its homogeneity (60 kDa) was confirmed by SDS-PAGE. LC-MS/MS analysis of CcLAAO showed similarities with other LAAO enzymes from Echis ocellatus and Viridovipera stejnegeri venoms. CcLAAO presents an antibacterial activity against three bacterial strains (Staphylococcus aureus, Methicillin-resistant S. aureus, and Pseudomonas aeruginosa) with MIC values of 10, 10, and 20 ?g/mL, respectively. However, no effect was observed against Escherichia coli and yeast strains. Kinetic parameters of CcLAAO evaluated on L-leucine at pH 8.0 and 20°C were Km = 0.06 mmol and Vmax = 164 mmol/min. PMID:24817275

  8. Synthesis and antibacterial activity evaluation of two androgen derivatives.

    PubMed

    Lauro, Figueroa-Valverde; Francisco, Díaz-Cedillo; Elodia, García-Cervera; Eduardo, Pool-Gómez; Maria, López-Ramos; Marcela, Rosas-Nexticapa; Lenin, Hau-Heredia; Bety, Sarabia-Alcocer

    2015-01-01

    In this study two androgen derivatives were synthesized using several strategies; the first stage an aza-steroid derivative (3) was developed by the reaction of a testosterone derivative (1) with thiourea (2) in presence of hydrogen chloride. The second step, involves the synthesis of an amino-steroid derivative (4) by the reaction of 1 with 2 using boric acid as catalyst. The third stage was achieved by the preparation of an aminoaza-androgen derivative (6) by the reaction of 3 with ethylenediamine using boric acid as catalyst. In addition, the compound 6 was made reacting with dihydrotestosterone to form a new androgen derivative (7) in presence of boric acid. The following step was achieved by the reaction of 7 with chloroacetyl chloride to synthesize an azetidinone-androgen derivative (8) using triethylamine as catalyst. Additionally, a thiourea-androgen derivative (9) was synthetized by the reaction of 4 with dihydrotestosterone using boric acid as catalyst. Finally, the compound 9 was made reacting with chloroacetyl chloride in presence of triethylamine to synthesize a new azetidinone-androgen derivative (10). On the other hand, antibacterial activity of compounds synthesized was evaluated on Gram negative (Escherichia coli and Vibrio cholerae) and Gram positive (Staphylococos aureus) bacteria. The results indicate that only the compound 3 and 8 decrease the growth bacterial of E. coli and V. cholerae. Nevertheless, growth bacterial of S. aureus was not inhibited by these compounds. These data indicate that antibacterial activity exerted by the compounds 3 and 8 depend of their structure chemical in comparison with the controls and other androgen derivatives that are involved in this study. PMID:25448363

  9. Improvement of antibacterial activity of some sulfa drugs through linkage to certain phthalazin-1(2H)-one scaffolds.

    PubMed

    Ibrahim, Hany S; Eldehna, Wagdy M; Abdel-Aziz, Hatem A; Elaasser, Mahmoud M; Abdel-Aziz, Marwa M

    2014-10-01

    RAB1 5 is a lead antibacterial agent in which trimethoprim is linked to phthalazine moiety. Similarly, our strategy in this research depends on the interconnection between some sulfa drugs and certain phthalazin-1(2H)-one scaffolds in an attempt to enhance their antibacterial activity. This approach was achieved through the combination of 4-substituted phthalazin-1(2H)-ones 9a, b or 14a, b with sulfanilamide 1a, sulfathiazole 1b or sulfadiazine 1c through amide linkers 6a, b to produce the target compounds 10a-d and 15a-e, respectively. The antibacterial activity of the newly synthesized compounds showed that all tested compounds have antibacterial activity higher than that of their reference sulfa drugs 1a-c. Compound 10c represented the highest antibacterial activity against Gram-positive bacteria Streptococcus pneumonia and Staphylococcus aureus with MIC = 0.39 ?mol/mL. Moreover, compound 10d displayed excellent antibacterial activity against Gram-negative bacteria Escherichia coli and Salmonella typhimurium with MIC = 0.39 and 0.78 ?mol/mL, respectively. PMID:25113876

  10. Class D ?-lactamases do exist in Gram-positive bacteria.

    PubMed

    Toth, Marta; Antunes, Nuno Tiago; Stewart, Nichole K; Frase, Hilary; Bhattacharya, Monolekha; Smith, Clyde A; Vakulenko, Sergei B

    2016-01-01

    Production of ?-lactamases of one of four molecular classes (A, B, C and D) is the major mechanism of bacterial resistance to ?-lactams, the largest class of antibiotics, which have saved countless lives since their inception 70 years ago. Although several hundred efficient class D enzymes have been identified in Gram-negative pathogens over the last four decades, none have been reported in Gram-positive bacteria. Here we demonstrate that efficient class D ?-lactamases capable of hydrolyzing a wide array of ?-lactam substrates are widely disseminated in various species of environmental Gram-positive organisms. Class D enzymes of Gram-positive bacteria have a distinct structural architecture and employ a unique substrate-binding mode that is quite different from that of all currently known class A, C and D ?-lactamases. These enzymes thus constitute a previously unknown reservoir of novel antibiotic-resistance enzymes. PMID:26551395

  11. Diversity of pigmented Gram-positive bacteria associated with marine macroalgae from Antarctica.

    PubMed

    Leiva, Sergio; Alvarado, Pamela; Huang, Ying; Wang, Jian; Garrido, Ignacio

    2015-12-01

    Little is known about the diversity and roles of Gram-positive and pigmented bacteria in Antarctic environments, especially those associated with marine macroorganisms. This work is the first study about the diversity and antimicrobial activity of culturable pigmented Gram-positive bacteria associated with marine Antarctic macroalgae. A total of 31 pigmented Gram-positive strains were isolated from the surface of six species of macroalgae collected in the King George Island, South Shetland Islands. On the basis of 16S rRNA gene sequence similarities ?99%, 18 phylotypes were defined, which were clustered into 11 genera of Actinobacteria (Agrococcus, Arthrobacter, Brachybacterium, Citricoccus, Kocuria, Labedella, Microbacterium, Micrococcus, Rhodococcus, Salinibacterium and Sanguibacter) and one genus of the Firmicutes (Staphylococcus). It was found that five isolates displayed antimicrobial activity against a set of macroalgae-associated bacteria. The active isolates were phylogenetically related to Agrococcus baldri, Brachybacterium rhamnosum, Citricoccus zhacaiensis and Kocuria palustris. The results indicate that a diverse community of pigmented Gram-positive bacteria is associated with Antartic macroalgae and suggest its potential as a promising source of antimicrobial and pigmented natural compounds. PMID:26507390

  12. Evaluation of the antibacterial and antibiofilm activities of novel CRAMP-vancomycin conjugates with diverse linkers.

    PubMed

    Mishra, Nigam M; Briers, Yves; Lamberigts, Chris; Steenackers, Hans; Robijns, Stijn; Landuyt, Bart; Vanderleyden, Jos; Schoofs, Liliane; Lavigne, Rob; Luyten, Walter; Van der Eycken, Erik V

    2015-07-21

    We report the design, synthesis and antibacterial activity analysis of conjugates of vancomycin and cathelicidin-related antimicrobial peptides (CRAMP). Vancomycin inhibits the nascent peptidoglycan synthesis and is highly active against Gram-positive bacteria, whereas Gram-negative bacteria are generally insensitive due to a protective outer membrane. CRAMP is known to translocate across the Gram-negative outer membrane by a self-promoted uptake mechanism. Vancomycin-CRAMP conjugates were synthesized using click chemistry with diverse hydrophilic and hydrophobic linkers, with CRAMP functioning as a carrier peptide for the transfer of vancomycin through the outer membrane. Small hydrophobic linkers with an aromatic group result in the most active conjugates against planktonic Gram-negative bacteria, while maintaining the high activity of vancomycin against Gram-positive bacteria. These conjugates thus show a broad-spectrum activity, which is absent in CRAMP or vancomycin alone, and which is strongly improved compared to an equimolar mixture of CRAMP and vancomycin. In addition, these conjugates also show a strong inhibitory activity against S. Typhimurium biofilm formation. PMID:26068402

  13. Wall Teichoic Acids of Gram-Positive Bacteria

    PubMed Central

    Brown, Stephanie; Santa Maria, John P.; Walker, Suzanne

    2013-01-01

    The peptidoglycan layers of many gram-positive bacteria are densely functionalized with anionic glycopolymers called wall teichoic acids (WTAs). These polymers play crucial roles in cell shape determination, regulation of cell division, and other fundamental aspects of gram-positive bacterial physiology. Additionally, WTAs are important in pathogenesis and play key roles in antibiotic resistance. We provide an overview of WTA structure and biosynthesis, review recent studies on the biological roles of these polymers, and highlight remaining questions. We also discuss prospects for exploiting WTA biosynthesis as a target for new therapies to overcome resistant infections. PMID:24024634

  14. Silver-doped manganese dioxide and trioxide nanoparticles inhibit both gram positive and gram negative pathogenic bacteria.

    PubMed

    Kunkalekar, R K; Prabhu, M S; Naik, M M; Salker, A V

    2014-01-01

    Palladium, ruthenium and silver-doped MnO2 and silver doped Mn2O3 nanoparticles were synthesized by simple co-precipitation technique. SEM-TEM analysis revealed the nano-size of these synthesized samples. XPS data illustrates that Mn is present in 4+ and 3+ oxidation states in MnO2 and Mn2O3 respectively. Thermal analysis gave significant evidence for the phase changes with increasing temperature. Antibacterial activity of these synthesized nanoparticles on three Gram positive bacterial cultures (Staphylococcus aureus ATCC 6538, Streptococcus epidermis ATCC 12228, Bacillus subtilis ATCC 6633) and three Gram negative cultures (Escherichia coli ATCC 8739, Salmonella abony NCTC 6017 and Klebsiella pneumoniae ATCC 1003) was investigated using a disc diffusion method and live/dead assay. Only Ag-doped MnO2 and Ag-doped Mn2O3 nanoparticles showed antibacterial property against all six-test bacteria but Ag-doped MnO2 was found to be more effective than Ag-doped Mn2O3. PMID:24140741

  15. The Antibacterial Activity of Cassia fistula Organic Extracts

    PubMed Central

    Seyyednejad, Seyyed Mansour; Motamedi, Hossein; Vafei, Mouzhan; Bakhtiari, Ameneh

    2014-01-01

    Background: Cassia fistula, is a flowering plant and a member of Fabaceae family. Its leaves are compound of 4 - 8 pairs of opposite leaflets. There are many Cassia species around the world which are used in herbal medicine. Objectives: This study was designed to examine in vitro anti-bacterial activity of methanolic and ethanolic extracts of C. fistula native to Khuzestan, Iran. Materials and Methods: The microbial inhibitory effect of methanolic and ethanolic extracts of C. fistula was tested on 3 Gram positive: Bacillus cereus, Staphylococcus aureus and S. epidermidis and 5 Gram negative: Salmonella Typhi, Kelebsiella pneumoniae, Escherichia coli, Pseudomonas aeruginosa, and Proteus mirabilis bacterial species using disc diffusion method at various concentrations. The minimum inhibitory and bactericidal concentrations (MIC and MBC) were measured by the tube dilution assay. Results: The extract of C. fistula was effective against B. cereus, S. aureus, S. epidermidis, E. coli and K. pneumoniae. The most susceptible microorganisms to ethanolic and methanolic extracts were E. coli and K. pneumoniae, respectively. Also B. cereus and S. aureus showed the least sensitivity to ethanolic and methanolic extracts, respectively. The MIC (minimum inhibitory concentration) and MBC (minimum bactericidal concentration) of ethanolic extracts against S. aureus, E. coli, S. epidermidis and K. pneumoniae were also determined. Conclusions: With respect to the obtained results and regarding to the daily increase of the resistant microbial strains to the commercial antibiotics, it can be concluded that these extracts can be proper candidates of antibacterial substance against pathogenic bacterial species especially S. aureus, E. coli, K. pneumoniae and S. epidermidis. PMID:25147664

  16. Evaluation of antibacterial and anthelmintic activities with total phenolic contents of Piper betel leaves

    PubMed Central

    Akter, Kazi Nahid; Karmakar, Palash; Das, Abhijit; Anonna, Shamima Nasrin; Shoma, Sharmin Akter; Sattar, Mohammad Mafruhi

    2014-01-01

    Objective: The study was conducted to investigate the antibacterial and anthelmintic activities and to determine total phenolic contents of methanolic extract of Piper betel leaves. Materials and Methods: The extract was subjected to assay for antibacterial activity using both gram positive and gram negative bacterial strains through disc diffusion method; anthelmintic activity with the determination of paralysis and death time using earthworm (Pheritima posthuma) at five different concentrations and the determination of total phenolic contents using the Folin-ciocalteau method. Results: The extract showed significant (p<0.01) zone of inhibitions against gram positive Staphylococcus aureus [(6.77±0.25) mm] and Gram negative Escherichia coli [(8.53±0.25) mm], Salmonella typhi [(5.20±0.26) mm], Shigella dysenteriae [(11.20±0.26) mm] compared to positive control Azithromycin (ranging from 20.10±0.17 to 25.20±0.35 mm) while no zone inhibitory activity was found for both the extract and the standard drug against Gram positive Bacillus cereus. The extract also showed potent anthelmintic activity requiring less time for paralysis and death compared to the standard drug albendazole (10 mg/ml). At concentrations 10, 20, 40, 60 and 80 mg/ml, leaves extract showed paralysis at mean time of 9.83±0.60, 8.50±0.29, 6.60±0.17, 6.20±0.44 and 4.16±0.60; death at 11.33±0.88, 9.67±0.33, 7.83±0.17, 7.16±0.60 and 5.16±0.72 minutes, respectively. Whereas the standard drug showed paralysis and death at 19.33±0.71 and 51.00±0.23 minutes respectively. The extract confirmed the higher concentration of phenolic contents (124.42±0.14 mg of GAE /g of extract) when screened for total phenolic compounds. Conclusion: As results confirmed potential antibacterial and anthelmintic activities of Piper betel leaves extract, therefore it may be processed for further drug research. PMID:25386394

  17. Particle-Cell Contact Enhances Antibacterial Activity of Silver Nanoparticles

    PubMed Central

    Bondarenko, Olesja; Ivask, Angela; Käkinen, Aleksandr; Kurvet, Imbi; Kahru, Anne

    2013-01-01

    Background It is generally accepted that antibacterial properties of Ag nanoparticles (AgNPs) are dictated by their dissolved fraction. However, dissolution-based concept alone does not fully explain the toxic potency of nanoparticulate silver compared to silver ions. Methodology/Principal Findings Herein, we demonstrated that the direct contact between bacterial cell and AgNPs' surface enhanced the toxicity of nanosilver. More specifically, cell-NP contact increased the cellular uptake of particle-associated Ag ions – the single and ultimate cause of toxicity. To prove that, we evaluated the toxicity of three different AgNPs (uncoated, PVP-coated and protein-coated) to six bacterial strains: Gram-negative Escherichia coli, Pseudomonas fluorescens, P. putida and P. aeruginosa and Gram-positive Bacillus subtilis and Staphylococcus aureus. While the toxicity of AgNO3 to these bacteria varied only slightly (the 4-h EC50 ranged from 0.3 to 1.2 mg Ag/l), the 4-h EC50 values of protein-coated AgNPs for various bacterial strains differed remarkably, from 0.35 to 46 mg Ag/l. By systematically comparing the intracellular and extracellular free Ag+ liberated from AgNPs, we demonstrated that not only extracellular dissolution in the bacterial test environment but also additional dissolution taking place at the particle-cell interface played an essential role in antibacterial action of AgNPs. The role of the NP-cell contact in dictating the antibacterial activity of Ag-NPs was additionally proven by the following observations: (i) separation of bacterial cells from AgNPs by particle-impermeable membrane (cut-off 20 kDa, ?4 nm) significantly reduced the toxicity of AgNPs and (ii) P. aeruginosa cells which tended to attach onto AgNPs, exhibited the highest sensitivity to all forms of nanoparticulate Ag. Conclusions/Significance Our findings provide new insights into the mode of antibacterial action of nanosilver and explain some discrepancies in this field, showing that “Ag-ion” and “particle-specific” mechanisms are not controversial but, rather, are two faces of the same coin. PMID:23737965

  18. In vitro antibacterial and antifungal activities of Cassia fistula Linn. fruit pulp extracts

    PubMed Central

    Bhalodia, N. R.; Nariya, P. B.; Acharya, R. N.; Shukla, V. J.

    2012-01-01

    Aim of the study is to assess the antimicrobial activity Cassia fistula fruit pulp extracts on some bacterial and fungal strains. Hydro alcohol and chloroform extracts of Cassia fistula fruit pulp were evaluated for the potential antimicrobial activity. The antimicrobial activity was determined in both the extracts using the agar disc diffusion method. Extracts were effective on tested microorganisms. The antibacterial and antifungal activities of solvent extracts (5, 25, 50, 100, 250 ?g/mL) of C. fistula were tested against two gram positive, two gram negative human pathogenic bacteria and three fungi, respectively. Crude extracts of C. fistula exhibited moderate to strong activity against most of the bacteria tested. The tested bacterial strains were Staphylococcus aureus, Streptococcus pyogenes, Escherichia coil, Pseudomonas aeruginosa, and fungal strains were Aspergillus. niger, Aspergillus. clavatus, Candida albicans. The antibacterial potential of the extracts were found to be dose dependent. The antibacterial activities of the C. fistula were due to the presence of various secondary metabolites. Hence, these plants can be used to discover bioactive natural products that may serve as leads in the development of new pharmaceuticals research activities. PMID:23049197

  19. Novel Antimicrobial Peptides That Inhibit Gram Positive Bacterial Exotoxin Synthesis

    PubMed Central

    Merriman, Joseph A.; Nemeth, Kimberly A.; Schlievert, Patrick M.

    2014-01-01

    Gram-positive bacteria, such as Staphylococcus aureus, cause serious human illnesses through combinations of surface virulence factors and secretion of exotoxins. Our prior studies using the protein synthesis inhibitor clindamycin and signal transduction inhibitors glycerol monolaurate and ?-globin and ?-globin chains of hemoglobin indicate that their abilities to inhibit exotoxin production by S. aureus are separable from abilities to inhibit growth of the organism. Additionally, our previous studies suggest that inhibition of exotoxin production, in absence of ability to kill S. aureus and normal flora lactobacilli, will prevent colonization by pathogenic S. aureus, while not interfering with lactobacilli colonization. These disparate activities may be important in development of novel anti-infective agents that do not alter normal flora. We initiated studies to explore the exotoxin-synthesis-inhibition activity of hemoglobin peptides further to develop potential agents to prevent S. aureus infections. We tested synthesized ?-globin chain peptides, synthetic variants of ?-globin chain peptides, and two human defensins for ability to inhibit exotoxin production without significantly inhibiting S. aureus growth. All of these peptides were weakly or not inhibitory to bacterial growth. However, the peptides were inhibitory to exotoxin production with increasing activity dependent on increasing numbers of positively-charged amino acids. Additionally, the peptides could be immobilized on agarose beads or have amino acid sequences scrambled and still retain exotoxin-synthesis-inhibition. The peptides are not toxic to human vaginal epithelial cells and do not inhibit growth of normal flora L. crispatus. These peptides may interfere with plasma membrane signal transduction in S. aureus due to their positive charges. PMID:24748386

  20. Antibacterial activity of garlic extract on streptomycin-resistant Staphylococcus aureus and Escherichia coli solely and in synergism with streptomycin.

    PubMed

    Palaksha, M N; Ahmed, Mansoor; Das, Sanjoy

    2010-07-01

    This study focuses the significant antibacterial activity of Garlic (Allium sativum Linn.) extract on streptomycin-resistant strains solely and in synergism with streptomycin. Gram-positive Staphylococcus aureus ATCC BAA 1026 and gram-negative Escherichia coli ATCC 10536 were made resistant to standard antibiotic streptomycin used as a control in the experiment. Zones of inhibition of different treatment groups were measured by agar-well-diffusion assay and compared with control. Statistical comparison of sole extract and streptomycin synergism with streptomycin control had proved it significant. PMID:22096329

  1. Screening genomes of Gram-positive bacteria for

    E-print Network

    Screening genomes of Gram-positive bacteria for double-glycine-motif- containing peptides Secreted-positive bacteria, the double-glycine (GG) motif plays a key role in many peptide secretion systems involved Microbiology Comment #12;peptides and class II bacteriocins, produced by streptococci and lactic acid bacteria

  2. Antimicrobial Peptide Resistance Mechanisms of Gram-Positive Bacteria

    PubMed Central

    McBride, Shonna M.

    2014-01-01

    Antimicrobial peptides, or AMPs, play a significant role in many environments as a tool to remove competing organisms. In response, many bacteria have evolved mechanisms to resist these peptides and prevent AMP-mediated killing. The development of AMP resistance mechanisms is driven by direct competition between bacterial species, as well as host and pathogen interactions. Akin to the number of different AMPs found in nature, resistance mechanisms that have evolved are just as varied and may confer broad-range resistance or specific resistance to AMPs. Specific mechanisms of AMP resistance prevent AMP-mediated killing against a single type of AMP, while broad resistance mechanisms often lead to a global change in the bacterial cell surface and protect the bacterium from a large group of AMPs that have similar characteristics. AMP resistance mechanisms can be found in many species of bacteria and can provide a competitive edge against other bacterial species or a host immune response. Gram-positive bacteria are one of the largest AMP producing groups, but characterization of Gram-positive AMP resistance mechanisms lags behind that of Gram-negative species. In this review we present a summary of the AMP resistance mechanisms that have been identified and characterized in Gram-positive bacteria. Understanding the mechanisms of AMP resistance in Gram-positive species can provide guidelines in developing and applying AMPs as therapeutics, and offer insight into the role of resistance in bacterial pathogenesis. PMID:25419466

  3. In Vitro antibacterial and in Vivo cytotoxic activities of Grewia paniculata

    PubMed Central

    Nasrin, Mahmuda; Dash, Pritesh Ranjan; Ali, Mohammad Shawkat

    2015-01-01

    Objectives: Grewia paniculata (Family: Malvaceae) has been used to treat inflammation, respiratory disorders and fever. It is additionally employed for other health conditions including colds, diarrhea and as an insecticide in Bangladesh. The aim of the present study was to investigate the antibacterial and cytotoxic activities of different extracts of Grewia paniculata. Materials and Methods: The antibacterial activity was evaluated against both gram negative and gram positive bacteria using disc diffusion method by determination of the diameter of zone of inhibition. Cytotoxic activity was performed by brine shrimp (Artemia salina) lethality bioassay. Results: In disc diffusion method, all the natural products (400 ?g/disc) showed moderate to potent activity against all the tested bacteria. The ethanol extract of bark (EEB) and ethanol fraction of bark (EFB) (400 ?g/disc) exhibited highest activity against Shigella dysenteriae with a zone of inhibition of 23±1.63 mm and 23±1.77 mm respectively. In the brine shrimp lethality bioassay all the extracts showed moderate cytotoxic activity when compared with the standard drug vincristin sulphate. For example, LC50 value of the ethanol fraction of bark (EFB) was 3.01 ?g/ml while the LC50 of vincristine sulphate was 0.52 ?g/ml. Conclusions: The results suggest that all the natural products possess potent antibacterial and moderate cytotoxic. PMID:25949950

  4. Synergistic antibacterial activity of chitosan-silver nanocomposites on Staphylococcus aureus

    NASA Astrophysics Data System (ADS)

    Potara, Monica; Jakab, Endre; Damert, Annette; Popescu, Octavian; Canpean, Valentin; Astilean, Simion

    2011-04-01

    The approach of combining different mechanisms of antibacterial action by designing hybrid nanomaterials provides a new paradigm in the fight against resistant bacteria. Here, we present a new method for the synthesis of silver nanoparticles enveloped in the biopolymer chitosan. The method aims at the production of bionanocomposites with enhanced antibacterial properties. We find that chitosan and silver nanoparticles act synergistically against two strains of Gram-positive Staphylococcus aureus (S. aureus). As a result the bionanocomposites exhibit higher antibacterial activity than any component acting alone. The minimum inhibitory (MIC) and minimum bactericidal (MBC) concentrations of the chitosan-silver nanoparticles synthesized at 0 °C were found to be lower than those reported for other types of silver nanoparticles. Atomic force microscopy (AFM) revealed dramatic changes in morphology of S. aureus cells due to disruption of bacterial cell wall integrity after incubation with chitosan-silver nanoparticles. Finally, we demonstrate that silver nanoparticles can be used not only as antibacterial agents but also as excellent plasmonic substrates to identify bacteria and monitor the induced biochemical changes in the bacterial cell wall via surface enhanced Raman scattering (SERS) spectroscopy.

  5. 7-Azetidinylquinolones as antibacterial agents. Synthesis and structure-activity relationships.

    PubMed

    Frigola, J; Parés, J; Corbera, J; Vañó, D; Mercè, R; Torrens, A; Más, J; Valentí, E

    1993-04-01

    A series of novel antibacterial quinolones and naphthyridones has been prepared which contain 7-azetidinyl substituents in place of the usual piperazine or aminopyrrolidine groups. These azetidinyl derivatives were evaluated for in vitro activity by determining minimum inhibitory concentrations against a variety of bacteria. In vivo efficacy in the mouse infection model and blood levels in the mouse were determined for several compounds. The influence on the structure-activity relationships of varying substituents in the azetidine ring and at position 8 (CH, CF, CCl, N) and N-1 (ethyl, fluoroethyl, cyclopropyl, tert-butyl, 4-fluorophenyl, and 2,4-difluorophenyl) was also studied. Compounds with outstandingly broad-spectrum activity, particularly against Gram-positive organisms, improved in vivo efficacy, and high blood levels were identified in this work. 7-Azetidinyl-8-chloroquinolones were considered as warranting further development. PMID:8464033

  6. Anti-bacterial activity and brine shrimp lethality bioassay of methanolic extracts of fourteen different edible vegetables from Bangladesh

    PubMed Central

    Ullah, M. Obayed; Haque, Mahmuda; Urmi, Kaniz Fatima; Zulfiker, Abu Hasanat Md.; Anita, Elichea Synthi; Begum, Momtaj; Hamid, Kaiser

    2013-01-01

    Objective To investigate the antibacterial and cytotoxic activity of fourteen different edible vegetables methanolic extract from Bangladesh. Methods The antibacterial activity was evaluated using disc diffusion assay method against 12 bacteria (both gram positive and gram negative). The plant extracts were also screened for cytotoxic activity using the brine shrimp lethality bioassay method and the lethal concentrations (LC50) were determined at 95% confidence intervals by analyzing the data on a computer loaded with “Finney Programme”. Results All the vegetable extracts showed low to elevated levels of antibacterial activity against most of the tested strains (zone of inhibition=5-28 mm). The most active extract against all bacterial strains was from Xanthium indicum which showed remarkable antibacterial activity having the diameter of growth inhibition zone ranging from 12 to 28 mm followed by Alternanthera sessilis (zone of inhibition=6-21 mm). All extracts exhibited considerable general toxicity towards brine shrimps. The LC50 value of the tested extracts was within the range of 8.447 to 60.323 µg/mL with respect to the positive control (vincristine sulphate) which was 0.91 µg/mL. Among all studied extracts, Xanthium indicum displayed the highest cytotoxic effect with LC50 value of 8.447 µg/mL. Conclusions The results of the present investigation suggest that most of the studied plants are potentially good source of antibacterial and anticancer agents. PMID:23570009

  7. In vitro antibacterial activity of selected medicinal plants from lower Himalayas.

    PubMed

    Zulqarnain; Rahim, Abdur; Ahmad, Khalid; Ullah, Faizan; Ullah, Hamid; Nishan, Umar

    2015-03-01

    The present studies cover antibacterial activity of the crude methanolic extracts of 11 medicinal plants viz. Adhatoda vasica, Bauhenia variegate, Bombax ceiba, Carrisa opaca, Caryopteris grata, Debregeasia salicifolia, Lantana camara, Melia azedarach, Phyllanthus emblica, Pinus roxburghii and Olea ferruginea collected from lower Himalayas against two Gram positive (Staphylococcus aureus, Micrococcus luteus) and two Gram negative (Escherichia coli, Pseudomonas aureginosa) bacterial strains. The extracts were applied at four different concentrations (120 mg/mL, 90mg/mL, 60mg/mL and 30mg/mL) in dimethyl sulfoxide (DMSO) by using agar well diffusion method. Antibacterial activities against Staphylococcus aureus and Micrococcus luteus were observed formethanolic extracts of all the above mentioned plants. Greater antibacterial activity against Pseudomonas aeruginosa was only exhibited by Phyllanthus emblica, Pinus roxburghii, Debregeasia salicifolia and Lantana camara. Escherichia coli was highly resistant to all the plant extracts at all concentrations. It is inferred that methanolic crude extracts of the above mentioned plantsexhibitantibacterial activities against pathogenic bacteria, which proved the ethnobotanical importance of the selected plants that indigenous people use for cure against various diseases. PMID:25730791

  8. Walnut (Juglans regia L.) leaves: phenolic compounds, antibacterial activity and antioxidant potential of different cultivars.

    PubMed

    Pereira, José Alberto; Oliveira, Ivo; Sousa, Anabela; Valentão, Patrícia; Andrade, Paula B; Ferreira, Isabel C F R; Ferreres, Federico; Bento, Albino; Seabra, Rosa; Estevinho, Letícia

    2007-11-01

    Different cultivars of walnut (Juglans regia L.) leaves (Cv. Lara, Franquette, Mayette, Marbot, Mellanaise and Parisienne) grown in Portugal, were investigated in what concerns phenolic compounds and antimicrobial and antioxidant properties. Phenolics analysis was performed by reversed-phase HPLC/DAD and 10 compounds were identified and quantified: 3- and 5-caffeoylquinic acids, 3- and 4-p-coumaroylquinic acids, p-coumaric acid, quercetin 3-galactoside, quercetin 3-pentoside derivative, quercetin 3-arabinoside, quercetin 3-xyloside and quercetin 3-rhamnoside. The antimicrobial capacity was screened against Gram positive (Bacillus cereus, B. subtilis, Staphylococcus aureus) and Gram negative bacteria (Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae) and fungi (Candida albicans, Cryptococcus neoformans). Walnut leaves selectively inhibited the growth of Gram positive bacteria, being B. cereus the most susceptible one (MIC 0.1mg/mL). Gram negative bacteria and fungi were resistant to the extracts at 100mg/mL. Lara walnut leaves were also submitted to antibacterial assays using 18 clinical isolates of Staphylococcus sp. Antioxidant activity was accessed by the reducing power assay, the scavenging effect on DPPH (2,2-diphenyl-1-picrylhydrazyl) radicals and beta-carotene linoleate model system. In a general way, all of the studied walnut leaves cultivars presented high antioxidant activity (EC(50) values lower than 1mg/mL), being Cv. Lara the most effective one. PMID:17637491

  9. Antibacterial Activity of Geminized Amphiphilic Cationic Homopolymers.

    PubMed

    Wang, Hui; Shi, Xuefeng; Yu, Danfeng; Zhang, Jian; Yang, Guang; Cui, Yingxian; Sun, Keji; Wang, Jinben; Yan, Haike

    2015-12-22

    The current study is aimed at investigating the effect of cationic charge density and hydrophobicity on the antibacterial and hemolytic activities. Two kinds of cationic surfmers, containing single or double hydrophobic tails (octyl chains or benzyl groups), and the corresponding homopolymers were synthesized. The antimicrobial activity of these candidate antibacterials was studied by microbial growth inhibition assays against Escherichia coli, and hemolysis activity was carried out using human red blood cells. It was interestingly found that the homopolymers were much more effective in antibacterial property than their corresponding monomers. Furthermore, the geminized homopolymers had significantly higher antibacterial activity than that of their counterparts but with single amphiphilic side chains in each repeated unit. Geminized homopolymers, with high positive charge density and moderate hydrophobicity (such as benzyl groups), combine both advantages of efficient antibacterial property and prominently high selectivity. To further explain the antibacterial performance of the novel polymer series, the molecular interaction mechanism is proposed according to experimental data which shows that these specimens are likely to kill microbes by disrupting bacterial membranes, leading them unlikely to induce resistance. PMID:26606647

  10. Chemical Composition and In Vitro Antibacterial Activity of Mentha spicata Essential Oil against Common Food-Borne Pathogenic Bacteria.

    PubMed

    Shahbazi, Yasser

    2015-01-01

    The aim of the present study was to investigate chemical composition and antibacterial activity of essential oil from the leaf of Mentha spicata plant against common food-borne pathogenic bacteria (Staphylococcus aureus, Bacillus subtilis, Bacillus cereus, Listeria monocytogenes, Salmonella typhimurium, and Escherichia coli O157:H7). Chemical composition of the essential oil was identified by gas chromatography coupled with mass spectrometer detector (GC-MS). The antibacterial activity of the essential oil was evaluated by broth microdilution method and agar disk diffusion assay. According to the result of GC-MS analysis, 18 components were identified, accounting for 99.89% of the whole essential oil. The main components were carvone (78.76%), limonene (11.50%), ?-bourbonene (11.23%), cis-dihydrocarveol (1.43%), trans-caryophyllene (1.04%), menthone (1.01%), menthol (1%), and terpinen-4-ol (0.99). The essential oil exhibited moderate level of antibacterial activity against all test microorganisms. In general, Gram-positive bacteria were more susceptible to M. spicata essential oil than Gram-negative bacteria. L. monocytogenes was the most sensitive of the microorganisms to the antibacterial activity of M. spicata essential oil (inhibition zone = 22?mm and MIC and MBC = 2.5?µL/mL). Based on our results, the essential oil of M. spicata plant collected from Kermanshah province, west of Iran, has a potential to be applied as antibacterial agent. PMID:26351584

  11. Chemical Composition and In Vitro Antibacterial Activity of Mentha spicata Essential Oil against Common Food-Borne Pathogenic Bacteria

    PubMed Central

    Shahbazi, Yasser

    2015-01-01

    The aim of the present study was to investigate chemical composition and antibacterial activity of essential oil from the leaf of Mentha spicata plant against common food-borne pathogenic bacteria (Staphylococcus aureus, Bacillus subtilis, Bacillus cereus, Listeria monocytogenes, Salmonella typhimurium, and Escherichia coli O157:H7). Chemical composition of the essential oil was identified by gas chromatography coupled with mass spectrometer detector (GC-MS). The antibacterial activity of the essential oil was evaluated by broth microdilution method and agar disk diffusion assay. According to the result of GC-MS analysis, 18 components were identified, accounting for 99.89% of the whole essential oil. The main components were carvone (78.76%), limonene (11.50%), ?-bourbonene (11.23%), cis-dihydrocarveol (1.43%), trans-caryophyllene (1.04%), menthone (1.01%), menthol (1%), and terpinen-4-ol (0.99). The essential oil exhibited moderate level of antibacterial activity against all test microorganisms. In general, Gram-positive bacteria were more susceptible to M. spicata essential oil than Gram-negative bacteria. L. monocytogenes was the most sensitive of the microorganisms to the antibacterial activity of M. spicata essential oil (inhibition zone = 22?mm and MIC and MBC = 2.5?µL/mL). Based on our results, the essential oil of M. spicata plant collected from Kermanshah province, west of Iran, has a potential to be applied as antibacterial agent. PMID:26351584

  12. Assessment of Total Phenolic, Antioxidant, and Antibacterial Activities of Passiflora Species

    PubMed Central

    Ramaiya, Shiamala Devi; Bujang, Japar Sidik; Zakaria, Muta Harah

    2014-01-01

    This study focused on total phenolic content (TPC) and antioxidant and antibacterial activities of the leaves and stems of Passiflora quadrangularis, P. maliformis, and P. edulis extracted using three solvents: petroleum ether, acetone, and methanol. The maximum extraction yields of antioxidant components from the leaves and stems were isolated using methanol extracts of P. edulis (24.28%) and P. quadrangularis (9.76%), respectively. Among the leaf extracts, the methanol extract of P. maliformis had the significantly highest TPC and the strongest antioxidant activity, whereas among the stem extracts, the methanol extract of P. quadrangularis showed the highest phenolic amount and possessed the strongest antioxidant activity. The antibacterial properties of the Passiflora species were tested using the disc diffusion method against 10 human pathogenic bacteria. The largest inhibition zone was observed for the methanol extract of P. maliformis against B. subtilis. Generally, extracts from the Passiflora species exhibit distinct inhibition against Gram-positive but not Gram-negative bacteria. Based on the generated biplot, three clusters of bacteria were designated according to their performance towards the tested extracts. The present study revealed that methanol extracts of the Passiflora contain constituents with significant phenolic, antioxidant, and antibacterial properties for pharmaceutical and nutraceutical uses. PMID:25028673

  13. Preparation and Antibacterial Activity Evaluation of 18-?-glycyrrhetinic Acid Loaded PLGA Nanoparticles

    PubMed Central

    Darvishi, Behrad; Manoochehri, Saeed; Kamalinia, Golnaz; Samadi, Nasrin; Amini, Mohsen; Mostafavi, Seyyed Hossein; Maghazei, Shahab; Atyabi, Fatemeh; Dinarvand, Rassoul

    2015-01-01

    The aim of the present study was to formulate poly (lactide-co-glycolide) (PLGA) nanoparticles loaded with 18-?-glycyrrhetinic acid (GLA) with appropriate physicochemical properties and antimicrobial activity. GLA loaded PLGA nanoparticles were prepared with different drug to polymer ratios, acetone contents and sonication times and the antibacterial activity of the developed nanoparticles was examined against different gram-negative and gram-positive bacteria. The antibacterial effect was studied using serial dilution technique to determine the minimum inhibitory concentration of nanoparticles. Results demonstrated that physicochemical properties of nanoparticles were affected by the above mentioned parameters where nanoscale size particles ranging from 175 to 212 nm were achieved. The highest encapsulation efficiency (53.2 ± 2.4%) was obtained when the ratio of drug to polymer was 1:4. Zeta potential of the developed nanoparticles was fairly negative (-11±1.5). In-vitro release profile of nanoparticles showed two phases: an initial phase of burst release for 10 h followed by a slow release pattern up to the end. The antimicrobial results revealed that the nanoparticles were more effective than pure GLA against P. aeuroginosa, S. aureus and S. epidermidis. This improvement in antibacterial activity of GLA loaded nanoparticles when compared to pure GLA may be related to higher nanoparticles penetration into infected cells and a higher amount of GLA delivery in its site of action. Herein, it was shown that GLA loaded PLGA nanoparticles displayed appropriate physicochemical properties as well as an improved antimicrobial effect. PMID:25901144

  14. Antibiotic-decorated titanium with enhanced antibacterial activity through adhesive polydopamine for dental/bone implant

    PubMed Central

    He, Shu; Zhou, Ping; Wang, Linxin; Xiong, Xiaoling; Zhang, Yifei; Deng, Yi; Wei, Shicheng

    2014-01-01

    Implant-associated infections, which are normally induced by microbial adhesion and subsequent biofilm formation, are a major cause of morbidity and mortality. Therefore, practical approaches to prevent implant-associated infections are in great demand. Inspired by adhesive proteins in mussels, here we have developed a novel antibiotic-decorated titanium (Ti) material with enhanced antibacterial activity. In this study, Ti substrate was coated by one-step pH-induced polymerization of dopamine followed by immobilization of the antibiotic cefotaxime sodium (CS) onto the polydopamine-coated Ti through catechol chemistry. Contact angle measurement and X-ray photoelectron spectroscopy confirmed the presence of CS grafted on the Ti surface. Our results demonstrated that the antibiotic-grafted Ti substrate showed good biocompatibility and well-behaved haemocompatibility. In addition, the antibiotic-grafted Ti could effectively prevent adhesion and proliferation of Escherichia coli (Gram-negative) and Streptococcus mutans (Gram-positive). Moreover, the inhibition of biofilm formation on the antibiotic-decorated Ti indicated that the grafted CS could maintain its long-term antibacterial activity. This modified Ti substrate with enhanced antibacterial activity holds great potential as implant material for applications in dental and bone graft substitutes. PMID:24647910

  15. Daptomycin: a novel lipopeptide antibiotic against Gram-positive pathogens

    PubMed Central

    Beiras-Fernandez, Andres; Vogt, Ferdinand; Sodian, Ralf; Weis, Florian

    2010-01-01

    The aim of this review is to summarize the historical background of drug resistance of Gram-positive pathogens as well as to describe in detail the novel lipopeptide antibiotic daptomycin. Pharmacological and pharmacokinetic aspects are reviewed and the current clinical use of daptomycin is presented. Daptomycin seems to be a reliable drug in the treatment of complicated skin and skin structure infections, infective right-sided endocarditis, and bacteremia caused by Gram-positive agents. Its unique mechanism of action and its low resistance profile, together with its rapid bactericidal action make it a favorable alternative to vancomycin in multi-drug resistant cocci. The role of daptomycin in the treatment of prosthetic material infections, osteomyelitis, and urogenital infections needs to be evaluated in randomized clinical trials. PMID:21694898

  16. Virulence Plasmids of Nonsporulating Gram-Positive Pathogens

    PubMed Central

    Van Tyne, Daria; Gilmore, Michael S.

    2014-01-01

    SUMMARY Gram-positive bacteria are leading causes of many types of human infection, including pneumonia, skin and nasopharyngeal infections, as well as urinary tract and surgical wound infections among hospitalized patients. These infections have become particularly problematic because many of the species causing them have become highly resistant to antibiotics. The role of mobile genetic elements, such as plasmids, in the dissemination of antibiotic resistance among Gram-positive bacteria has been well studied; less well understood is the role of mobile elements in the evolution and spread of virulence traits among these pathogens. While these organisms are leading agents of infection, they are also prominent members of the human commensal ecology. It appears that these bacteria are able to take advantage of the intimate association between host and commensal, via virulence traits that exacerbate infection and cause disease. However, evolution into an obligate pathogen has not occurred, presumably because it would lead to rejection of pathogenic organisms from the host ecology. Instead, in organisms that exist as both commensal and pathogen, selection has favored the development of mechanisms for variability. As a result, many virulence traits are localized on mobile genetic elements, such as virulence plasmids and pathogenicity islands. Virulence traits may occur within a minority of isolates of a given species, but these minority populations have nonetheless emerged as a leading problem in infectious disease. This chapter reviews virulence plasmids in nonsporulating Gram-positive bacteria, and examines their contribution to disease pathogenesis. PMID:25544937

  17. Architecture and assembly of the Gram-positive cell wall

    PubMed Central

    Beeby, Morgan; Gumbart, James C.; Roux, Benoît; Jensen, Grant J.

    2013-01-01

    The bacterial cell wall is a mesh polymer of peptidoglycan – linear glycan strands crosslinked by flexible peptides – that determines cell shape and provides physical protection. While the glycan strands in thin “Gram-negative” peptidoglycan are known to run circumferentially around the cell, the architecture of the thicker “Gram-positive” form remains unclear. Using electron cryotomography, here we show that Bacillus subtilis peptidoglycan is a uniformly dense layer with a textured surface. We further show it rips circumferentially, curls and thickens at free edges, and extends longitudinally when denatured. Molecular dynamics simulations show that only atomic models based on the circumferential topology recapitulate the observed curling and thickening, in support of an “inside-to-outside” assembly process. We conclude that instead of being perpendicular to the cell surface or wrapped in coiled cables (two alternative models), the glycan strands in Gram-positive cell walls run circumferentially around the cell just as they do in Gram-negative cells. Together with providing insights into the architecture of the ultimate determinant of cell shape, this study is important because Gram-positive peptidoglycan is an important antibiotic target crucial to the viability of several important rod-shaped pathogens including Bacillus anthracis, Listeria monocytogenes, and Clostridium difficile. PMID:23600697

  18. Microplate assay for screening the antibacterial activity of Schiff bases derived from substituted benzopyran-4-one

    NASA Astrophysics Data System (ADS)

    Amin, Rehab M.; Abdel-Kader, Nora S.; El-Ansary, Aida L.

    Schiff bases (SB1-SB3) were synthesized from the condensation of 6-formyl-7-hydroxy-5-methoxy-2-methylbenzopyran-4-one with 2-aminopyridine (SB1), p-phenylenediamine (SB2) and o-phenylenediamine (SB3), while Schiff bases (SB4-SB6) were synthesized by condensation of 5,7-dihydroxy-6-formyl-2-methylbenzopyran-4-one with 2-aminopyridine (SB4), p-phenylenediamine (SB5) and o-phenylenediamine (SB6). Schiff bases were characterized using elemental analysis, IR, UV-Vis, 1H NMR, 13C NMR and mass spectroscopy. These compounds were screened for antibacterial activities by micro-plate assay technique. Escherichia coli and Staphylococcus capitis were exposed to different concentrations of the Schiff bases. Results showed that the antibacterial effect of these Schiff bases on Gram-negative bacteria were higher than that on Gram-positive bacteria moreover, the Schiff bases containing substituent OCH3 on position five have higher antibacterial activity than that containing hydroxy group on the same position.

  19. Superior Antibacterial Activity of Fe3O4-TiO2 Nanosheets under Solar Light.

    PubMed

    Ma, Shuanglong; Zhan, Sihui; Jia, Yanan; Zhou, Qixing

    2015-10-01

    Fe3O4-TiO2 nanosheets (Fe3O4-TNS) were synthesized by means of lamellar reverse micelles and solvothermal method, which were characterized by TEM, XRD, XPS, BET, and magnetic property analysis. It can be found that Fe3O4-TNS nanosheets exhibited better photocatalytic antibacterial activity toward Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus than pure Fe3O4 and TNS, and the antibacterial efficiency could reach 87.2% and 93.7% toward E. coli and S. aureus with 100 ?g/mL Fe3O4-TNS after 2 h of simulated solar light illumination, respectively. The photocatalytic destruction of bacteria was further confirmed by fluorescent-based cell live/dead test and SEM images. It was uncovered that Fe3O4-TNS inactivated G- E. coli and G+ S. aureus by different mechanisms: the destruction of outer membranes and ruptured cell bodies were responsible for the bactericidal effect against E. coli, while the antibacterial effect toward S. aureus were due to the fact that the cells were adsorbed in form of clusters by massive Fe3O4-TNS, which could restrict their activities and cause malfunction of the selective permeable barriers. Furthermore, the antibacterial mechanism was studied by employing scavengers to understand exact roles of different reactive species, indicating the key roles of h(+) and H2O2. The recovery and reusability experiments indicated that Fe3O4-TNS still retained more than 90% bacteria removal efficiency even after five cycles. Considering the easy magnetic separation, bulk availability, and high antibacterial activity of Fe3O4-TNS, it is a promising candidate for cleaning the microbial contaminated water environment. PMID:26372171

  20. Antibacterial activity-guided purification and identification of a novel C-20 oxygenated ent-kaurane from Rabdosia serra (MAXIM.) HARA.

    PubMed

    Lin, Lianzhu; Zhu, Dashuai; Zou, Linwu; Yang, Bao; Zhao, Mouming

    2013-08-15

    The objective of this work was to conduct an activity-guided isolation of antibacterial compounds from Rabdosia serra. The ethanol extracts of R. serra leaf and stem were partitioned sequentially into petroleum ether, ethyl acetate, butanol and water fractions, respectively. The ethanol extract of leaf evidenced broad-spectrum antibacterial activity against gram-positive bacterial, including Bacillus subtilis, Bacillus cereus, Staphylococcus aureus, and Listeria monocytogenes. The ethyl acetate fractions of leaf and stem exhibited strong inhibition against gram-positive bacteria, and were then purified further. On the basis of antibacterial assay-guided purification, three phenolic compounds (rosmarinic acid, methyl rosmarinate and pedalitin) and four C-20 oxygenated ent-kauranes (effusanin E, lasiodin, rabdosichuanin D and a new compound namely effusanin F) were obtained, whose contents were determined by HPLC analysis. The broth microdilution method confirmed the important inhibition potential of C-20 oxygenated ent-kauranes with low minimum inhibitory concentration (MIC) values. Effusanin E, lasiodin and effusanin F could be useful for the development of new antibacterial agents. PMID:23561188

  1. Antifungal and Antibacterial Metabolites from a French Poplar Type Propolis

    PubMed Central

    Boisard, Séverine; Le Ray, Anne-Marie; Landreau, Anne; Kempf, Marie; Cassisa, Viviane; Flurin, Catherine; Richomme, Pascal

    2015-01-01

    During this study, the in vitro antifungal and antibacterial activities of different extracts (aqueous and organic) obtained from a French propolis batch were evaluated. Antifungal activity was evaluated by broth microdilution on three pathogenic strains: Candida albicans, C. glabrata, and Aspergillus fumigatus. Antibacterial activity was assayed using agar dilution method on 36 Gram-negative and Gram-positive strains including Staphylococcus aureus. Organic extracts showed a significant antifungal activity against C. albicans and C. glabrata (MIC80 between 16 and 31?µg/mL) but only a weak activity towards A. fumigatus (MIC80 = 250?µg/mL). DCM based extracts exhibited a selective Gram-positive antibacterial activity, especially against S. aureus (SA) and several of its methicillin-resistant (MRSA) and methicillin-susceptible (MSSA) strains (MIC100 30–97?µg/mL). A new and active derivative of catechin was also identified whereas a synergistic antimicrobial effect was noticed during this study. PMID:25873978

  2. Silver deposition on polypyrrole films electrosynthesised onto Nitinol alloy. Corrosion protection and antibacterial activity.

    PubMed

    Saugo, M; Flamini, D O; Brugnoni, L I; Saidman, S B

    2015-11-01

    The electrosynthesis of polypyrrole films onto Nitinol from sodium salicylate solutions of different concentrations is reported. The morphology and corrosion protection properties of the resulting coatings were examined and they both depend on the sodium salicylate concentration. The immobilisation of silver species in PPy films constituted by hollow rectangular microtubes was studied as a function of the polymer oxidation degree. The highest amount of silver was deposited when the coated electrode was prepolarised at -1.00V (SCE) before silver deposition, suggesting an increase in the amount of non-oxidised segments in the polymer. Finally, the antibacterial activity of the coating against the Gram positive Staphylococcus aureus and Staphylococcus epidermidis bacteria was evaluated. Both strains resulted sensitive to the modified coatings, obtaining a slightly better result against S. aureus. PMID:26249570

  3. Bioinspired synthesis of highly stabilized silver nanoparticles using Ocimum tenuiflorum leaf extract and their antibacterial activity.

    PubMed

    Patil, Rupali S; Kokate, Mangesh R; Kolekar, Sanjay S

    2012-06-01

    Biosynthesis of nanoparticles is under exploration due to wide biomedical applications and research interest in nanotechnology. We herein reports bioinspired synthesis of silver nanoparticles with the aid of novel, non toxic ecofriendly biological material namely Ocimum tenuiflorum leaf extract. It acts as reducing as well as stabilizing agent. An intense surface plasmon resonance band at ?450 nm in the UV-visible spectrum clearly reveals the formation of silver nanoparticles. The photoluminescence spectrum was recorded to study excitation and emission. TEM and PSD by dynamic light scattering studies showed that size of silver nanoparticles to be in range 25-40 nm. Face centered cubic structure of silver nanoparticles are confirmed by SAED pattern. The charge on synthesized silver nanoparticles was determined by zeta potential. The colloidal solution of silver nanoparticles were found to exhibit high antibacterial activity against three different strains of bacteria Escherichia coli (Gram negative), Corney bacterium (gram positive), Bacillus substilus (spore forming). PMID:22381796

  4. Synthesis of silver nanoparticles using A. indicum leaf extract and their antibacterial activity

    NASA Astrophysics Data System (ADS)

    Ashokkumar, S.; Ravi, S.; Kathiravan, V.; Velmurugan, S.

    2015-01-01

    Green synthesis of silver nanoparticles has been achieved using environmentally acceptable plant extract. It is observed that Abutilon indicum leaf extract can reduce silver ions into silver nanoparticles within 15 min of reaction time. The formation and stability of the reduced silver nanoparticles in the colloidal solution were monitored by UV-Vis spectrophotometer analysis. The mean particle diameter of silver nanoparticles was calculated from the XRD pattern. FT-IR spectra of the leaf extract after the development of nanoparticles are determined to allow identification of possible functional groups responsible for the conversion of metal ions to metal nanoparticles. The AgNPs thus obtained showed highly potent antibacterial activity toward Gram-positive (Staphyloccocus aureus and Bacillus subtilis) and Gram-negative (Salmonella typhi and Escherichia coli) microorganisms.

  5. Synthesis of silver nanoparticles using A. indicum leaf extract and their antibacterial activity.

    PubMed

    Ashokkumar, S; Ravi, S; Kathiravan, V; Velmurugan, S

    2015-01-01

    Green synthesis of silver nanoparticles has been achieved using environmentally acceptable plant extract. It is observed that Abutilon indicum leaf extract can reduce silver ions into silver nanoparticles within 15 min of reaction time. The formation and stability of the reduced silver nanoparticles in the colloidal solution were monitored by UV-Vis spectrophotometer analysis. The mean particle diameter of silver nanoparticles was calculated from the XRD pattern. FT-IR spectra of the leaf extract after the development of nanoparticles are determined to allow identification of possible functional groups responsible for the conversion of metal ions to metal nanoparticles. The AgNPs thus obtained showed highly potent antibacterial activity toward Gram-positive (Staphyloccocus aureus and Bacillus subtilis) and Gram-negative (Salmonella typhi and Escherichia coli) microorganisms. PMID:24997264

  6. Synthesis and evaluation of isatin-?-thiosemicarbazones as novel agents against antibiotic-resistant Gram-positive bacterial species.

    PubMed

    Zhang, Xu-Meng; Guo, Hui; Li, Zai-Shun; Song, Fu-Hang; Wang, Wei-Min; Dai, Huan-Qin; Zhang, Li-Xin; Wang, Jian-Guo

    2015-08-28

    Methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus (VRE) have caused an increasing mortality rate, which means that antibiotic resistance is becoming an important health issue. In the course to screen new agents for resistant bacteria, we identified that a series of isatin-?-thiosemicarbazones (IBTs) could inhibit the growth of MRSA and VRE. This was the first time that the "familiar" IBT compounds exhibited significant anti Gram-positive pathogen activity. Against a clinical isolated MRSA strain, 20 of the 51 synthesized compounds showed minimum inhibitory concentration (MIC) data of 0.78 mg/L and another 12 novel compounds had MICs of 0.39 mg/L. Moreover, these compounds also inhibited Enterococcus faecalis and VRE at similar levels, indicating that IBTs might have different mode of action compared with vancomycin. For these IBTs, comparative field analysis (CoMFA) models were further established to understand the structure-activity relationships in order to design new compounds from steric and electrostatic contributions. This work has suggested that IBTs can be considered as potential lead compounds to discover antibacterial inhibitors to combat drug resistance. PMID:26185006

  7. Antibacterial nanofiber materials activated by light.

    PubMed

    Jesenská, So?a; Plíštil, Lukáš; Kubát, Pavel; Lang, Kamil; Brožová, Libuše; Popelka, St?pán; Szatmáry, Lórant; Mosinger, Ji?í

    2011-12-15

    Electrospun polymeric nanofiber materials doped with 5,10,15,20-tetraphenylporphyrin (TPP) photosensitizer were prepared from four different polymers and were characterized with microscopic methods, steady-state, and time-resolved fluorescence and absorption spectroscopy. The polymers used included polyurethane Larithane™ (PUR), polystyrene (PS), polycaprolactone (PCL), and polyamide 6 (PA6). The antibacterial activity of all nanofiber materials against E. coli was activated by visible light and it was dependent on oxygen permeability/diffusion coefficients and the diameter of the polymeric nanofibers. This activity is based on oxidation ability of singlet oxygen O?(¹?(g)) that is generated upon irradiation. All tested nanofiber materials exhibited prolonged antibacterial properties, even in the dark after long-duration irradiation. The post-irradiation effect was explained by the photogeneration of H?O?, which provided the material with long-lasting antibacterial properties. PMID:21972201

  8. Electrospun chitosan nanofibers with controlled levels of silver nanoparticles. Preparation, characterization and antibacterial activity.

    PubMed

    Lee, Sang Jin; Heo, Dong Nyoung; Moon, Ji-Hoi; Ko, Wan-Kyu; Lee, Jung Bok; Bae, Min Soo; Park, Se Woong; Kim, Ji Eun; Lee, Dong Hyun; Kim, Eun-Cheol; Lee, Chang Hoon; Kwon, Il Keun

    2014-10-13

    The ideal wound dressing would have properties that allow for absorption of exudates, and inhibition of microorganism for wound protection. In this study, we utilized an electrospinning (ELSP) technique to design a novel wound dressing. Chitosan (CTS) nanofibers containing various ratios of silver nanoparticles (AgNPs) were obtained. AgNPs were generated directly in the CTS solution by using a chemical reduction method. The formation and presence of AgNPs in the CTS/AgNPs composite was confirmed by x-ray diffraction (XRD), ultraviolet-visible spectroscopy (UV) and thermogravimetric analysis (TGA). The electrospun CTS/AgNPs nanofibers were characterized morphologically by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). These nanofibers were subsequently tested to evaluate their antibacterial activity against gram-negative Pseudomonas aeruginosa (P. aeruginosa) and gram-positive Methicillin-resistant Staphylococcus aureus (MRSA). Results of this antibacterial testing suggest that CTS/AgNPs nanofibers may be effective in topical antibacterial treatment in wound care. PMID:25037384

  9. Enhanced antibacterial activity of bimetallic gold-silver core-shell nanoparticles at low silver concentration

    NASA Astrophysics Data System (ADS)

    Banerjee, Madhuchanda; Sharma, Shilpa; Chattopadhyay, Arun; Ghosh, Siddhartha Sankar

    2011-12-01

    Herein we report the development of bimetallic Au@Ag core-shell nanoparticles (NPs) where gold nanoparticles (Au NPs) served as the seeds for continuous deposition of silver atoms on its surface. The core-shell structure and morphology were examined by UV-Vis spectroscopy, transmission electron microscopy (TEM), energy dispersive X-ray (EDX) analysis and X-ray diffraction (XRD). The core-shell NPs showed antibacterial activity against both Gram negative (Escherichia coli and Pseudomonas aeruginosa) and Gram positive (Enterococcus faecalis and Pediococcus acidilactici) bacteria at low concentration of silver present in the shell, with more efficacy against Gram negative bacteria. TEM and flow cytometric studies showed that the core-shell NPs attached to the bacterial surface and caused membrane damage leading to cell death. The enhanced antibacterial properties of Au@Ag core-shell NPs was possibly due to the more active silver atoms in the shell surrounding gold core due to high surface free energy of the surface Ag atoms owing to shell thinness in the bimetallic NP structure.Herein we report the development of bimetallic Au@Ag core-shell nanoparticles (NPs) where gold nanoparticles (Au NPs) served as the seeds for continuous deposition of silver atoms on its surface. The core-shell structure and morphology were examined by UV-Vis spectroscopy, transmission electron microscopy (TEM), energy dispersive X-ray (EDX) analysis and X-ray diffraction (XRD). The core-shell NPs showed antibacterial activity against both Gram negative (Escherichia coli and Pseudomonas aeruginosa) and Gram positive (Enterococcus faecalis and Pediococcus acidilactici) bacteria at low concentration of silver present in the shell, with more efficacy against Gram negative bacteria. TEM and flow cytometric studies showed that the core-shell NPs attached to the bacterial surface and caused membrane damage leading to cell death. The enhanced antibacterial properties of Au@Ag core-shell NPs was possibly due to the more active silver atoms in the shell surrounding gold core due to high surface free energy of the surface Ag atoms owing to shell thinness in the bimetallic NP structure. Electronic supplementary information (ESI) available. See DOI: 10.1039/c1nr10703h

  10. Biotransformation of fluoroquinolone antibiotics by ligninolytic fungi--Metabolites, enzymes and residual antibacterial activity.

    PubMed

    ?van?arová, Monika; Moeder, Monika; Filipová, Alena; Cajthaml, Tomáš

    2015-10-01

    A group of white rot fungi (Irpex lacteus, Panus tigrinus, Dichomitus squalens, Trametes versicolor and Pleurotus ostreatus) was investigated for the biodegradation of norfloxacin (NOR), ofloxacin (OF) and ciprofloxacin (CIP). The selected fluoroquinolones were readily degraded almost completely by I. lacteus and T. versicolor within 10 and 14 d of incubation in liquid medium, respectively. The biodegradation products were identified by liquid chromatography-mass spectrometry. The analyses indicated that the fungi use similar mechanisms to degrade structurally related antibiotics. The piperazine ring of the molecules is preferably attacked via either substitution or/and decomposition. In addition to the degradation efficiency, attention was devoted to the residual antibiotic activities estimated using Gram-positive and Gram-negative bacteria. Only I. lacteus was able to remove the antibiotic activity during the course of the degradation of NOR and OF. The product-effect correlations evaluated by Principal Component Analysis (PCA) enabled elucidation of the participation of the individual metabolites in the residual antibacterial activity. Most of the metabolites correlated with the antibacterial activity, explaining the rather high residual activity remaining after the biodegradation. PCA of ligninolytic enzyme activities indicated that manganese peroxidase might participate in the degradation. PMID:25592459

  11. Mercury(II) complexes of unsymmetric phosphorus ylides: Synthesis, spectroscopic and antibacterial activity studies

    NASA Astrophysics Data System (ADS)

    Sabounchei, Seyyed Javad; Panahimehr, Mohammad; Hosseinzadeh, Marjan; Karamian, Roya; Asadbegy, Mostafa; Masumi, Azadeh

    2014-03-01

    The reaction of Ph2PCH2PPh2 (dppm) with 2-bromo-3-nitroacetophenone and 2,2?,4?-trichloroacetophenone in chloroform produce the new phosphonium salts [Ph2PCH2PPh2CH2C(O)C6H4NO2]Br (1) and [Ph2PCH2PPh2CH2C(O)C6H3Cl2]Cl (2). Further, by reaction of the monophosphonium salts of dppm with the strong base triethylaminethe corresponding bidentate phosphorus ylides, Ph2PCH2PPh2C(H)C(O)C6H4NO2 (3) and Ph2PCH2PPh2C(H)C(O)C6H3Cl2 (4) were obtained. The reaction of these ligands with mercury(II) halides in dry methanol led to the formation of the mononuclear complexes {HgX2[(Ph2PCH2PPh2C(H)C(O)C6H4NO2)]} [X = Cl (5), Br (6), I (7)] and {HgX2[(Ph2PCH2PPh2C(H)C(O)C6H3Cl2)]} [X = Cl (8), Br (9), I (10)]. Characterization of the obtained compounds was performed by elemental analysis, IR, 1H, 31P and 13C NMR. The structure of compound 1 being unequivocally determined by single crystal X-ray diffraction techniques. The mass spectrum of compound 6 (as an instance) also demonstrates the synthesize of these compounds. In all complexes the title ylides are coordinated through the ylidic carbon and the phosphine atom. These compounds form five membered ring under complexation. The antibacterial effects of DMSO solutions of the ligands and their metal complexes were evaluated by the disc diffusion method against six Gram positive and negative bacteria. All compounds represent antibacterial activity against these bacteria with high levels of inhibitory potency exhibited against the Gram positive species.

  12. Performance properties and antibacterial activity of crosslinked films of quaternary ammonium modified starch and poly(vinyl alcohol).

    PubMed

    Sekhavat Pour, Zahra; Makvandi, Pooyan; Ghaemy, Mousa

    2015-09-01

    There has been a growing interest in developing antibacterial polymeric materials. In the present work, novel antibacterial cross-linked blend films were prepared based on polyvinyl alcohol (PVA) and quaternary ammonium starch (ST-GTMAC) using citric acid (CA) as plasticizer and glutaraldehyde (GA) as cross-linker. The ST-GTMAC was successfully synthesized from reaction between water-soluble oxidized starch and glycidyltrimethylammonium chloride (GTMAC). The effect of ST-GTMAC, CA and GA contents on the swelling, solubility, mechanical and thermal properties of the films was investigated. It was found that incorporation of ST-GTMAC reduced UV-transmittance and provided antibacterial properties, increasing GA content increased tensile strength and decreased solubility and swelling degree of the films, while CA acted as plasticizer when its concentration was above 10 wt%. The results showed that ST-GTMAC/PVA/CA/GA film has fair antibacterial activity against Gram-positive (Staphylococcus aureus and Bacillus subtilis) and Gram-negative (Escherichia coli and Pseudomonas aeruginosa) bacteria. These results suggest that the prepared film might be used as potential antibacterial material in medical and packaging applications. PMID:26188297

  13. Antibacterial, antioxidant and tyrosinase-inhibition activities of pomegranate fruit peel methanolic extract

    PubMed Central

    2012-01-01

    Background This study evaluated, using in vitro assays, the antibacterial, antioxidant, and tyrosinase-inhibition activities of methanolic extracts from peels of seven commercially grown pomegranate cultivars. Methods Antibacterial activity was tested on Gram-positive (Bacillus subtilis and Staphylococcus aureus) and Gram-negative bacteria (Escherichia coli and Klebsiella pneumonia) using a microdilution method. Several potential antioxidant activities, including radical-scavenging ability (RSA), ferrous ion chelating (FIC) and ferric ion reducing antioxidant power (FRAP), were evaluated. Tyrosinase enzyme inhibition was investigated against monophenolase (tyrosine) and diphenolase (DOPA), with arbutin and kojic acid as positive controls. Furthermore, phenolic contents including total flavonoid content (TFC), gallotannin content (GTC) and total anthocyanin content (TAC) were determined using colourimetric methods. HPLC-ESI/MSn analysis of phenolic composition of methanolic extracts was also performed. Results Methanolic peel extracts showed strong broad-spectrum activity against Gram-positive and Gram-negative bacteria, with the minimum inhibitory concentrations (MIC) ranging from 0.2 to 0.78 mg/ml. At the highest concentration tested (1000 ?g/ml), radical scavenging activities were significantly higher in Arakta (83.54%), Ganesh (83.56%), and Ruby (83.34%) cultivars (P< 0.05). Dose dependent FIC and FRAP activities were exhibited by all the peel extracts. All extracts also exhibited high inhibition (>50%) against monophenolase and diphenolase activities at the highest screening concentration. The most active peel extract was the Bhagwa cultivar against monophenolase and the Arakta cultivar against diphenolase with IC50 values of 3.66 ?g/ml and 15.88 ?g/ml, respectively. High amounts of phenolic compounds were found in peel extracts with the highest and lowest total phenolic contents of 295.5 (Ganesh) and 179.3 mg/g dry extract (Molla de Elche), respectively. Catechin, epicatechin, ellagic acid and gallic acid were found in all cultivars, of which ellagic acid was the most abundant comprising of more than 50% of total phenolic compounds detected in each cultivar. Conclusions The present study showed that the tested pomegranate peels exhibited strong antibacterial, antioxidant and tyrosinase-inhibition activities. These results suggest that pomegranate fruit peel could be exploited as a potential source of natural antimicrobial and antioxidant agents as well as tyrosinase inhibitors. PMID:23110485

  14. Antibacterial activity of a cell wall hydrolase from Lactobacillus paracasei NRRL B-50314 produced by recombinant Bacillus megaterium.

    PubMed

    Liu, Siqing; Rich, Joseph O; Anderson, Amber

    2015-02-01

    The cell-free supernatant (CFS) from Lactobacillus paracasei NRRL B-50314 culture has been previously reported as containing antibacterial activity against a wide variety of Gram-positive bacteria. The CFS protein gel slice corresponding to antibacterial activities was subjected to trypsin digestion and ion trap MASS (Gel/LC-MS/MS) analysis. BlastP search of the resulted IQAVISIAEQQIGKP sequence led to a hypothetical cell-wall associated hydrolase (designated as CWH here) from Lactobacillus paracasei ATCC 25302. Further analyses of CWH revealed that the IQAVISIAEQQIGKP belongs to a highly conserved region of the NlpC/P60 superfamily. The L. paracasei NRRL B-50314 CWH gene, cloned in pStrepHIS1525CWH477, was introduced into Bacillus megaterium MS 941. The production of CWH477 protein was induced by xylose. The CWH477 protein was purified by using NiNTA column, and elution fraction E2 showed highest antibacterial activity. This study and bioinformatics analyses suggested that the antibacterial activity of CWH could originate from its cell wall degrading enzymatic function. PMID:25533632

  15. Type IV Pili in Gram-Positive Bacteria

    PubMed Central

    Craig, Lisa

    2013-01-01

    SUMMARY Type IV pili (T4P) are surface-exposed fibers that mediate many functions in bacteria, including locomotion, adherence to host cells, DNA uptake (competence), and protein secretion and that can act as nanowires carrying electric current. T4P are composed of a polymerized protein, pilin, and their assembly apparatuses share protein homologs with type II secretion systems in eubacteria and the flagella of archaea. T4P are found throughout Gram-negative bacterial families and have been studied most extensively in certain model Gram-negative species. Recently, it was discovered that T4P systems are also widespread among Gram-positive species, in particular the clostridia. Since Gram-positive and Gram-negative bacteria have many differences in cell wall architecture and other features, it is remarkable how similar the T4P core proteins are between these organisms, yet there are many key and interesting differences to be found as well. In this review, we compare the two T4P systems and identify and discuss the features they have in common and where they differ to provide a very broad-based view of T4P systems across all eubacterial species. PMID:24006467

  16. [New gram-positive opportunistic bacteria: pathogenic role and treatment].

    PubMed

    Philippon, A; Barbut, F

    1997-05-17

    NOVEL BACTERIA: The appearance of novel bacterial species among Gram positive microorganisms is mainly related to progress in bacterial taxonomy justifying such nomen species, i.e. C. jeikeium, C. urealyticum or R. equi. Another feature of such emergence of "Novel" bacteria is related to the rise in the number of clinical observations mediated by some well-known species described elsewhere such as in food bacteriology. PREDISPOSING FACTORS: Among Gram positive microorganisms, emergence for some species and renaissance or rebirth for others is mainly explained by natural resistance to widely used antibiotics including beta-lactams such as third generation cephalosporins, aminoglycosides, or more recently glycopeptides and the combined effect of several predisposing factors (hospitalized patients, underlying disease or prematurity, interruption of the normal integumentary defense via intravascular catheters). Clinical features depend on the bacterial species. Bacteriological diagnosis is easily obtained in terms of isolation and identification. Nevertheless, as for any opportunistic pathogen, a distinction must be made between colonization and infection. Finally successful treatment regimens depend on the bacterial species and may include surgery. PMID:9205480

  17. 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 (?Hagg) 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 1-2?M for Gram-positive and 4-16?M 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. PMID:25936261

  18. Synthesis, characterization and antibacterial activity of biodegradable films prepared from Schiff bases of zein.

    PubMed

    Soliman, E A; Khalil, A A; Deraz, S F; El-Fawal, G; Elrahman, S Abd

    2014-10-01

    Pure zein is known to be very hydrophobic, but is still inappropriate for coating and film applications because of their brittle nature. In an attempt to improve the flexibility and the antimicrobial activity of these coatings and films, Chemical modification of zein through forming Schiff bases with different phenolic aldhydes was tried. Influence of this modifications on mechanical, topographical, wetting properties and antimicrobial activity of zein films were evaluated. The chemical structure of the Schiff bases films were characterized by ATR-FTIR spectroscopy. The results indicate an improvement in mechanical properties with chemically modification of zein to form Schiff bases leading to a reduction in the elastic modulus. An increase in the elongation at break has been observed, but with slight influence on tensile strength. Plasticized zein films have similar initial contact angle (?40°). An increase in reaction temperature and time increases film's affinity towards water. As shown by contact angle measurements, a noticeable relation was found between film composition and the hydrophilicity. Surface topography also varied by forming Schiff bases, becoming rougher than zein-based films. The antibacterial activities of zein and Schiff bases of zein-based films were investigated against gram-positive bacteria (Listeria innocua, Listeria monocytogenes, Bacillus cereus and Clostridium sporogenes) and gram-negative bacteria (Escherichia coli, Yersinia enterocolitica and Salmonella enterica). It was found that the antibacterial activity of the Schiff bases-based films was more effective than that of zein-based films. PMID:25328181

  19. Fatty acid composition, antioxidant and antibacterial activities of Adonis wolgensis L. extract

    PubMed Central

    Mohadjerani, Maryam; Tavakoli, Rahmatollah; Hosseinzadeh, Rahman

    2014-01-01

    Objectives: The objective of this study was to analyze the fatty acid content, antioxidant, and antibacterial activities of hydro-methanolic extract of Adonis wolgensis L. (A. wolgensis L.) growing wild in north of Iran. Materials and Methods: Oils of A. wolgensis L. was obtained by means of Soxhlet apparatus from leaves and stems. Methyl esters were derived from the oily mixtures by trans-esterification process and were analyzed by GC/FID and GC/MS systems. Phenolic compounds extraction was done with aqueous methanol (90%). This extract was investigated for antioxidant activity using DPPH radical scavenging and reducing power methods and was also tested against a panel of microorganisms. Results: Linolenic acid (45.83%) and oleic acid (47.54%) were the most abundant fatty acids in leaves and stems, respectively. Hydro-methanolic extract with the high amount of total phenolics (9.20 ±0.011 mg GAE per dry matter) was the potent antioxidant in the assays. Results obtained from measurements of MIC for extract, indicated that E. coli, S. aureus, and S. enteritidis were the most sensitive microorganisms tested, but no activity was observed against Gram-positive microorganism (B. subtilis). Conclusion: The results obtained from the present study indicated that the oil of A. wolgensis leaves and stems contained a high source of poly-unsaturated fatty acids (PUFAs). These results also showed that hydro-methanolic extract of this plant contained significant antioxidant and antibacterial activities. PMID:25050298

  20. A novel green synthesis of silver nanoparticles using soluble starch and its antibacterial activity

    PubMed Central

    Yakout, Sobhy M; Mostafa, Ashraf A

    2015-01-01

    A green method of Silver nanoparticles (AgNPs) preparation has been established. This method depends on reduction of silver nitrate with soluble starch. The formation of AgNPs was observed by the color change from colorless to dark brown through the starch addition into silver nitrate solution. It was observed that use of starch makes convenient method for the synthesis of silver nanoparticles and can reduce silver ions into the produced silver nanoparticles within one hour of reaction time without using any harsh conditions. The prepared silver nanoparticles were characterized by using UV-visible spectroscopy and evaluated for its antimicrobial activity. The synthesized green AgNPs showed a potential antibacterial activity that was stronger against Gram positive pathogenic bacteria (Staphylococus aureus and Streptococus pyogenes) than against Gram negative pathogenic bacteria (Salmonella typhi, Shigellasonnei and Pseudomonas aeruginosa). Inhibition zones diameter of antibacterial activity depends upon nanoparticles concentration as AgNPs exhibited greater inhibition zone for S.aureus (16.4 mm) followed by P. aeruginosa and S. pyogenes while the least activity was observed for S. typhi (10.4 mm) at 40 ?l/ disc. These results suggested that AgNPs can be used as an effective antiseptic agents in medical fields and process of synthesis creates new opportunities in process development for the synthesis of safe and eco-friendly AgNPs. PMID:26064246

  1. Synthesis, Structure–Activity Relationship Studies, and Antibacterial Evaluation of 4-Chromanones and Chalcones, as Well as Olympicin A and Derivatives

    PubMed Central

    2015-01-01

    On the basis of recently reported abyssinone II and olympicin A, a series of chemically modified flavonoid phytochemicals were synthesized and evaluated against Mycobacterium tuberculosis and a panel of Gram-positive and -negative bacterial pathogens. Some of the synthesized compounds exhibited good antibacterial activities against Gram-positive pathogens including methicillin resistant Staphylococcus aureus with minimum inhibitory concentration as low as 0.39 ?g/mL. SAR analysis revealed that the 2-hydrophobic substituent and the 4-hydrogen bond donor/acceptor of the 4-chromanone scaffold together with the hydroxy groups at 5- and 7-positions enhanced antibacterial activities; the 2?,4?-dihydroxylated A ring and the lipophilic substituted B ring of chalcone derivatives were pharmacophoric elements for antibacterial activities. Mode of action studies performed on selected compounds revealed that they dissipated the bacterial membrane potential, resulting in the inhibition of macromolecular biosynthesis; further studies showed that selected compounds inhibited DNA topoisomerase IV, suggesting complex mechanisms of actions for compounds in this series. PMID:25238443

  2. Microwave-assisted synthesis, characterization and antibacterial activity of Ag/ZnO nanoparticles supported bentonite clay.

    PubMed

    Motshekga, Sarah C; Ray, Suprakas S; Onyango, Maurice S; Momba, Maggie N B

    2013-11-15

    Composites of silver-zinc oxide nanoparticles supported on bentonite clay were synthesized by the microwave-assisted synthesis method for use as an antibacterial material. Silver nitrate was used as the precursor of silver nanoparticles while zinc oxide nanoparticles were commercially sourced. The composites were characterized by powder X-ray diffraction (XRD), transmission electron microscope (TEM), Fourier transform infrared (FTIR) and BET surface area measurements. XRD spectra showed peaks of silver confirming the formation of the silver and not of the silver nitrate or any other impurity of the metal. Meanwhile TEM confirmed the formation of silver and zinc oxide nanoparticles on the clay layers, with particle sizes ranging from 9-30 nm and 15-70 nm, respectively. The antibacterial activities of the composites were evaluated against Gram negative Escherichia coli bacteria and Gram positive Enterococcus faecalis bacteria by the disc diffusion method. Whereas both composites of Ag-clay and ZnO-clay showed good antibacterial activity against bacteria, a better antibacterial activity was observed with Ag/ZnO-clay composite. The results therefore reveal that Ag/ZnO-clay composite is a promising bactericide that can be used for deactivating microbes in water. PMID:24076479

  3. Considering the antibacterial activity of Zataria multiflora Boiss essential oil treated with gamma-irradiation in vitro and in vivo systems

    NASA Astrophysics Data System (ADS)

    Faezeh, Fatema; Salome, Dini; Abolfazl, Dadkhah; Reza, Zolfaghari Mohammad

    2015-01-01

    The aim of the present study was to evaluate the antibacterial activities of essential oils (EOs) obtained from the aerial parts of Zataria multiflora Boiss against Bacillus cereus, Pseudomonas aeroginosa, Escherichia coli and Staphylococcus aureus by in vivo and in vitro methods. Also, the effects of gamma-irradiation (0, 10 and 25 kGy) as a new microbial decontamination on the antibacterial activities of Z. multiflora were examined. For this purpose, the collected herbs were exposed to radiation at doses of 0, 10 and 25 kGy following essential oil (EOs) extraction by steam distillation. Then, the in vitro antibacterial potency of the irradiated and non-irradiated oils was determined by using disc diffusion, agar well diffusion and MIC and MBC determination assays. The in vivo antibacterial activity was also studied in sepsis model induced by CLP surgery by Colony forming units (CFUs) determination. The results showed that the extracted oils were discovered to be effective against all the gram positive and gram negative pathogens in vitro system. In addition, the oil significantly diminished the increased CFU count observed in CLP group. Moreover, the irradiated samples were found to possess the antibacterial activities as the non-irradiated ones both in vitro and in vivo systems. These data indicated the potential use of gamma-irradiation as a safe technique for preservation of Z. multiflora as a medicinal plant with effective antibacterial activities.

  4. Antibacterial, cytotoxicity and anticoagulant activities from Hypnea esperi and Caulerpa prolifera marine algae.

    PubMed

    Selim, Samy; Amin, Abeer; Hassan, Sherif; Hagazey, Mohamed

    2015-03-01

    Extracts from 2 algal species (Hypnea esperi and Caulerpa prolifera) from Suez Canal region, Egypt were screened for the production of antibacterial compounds against some pathogenic bacteria. The bacteria tested included Escherichia coli, Pseudomonas aeruginosa, Salmonella typhimurium, Aeromonas hydrophila, Bacillus subtilis and Staphylococcus aureus. Algal species displayed antibacterial activity. The methanolic extracts showed variable response by producing various zones of inhibition against studied bacteria. The tested Gram-negative bacteria were less affected by studied algal extracts than Gram-positive bacteria. We determined some biopotentials properties such as cytotoxicity and anticoagulant activity of most potent algal active extracts. The secondary metabolites of only Hypnea esperi algal extract effectively prevented the blood clotting to the extent of 120 seconds. Minimum inhibitory concentration (MIC) indicated that all potent tested algal extract C inhibits Bacillus subtilis and Staphylococcus aureus. Minimum bactericidal concentration (MBC) was between 1 and 1.4mg/ml. The algal isolates from Egypt have been found showing promising results against infectious bacteria instead of some synthetic antibiotics. PMID:25730785

  5. Antitubercular and antibacterial activity of quinonoid natural products against multi-drug resistant clinical isolates.

    PubMed

    Dey, Diganta; Ray, Ratnamala; Hazra, Banasri

    2014-07-01

    Multi-drug resistant Mycobacterium tuberculosis and other bacterial pathogens represent a major threat to human health. In view of the critical need to augment the current drug regime, we have investigated therapeutic potential of five quinonoids, viz. emodin, diospyrin, plumbagin, menadione and thymoquinone, derived from natural products. The antimicrobial activity of quinonoids was evaluated against a broad panel of multi-drug and extensively drug-resistant tuberculosis (M/XDR-TB) strains, rapid growing mycobacteria and other bacterial isolates, some of which were producers of ?-lactamase, Extended-spectrum ?-lactamase (ESBL), AmpC ?-lactamase, metallo-beta-lactamase (MBL) enzymes, as well as their drug-sensitive ATCC counterparts. All the tested quinones exhibited antimycobacterial and broad spectrum antibacterial activity, particularly against M. tuberculosis (lowest MIC 0.25?µg/mL) and Gram-positive bacteria (lowest MIC <4?µg/mL) of clinical origin. The order of antitubercular activity of the tested quinonoids was plumbagin?>?emodin?~?menadione?~?thymoquinone?>?diospyrin, whereas their antibacterial efficacy was plumbagin?>?menadione?~?thymoquinone?>?diospyrin?>?emodin. Furthermore, this is the first evaluation performed on these quinonoids against a broad panel of drug-resistant and drug-sensitive clinical isolates, to the best of our knowledge. PMID:24318724

  6. Chemical composition, antibacterial and antioxidant activities of six essentials oils from the Alliaceae family.

    PubMed

    Mnayer, Dima; Fabiano-Tixier, Anne-Sylvie; Petitcolas, Emmanuel; Hamieh, Tayssir; Nehme, Nancy; Ferrant, Christine; Fernandez, Xavier; Chemat, Farid

    2014-01-01

    Six essential oils (EOs) from the Alliaceae family, namely garlic (Allium sativum), onion (Allium cepa), leek (Allium porrum), Chinese chive (Allium tuberosum), shallot (Allium ascalonicum) and chive (Allium schoenoprasum) were characterized by GC and GC-MS and evaluated for their functional food properties. Antibacterial properties were tested on five food-borne pathogens: Two Gram-positive Staphylococcus aureus (ATCC 25923), Listeria monocytogenes (ATCC 19115) and three Gram-negative Salmonella Typhimurium (ATCC 14028), Escherichia coli (ATCC 8739) and Campylobacter jejuni (ATCC 33291) bacteria. Antioxidant and radical-scavenging properties were tested by means of Folin-Ciocalteu and 2,2-diphenyl-1-picrylhydrazyl (DPPH) assays. Garlic, Chinese chive and onion EOs had the highest antibacterial activity whereas shallot and leek EOs were the strongest antioxidants. Heating caused a decrease in the antioxidant activity of these Eos, as shown in the Total Polar Materials (TPM) test. Suggestions on relationships between chemical composition and biological activities are presented. Results show that the EOs could be of value in the food industry as alternatives to synthetic antioxidants. PMID:25470273

  7. Honey: its medicinal property and antibacterial activity

    PubMed Central

    Mandal, Manisha Deb; Mandal, Shyamapada

    2011-01-01

    Indeed, medicinal importance of honey has been documented in the world's oldest medical literatures, and since the ancient times, it has been known to possess antimicrobial property as well as wound-healing activity. The healing property of honey is due to the fact that it offers antibacterial activity, maintains a moist wound condition, and its high viscosity helps to provide a protective barrier to prevent infection. Its immunomodulatory property is relevant to wound repair too. The antimicrobial activity in most honeys is due to the enzymatic production of hydrogen peroxide. However, another kind of honey, called non-peroxide honey (viz., manuka honey), displays significant antibacterial effects even when the hydrogen peroxide activity is blocked. Its mechanism may be related to the low pH level of honey and its high sugar content (high osmolarity) that is enough to hinder the growth of microbes. The medical grade honeys have potent in vitro bactericidal activity against antibiotic-resistant bacteria causing several life-threatening infections to humans. But, there is a large variation in the antimicrobial activity of some natural honeys, which is due to spatial and temporal variation in sources of nectar. Thus, identification and characterization of the active principle(s) may provide valuable information on the quality and possible therapeutic potential of honeys (against several health disorders of humans), and hence we discussed the medicinal property of honeys with emphasis on their antibacterial activities. PMID:23569748

  8. Antibacterial and antifungal activities of crude plant extracts from Colombian biodiversity.

    PubMed

    Niño, Jaime; Mosquera, Oscar M; Correa, Yaned M

    2012-12-01

    On a global scale, people have used plants to treat diseases and infections, and this has raised interest on the plant biodiversity potencial in the search of antimicrobial principles. In this work, 75 crude n-hexanes, dichloromethane and methanol extracts from the aerial parts of 25 plants belonging to four botanical families (Asteraceae, Euphorbiaceae, Rubiaceae and Solanaceae), collected at the Natural Regional Park Ucumari (Risaralda, Colombia), were evaluated for their antibacterial and antifungal activities by the agar well diffusion method. The antibacterial activities were assayed against two Gram-positive bacteria Staphylococcus aureus and Bacillus subtilis, and three Gram-negative ones named, Klebsiella pneumoniae, Escherichia coli and Pseudomonas aeruginosa. In addition, the same plant extracts were tested against the yeast Candida albicans and the fungi Aspergillus fumigatus and Fusarium solani. Overall, the plant extracts examined displayed better bactericide rather than fungicide activities. In general, the best antibacterial activity was showed by the plant extracts from the Rubiaceae family, followed in order by the extracts from the Euphorbiaceae and Solanaceae ones. It is important to emphasize the great activity displayed by the methanol extract of Alchornea coelophylla (Euphorbiaceae) that inhibited four out of five bacteria tested (B. Subtilis, P. aeruginosa, S. aureus and E. coli). Furthermore, the best Minimal Inhibitory Concentration for the extracts with antifungal activities were displayed by the dichloromethane extracts from Acalypha diversifolia and Euphorbia sp (Euphorbiaceae). The most susceptible fungus evaluated was F. Solani since 60% and 20% of the dichloromethane and methanol extracts evaluated inhibited the growth of this phytopathogenic fungus. The antimicrobial activity of the different plant extracts examined in this work could be related to the secondary metabolites contents and their interaction and susceptibility of pathogenic microorganism evaluated. PMID:23342508

  9. Papain-templated Cu nanoclusters: assaying and exhibiting dramatic antibacterial activity cooperating with H2O2

    NASA Astrophysics Data System (ADS)

    Miao, Hong; Zhong, Dan; Zhou, Zinan; Yang, Xiaoming

    2015-11-01

    Herein, papain-functionalized Cu nanoclusters (CuNCs@Papain) were originally synthesized in aqueous solution together with a quantum yield of 14.3%, and showed obviously red fluorescence at 620 nm. Meanwhile, their corresponding fluorescence mechanism was fully elucidated by fluorescence spectroscopy, HR-TEM, FTIR spectroscopy, and XPS. Subsequently, the as-prepared CuNCs were employed as probes for detecting H2O2. Using CuNCs as probes, H2O2 was determined in the range from 1 ?M to 50 ?M based on a linear decrease of fluorescence intensity as well as a detection limit of 0.2 ?M with a signal-to-noise ratio of 3. More significantly, it has been proved that CuNCs could convert H2O2 to &z.rad;OH, which exhibited dramatic antibacterial activity. Both in vitro and in vivo experiments were performed to validate their antibacterial activity against Gram-positive/negative bacteria and actual wound infection, suggesting their potential for serving as one type of promising antibacterial material.Herein, papain-functionalized Cu nanoclusters (CuNCs@Papain) were originally synthesized in aqueous solution together with a quantum yield of 14.3%, and showed obviously red fluorescence at 620 nm. Meanwhile, their corresponding fluorescence mechanism was fully elucidated by fluorescence spectroscopy, HR-TEM, FTIR spectroscopy, and XPS. Subsequently, the as-prepared CuNCs were employed as probes for detecting H2O2. Using CuNCs as probes, H2O2 was determined in the range from 1 ?M to 50 ?M based on a linear decrease of fluorescence intensity as well as a detection limit of 0.2 ?M with a signal-to-noise ratio of 3. More significantly, it has been proved that CuNCs could convert H2O2 to &z.rad;OH, which exhibited dramatic antibacterial activity. Both in vitro and in vivo experiments were performed to validate their antibacterial activity against Gram-positive/negative bacteria and actual wound infection, suggesting their potential for serving as one type of promising antibacterial material. Electronic supplementary information (ESI) available: Relevant figures. See DOI: 10.1039/c5nr05362e

  10. Fabrication of silver nanoparticles doped in the zeolite framework and antibacterial activity

    PubMed Central

    Shameli, Kamyar; Ahmad, Mansor Bin; Zargar, Mohsen; Yunus, Wan Md Zin Wan; Ibrahim, Nor Azowa

    2011-01-01

    Using the chemical reduction method, silver nanoparticles (Ag NPs) were effectively synthesized into the zeolite framework in the absence of any heat treatment. Zeolite, silver nitrate, and sodium borohydride were used as an inorganic solid support, a silver precursor, and a chemical reduction agent, respectively. Silver ions were introduced into the porous zeolite lattice by an ion-exchange path. After the reduction process, Ag NPs formed in the zeolite framework, with a mean diameter of about 2.12–3.11 nm. The most favorable experimental condition for the synthesis of Ag/zeolite nanocomposites (NCs) is described in terms of the initial concentration of AgNO3. The Ag/zeolite NCs were characterized by ultraviolet-visible spectroscopy, powder X-ray diffraction, transmission electron microscopy, scanning electron microscopy, energy dispersive X-ray fluorescence, and Fourier transform infrared. The results show that Ag NPs form a spherical shape with uniform homogeneity in the particle size. The antibacterial activity of Ag NPs in zeolites was investigated against Gram-negative bacteria (ie, Escherichia coli and Shigella dysentriae) and Gram-positive bacteria (ie, Staphylococcus aureus and methicillin-resistant Staphylococcus aureus) by disk diffusion method using Mueller–Hinton agar at different sizes of Ag NPs. All of the synthesized Ag/zeolite NCs were found to have antibacterial activity. These results show that Ag NPs in the zeolite framework can be useful in different biological research and biomedical applications. PMID:21383858

  11. Silver Nanoparticles Stabilized Using Chitosan Films: Preparation, Properties and Antibacterial Activity.

    PubMed

    Kolarova, K; Vosmanska, V; Rimpelova, S; Ulbrich, P; Svorcik, V

    2015-12-01

    In this work we present silver nanoparticles coated with chitosan films synthesized by a simple, environmentally friendly method. Silver nanoparticles were prepared and stabilized by reduction of silver nitrate with chitosan without addition of harmful reduction agents. The presence of silver nanoparticles in the solid films was studied by the X-ray diffraction spectroscopy and X-ray photoelectron spectroscopy. Solid films were dissolved and the solution was observed by the ultraviolet-visible spectroscopy and transmission electron microscopy. The amount of silver in the solid samples was studied by atomic absorption spectroscopy. Antibacterial activity of solid films with silver nanoparticles was tested by disc test on two bacterial strains, Gram-positive Staphylococcus epidermidis and Gram-negative Escherichia coli. The presence of silver nanoparticles was confirmed both in solid film and in solution by the above mentioned methods. The films exhibited strong antibacterial activity against both bacterial strains. These films could be used as a wound dressing, antimicrobial packaging material or for long-term storage of silver nanoparticles for various applications. PMID:26682457

  12. Baseline activity of telavancin against Gram-positive clinical isolates responsible for documented infections in U.S. hospitals (2011-2012) as determined by the revised susceptibility testing method.

    PubMed

    Mendes, Rodrigo E; Farrell, David J; Sader, Helio S; Flamm, Robert K; Jones, Ronald N

    2015-01-01

    Telavancin had MIC50 and MIC90 values of 0.03 and 0.06 ?g/ml (100.0% susceptible), respectively, against methicillin-resistant and -susceptible Staphylococcus aureus. Telavancin was active against vancomycin-susceptible Enterococcus faecalis (MIC50/90, 0.12/0.12 ?g/ml; 100% susceptible) and Enterococcus faecium (MIC50/90, 0.03/0.06 ?g/ml), while higher MIC values were obtained against vancomycin-resistant E. faecium (MIC50/90, 1/2 ?g/ml) and E. faecalis (MIC50/90, >2/>2 ?g/ml). Streptococci showed telavancin modal MIC results of ? 0.015 ?g/ml, except against Streptococcus agalactiae (i.e., 0.03 ?g/ml). This study reestablishes the telavancin spectrum of activity against isolates recovered from the United States (2011-2012) using the revised broth microdilution method. PMID:25348529

  13. Anthemis wiedemanniana essential oil prevents LPS-induced production of NO in RAW 264.7 macrophages and exerts antiproliferative and antibacterial activities in vitro.

    PubMed

    Conforti, Filomena; Menichini, Federica; Formisano, Carmen; Rigano, Daniela; Senatore, Felice; Bruno, Maurizio; Rosselli, Sergio; Celik, Sezgin

    2012-01-01

    Anthemis wiedemanniana is known in folk medicine for the treatment of microbial infections, cancer and also urinary and pulmonary problems. In this study, the chemical composition of the essential oil from A. wiedemanniana was evaluated and its antibacterial activity was tested against 10 bacterial strains. The oil was also tested for its potentiality to inhibit nitric oxide production in RAW 264.7 macrophages and for its cytotoxicity against four human cancer cell lines. A. wiedemanniana oil, rich of oxygenated monoterpenes (25.4%), showed a good antibacterial activity against Gram-positive bacteria and a good activity against the two Gram-negative bacteria, Escherichia coli and Proteus vulgaris. Besides that, it exhibited a high inhibitory effect on the LPS-induced nitrite production and a strong cytotoxic activity, especially against amelanotic melanoma (C32) and large lung cell carcinoma (COR-L23) cell lines. PMID:22124231

  14. Evaluation of Antibacterial Activity, Phytochemical Constituents, and Cytotoxicity Effects of Thai Household Ancient Remedies

    PubMed Central

    Sinvaraphan, Naruephan; Chaipak, Ploypailin; Luxsananuwong, Atita; Voravuthikunchai, Supayang Piyawan

    2014-01-01

    Abstract Aim: Household ancient remedies reported here are described in the National List of Essential Medicines and have traditionally been used in Thailand to treat infection-related ailments. However, the safety and effectiveness of these remedies have been poorly evaluated. The aim of this study was to evaluate the antibacterial properties of these remedies against seven gram-positive and gram-negative multidrug-resistant bacteria species. Phytochemical constituents and cytotoxicity of these remedies were also determined. Methods: Seven remedies, consisting of Um-Ma-Luk-Ka-Wa-Tee, Chan-Ta-Lee-La, Kheaw-Hom, Learng-Pid-Sa-Mud, Pra-Sa-Chan-Dang, Dhart-Ban-Chob, and Tree-Hom, were prepared by a licensed traditional medical doctor using a mixture of medicinal plants. Antibacterial activity of ethanol extracts of the remedies was determined by using a broth microdilution method. Qualitative phytochemical screening analysis was carried out to identify the presence of major components. Cytotoxicity activities of the extracts against Vero cells were assessed by green fluorescent protein–based assay. Results: With the exception of Dhart-Ban-Chob extract, significant minimum inhibitory concentrations (MICs) of <16 to 32??g/mL were observed for the remedy extracts depending on the bacterial strains. The Um-Ma-Luk-Ka-Wa-Tee extract was noncytotoxic against Vero cells and possessed the highest activity, with MICs of <16 to 31??g/mL against all methicillin-resistant Staphylococcus aureus isolates. Conclusions: Remarkable antibacterial activities against multidrug-resistant pathogens, as well as low toxicity on Vero cells, of Um-Ma-Luk-Ka-Wa-Tee support the use of this remedy in traditional medicine. Further investigation on other biological activities related to traditional applications, appropriate biomarkers, and treatment mechanisms of the household remedy are required. PMID:25415453

  15. Bis-phosphonium salts of pyridoxine: the relationship between structure and antibacterial activity.

    PubMed

    Pugachev, Mikhail V; Shtyrlin, Nikita V; Sapozhnikov, Sergey V; Sysoeva, Lubov P; Iksanova, Alfiya G; Nikitina, Elena V; Musin, Rashid Z; Lodochnikova, Olga A; Berdnikov, Eugeny A; Shtyrlin, Yurii G

    2013-12-01

    A series of 23 novel bis-phosphonium salts based on pyridoxine were synthesized and their antibacterial activities were evaluated in vitro. All compounds were inactive against gram-negative bacteria and exhibited the structure-dependent activity against gram-positive bacteria. The antibacterial activity enhanced with the increase in chain length at acetal carbon atom in the order n-Pr>Et>Me. Further increasing of length and branching of alkyl chain leads to the reduction of antibacterial activity. Replacement of the phenyl substituents at the phosphorus atoms in 5,6-bis(triphenylphosphonio(methyl))-2,2,8-trimethyl-4H-[1,3]-dioxino[4,5-c]pyridine dichloride (compound 1) with n-butyl, m-tolyl or p-tolyl as well as chloride anions in the compound 1 with bromides (compound 14a) increased the activity against Staphylococcus aureus and Staphylococcus epidermidis up to 5 times (MICs=1-1.25 ?g/ml). But in practically all cases chemical modifications of compound 1 led to the increase of its toxicity for HEK-293 cells. The only exception is compound 5,6-bis[tributylphosphonio(methyl)]-2,2,8-trimethyl-4H-[1,3]dioxino[4,5-c]pyridine dichloride (10a) which demonstrated lower MIC values against S. aureus and S. epidermidis (1 ?g/ml) and lower cytotoxicity on HEK-293 cells (CC(50)=200 ?g/ml). Compound 10a had no significant mutagenic and genotoxic effects and was selected for further evaluation. It should be noted that all bis-phosphonium salt based on pyridoxine were much more toxic than vancomycin. PMID:24139168

  16. Green synthesis of silk sericin-capped silver nanoparticles and their potent anti-bacterial activity

    PubMed Central

    2014-01-01

    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. PMID:24533676

  17. Electrodeposition, characterization, and antibacterial activity of zinc/silver particle composite coatings

    NASA Astrophysics Data System (ADS)

    Reyes-Vidal, Y.; Suarez-Rojas, R.; Ruiz, C.; Torres, J.; ??lu, ?tefan; Méndez, Alia; Trejo, G.

    2015-07-01

    Composite coatings consisting of zinc and silver particles (Zn/AgPs) with antibacterial activity were prepared using an electrodeposition technique. The morphology, composition, and structure of the Zn/AgPs composite coatings were analyzed using scanning electron microscopy (SEM) coupled with energy-dispersive spectroscopy (EDS), inductively coupled plasma (ICP) spectrometry, and X-ray diffraction (XRD). The antibacterial properties of the coatings against the microorganisms Escherichia coli as a model Gram-negative bacterium and Staphylococcus aureus as a model Gram-positive bacterium were studied quantitatively and qualitatively. The results revealed that the dispersant cetyltrimethylammonium bromide (CTAB) assisted in the formation of a stable suspension of Ag particles in the electrolytic bath for 24 h. Likewise, a high concentration of CTAB in the electrolytic bath promoted an increase in the number of Ag particles occluded in the Zn/AgPs coatings. The Zn/AgPs coatings that were obtained were compact, smooth, and shiny materials. Antimicrobial tests performed on the Zn/AgPs coatings revealed that the inhibition of bacterial growth after 30 min of contact time was between 91% and 98% when the AgPs content ranged from 4.3 to 14.0 mg cm-3.

  18. Chemical composition and antibacterial and cytotoxic activities of Allium hirtifolium Boiss.

    PubMed

    Ismail, Salmiah; Jalilian, Farid Azizi; Talebpour, Amir Hossein; Zargar, Mohsen; Shameli, Kamyar; Sekawi, Zamberi; Jahanshiri, Fatemeh

    2013-01-01

    Allium hirtifolium Boiss. known as Persian shallot, is a spice used as a traditional medicine in Iran and, Mediterranean region. In this study, the chemical composition of the hydromethanolic extract of this plant was analyzed using GC/MS. The result showed that 9-hexadecenoic acid, 11,14-eicosadienoic acid, and n-hexadecanoic acid are the main constituents. The antibacterial activity of the shallot extract was also examined by disk diffusion and microdilution broth assays. It was demonstrated that Persian shallot hydromethanolic extract was effective against 10 different species of pathogenic bacteria including methicillin resistant Staphylococcus aureus (MRSA), methicillin sensitive Staphylococcus aureus (MSSA), Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pneumoniae, Escherichia coli, Escherichia coli O157:H7, Salmonella typhimurium, Proteus mirabilis, and Klebsiella pneumoniae. Specifically, the minimum concentration of the extract which inhibited bacterial growth (MIC values) was 1.88?mg/mL for most of the gram-positive bacteria. This concentration was not much different from the concentration that was safe for mammalian cells (1.50 mg/mL) suggesting that the hydromethanolic extract of Persian shallot may be a safe and strong antibacterial agent. PMID:23484141

  19. 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.

  20. Synthesis and characterization of dextran-capped silver nanoparticles with enhanced antibacterial activity.

    PubMed

    Yang, Guili; Lin, Qiuxia; Wang, Chunren; Li, Junjie; Wang, Jian; Zhou, Jin; Wang, Yan; Wang, Changyong

    2012-05-01

    Dextran-capped silver nanoparticles were synthesized by reducing silver nitrate with NaBH4 in the presence of dextran as capping agent. The characters of silver nanoparticles were investigated using UV-Vis spectrophotometer, nano-grainsize analyzer, X-ray diffraction, and transmission electron microscopy. Results showed that the silver nanoparticles capped with dextran were in uniform shape and narrow size distribution. Moreover, compared with polyvinylpyrrolidone (PVP)-capped silver nanoparticles, the dextran-capped ones possessed better stability. Antibacterial tests of these silver nanoparticles were carried out for Escherichia coli, Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa, and Klebsiella pneumoniae. Results suggested that the dextran-capped silver nanoparticles had high antibacterial activity against both Gram-positive and Gram-negative bacteria. In addition, the cytotoxicity in vitro of the dextran-capped silver nanoparticles was investigated using mouse fibrosarcoma cells (L929). The toxicity was evaluated by the changes of cell morphology and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide assay. Results indicated that these silver nanoparticles had slight effect on the survival and proliferation of L-929 cells at their minimal inhibitory concentration (MIC). After modified by dextran, the physiochemical properties of the silver nanoparticles had been improved. We anticipated that these dextran-capped silver nanoparticles could be integrated into systems for biological and pharmaceutical applications. PMID:22852305

  1. Chemical composition, antibacterial activity, and mechanism of action of the essential oil from Amomum kravanh.

    PubMed

    Diao, Wen-Rui; Zhang, Liang-Liang; Feng, Sai-Sai; Xu, Jian-Guo

    2014-10-01

    Amomum kravanh is widely cultivated and used as a culinary spice. In this work, the chemical composition of the essential oil obtained by hydrodistillation of A. kravanh fruits was analyzed by gas chromatography-mass spectrometry, and 34 components were identified. 1,8-Cineole (68.42%) was found to be the major component, followed by ?-pinene (5.71%), ?-terpinene (2.63%), and ?-pinene (2.41%). The results of antibacterial tests showed that the sensitivities to the essential oil of different foodborne pathogens tested were different based on the Oxford cup method, MIC, and MBC assays, and the essential oil exhibited the best antibacterial activity against Bacillus subtilis, a gram-positive bacterium, and Escherichia coli, a gram-negative bacterium. Growth in the presence of Amomum kravanh at the MIC, as measured by monitoring optical density over time, demonstrated that the essential oil was bacteriostatic after 12 h to both B. subtilis and E. coli. Observations of cell membrane permeability, cell constituent release assay, and transmission electron microscopy indicated that this essential oil may disrupt the cell wall and cell membrane permeability, leading to leakage of intracellular constituents in both B. subtilis and E. coli. PMID:25285491

  2. A versatile effect of chitosan-silver nanocomposite for surface plasmonic photocatalytic and antibacterial activity.

    PubMed

    Nithya, Arjunan; JeevaKumari, Henry Linda; Rokesh, Karuppannan; Ruckmani, Kandasamy; Jeganathan, Kulandaivel; Jothivenkatachalam, Kandasamy

    2015-12-01

    Chitosan-silver (CS-Ag) nanocomposite was green synthesised without the aid of any external chemical-reducing agents. The synthesised nanocomposite was characterised by UV-visible spectroscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), thermo-gravimetric analysis (TGA), differential scanning calorimetry (DSC), field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDX), atomic force microscopy (AFM), high-resolution transmission electron microscopy (HR-TEM) with selected area electron diffraction (SAED), X-ray photoelectron spectroscopy (XPS), and zeta potential analyser. The particle size of the synthesised CS-Ag nanocomposite was around 20nm and was found to be thermally stable in comparison with pure chitosan. The prepared nanocomposite acts as a photocatalyst for dye decolourisation, with a maximum of 81% of methyl orange (MO) decolourisation that occurred under visible light irradiation. The kinetics was found to follow pseudo-first-order according to Langmuir-Hinshelwood (L-H) model. The nanocomposite also proved to be an excellent antimicrobial agent against both Gram-positive and Gram-negative bacteria, possessing a broad spectrum of antimicrobial activity. The zone of inhibition ranged between 16.000±1.000 and 19.333±1.155 (mm), proving its high susceptibility than chitosan itself. The minimum inhibitory concentration (MIC) values were from 8 to 64?g/mL, whereas the minimum bactericidal concentration (MBC) values ranged from 16 to 128?g/mL, with the highest antibacterial activity shown against Gram-positive Staphlococcus aureus. This report illustrates the eco-friendly approach for the reduction of silver using chitosan as a reducing agent, and its potential to dye decay and microbial contaminants. PMID:26562805

  3. Antibacterial and antifungal activities of polyketide metabolite from marine Streptomyces sp. AP-123 and its cytotoxic effect.

    PubMed

    Arasu, Mariadhas Valan; Duraipandiyan, Veeramuthu; Ignacimuthu, Savarimuthu

    2013-01-01

    A Gram positive, filamentous, spore forming antagonistic Streptomyces sp. AP-123 derived from marine region of Andra Pradesh, India, was studied for its medical importance. Among the 210 Streptomyces strains screened at 64.3% exhibited activity against Gram positive bacteria, 48.5% showed activity towards Gram negative bacteria, 38.8% exhibited both Gram positive and negative bacteria and 80.85% strains revealed significant antifungal activity. However, primary screening revealed that Streptomyces sp. AP-123 exhibited significant antimicrobial activity against all the tested bacteria compared to other Streptomyces strains. The presence of l-diaminopimelic acid and glycine in the cell wall hydrolysates and streptomycin resistance indicated the strain belonged to Streptomyces genus. The 16S rDNA gene based phylogenetic affiliation was determined by using bioinformatic tools and it was identified as Streptomyces sp. AP-123 with 99% sequence similarity to Streptomyces flavogriseus. The antimicrobial substances were extracted by hexane and ethyl acetate from spent medium in which Streptomyces sp. AP-123 was cultivated at 30 °C for 5 d. The antimicrobial activity was assessed using broth micro-dilution technique. A compound was obtained by eluting the crude extract using varying concentrations of solvents followed by the chromatographic purification. Based on the IR, (13)C NMR and (1)H NMR spectral data, the compound was identified as polyketide related antibiotic. It exhibited significant antibacterial activity against Gram positive and Gram negative bacteria and also showed a potent cytotoxic activity against cell lines viz. Vero (Green monkey kidney) and HEP2 (laryngeal carcinoma cells) in vitro. The lowest Minimum Inhibitory Concentration (MIC) of the compound against Bacillus subtilis and Staphylococcus aureus were 25 and 37.5 ?g mL(-1), respectively. Against Escherichia coli and Pseudomonas aeruginosa it exhibited MIC of 50 and 37.58 ?g mL(-1), respectively. However, against Candida albicans and filamentous fungus, Aspergillus niger the MIC values were 12.5 and 25 ?g mL(-1), respectively. Cloning and sequence analysis of ketoacyl synthase (KS) gene revealed similarity to the type II polyketide synthase (PKS) gene of Streptomyces species. PMID:22963878

  4. Synthesis, Antibacterial and Antitubercular Activities of Some 5H-Thiazolo[3,2-a]pyrimidin-5-ones and Sulfonic Acid Derivatives.

    PubMed

    Cai, Dong; Zhang, Zhi-Hua; Chen, Yu; Yan, Xin-Jia; Zou, Liang-Jing; Wang, Ya-Xin; Liu, Xue-Qi

    2015-01-01

    A series of 5H-thiazolo[3,2-a]pyrimidin-5-ones were synthesized by the cyclization reactions of S-alkylated derivatives in concentrated H?SO?. Upon treatment of S-alkylated derivatives at different temperatures, intramolecular cyclization to 7-(substituted phenylamino)-5H-thiazolo[3,2-a]pyrimidin-5-ones or sulfonation of cyclized products to sulfonic acid derivatives occurred. The structures of the target compounds were confirmed by IR, ¹H-NMR, (13)C-NMR and HRMS studies. The compounds were evaluated for their preliminary in vitro antibacterial activity against some Gram-positive and Gram-negative bacteria and screened for antitubercular activity against Mycobacterium tuberculosis by the broth dilution assay method. Some compounds showed good antibacterial and antitubercular activities. PMID:26378507

  5. Chemical composition and in vitro antioxidant and antibacterial activity of Heracleum transcaucasicum and Heracleum anisactis roots essential oil

    PubMed Central

    Torbati, Mohammadali; Nazemiyeh, Hossein; Lotfipour, Farzaneh; Nemati, Mahboob; Asnaashari, Solmaz; Fathiazad, Fatemeh

    2014-01-01

    Introduction: In vitro antioxidant and antibacterial activity and volatile compositions of two Heracleum species (Apiaceae) including Heracleum transcaucasicum and Heracleum anisactis roots Essential Oil (EO) were investigated. Methods: The volatile compositions of EOs were analyzed by GC/Mass spectroscopy. To detect the antioxidant activity of essential oils TLC-bioautography and DPPH radical scavenging assay by spectrophotometry was performed. Additionally, the antibacterial activity of two essential oils were studied and compared against four pathogenic bacteria by agar disc diffusion method and MIC values of the EOs were determined using the broth dilution method. Results: Myristicin was the dominant component in both EOs. It was identified as 96.87% and 95.15% of the essential oil composition of H. transcaucasicum and H. anisactis roots, respectively. The TLC-bioautography showed antioxidant spots in both EOs and IC50 of H. anisactis and H. transcaucasicum EO was found to be 54 ?g × ml (-1) and 77 ?g × ml (-1), respectively. Regarding the antimicrobial assay, H. anisactis EO exhibited weak to moderate antibacterial activity against gram-positive bacteria and also Escherichia coli, whereas the essential oil from H. transcaucasicum was inactive. Conclusion: Based on the results from this study, both tested EOs mainly consist of myristicin. Despite the presence of myristicin with known antibacterial property, the EO from H. transcacausicum showed no antibacterial activity. Thus it is supposed that the biological activity of plants is remarkably linked to the extracts’ chemical profile and intercomponents’ synergistic or antagonistic effect could play a crucial role in bioactivity of EOs and other plant extracts. PMID:25035849

  6. Antioxidant and antibacterial activities of bark extracts from Commiphora berryi and Commiphora caudata.

    PubMed

    Kumari, Ramesh; Meyyappan, Arumugam; Nandi, Debkumar; Agrawalla, Bikram Keshari; Chowdhury, Avik Acharya; Selvamani, Palanisamy; Latha, Subbaiah; Giri, Venkatachalam Sesha; Mukherjee, Joydeep; Bandyopadhyay, Santu; Jaisankar, Parasuraman

    2011-09-01

    This study investigates the in vitro antioxidant and antimicrobial activities of eight extracts obtained from the dried barks of Commiphora berryi and Commiphora caudata (Burseraceae). The radical scavenging activity was assessed by 1,1-diphenyl-2-picryl hydrazyl (DPPH) and nitric oxide assays. The methanolic extracts of C. berryi and C. caudata showed significant DPPH radical scavenging activity, with IC?? values of 26.92 and 21.16?µg?mL?¹, respectively, and low radical scavenging activity against the nitric oxide assay. The antimicrobial activity of the plants was tested against the Gram-positive and Gram-negative bacteria. The ethyl acetate, chloroform and petroleum ether extracts of C. berryi showed good antibacterial activity against Pseudomonas aeruginosa, with a minimum inhibitory concentration (MIC) of 0.26?mg?mL?¹, whereas the ethyl acetate and methanol extracts of C. caudata showed moderate antimicrobial activity with an MIC of more than 2.0?mg?mL?¹ against P. aeruginosa compared to the petroleum ether and chloroform extracts, which showed an MIC of 1.1?mg?mL?¹. The methanolic extracts of C. berryi and C. caudata also showed moderate cytotoxic activity against a human mammary carcinoma cell line (MCF-7), with values IC?? of 82.6 and 88.4?µg?mL?¹, respectively. PMID:21416452

  7. Glucosamine sulfate--environmental antibacterial activity.

    PubMed

    Rozin, Alexander P

    2009-10-01

    We have recently showed antibacterial activity against E. coli in vitro of a trademark Mega-Gluflex-containing glucosamine sulfate (GS) and chondroitin sulfate (CS). The purpose of this study was to examine the antibacterial activity of GS as a new trademark Arthryl (Manufacturer Rottapharm Ltd, Ireland; Distributor in Israel Rafa Laboratories Ltd) in vitro. We used cabbage and chicken broths and milk (every media of 20 ml) left opened for 1 week with and without Arthryl supplements 1,500 mg, the content of one package of the medication. A similar volume (20 ml) is ingested in taking the medication. Experiments with three repeatable results were taken for consideration. Arthryl inhibited environmental bacterial colonies' growth in every media but fungi growth was not impaired. Milk stayed liquid for the whole week with supplement of the Arthryl compared with sour milk transformation without Arthryl. Sample B showed inhibitory properties of the bacterial colonies on the fungi growth. The sample with Arthryl showed progressive growth of fungi without bacterial growth after 10 days of follow up compared with bacterial growth on media without Arthryl. Glucosamine sulfate as a new trademark Arthryl has environmental antibacterial properties but does not inhibit growth of fungal colonies. PMID:19495827

  8. Green Synthesis of Silver Nanoparticles, Their Characterization, Application and Antibacterial Activity

    PubMed Central

    Okafor, Florence; Janen, Afef; Kukhtareva, Tatiana; Edwards, Vernessa; Curley, Michael

    2013-01-01

    Our research focused on the production, characterization and application of silver nanoparticles (AgNPs), which can be utilized in biomedical research and environmental cleaning applications. We used an environmentally friendly extracellular biosynthetic technique for the production of the AgNPs. The reducing agents used to produce the nanoparticles were from aqueous extracts made from the leaves of various plants. Synthesis of colloidal AgNPs was monitored by UV-Visible spectroscopy. The UV-Visible spectrum showed a peak between 417 and 425 nm corresponding to the Plasmon absorbance of the AgNPs. The characterization of the AgNPs such as their size and shape was performed by Atom Force Microscopy (AFM), and Transmission Electron Microscopy (TEM) techniques which indicated a size range of 3 to 15 nm. The anti-bacterial activity of AgNPs was investigated at concentrations between 2 and 15 ppm for Gram-negative and Gram-positive bacteria. Staphylococcus aureus and Kocuria rhizophila, Bacillus thuringiensis (Gram-positive organisms); Escherichia coli, Pseudomonas aeruginosa, and Salmonella typhimurium (Gram-negative organisms) were exposed to AgNPs using Bioscreen C. The results indicated that AgNPs at a concentration of 2 and 4 ppm, inhibited bacterial growth. Preliminary evaluation of cytotoxicity of biosynthesized silver nanoparticles was accomplished using the InQ™ Cell Research System instrument with HEK 293 cells. This investigation demonstrated that silver nanoparticles with a concentration of 2 ppm and 4 ppm were not toxic for human healthy cells, but inhibit bacterial growth. PMID:24157517

  9. Green synthesis of silver nanoparticles, their characterization, application and antibacterial activity.

    PubMed

    Okafor, Florence; Janen, Afef; Kukhtareva, Tatiana; Edwards, Vernessa; Curley, Michael

    2013-10-01

    Our research focused on the production, characterization and application of silver nanoparticles (AgNPs), which can be utilized in biomedical research and environmental cleaning applications. We used an environmentally friendly extracellular biosynthetic technique for the production of the AgNPs. The reducing agents used to produce the nanoparticles were from aqueous extracts made from the leaves of various plants. Synthesis of colloidal AgNPs was monitored by UV-Visible spectroscopy. The UV-Visible spectrum showed a peak between 417 and 425 nm corresponding to the Plasmon absorbance of the AgNPs. The characterization of the AgNPs such as their size and shape was performed by Atom Force Microscopy (AFM), and Transmission Electron Microscopy (TEM) techniques which indicated a size range of 3 to 15 nm. The anti-bacterial activity of AgNPs was investigated at concentrations between 2 and 15 ppm for Gram-negative and Gram-positive bacteria. Staphylococcus aureus and Kocuria rhizophila, Bacillus thuringiensis (Gram-positive organisms); Escherichia coli, Pseudomonas aeruginosa, and Salmonella typhimurium (Gram-negative organisms) were exposed to AgNPs using Bioscreen C. The results indicated that AgNPs at a concentration of 2 and 4 ppm, inhibited bacterial growth. Preliminary evaluation of cytotoxicity of biosynthesized silver nanoparticles was accomplished using the InQ™ Cell Research System instrument with HEK 293 cells. This investigation demonstrated that silver nanoparticles with a concentration of 2 ppm and 4 ppm were not toxic for human healthy cells, but inhibit bacterial growth. PMID:24157517

  10. Antibacterial and Antifungal Activities of Stereum ostrea, an Inedible Wild Mushroom

    PubMed Central

    Imtiaj, Ahmed; Jayasinghe, Chandana; Lee, Geon Woo

    2007-01-01

    Antibacterial and antifungal activities of liquid culture filtrate, water and ethanol extract (solid culture) of Stereum ostrea were evaluated against 5 bacteria and 3 plant pathogenic fungi. To determine the minimal inhibitory concentration (MIC), we studied 5~300 mg/ml concentrations against bacteria and fungi separately. The MIC was 10 mg/ml for Bacillus subtilis and 40 mg/ml for Colletotrichum gloeosporioides and Colletotrichum miyabeanus. Liquid culture filtrate was more effective against Gram positive than Gram negative bacteria, and Staphylococcus aureus was the most inhibited (20.3 mm) bacterium. Water and ethanol extracts were effective against both Gram positive and Gram negative bacteria, and water extract was better than ethanol extract. In water and ethanol extract, inhibition zones were 23.6 and 21.0 mm (S. aureus) and 26.3 and 22.3 mm (Pseudomonas aeruginosa), respectively. For plant pathogenic fungi, the highest and lowest percent inhibition of mycelial growth (PIMG) was found 82.8 and 14.4 against C. miyabeanus and Botrytis cinerea in liquid culture filtrate, respectively. In water extract, the PIMG was found to be the highest 85.2 and lowest 41.7 for C. miyabeanus and C. gloeosporioides, respectively. The inhibitory effect of ethanol extract was better against C. miyabeanus than C. gloeosporioides and B. cinerea. Among 3 samples, water extract was the best against tested pathogenic fungi. This study offers that the extracts isolated from S. ostrea contain potential compounds which inhibit the growth of both bacteria and fungi. PMID:24015099

  11. Decade-long use of the antimicrobial peptide combination tyrothricin does not pose a major risk of acquired resistance with gram-positive bacteria and Candida spp.

    PubMed

    Stauss-Grabo, M; Atiye, S; Le, T; Kretschmar, M

    2014-11-01

    Tyrothricin, an antimicrobial peptide combination produced by Bacillus brevis consisting of gramicidins and tyrocidins commands broad antimicrobial activity against gram-positive bacteria and some yeasts in vitro. The polypeptide and its components have been used therapeutically for about 60 years in the local treatment of infected skin and infected oro-pharyngeal mucous membranes. Though older studies suggest that resistance development of originally susceptible microorganisms towards tyrothricin is a rare event, data concerning recent state of resistance are lacking. In the present in vitro study the susceptibility to tyrothricin of clinical isolates of bacterial and yeast origin from superficial swabs of the skin and mucous membranes of outpatients and inpatients obtained from clinical material in the second half of the year 2003 was determined. Using a microdilution assay, the minimum inhibitory concentration (MIC and MIC90, defined as the concentration that inhibits at least 90 percent of the tested strains) of 20 strains each of Staphylococcus aureus of the variety MSSA (susceptible to methicillin), Staphylococcus aureus of the variety MRSA (methicillin resistant), Staphylococcus haemolyticus, Streptococcus pyogenes, Enterococcus faecalis, Corynebacterium spec., Candida albicans and Candida parapsilosis was determined. All of the tested gram-positive bacteria turned out to be highly susceptible to tyrothricin with MICs ? 4mg/l. The tested yeast strains were susceptible to the polypeptide antibiotic as well, but (with MICs of 16 mg/l and 32 mg/l, respectively) to a lesser extent. No acquired resistance of the tested strains was determined, indicating that the risk of resistance development against topically applied tyrothricin is only marginal, if there is any at all. Thus, long-term-, i.e. decade-long use of topically applied tyrothricin and its components in the local treatment of infected skin does not pose a major risk with respect to acquired resistance of originally susceptible gram-positive bacteria and yeasts, not even in the case of Staphylococcus aureus, both with MSSA and MRSA strains. The broad anti-bacterial and anti-fungal activity of tyrothricin combined with its lacking risk for resistance development make the antimicrobial peptide a valuable addition to our therapeutic armamentarium in the treatment of infected skin. PMID:25985581

  12. Chemical composition and antibacterial activity of the essential oil from green huajiao (Zanthoxylum schinifolium) against selected foodborne pathogens.

    PubMed

    Diao, Wen-Rui; Hu, Qing-Ping; Feng, Sai-Sai; Li, Wei-Qin; Xu, Jian-Guo

    2013-06-26

    Green huajiao, which is the ripe pericarp of the fruit of Zanthoxylum schinifolium Sieb. et Zucc, is widely consumed in Asia as a spice. In this work, the chemical composition of the essential oil from green huajiao was analyzed by gas chromatography (GC) and GC/mass spectrometry (MS), and the majority of components were identified. Linalool (28.2%), limonene (13.2%), and sabinene (12.1%) were found to be the major components. The antibacterial activity, minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC) of the essential oil were evaluated against selected bacteria, including food-borne pathogens. The results showed that the sensitivities to the essential oil were different for different bacteria tested, and the susceptibility of Gram-positive bacteria tested was observed to be greater than that of Gram-negative bacteria. The antibacterial activity of the essential oil was particularly strong against Staphylococcus epidermidis , with MIC and MBC values of 2.5 and 5.0 mg/mL, respectively. A postcontact effect assay also confirmed the essential oil had a significant effect on the growth rate of surviving S. epidermidis . The antibacterial activity of the essential oil from green huajiao may be due to the increase in permeability of cell membranes, and the leakage of intracellular constituents, on the basis of the cell constituents' release assay and electron microscopy observations. PMID:23758080

  13. Ethnobotany and antibacterial activity of some plants used in traditional medicine of Zapotitlán de las Salinas, Puebla (México).

    PubMed

    Hernández, T; Canales, M; Avila, J G; Duran, A; Caballero, J; Romo de Vivar, A; Lira, R

    2003-10-01

    The village of Zapotitlán de las Salinas is situated in the Valley of Tehuacán-Cuicatlán, Puebla, Mexico. Plant species used by the local inhabitants to treat gastrointestinal diseases were identified using ethnobotanical, ethnographic and taxonomic methods. Out of 119 interviews, 44 plant species were registered, of which the following are the most frequently used (listed in descending order): Lippia graveolens H.B. et K. (Verbenaceae), Lantana achyranthifolia Desf. (Verbenaceae), Turnera diffusa (Willd.) ex Schult. (Turneraceae), Lippia oaxacana Rob. et Greenm. (Verbenaceae), Gymnolaena oaxacana (Greenm.) Rydb. (Asteraceae), Cordia curassavica (Jacq.) Roem. et Schult. (Boraginaceae), Lantana camara L. (Verbenaceae) and Acalypha hederacea Torrey (Euphorbiaceae). From these plants, hexane, chloroform and ethanol extracts were prepared in order to assess their antibacterial activity against 14 bacterial strains causing the most common gastrointestinal diseases in Mexican population. All hexane extracts showed antibacterial activity against Gram-positive and Gram-negative bacteria. There is a correlation between the frequency of mention (of plant use) and the antibacterial activity. In conclusion, the knowledge of plants most frequently used for gastrointestinal infections in Zapotitlán de las Salinas is supported by scientific rationale. PMID:12963140

  14. Teicoplanin or vancomycin in the treatment of gram-positive infections?

    PubMed

    Murphy, S; Pinney, R J

    1995-02-01

    The glycopeptide antibiotics vancomycin and teicoplanin have similar mechanisms of action on bacterial cell wall synthesis. Their spectra of activity are limited to Gram-positive bacteria, with the degree of bactericidal activity depending on the species of micro-organism. Staphylococcus aureus, Staphylococcus epidermis, enterococci and Clostridium difficile are generally sensitive, including methicillin-resistant strains of S. aureus and S. epidermidis. Glycopeptide resistance has recently emerged in staphylococci and enterococci. Vancomycin has a shorter half-life than teicoplanin and requires multiple dosing to maintain adequate serum levels. It can only be given by prolonged intravenous infusion over 1 h. In contrast, the pharmacokinetics of teicoplanin allow for once-daily dosing, either by rapid intravenous infusion or by the intramuscular route. The latter offers reliable absorption for patients with limited venous access and is also of benefit for out-patient therapy. Teicoplanin is a safer drug than vancomycin. It is associated with a lower incidence of nephrotoxicity or ototoxicity. Compared to vancomycin, the availability of the intramuscular route and the absence of a requirement for routine serum monitoring, together with the reduced need to treat drug-related side-effects make teicoplanin more cost-effective. It is as effective as vancomycin for most indications, is safe, easy to administer and an important agent for treating Gram-positive infections. Its role in hospitals is likely to increase if the price of drug acquisition is kept low. PMID:7775615

  15. Opioid Exacerbation of Gram-positive sepsis, induced by Gut Microbial Modulation, is Rescued by IL-17A Neutralization

    PubMed Central

    Meng, Jingjing; Banerjee, Santanu; Li, Dan; Sindberg, Gregory M.; Wang, Fuyuan; Ma, Jing; Roy, Sabita

    2015-01-01

    Sepsis is the predominant cause of mortality in ICUs, and opioids are the preferred analgesic in this setting. However, the role of opioids in sepsis progression has not been well characterized. The present study demonstrated that morphine alone altered the gut microbiome and selectively induced the translocation of Gram-positive gut bacteria in mice. Using a murine model of poly-microbial sepsis, we further demonstrated that morphine treatment led to predominantly Gram-positive bacterial dissemination. Activation of TLR2 by disseminated Gram-positive bacteria induced sustained up-regulation of IL-17A and IL-6. We subsequently showed that overexpression of IL-17A compromised intestinal epithelial barrier function, sustained bacterial dissemination and elevated systemic inflammation. IL-17A neutralization protected barrier integrity and improved survival in morphine-treated animals. We further demonstrated that TLR2 expressed on both dendritic cells and T cells play essential roles in IL-17A production. Additionally, intestinal sections from sepsis patients on opioids exhibit similar disruption in gut epithelial integrity, thus establishing the clinical relevance of this study. This is the first study to provide a mechanistic insight into the opioid exacerbation of sepsis and show that neutralization of IL-17A might be an effective therapeutic strategy to manage Gram-positive sepsis in patients on an opioid regimen. PMID:26039416

  16. Injectable bioadhesive hydrogels with innate antibacterial properties

    NASA Astrophysics Data System (ADS)

    Giano, Michael C.; Ibrahim, Zuhaib; Medina, Scott H.; Sarhane, Karim A.; Christensen, Joani M.; Yamada, Yuji; Brandacher, Gerald; Schneider, Joel P.

    2014-06-01

    Surgical site infections cause significant postoperative morbidity and increased healthcare costs. Bioadhesives used to fill surgical voids and support wound healing are typically devoid of antibacterial activity. Here we report novel syringe-injectable bioadhesive hydrogels with inherent antibacterial properties prepared from mixing polydextran aldehyde and branched polyethylenimine. These adhesives kill both Gram-negative and Gram-positive bacteria, while sparing human erythrocytes. An optimal composition of 2.5?wt% oxidized dextran and 6.9?wt% polyethylenimine sets within seconds forming a mechanically rigid (~\

  17. Papain-templated Cu nanoclusters: assaying and exhibiting dramatic antibacterial activity cooperating with H2O2.

    PubMed

    Miao, Hong; Zhong, Dan; Zhou, Zinan; Yang, Xiaoming

    2015-12-01

    Herein, papain-functionalized Cu nanoclusters (CuNCs@Papain) were originally synthesized in aqueous solution together with a quantum yield of 14.3%, and showed obviously red fluorescence at 620 nm. Meanwhile, their corresponding fluorescence mechanism was fully elucidated by fluorescence spectroscopy, HR-TEM, FTIR spectroscopy, and XPS. Subsequently, the as-prepared CuNCs were employed as probes for detecting H2O2. Using CuNCs as probes, H2O2 was determined in the range from 1 ?M to 50 ?M based on a linear decrease of fluorescence intensity as well as a detection limit of 0.2 ?M with a signal-to-noise ratio of 3. More significantly, it has been proved that CuNCs could convert H2O2 to ?OH, which exhibited dramatic antibacterial activity. Both in vitro and in vivo experiments were performed to validate their antibacterial activity against Gram-positive/negative bacteria and actual wound infection, suggesting their potential for serving as one type of promising antibacterial material. PMID:26514845

  18. Synthesis, characterization and magnetic properties of hematite (?-Fe2O3) nanoparticles on polysaccharide templates and their antibacterial activity

    NASA Astrophysics Data System (ADS)

    Rafi, M. Mohamed; Ahmed, K. Syed Zameer; Nazeer, K. Prem; Siva Kumar, D.; Thamilselvan, M.

    2015-04-01

    The present study is to synthesize iron oxide nanoparticles on different polysaccharide templates calcined at controlled temperature, characterizing them for spectroscopic and magnetic studies leading to evaluate their antibacterial property. The synthesized iron oxide nanoparticles were characterized by X-ray diffractometer (XRD), Fourier transform infrared spectroscopy, high resolution scanning electron microscopy (HRSEM), high resolution transmission electron microscopy (HRTEM) and vibrating sample magnetometer. The iron oxide nanoparticles were tested for antibacterial activity against gram-positive and gram-negative bacterial species. The XRD confirms the crystalline nature of iron oxide nanoparticles with the mean crystallite size of 10 nm. The functional groups of the synthesized iron oxide nanoparticles were 547, 543 and 544 cm-1 characterizing the Fe-O and the broad bands at 3,398, 3,439 and 3,427 cm-1 were attributed to the stretching vibrations of hydroxyl group absorbed by iron oxide nanoparticles. HRTEM analyses revealed that the average particle size of the hematite nanoparticles are about 85, 92 and 77 nm for AF, DF and GF, respectively, which was a coincident with the results obtained from the HRSEM analysis. Magnetic measurement exhibited ferromagnetic behavior of the ?-Fe2O3 at the room temperature with higher coercivity of H C = 2,303, 2,333 and 1,019 Oe for AF, DF and GF, respectively. Antibacterial test showed the inhibition against Aeromonas hydrophila and Escherichia coli with significant antagonistic activity.

  19. Wound-dressing materials with antibacterial activity from electrospun polyurethane-dextran nanofiber mats containing ciprofloxacin HCl.

    PubMed

    Unnithan, Afeesh R; Barakat, Nasser A M; Pichiah, P B Tirupathi; Gnanasekaran, Gopalsamy; Nirmala, R; Cha, Youn-Soo; Jung, Che-Hun; El-Newehy, Mohamed; Kim, Hak Yong

    2012-11-01

    Dextran is a versatile biomacromolecule for preparing electrospun nanofibrous membranes by blending with either water-soluble bioactive agents or hydrophobic biodegradable polymers for biomedical applications. In this study, an antibacterial electrospun scaffold was prepared by electrospinning of a solution composed of dextran, polyurethane (PU) and ciprofloxacin HCl (CipHCl) drug. The obtained nanofiber mats have good morphology. The mats were characterized by various analytical techniques. The interaction parameters between fibroblasts and the PU-dextran and PU-dextran-drug scaffolds such as viability, proliferation, and attachment were investigated. The results indicated that the cells interacted favorably with the scaffolds especially the drug-containing one. Moreover, the composite mat showed good bactericidal activity against both of Gram-positive and Gram-negative bacteria. Overall, our results conclude that the introduced scaffold might be an ideal biomaterial for wound dressing applications. PMID:22944448

  20. Antibacterial activity of metal complexes of benzil and benzoin thiosemicarbazones.

    PubMed

    Offiong, O E; Martelli, S

    1994-01-01

    The metal (II) complexes of benzyl and benzoin thiosemicarbazones have been synthesized and characterized. They were studied for their antibacterial, antifungal and amoebicidal activity in vitro and for their toxicity in vivo. The ligands and their metal complexes exhibited low antibacterial and amoebicidal activity. The metal chelates of benzoin thiosemicarbazone seem to be the most active compounds. PMID:7945719

  1. Chemical composition, olfactory analysis and antibacterial activity of Thymus vulgaris chemotypes geraniol, 4-thujanol/terpinen-4-ol, thymol and linalool cultivated in southern France.

    PubMed

    Schmidt, Erich; Wanner, Jürgen; Hiiferl, Martina; Jirovetz, Leopold; Buchbauer, Gerhard; Gochev, Velizar; Girova, Tania; Stoyanova, Albena; Geissler, Margit

    2012-08-01

    The essential oils of four chemotypes of Thymus vulgaris L. (Lamiaceae) were analyzed for their composition and antibacterial activity to assess their different properties. GC-MS and GC-FID analyses revealed that the essentials oils can be classified into the chemotypes thymol (41.0% thymol), geraniol (26.4% geraniol), linalool (72.5% linalool) and 4-thujanol/terpinen-4-ol (42.2% cis- and 7.3% trans-sabinene hydrate, 6.5 % terpinen-4-ol). The olfactory examination confirmed the explicit differences between these chemotypes. Furthermore, antibacterial activity was investigated against several strains of two Gram-positive (Brochothrix thermosphacta and Staphylococcus aureus) and four Gram-negative food-borne bacteria (Escherichia coli, Salmonella abony, Pseudomonas aeruginosa and P. fragi). All essential oil samples were demonstrated to be highly effective against Gram-positive strains, whereas the impact on Gram-negative microorganisms was significantly smaller, but still considerable. The results obtained indicate that, despite their different properties, the essential oils of selected T. vulgaris chemotypes are potent antimicrobials to be employed as useful additives in food products as well as for therapeutic applications. PMID:22978238

  2. Synthesis, electronic properties, antioxidant and antibacterial activity of some new benzimidazoles.

    PubMed

    Mavrova, Anelia Ts; Yancheva, Denitsa; Anastassova, Neda; Anichina, Kamelya; Zvezdanovic, Jelena; Djordjevic, Aleksandra; Markovic, Dejan; Smelcerovic, Andrija

    2015-10-01

    Two groups of benzimidazole derivatives were synthesized using as precursors 5(6)-substituted 2-mercapto-benzimidazol-thiols and their antioxidant activity was investigated using TBA-MDA test. In the group of 1,3-disubstituted-benzimidazol-2-imines the highest lipid peroxidation inhibition effect 74.04% (IC??=141.89 ?g/mL) revealed ethyl [3-(2-ethoxy-2-oxoethyl)-2-imino-5-benzoyl-2,3-dihydro-1H-benzimdazol-1-yl]acetate 12 while in the group of 2-substituted-1,3-thiazolo[3,2-a]benzimidazolones the highest inhibition effect showed 2-(4-fluorobenzylidene)-7-(phenylcarbonyl)[1,3]thiazolo[3,2-a]benzimidazol-3(2H)-one 17 90.76% (IC??=53.70 ?g/mL). In order to estimate the capability of the studied benzimidazoles to act as radical scavengers the structure of the most active derivative within the both subseries was optimized at B3LYP/6-311++G(??) level and the respective bond dissociation enthalpies were calculated. The appropriate models for the HAT and SET-mechanism of the antioxidant activity were proposed. The antibacterial activity of the compounds was evaluated against two Gram-positive bacteria (Bacillus subtilis ATCC 6633 and Staphylococcus aureus ATCC 6538) and three Gram-negative bacteria (Escherichia coli ATCC 8739, Pseudomonas aeruginosa ATCC 9027 and Salmonella abony NCTC 6017). 1,3-Diphenylpropyl-5-methyl-1,3-dihydro-2H-benzimidazol-2-imine 14 exhibited significant activity against B. subtilis, S. aureus, S. abony and E. coli (with MIC values of 0.125, 0.016, 0.50 and 0.50mg/mL, respectively). The group of thiazolobenzimidazolones did not reveal antibacterial activity against the tested strains. PMID:26344590

  3. In vitro Antioxidant and Antibacterial Activities of Methanol Extract of Kyllinga nemoralis.

    PubMed

    Sindhu, T; Rajamanikandan, S; Srinivasan, P

    2014-03-01

    The present study was designed to evaluate the antioxidant and antibacterial activity of methanol extract of Kyllinga nemoralis. Six different in vitro antioxidant assays including 2,2-diphenyl-1-picrylhydrazyl, hydroxyl radical, superoxide anion radical, hydrogen peroxide radical, ferric reducing antioxidant power assay and reducing power were carried out to ensure the scavenging effect of the plant on free radicals. In addition, total antioxidant capacity assay, total phenolic contents, tannins, flavonoids and flavonol contents of the plant were also analysed by the standard protocols. Kyllinga nemoralis exhibited high antioxidant activity on 2,2-diphenyl-1-picrylhydrazyl assay (IC50= 90 ?g/ml), superoxide radical scavenging assay (IC50= 180 ?g/ml) and hydrogen peroxide radical scavenging assay (IC50= 200 ?g/ml), compared with standards. These observations provide comprehensible supporting evidence for the antioxidant potential of the plant extract. Reducing power (IC50= 213.16 ?g/ml) and hydroxyl radical scavenging activity (IC50= 223 ?g/ml) of the plant extract was remarkable. The methanol extract of K. nemoralis exhibited significant antimicrobial activity against Gram-positive human pathogenic bacteria. Standard in vitro antioxidant assays assessed the electron donating ability of the plant extract in scavenging free radicals. The inhibitory effect of the plant extract against bacterial pathogens may be due to the presence of phytochemicals. Thus, the results suggest that Kyllinga nemoralis is a potential source of antioxidants and could serve as the base for drug development. PMID:24843192

  4. In vitro Antioxidant and Antibacterial Activities of Methanol Extract of Kyllinga nemoralis

    PubMed Central

    Sindhu, T.; Rajamanikandan, S.; Srinivasan, P.

    2014-01-01

    The present study was designed to evaluate the antioxidant and antibacterial activity of methanol extract of Kyllinga nemoralis. Six different in vitro antioxidant assays including 2,2-diphenyl-1-picrylhydrazyl, hydroxyl radical, superoxide anion radical, hydrogen peroxide radical, ferric reducing antioxidant power assay and reducing power were carried out to ensure the scavenging effect of the plant on free radicals. In addition, total antioxidant capacity assay, total phenolic contents, tannins, flavonoids and flavonol contents of the plant were also analysed by the standard protocols. Kyllinga nemoralis exhibited high antioxidant activity on 2,2-diphenyl-1-picrylhydrazyl assay (IC50= 90 ?g/ml), superoxide radical scavenging assay (IC50= 180 ?g/ml) and hydrogen peroxide radical scavenging assay (IC50= 200 ?g/ml), compared with standards. These observations provide comprehensible supporting evidence for the antioxidant potential of the plant extract. Reducing power (IC50= 213.16 ?g/ml) and hydroxyl radical scavenging activity (IC50= 223 ?g/ml) of the plant extract was remarkable. The methanol extract of K. nemoralis exhibited significant antimicrobial activity against Gram-positive human pathogenic bacteria. Standard in vitro antioxidant assays assessed the electron donating ability of the plant extract in scavenging free radicals. The inhibitory effect of the plant extract against bacterial pathogens may be due to the presence of phytochemicals. Thus, the results suggest that Kyllinga nemoralis is a potential source of antioxidants and could serve as the base for drug development. PMID:24843192

  5. Antibacterial activity of endophytic fungi from leaves of Indigofera suffruticosa Miller (Fabaceae)

    PubMed Central

    dos Santos, Irailton Prazeres; da Silva, Luís Cláudio Nascimento; da Silva, Márcia Vanusa; de Araújo, Janete Magali; Cavalcanti, Marilene da Silva; Lima, Vera Lucia de Menezes

    2015-01-01

    Endophytic fungi were isolated from healthy leaves of Indigofera suffruticosa Miller, a medicinal plant found in Brazil which is used in folk medicine to treat various diseases. Among 65 endophytic fungi isolated, 18 fungi showed activity against at least one tested microorganism in preliminary screening, and the best results were obtained with Nigrospora sphaerica (URM-6060) and Pestalotiopsis maculans (URM-6061). After fermentation in liquid media and in semisolid media, only N. sphaerica demonstrated antibacterial activity (in Potato Dextrose Broth-PDB and in semisolid rice culture medium). In the next step, a methanolic extract from rice culture medium (NsME) and an ethyl acetate extract (NsEAE) from the supernatant of PDB were prepared and both exhibited antimicrobial activity against Gram-negative and Gram-positive bacteria. The best result was observed against Staphylococcus aureus, with minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values of 1.56 mg/mL and 6.25 mg/mL, respectively, for NsME and MIC and MBC values of 0.39 mg/mL and 3.12 mg/mL, respectively, for NsEAE. This study is the first report about the antimicrobial activity of endophytic fungi residing in I. suffruticosa leaves, in which the fungus N. sphaerica demonstrated the ability to produce bioactive agents with pharmaceutical potential, and may provide a new lead in the pursuit of new biological sources of drug candidates. PMID:25999918

  6. Antibacterial Activity of Eravacycline (TP-434), a Novel Fluorocycline, against Hospital and Community Pathogens

    PubMed Central

    O'Brien, W.; Fyfe, C.; Grossman, T. H.

    2013-01-01

    Eravacycline (TP-434 or 7-fluoro-9-pyrrolidinoacetamido-6-demethyl-6-deoxytetracycline) is a novel fluorocycline that was evaluated for antimicrobial activity against panels of recently isolated aerobic and anaerobic Gram-negative and Gram-positive bacteria. Eravacycline showed potent broad-spectrum activity against 90% of the isolates (MIC90) in each panel at concentrations ranging from ?0.008 to 2 ?g/ml for all species panels except those of Pseudomonas aeruginosa and Burkholderia cenocepacia (MIC90 values of 32 ?g/ml for both organisms). The antibacterial activity of eravacycline was minimally affected by expression of tetracycline-specific efflux and ribosomal protection mechanisms in clinical isolates. Furthermore, eravacycline was active against multidrug-resistant bacteria, including those expressing extended-spectrum ?-lactamases and mechanisms conferring resistance to other classes of antibiotics, including carbapenem resistance. Eravacycline has the potential to be a promising new intravenous (i.v.)/oral antibiotic for the empirical treatment of complicated hospital/health care infections and moderate-to-severe community-acquired infections. PMID:23979750

  7. Chemical conjugation of 2-hexadecynoic acid to C5-curcumin enhances its antibacterial activity against multi-drug resistant bacteria.

    PubMed

    Sanabria-Ríos, David J; Rivera-Torres, Yaritza; Rosario, Joshua; Gutierrez, Ricardo; Torres-García, Yeireliz; Montano, Nashbly; Ortíz-Soto, Gabriela; Ríos-Olivares, Eddy; Rodríguez, José W; Carballeira, Néstor M

    2015-11-15

    The first total synthesis of a C5-curcumin-2-hexadecynoic acid (C5-Curc-2-HDA, 6) conjugate was successfully performed. Through a three-step synthetic route, conjugate 6 was obtained in 13% overall yield and tested for antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA) strains. Our results revealed that 6 was active against eight MRSA strains at MICs that range between 31.3 and 62.5?g/mL. It was found that the presence of 2-hexadecynoic acid (2-HDA, 4) in conjugate 6 increased 4-8-fold its antibacterial activity against MRSA strains supporting our hypothesis that the chemical connection of 4 to C5-curcumin (2) increases the antibacterial activity of 2 against Gram-positive bacteria. Combinational index (CIn) values that range between 1.6 and 2.3 were obtained when eight MRSA strains were treated with an equimolar mixture of 2 and 4. These results demonstrated that an antagonistic effect is taking place. Finally, it was investigated whether conjugate 6 can affect the replication process of S. aureus, since this compound inhibited the supercoiling activity of the S. aureus DNA gyrase at minimum inhibitory concentrations (MIC) of 250?g/mL (IC50=100.2±13.9?g/mL). Moreover, it was observed that the presence of 4 in conjugate 6 improves the anti-topoisomerase activity of 2 towards S. aureus DNA gyrase, which is in agreement with results obtained from antibacterial susceptibility tests involving MRSA strains. PMID:26483137

  8. Artificial activation of toxinantitoxin systems as an antibacterial strategy

    E-print Network

    Hergenrother, Paul J.

    Artificial activation of toxin­antitoxin systems as an antibacterial strategy Julia J. Williams1 genomes has been revealed. The exploitation of TA systems as an antibacterial strategy via artificial advances, and challenges associated with artificial toxin activation. Toxin­antitoxin systems

  9. Volatile compounds of Lamiaceae exhibit a synergistic antibacterial activity with streptomycin.

    PubMed

    Araújo, Sthéfane G; Alves, Lucas F; Pinto, Maria Eduarda A; Oliveira, Graziela T; Siqueira, Ezequias P; Ribeiro, Rosy I M A; Ferreira, Jaqueline M S; Lima, Luciana A R S

    2014-01-01

    Bacterial infections cause thousands of deaths in the world every year. In most cases, infections are more serious because the patient is already weakened, and often, the bacteria are already resistant to the antibiotics used. Counterparting this negative scenario, the interest in medicinal plants as an alternative to the synthetic antimicrobial drugs is blossoming worldwide. In the present work, we identified the volatile compounds of ethanol extracts of Melissa officinalis, Mentha sp., Ocimum basilicum, Plectranthus barbatus, and Rosmarinus officinalis by gas chromatography/mass spectrometry (GC/MS). Also was evaluated antimicrobial activity of ethanol extracts against 6 bacteria of clinical interest, and was tested the interaction of these extracts with a commercial antibiotic streptomycin. Phytol was a compound identified in all extracts by GC/MS, being majoritary component in Plectranthus barbatus and Rosmarinus officinalis. The Gram-positive bacteria were more sensitive to ethanol extracts, and Plectranthus barbatus and Rosmarinus officinalis were the most active extracts. Ethanol extracts exhibited a synergetic effect with streptomycin. These results encourage additional studies, in order to evaluate the possibilities of using ethanol extracts of Lamiaceae family as natural source for antibacterial activity. PMID:25763039

  10. Volatile compounds of Lamiaceae exhibit a synergistic antibacterial activity with streptomycin

    PubMed Central

    Araújo, Sthéfane G.; Alves, Lucas F.; Pinto, Maria Eduarda A.; Oliveira, Graziela T.; Siqueira, Ezequias P.; Ribeiro, Rosy I. M. A.; Ferreira, Jaqueline M. S.; Lima, Luciana A. R. S.

    2014-01-01

    Bacterial infections cause thousands of deaths in the world every year. In most cases, infections are more serious because the patient is already weakened, and often, the bacteria are already resistant to the antibiotics used. Counterparting this negative scenario, the interest in medicinal plants as an alternative to the synthetic antimicrobial drugs is blossoming worldwide. In the present work, we identified the volatile compounds of ethanol extracts of Melissa officinalis, Mentha sp., Ocimum basilicum, Plectranthus barbatus, and Rosmarinus officinalis by gas chromatography/mass spectrometry (GC/MS). Also was evaluated antimicrobial activity of ethanol extracts against 6 bacteria of clinical interest, and was tested the interaction of these extracts with a commercial antibiotic streptomycin. Phytol was a compound identified in all extracts by GC/MS, being majoritary component in Plectranthus barbatus and Rosmarinus officinalis. The Gram-positive bacteria were more sensitive to ethanol extracts, and Plectranthus barbatus and Rosmarinus officinalis were the most active extracts. Ethanol extracts exhibited a synergetic effect with streptomycin. These results encourage additional studies, in order to evaluate the possibilities of using ethanol extracts of Lamiaceae family as natural source for antibacterial activity. PMID:25763039

  11. Influence of the Multivalency of Ultrashort Arg-Trp-Based Antimicrobial Peptides (AMP) on Their Antibacterial Activity.

    PubMed

    Hoffknecht, Barbara C; Worm, Dennis J; Bobersky, Sandra; Prochnow, Pascal; Bandow, Julia E; Metzler-Nolte, Nils

    2015-09-01

    Peptide dendrimers are a class of molecules of high interest in the search for new antibiotics. We used microwave-assisted, copper(I)-catalyzed alkyne-azide cycloaddition (CuAAC; "click" chemistry) for the simple and versatile synthesis of a new class of multivalent antimicrobial peptides (AMPs) containing solely arginine and tryptophan residues. To investigate the influence of multivalency on antibacterial activity, short solid-phase- synthesized azide-modified Arg-Trp-containing peptides were "clicked" to three different alkyne-modified benzene scaffolds to access scaffolds with one, two, or three peptides. The antibacterial activity of 15 new AMPs was investigated by minimal inhibitory concentration (MIC) assays on five different bacterial strains, including a multidrug-resistant Staphylococcus aureus (MRSA) strain. With ultrashort (2-3 residues) peptides, a clear synergistic effect of the trivalent display was observed, whereas this effect was not apparent with longer peptides. The best candidates showed activities in the low-micromolar range against Gram-positive MRSA. Surprisingly, the best activity against Gram-negative Acinetobacter baumannii was observed with an ultrashort dipeptide on the trivalent scaffold (MIC: 7.5??M). The hemolytic activity was explored for the three most active peptides. At concentrations ten times the MIC values, <1?% hemolysis of red blood cells was observed. PMID:26149664

  12. Potent antibacterial activity of a novel silver nanoparticle-halloysite nanotube nanocomposite powder.

    PubMed

    Zhang, Yatao; Chen, Yifeng; Zhang, Haoqin; Zhang, Bing; Liu, Jindun

    2013-01-01

    Halloysite nanotubes (HNTs), natural nanotube, have been developed as a support for loading of antibacterial agents. Firstly, HNTs were modified by silane coupling agent (KH-792). And then, modified HNTs were immersed in silver nitrate solution and a complex reaction between the two amino groups of KH-792 and silver ions formed, leading to large clusters on the surface of HNTs. Finally, these silver containing clusters were converted into silver nanoparticles (Ag NPs) with about 5nm diameter by reduction process. A new antibacterial agent, Ag NPs/HNTs, was characterized by X-ray fluorescence (XRF), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and scanning transmission electron microscopy-energy dispersive X-ray analysis (STEM-EDX). The antibacterial test indicated that Ag NPs/HNTs showed good antibacterial performance against Gram-negative bacteria (Escherichia coli) and Gram-positive bacteria (Staphylococcus aureus). PMID:23123339

  13. Temporin-SHa peptides grafted on gold surfaces display antibacterial activity.

    PubMed

    Lombana, Andres; Raja, Zahid; Casale, Sandra; Pradier, Claire-Marie; Foulon, Thierry; Ladram, Ali; Humblot, Vincent

    2014-07-01

    Development of resistant bacteria onto biomaterials is a major problem leading to nosocomial infections. Antimicrobial peptides are good candidates for the generation of antimicrobial surfaces because of their broad-spectrum activity and their original mechanism of action (i.e. rapid lysis of the bacterial membrane) making them less susceptible to the development of bacterial resistance. In this study, we report on the covalent immobilisation of temporin-SHa on a gold surface modified by a thiolated self-assembled monolayer. Temporin-SHa (FLSGIVGMLGKLF amide) is a small hydrophobic and low cationic antimicrobial peptide with potent and very broad-spectrum activity against Gram-positive and Gram-negative bacteria, yeasts and parasites. We have analysed the influence of the binding mode of temporin-SHa on the antibacterial efficiency by using a covalent binding either via the peptide NH2 groups (random grafting of ?- and ?-NH2 to the surface) or via its C-terminal end (oriented grafting using the analogue temporin-SHa-COOH). The surface functionalization was characterised by IR spectroscopy (polarisation modulation reflection absorption IR spectroscopy) while antibacterial activity against Listeria ivanovii was assessed by microscopy techniques, such as atomic force microscopy and scanning electron microscopy equipped with a field emission gun. Our results revealed that temporin-SHa retains its antimicrobial activity after covalent grafting. A higher amount of bound temporin-SHa is observed for the C-terminally oriented grafting compared with the random grafting (NH2 groups). Temporin-SHa therefore represents an attractive candidate as antimicrobial coating agent. PMID:24919960

  14. Biocontrol of plant disease: a (Gram-) positive perspective Elizabeth A.B. Emmert Y

    E-print Network

    Handelsman, Jo

    to the downfall of a biocontrol agent. Knowledge of the biological environment in which the agent will be used utilizing Gram-positive biocontrol agents that have been researched in depth and provide modelsMiniReview Biocontrol of plant disease: a (Gram-) positive perspective Elizabeth A.B. Emmert Y , Jo

  15. Novel conductive polypyrrole/zinc oxide/chitosan bionanocomposite: synthesis, characterization, antioxidant, and antibacterial activities.

    PubMed

    Ebrahimiasl, Saeideh; Zakaria, Azmi; Kassim, Anuar; Basri, Sri Norleha

    2015-01-01

    An antibacterial and conductive bionanocomposite (BNC) film consisting of polypyrrole (Ppy), zinc oxide (ZnO) nanoparticles (NPs), and chitosan (CS) was electrochemically synthesized on indium tin oxide (ITO) glass substrate by electrooxidation of 0.1 M pyrrole in aqueous solution containing appropriate amounts of ZnO NPs uniformly dispersed in CS. This method enables the room temperature electrosynthesis of BNC film consisting of ZnO NPs incorporated within the growing Ppy/CS composite. The morphology of Ppy/ZnO/CS BNC was characterized by scanning electron microscopy. ITO-Ppy/CS and ITO-Ppy/ZnO/CS bioelectrodes were characterized using the Fourier transform infrared technique, X-ray diffraction, and thermogravimetric analysis. The electrical conductivity of nanocomposites was investigated by a four-probe method. The prepared nanocomposites were analyzed for antioxidant activity using the 2,2-diphenyl-1-picrylhydrazyl assay. The results demonstrated that the antioxidant activity of nanocomposites increased remarkably by addition of ZnO NPs. The electrical conductivity of films showed a sudden decrease for lower weight ratios of ZnO NPs (5 wt%), while it was increased gradually for higher ratios (10, 15, and 20 wt%). The nanocomposites were analyzed for antibacterial activity against Gram-positive and Gram-negative bacteria. The results indicated that the synthesized BNC is effective against all of the studied bacteria, and its effectiveness is higher for Pseudomonas aeruginosa. The thermal stability and physical properties of BNC films were increased by an increase in the weight ratio of ZnO NPs, promising novel applications for the electrically conductive polysaccharide-based nanocomposites, particularly those that may exploit the antimicrobial nature of Ppy/ZnO/CS BNCs. PMID:25565815

  16. Novel conductive polypyrrole/zinc oxide/chitosan bionanocomposite: synthesis, characterization, antioxidant, and antibacterial activities

    PubMed Central

    Ebrahimiasl, Saeideh; Zakaria, Azmi; Kassim, Anuar; Basri, Sri Norleha

    2015-01-01

    An antibacterial and conductive bionanocomposite (BNC) film consisting of polypyrrole (Ppy), zinc oxide (ZnO) nanoparticles (NPs), and chitosan (CS) was electrochemically synthesized on indium tin oxide (ITO) glass substrate by electrooxidation of 0.1 M pyrrole in aqueous solution containing appropriate amounts of ZnO NPs uniformly dispersed in CS. This method enables the room temperature electrosynthesis of BNC film consisting of ZnO NPs incorporated within the growing Ppy/CS composite. The morphology of Ppy/ZnO/CS BNC was characterized by scanning electron microscopy. ITO–Ppy/CS and ITO–Ppy/ZnO/CS bioelectrodes were characterized using the Fourier transform infrared technique, X-ray diffraction, and thermogravimetric analysis. The electrical conductivity of nanocomposites was investigated by a four-probe method. The prepared nanocomposites were analyzed for antioxidant activity using the 2,2-diphenyl-1-picrylhydrazyl assay. The results demonstrated that the antioxidant activity of nanocomposites increased remarkably by addition of ZnO NPs. The electrical conductivity of films showed a sudden decrease for lower weight ratios of ZnO NPs (5 wt%), while it was increased gradually for higher ratios (10, 15, and 20 wt%). The nanocomposites were analyzed for antibacterial activity against Gram-positive and Gram-negative bacteria. The results indicated that the synthesized BNC is effective against all of the studied bacteria, and its effectiveness is higher for Pseudomonas aeruginosa. The thermal stability and physical properties of BNC films were increased by an increase in the weight ratio of ZnO NPs, promising novel applications for the electrically conductive polysaccharide-based nanocomposites, particularly those that may exploit the antimicrobial nature of Ppy/ZnO/CS BNCs. PMID:25565815

  17. Antibacterial activity of optically transparent nanocomposite films based on chitosan or its derivatives and silver nanoparticles.

    PubMed

    Pinto, Ricardo J B; Fernandes, Susana C M; Freire, Carmen S R; Sadocco, Patrizia; Causio, Jessica; Neto, Carlos Pascoal; Trindade, Tito

    2012-02-01

    Colloidal silver nanoparticles (NPs) were prepared using the citrate and borohydride reduction methods and were then investigated as fillers in three matrices: unmodified chitosan, water-soluble chitosan and a N-alkyl chitosan derivative. The nanocomposites were used to prepare cast thin films (9-19 ?m thickness) and characterized for their optical and antimicrobial properties. The optical properties of the materials were adjusted either by varying the Ag NPs content in the films (0.5-3.9% w/w) or by using samples of Ag NPs with distinct particle size distributions. The antibacterial activity towards both Gram-positive (Staphylococcus aureus) and Gram-negative bacteria (Klebsiella pneumoniae and Escherichia coli) was investigated for the various composites. For the unmodified chitosan nanocomposites, the bactericidal effect depended on their Ag content while such an effect was always observed for water-soluble chitosan and N-alkyl chitosan based materials. This research provides a basis for the evaluation of chitosan/silver composites in applications requiring flexible films with tuned optical properties and antimicrobial activity. PMID:22154478

  18. Synthesis, antibacterial activity, antibacterial mechanism and food applications of ZnO nanoparticles: a review.

    PubMed

    Shi, Lu-E; Li, Zhen-Hua; Zheng, Wei; Zhao, Yi-Fan; Jin, Yong-Fang; Tang, Zhen-Xing

    2014-01-01

    Bacterial contamination reduces the shelf-life of foods and presents serious risks to human health. Nanotechnology provides the opportunity for the development of new antibacterial agents. Nano-inorganic metal oxides have shown the potential to reduce bacterial contamination of foods. When the particle size of materials decreases from the micrometre to the nanometre range, nano-functional properties such as diffusivity, mechanical strength, chemical reactivity and biological properties are improved. Significantly, ZnO has been used in many applications with particular success. Many studies have shown that ZnO nanoparticles have enhanced antibacterial activity. This review discusses the main synthetic methods, antibacterial activity, antibacterial mechanisms and food applications of ZnO nanoparticles. PMID:24219062

  19. Sonodynamic excitation of Rose Bengal for eradication of gram-positive and gram-negative bacteria.

    PubMed

    Nakonechny, Faina; Nisnevitch, Michael; Nitzan, Yeshayahu; Nisnevitch, Marina

    2013-01-01

    Photodynamic antimicrobial chemotherapy based on photosensitizers activated by illumination is limited by poor penetration of visible light through skin and tissues. In order to overcome this problem, Rose Bengal was excited in the dark by 28?kHz ultrasound and was applied for inactivation of bacteria. It is demonstrated, for the first time, that the sonodynamic technique is effective for eradication of gram-positive Staphylococcus aureus and gram-negative Escherichia coli. The net sonodynamic effect was calculated as a 3-4 log10 reduction in bacteria concentration, depending on the cell and the Rose Bengal concentration and the treatment time. Sonodynamic treatment may become a novel and effective form of antimicrobial therapy and can be used for low-temperature sterilization of medical instruments and surgical accessories. PMID:23509759

  20. Purification Techniques of Bacteriocins from Lactic Acid Bacteria and Other Gram-Positive Bacteria

    NASA Astrophysics Data System (ADS)

    Saavedra, Lucila; Sesma, Fernando

    The search for new antimicrobial peptides produced by lactic acid ­bacteria and other Gram-positive microorganisms has become an interesting field of research in the past decades. The fact that bacteriocins are active against numerous foodborne and human pathogens, are produced by generally regarded as safe (GRAS) microorganisms, and are readily degraded by proteolytic host systems makes them attractive candidates for biotechnological applications. However, before suggesting or choosing a new bacteriocin for future technology developments, it is necessary to elucidate its biochemical structure and its mode of action, which may be carried out once the bacteriocin is purified to homogeneity. This chapter focuses on describing the main strategies used for the purification of numerous bacteriocins.

  1. Regulating the Intersection of Metabolism and Pathogenesis in Gram-positive Bacteria

    PubMed Central

    RICHARDSON, ANTHONY R.; SOMERVILLE, GREG A.; SONENSHEIN, ABRAHAM L.

    2015-01-01

    Pathogenic bacteria must contend with immune systems that actively restrict the availability of nutrients and cofactors, and create a hostile growth environment. To deal with these hostile environments, pathogenic bacteria have evolved or acquired virulence determinants that aid in the acquisition of nutrients. This connection between pathogenesis and nutrition may explain why regulators of metabolism in nonpathogenic bacteria are used by pathogenic bacteria to regulate both metabolism and virulence. Such coordinated regulation is presumably advantageous because it conserves carbon and energy by aligning synthesis of virulence determinants with the nutritional environment. In Gram-positive bacterial pathogens, at least three metabolite-responsive global regulators, CcpA, CodY, and Rex, have been shown to coordinate the expression of metabolism and virulence genes. In this chapter, we discuss how environmental challenges alter metabolism, the regulators that respond to this altered metabolism, and how these regulators influence the host-pathogen interaction. PMID:26185086

  2. Antibacterial activity of Thymoquinone, an active principle of Nigella sativa and its potency to prevent bacterial biofilm formation

    PubMed Central

    2011-01-01

    Background Thymoquinone is an active principle of Nigella sativa seed known as "Habbah Al-Sauda" in Arabic countries and "Sinouj" in Tunisia. Bacterial biofilms tend to exhibit significant tolerance to antimicrobials drugs during infections. Methods The antibacterial activity of Thymoquinone (TQ) and its biofilm inhibition potencies were investigated on 11 human pathogenic bacteria. The growth and development of the biofilm were assessed using the crystal violet (CV) and the 2, 3-bis [2-methyloxy-4-nitro-5-sulfophenyl]-2H-tetrazolium-5-carboxanilide (XTT) reduction assay. Results TQ exhibited a significant bactericidal activity against the majority of the tested bacteria (MICs values ranged from 8 to 32 ?g/ml) especially Gram positive cocci (Staphylococcus aureus ATCC 25923 and Staphylococcus epidermidis CIP 106510). Crystal violet assay demonstrated that the minimum biofilm inhibition concentration (BIC50) was reached with 22 and 60 ?g/ml for Staphylococcus aureus ATCC 25923 and Staphylococcus epidermidis CIP 106510 respectively. In addition our data revealed that cells oxidative activity was influenced by TQ supplementation. In the same way, TQ prevented cell adhesion to glass slides surface. Conclusion The ability of TQ to prevent biofilm formation warrants further investigation to explore its use as bioactive substances with antibiofilm potential. PMID:21489272

  3. Essential oil composition and antibacterial activity of Origanum vulgare subsp. glandulosum Desf. at different phenological stages.

    PubMed

    Béjaoui, Afef; Chaabane, Hédia; Jemli, Maroua; Boulila, Abdennacer; Boussaid, Mohamed

    2013-12-01

    Variation in the quantity and quality of the essential oil (EO) of wild population of Origanum vulgare at different phenological stages, including vegetative, late vegetative, and flowering set, is reported. The oils of air-dried samples were obtained by hydrodistillation. The yield of oils (w/w%) at different stages were in the order of late vegetative (2.0%), early vegetative (1.7%), and flowering (0.6%) set. The oils were analyzed by gas chromatography (GC) and GC-mass spectrometry (GC-MS). In total, 36, 33, and 16 components were identified and quantified in vegetative, late vegetative, and flowering set, representing 94.47%, 95.91%, and 99.62% of the oil, respectively. Carvacrol was the major compound in all samples. The ranges of major constituents were as follows: carvacrol (61.08-83.37%), p-cymene (3.02-9.87%), and ?-terpinene (4.13-6.34%). Antibacterial activity of the oils was tested against three Gram-positive and two Gram-negative bacteria by the disc diffusion method and determining their diameter of inhibition and the minimum inhibitory concentration (MIC) values. The inhibition zones and MIC values for bacterial strains, which were sensitive to the EO of O. vulgare subsp. glandulosum, were in the range of 9-36 mm and 125-600 ?g/mL, respectively. The oils of various phenological stages showed high activity against all tested bacteria, of which Bacillus subtilis was the most sensitive and resistant strain, respectively. Thus, they represent an inexpensive source of natural antibacterial substances that exhibited potential for use in pathogenic systems. PMID:24320986

  4. Extracellular vesicles produced by the Gram-positive bacterium Bacillus subtilis are disrupted by the lipopeptide surfactin.

    PubMed

    Brown, Lisa; Kessler, Anne; Cabezas-Sanchez, Pablo; Luque-Garcia, Jose L; Casadevall, Arturo

    2014-07-01

    Previously, extracellular vesicle production in Gram-positive bacteria was dismissed due to the absence of an outer membrane, where Gram-negative vesicles originate, and the difficulty in envisioning how such a process could occur through the cell wall. However, recent work has shown that Gram-positive bacteria produce extracellular vesicles and that the vesicles are biologically active. In this study, we show that Bacillus subtilis produces extracellular vesicles similar in size and morphology to other bacteria, characterized vesicles using a variety of techniques, provide evidence that these vesicles are actively produced by cells, show differences in vesicle production between strains, and identified a mechanism for such differences based on vesicle disruption. We found that in wild strains of B. subtilis, surfactin disrupted vesicles while in laboratory strains harbouring a mutation in the gene sfp, vesicles accumulated in the culture supernatant. Surfactin not only lysed B. subtilis vesicles, but also vesicles from Bacillus anthracis, indicating a mechanism that crossed species boundaries. To our knowledge, this is the first time a gene and a mechanism has been identified in the active disruption of extracellular vesicles and subsequent release of vesicular cargo in Gram-positive bacteria. We also identify a new mechanism of action for surfactin. PMID:24826903

  5. Antibacterial and Antibiofilm Activities of Makaluvamine Analogs

    PubMed Central

    Nijampatnam, Bhavitavya; Nadkarni, Dwayaja H.; Wu, Hui; Velu, Sadanandan E.

    2015-01-01

    Streptococcus mutans is a key etiological agent in the formation of dental caries. The major virulence factor is its ability to form biofilms. Inhibition of S. mutans biofilms offers therapeutic prospects for the treatment and the prevention of dental caries. In this study, 14 analogs of makaluvamine, a marine alkaloid, were evaluated for their antibacterial activity against S. mutans and for their ability to inhibit S. mutans biofilm formation. All analogs contained the tricyclic pyrroloiminoquinone core of makaluvamines. The structural variations of the analogs are on the amino substituents at the 7-position of the ring and the inclusion of a tosyl group on the pyrrole ring N of the makaluvamine core. The makaluvamine analogs displayed biofilm inhibition with IC50 values ranging from 0.4 ?M to 88 ?M. Further, the observed bactericidal activity of the majority of the analogs was found to be consistent with the anti-biofilm activity, leading to the conclusion that the anti-biofilm activity of these analogs stems from their ability to kill S. mutans. However, three of the most potent N-tosyl analogs showed biofilm IC50 values at least an order of magnitude lower than that of bactericidal activity, indicating that the biofilm activity of these analogs is more selective and perhaps independent of bactericidal activity. PMID:25767719

  6. Synthesis, spectroscopic characterization, structural studies and antibacterial and antitumor activities of diorganotin complexes with 3-methoxysalicylaldehyde thiosemicarbazone

    NASA Astrophysics Data System (ADS)

    Khandani, Marzieh; Sedaghat, Tahereh; Erfani, Nasrollah; Haghshenas, Mohammad Reza; Khavasi, Hamid Reza

    2013-04-01

    Three organotin(IV) complexes, Ph2Sn(mstsc) (1), Me2Sn(mstsc) (2) and Bu2Sn(mstsc) (3), have been synthesized from reaction of R2SnCl2 (R = Ph, Me and Bu) with 3-methoxysalicylaldehyde thiosemicarbazone (H2mstsc). The synthesized complexes have been characterized by elemental analysis and FT-IR, 1H, 13C and 119Sn NMR spectroscopy. The structures of 2 and 3 have been also confirmed by X-ray crystallography. On the basis of spectral and structural data thiosemicarbazone acts as a tridentate dianionic ligand and coordinates to tin through phenolic oxygen, the azomethine nitrogen and thiolate sulfur atoms. The metal coordination geometry for 2 and 3 is described as distorted square pyramid and the crystal lattices are stabilized by intermolecular hydrogen bands. On the basis of 119Sn NMR data, coordination number of tin retains five in solution. The in vitro antibacterial activity of ligand and its complexes has been evaluated against one Gram-positive and three Gram-negative bacteria. Complex 2 exhibited good activity along with the standard antibacterial drugs. The in vitro cytotoxicities of the synthesized compounds against Jurkat cells were evaluated by the standard WST-1 assay. The activity decreases in the order 3 > 1 > 2 = H2mstsc.

  7. Bivalent transition metal complexes of coumarin-3-yl thiosemicarbazone derivatives: Spectroscopic, antibacterial activity and thermogravimetric studies

    NASA Astrophysics Data System (ADS)

    Refat, Moamen S.; El-Deen, Ibrahim M.; Anwer, Zeinab M.; El-Ghol, Samir

    2009-02-01

    Schiff base complexes of Cu(II), Co(II) and Ni(II) with two coumarin-3-yl thiosemicarbazone derivatives (1E)-1-(1-(2-oxo-2H-chromen-3-yl)ethylidene)thiosemicarbazide (OCET) and (1E)-1-(1-(6-bromo-2-oxo-2H-chromen-3-yl)ethylidene)thiosemicarbazide (BOCET) were synthesized by the reaction of Cu(II), Co(II) and Ni(II) chlorides with each mentioned ligand with molar ratio 1:2 metal-to-ligand. Both ligands and their metal complexes were characterized by different physicochemical methods, elemental analysis, molar conductivity, (UV-vis, Mass, Infrared, 1H NMR spectra) and also thermal analysis (TG and DTG) techniques. The discussion of the outcome data of the prepared complexes indicate that the coumarin-3-yl thiosemicarbazone derivatives ligands behave as a bidentate ligand through both thione sulphur and azomethine nitrogen with 1:2 (metal:ligand) stoichiometry for all complexes. The molar conductance measurements proved that the complexes are electrolytes. The kinetic thermodynamic parameters such as: E?, ? H?, ? S?and ? G?are calculated from the DTG curves, all complexes are more ordered except Ni(II) complexes. The antibacterial activity of the coumarin-3-yl thiosemicarbazone derivatives and their metal complexes was evaluated against some kinds of Gram positive and Gram negative bacteria.

  8. Synthesis, characterization, antibacterial activity and quantum chemical studies of N'-Acetyl propane sulfonic acid hydrazide

    NASA Astrophysics Data System (ADS)

    Alyar, Saliha; Alyar, Hamit; Ozdemir, Ummuhan Ozmen; Sahin, Omer; Kaya, Kerem; Ozbek, Neslihan; Gunduzalp, Ayla Balaban

    2015-08-01

    A new N'-Acetyl propane sulfonic acid hydrazide, C3H7sbnd SO2sbnd NHsbnd NHsbnd COCH3 (Apsh, an sulfon amide compound) has been synthesized for the first time. The structure of Apsh was investigated using elemental analysis, spectral (IR, 1H/13C NMR) measurements. In addition, molecular structure of the Apsh was determined by single crystal X-ray diffraction technique and found that the compound crystallizes in monoclinic, space group P 21/c. 1H and 13C shielding tensors for crystal structure were calculated with GIAO/DFT/B3LYP/6-311++G(d,p) methods in CDCl3. The structure of Apsh is optimized using Density Functional Theory (DFT) method. The vibrational band assignments were performed at B3LYP/6-311++G(d,p) theory level combined with scaled quantum mechanics force field (SQMFF) methodology. The theoretical IR frequencies are found to be in good agreement with the experimental IR frequencies. Nonlinear optical (NLO) behaviour of Apsh is also examined by the theoretically predicted values of dipole moment (?), polarizability (?0) and first hyperpolarizability (?tot). The antibacterial activities of synthesized compound were studied against Gram positive bacteria: Staphylococcus aureus ATCC 25923, Enterococcus faecalis ATCC 23212, Staphylococcus epidermidis ATCC 34384, Gram negative bacteria: Eschericha coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853, Klebsiella pneumoniae ATCC 70063 by using microdilution method (as MICs) and disc diffusion method.

  9. Water-dispersible silver nanoparticles-decorated carbon nanomaterials: synthesis and enhanced antibacterial activity

    NASA Astrophysics Data System (ADS)

    Dinh, Ngo Xuan; Chi, Do Thi; Lan, Nguyen Thi; Lan, Hoang; Van Tuan, Hoang; Van Quy, Nguyen; Phan, Vu Ngoc; Huy, Tran Quang; Le, Anh-Tuan

    2015-04-01

    In recent years, a growing number of outbreak of infectious diseases have emerged all over the world. The outbreak of re-emerging and emerging infectious diseases is a considerable burden on global economies and public health. Nano-antimicrobials have been studied as an effective solution for the prevention of infectious diseases. In this work, we demonstrated a modified photochemical approach for the preparation of carbon nanotubes-silver nanoparticles (CNTs-Ag) and graphene oxide-silver nanoparticles (GO-Ag) nanocomposites, which can be stably dispersible in aqueous solution. The formation of silver nanoparticles (Ag-NPs) on the functionalized CNTs and GO nanosheets was analyzed by X-ray diffraction, transmission electron microscopy, Raman spectroscopy and UV-Vis measurements. These analyses indicated that the average particle sizes of Ag-NPs deposited on GO/CNTs nanostructures were ~6-7 nm with nearly uniform size distribution. Moreover, these nanocomposites were found to exhibit enhanced antibacterial activity against two strains of infectious bacteria including Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus bacteria as compared to bare Ag-NPs. Our obtained studies showed a high potential of GO-Ag and CNTs-Ag nanocomposites as effective and long-term disinfection solution to eliminate infectious bacterial pathogens.

  10. CHEMICAL COMPOSITION AND ANTIBACTERIAL ACTIVITY OF SOME MEDICINAL PLANTS FROM LAMIACEAE FAMILY.

    PubMed

    Koz?owska, Mariola; Laudy, Agnieszka E; Przyby?, Jaros?aw; Ziarno, Ma?gorzata; Majewska, Ewa

    2015-01-01

    Chemical composition and antibacterial activity of aqueous (ethanolic and methanolic) extracts from herbs often used in Polish cuisine and traditional herbal medicine including thyme (Thymus vulgaris L.), rosemary (Rosmarinus officinalis L.), oregano (Origanum vulgare L.), peppermint (Mentha piperita L.) and sage (Salvia officinalis L.) were compared. The aqueous ethanolic extracts contained slightly higher levels of phenolics compared to the aqueous methanolic extracts. In turn, GC-MS analysis showed that the aqueous methanolic extracts of thyme, rosemary and sage contained several additional compounds such as eugenol or ledol. The present studies also indicated that the bacterial species applied in the experiment exhibited different sensitivities towards tested extracts. Staphylococcus aureus strains were found to be the most sensitive bacteria to aqueous (ethanolic and methanolic) rosemary and sage extracts and aqueous methanolic thyme extract. Klebsiella pneumoniae ATCC 13883 and Proteus vulgaris NCTC 4635 were more susceptible to the aqueous methanolic thyme extract. However, Listeria monocytogenes 1043S was the most sensitive to the aqueous ethanolic rosemary extract. Gram-positive bacteria were generally more sensitive to the tested extracts than Gram-negative ones. PMID:26647633

  11. Facile green synthesis of silver nanoparticles using seed aqueous extract of Pistacia atlantica and its antibacterial activity.

    PubMed

    Sadeghi, Babak; Rostami, Amir; Momeni, S S

    2015-01-01

    In the present work, we describe the synthesis of silver nanoparticles (Ag-NPs) using seed aqueous extract of Pistacia atlantica (PA) and its antibacterial activity. UV-visible spectroscopy, X-ray diffraction (XRD), Fourier transform infra red spectroscopy (FTIR), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and X-ray energy dispersive spectrophotometer (EDAX) were performed to ascertain the formation of Ag-NPs. It was observed that the growths of Ag-NPs are stopped within 35 min of reaction time. The synthesized Ag-NPs were characterized by a peak at 446 nm in the UV-visible spectrum. XRD confirmed the crystalline nature of the nanoparticles of 27 nm size. The XRD peaks at 38°, 44°, 64° and 77° can be indexed to the (111), (200), (220) and (311) Bragg's reflections of cubic structure of metallic silver, respectively. The FTIR result clearly showed that the extracts containing OH as a functional group act in capping the nanoparticles synthesis. Antibacterial activities of Ag-NPs were tested against the growth of Gram-positive (S. aureus) using SEM. The inhibition was observed in the Ag-NPs against S. aureus. The results suggest that the synthesized Ag-NPs act as an effective antibacterial agent. It is confirmed that Ag-NPs are capable of rendering high antibacterial efficacy and hence has a great potential in the preparation of used drugs against bacterial diseases. The scanning electron microscopy (SEM), indicated that, the most strains of S. aureus was damaged and extensively disappeared by addition of Ag-NPs. The results confirmed that the (PA) is a very good eco friendly and nontoxic source for the synthesis of Ag-NPs as compared to the conventional chemical/physical methods. PMID:25022505

  12. Facile green synthesis of silver nanoparticles using seed aqueous extract of Pistacia atlantica and its antibacterial activity

    NASA Astrophysics Data System (ADS)

    Sadeghi, Babak; Rostami, Amir; Momeni, S. S.

    2015-01-01

    In the present work, we describe the synthesis of silver nanoparticles (Ag-NPs) using seed aqueous extract of Pistacia atlantica (PA) and its antibacterial activity. UV-visible spectroscopy, X-ray diffraction (XRD), Fourier transform infra red spectroscopy (FTIR), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and X-ray energy dispersive spectrophotometer (EDAX) were performed to ascertain the formation of Ag-NPs. It was observed that the growths of Ag-NPs are stopped within 35 min of reaction time. The synthesized Ag-NPs were characterized by a peak at 446 nm in the UV-visible spectrum. XRD confirmed the crystalline nature of the nanoparticles of 27 nm size. The XRD peaks at 38°, 44°, 64° and 77° can be indexed to the (1 1 1), (2 0 0), (2 2 0) and (3 1 1) Bragg's reflections of cubic structure of metallic silver, respectively. The FTIR result clearly showed that the extracts containing OH as a functional group act in capping the nanoparticles synthesis. Antibacterial activities of Ag-NPs were tested against the growth of Gram-positive (S. aureus) using SEM. The inhibition was observed in the Ag-NPs against S. aureus. The results suggest that the synthesized Ag-NPs act as an effective antibacterial agent. It is confirmed that Ag-NPs are capable of rendering high antibacterial efficacy and hence has a great potential in the preparation of used drugs against bacterial diseases. The scanning electron microscopy (SEM), indicated that, the most strains of S. aureus was damaged and extensively disappeared by addition of Ag-NPs. The results confirmed that the (PA) is a very good eco friendly and nontoxic source for the synthesis of Ag-NPs as compared to the conventional chemical/physical methods.

  13. Structure-activity relationship of carbacephalosporins and cephalosporins: antibacterial activity and interaction with the intestinal proton-dependent dipeptide transport carrier of Caco-2 cells.

    PubMed Central

    Snyder, N J; Tabas, L B; Berry, D M; Duckworth, D C; Spry, D O; Dantzig, A H

    1997-01-01

    An intestinal proton-dependent peptide transporter located on the lumenal surface of the enterocyte is responsible for the uptake of many orally absorbed beta-lactam antibiotics. Both cephalexin and loracarbef are transported by this mechanism into the human intestinal Caco-2 cell line. Forty-seven analogs of the carbacephalosporin loracarbef and the cephalosporin cephalexin were prepared to evaluate the structural features necessary for uptake by this transport carrier. Compounds were evaluated for their antibacterial activities and for their ability to inhibit 1 mM cephalexin uptake and, subsequently, uptake into Caco-2 cells. Three clinically evaluated orally absorbed carbacephems were taken up by Caco-2 cells, consistent with their excellent bioavailability in humans. Although the carrier preferred the L stereoisomer, these compounds lacked antibacterial activity and were hydrolyzed intracellularly in Caco-2 cells. Compounds modified at the 3 position of cephalexin and loracarbef with a cyclopropyl or a trifluoromethyl group inhibited cephalexin uptake. Analogs with lipophilic groups on the primary amine of the side chain inhibited cephalexin uptake, retained activity against gram-positive bacteria but lost activity against gram-negative bacteria. Substitution of the phenylglycl side chain with phenylacetyl side chains gave similar results. Compounds which lacked an aromatic ring in the side chain inhibited cephalexin uptake but lost all antibacterial activity. Thus, the phenylglycl side chain is not absolutely required for uptake. Different structural features are required for antibacterial activity and for being a substrate of the transporter. Competition studies with cephalexin indicate that human intestinal Caco-2 cells may be a useful model system for initially guiding structure-activity relationships for the rational design of new oral agents. PMID:9257735

  14. Alkyl sulfonic acide hydrazides: Synthesis, characterization, computational studies and anticancer, antibacterial, anticarbonic anhydrase II (hCA II) activities

    NASA Astrophysics Data System (ADS)

    O. Ozdemir, Ummuhan; ?lbiz, Firdevs; Balaban Gunduzalp, Ayla; Ozbek, Neslihan; Karagoz Genç, Zuhal; Hamurcu, Fatma; Tekin, Suat

    2015-11-01

    Methane sulfonic acide hydrazide, CH3SO2NHNH2 (1), ethane sulfonic acide hydrazide, CH3CH2SO2NHNH2 (2), propane sulfonic acide hydrazide, CH3CH2CH2SO2NHNH2 (3) and butane sulfonic acide hydrazide, CH3CH2CH2CH2SO2NHNH2 (4) have been synthesized as homologous series and characterized by using elemental analysis, spectrophotometric methods (1H-13C NMR, FT-IR, LC-MS). In order to gain insight into the structure of the compounds, we have performed computational studies by using 6-311G(d, p) functional in which B3LYP functional were implemented. The geometry of the sulfonic acide hydrazides were optimized at the DFT method with Gaussian 09 program package. A conformational analysis of compounds were performed by using NMR theoretical calculations with DFT/B3LYP/6-311++G(2d, 2p) level of theory by applying the (GIAO) approach. The anticancer activities of these compounds on MCF-7 human breast cancer cell line investigated by comparing IC50 values. The antibacterial activities of synthesized compounds were studied against Gram positive bacteria; Staphylococcus aureus ATCC 6538, Bacillus subtilis ATCC 6633, Bacillus cereus NRRL-B-3711, Enterococcus faecalis ATCC 29212 and Gram negative bacteria; Escherichia coli ATCC 11230, Pseudomonas aeruginosa ATCC 15442, Klebsiella pneumonia ATCC 70063 by using the disc diffusion method. The inhibition activities of these compounds on carbonic anhydrase II enzyme (hCA II) have been investigated by comparing IC50 and Ki values. The biological activity screening shows that butane sulfonic acide hydrazide (4) has more activity than the others against tested breast cancer cell lines MCF-7, Gram negative/Gram positive bacteria and carbonic anhydrase II (hCA II) isoenzyme.

  15. 45S5Bioglass®-based scaffolds coated with selenium nanoparticles or with poly(lactide-co-glycolide)/selenium particles: Processing, evaluation and antibacterial activity.

    PubMed

    Stevanovi?, Magdalena; Filipovi?, Nenad; Djurdjevi?, Jelena; Luki?, Miodrag; Milenkovi?, Marina; Boccaccini, Aldo

    2015-08-01

    In the bone tissue engineering field, there is a growing interest in the application of bioactive glass scaffolds (45S5Bioglass(®)) due to their bone bonding ability, osteoconductivity and osteoinductivity. However, such scaffolds still lack some of the required functionalities to enable the successful formation of new bone, e.g. effective antibacterial properties. A large number of studies suggest that selenium (Se) has significant role in antioxidant protection, enhanced immune surveillance and modulation of cell proliferation. Selenium nanoparticles (SeNp) have also been reported to possess antibacterial as well as antiviral activities. In this investigation, uniform, stable, amorphous SeNp have been synthesized and additionally immobilized within spherical PLGA particles (PLGA/SeNp). These particles were used to coat bioactive glass-based scaffolds synthesized by the foam replica method. Samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and transmission electron microscopy (TEM). SeNp, 45S5Bioglass(®)/SeNp and 45S5Bioglass(®)/PLGA/SeNp showed a considerable antibacterial activity against Gram positive bacteria, Staphylococcus aureus and Staphylococcus epidermidis, one of the main causative agents of orthopedic infections. The functionalized Se-coated bioactive glass scaffolds represent a new family of bioactive, antibacterial scaffolds for bone tissue engineering applications. PMID:26047884

  16. Phytochemical constituents and antibacterial activity of some green leafy vegetables

    PubMed Central

    Bhat, Ramesa Shafi; Al-Daihan, Sooad

    2014-01-01

    Objective To investigate the antibacterial activity and photochemicals of five green leafy vegetables against a panel of five bacteria strains. Methods Disc diffusion method was used to determine the antibacterial activity, while kanamycin was used as a reference antibiotic. The phytochemical screening of the extracts was performed using standard methods. Results All methanol extracts were found active against all the test bacterial strains. Overall maximum extracts shows antibacterial activity which range from 6 to 15 mm. Proteins and carbohydrates was found in all the green leaves, whereas alkaloid, steroids, saponins, flavonoids, tannins were found in most of the test samples. Conclusions The obtain result suggests that green leafy vegetables have moderate antibacterial activity and contain various pharmacologically active compounds and thus provide the scientific basis for the traditional uses of the studied vegetables in the treatment of bacterial infections. PMID:25182436

  17. Plant mediated green synthesis and antibacterial activity of silver nanoparticles using Emblica officinalis fruit extract

    NASA Astrophysics Data System (ADS)

    Ramesh, P. S.; Kokila, T.; Geetha, D.

    2015-05-01

    A green straight forward method of synthesizing silver nanoparticles (AgNPs) in an aqueous medium was designed using Emblica officinalis (EO) fruit extract as stabilizer and reducer. The formation of AgNPs depends on the effect of extract concentration and pH were studied. The AgNPs was synthesized using E.officinalis (fruit extract) and nanoparticles were characterized using UV-Vis spectrophotometer, the presence of biomolecules of E.officinalis capped in AgNPs was found by FT-IR analysis, shape and size were examined by SEM and XRD. The XRD analysis respects the Bragg's law and confirmed the crystalline nature of silver nanoparticles. From XRD the average size of AgNPs was found to be around 15 nm. AFM has proved to be very helpful in the determination and verification of various morphological features and parameters. EO fruit extract mediated AgNPs was synthesized and confirmed through kinetic behavior of nanoparticles. The shape of the bio-synthesized AgNPs was spherical. Potent biomolecules of E.officinalis such as polyphenols, glucose, and fructose was capped with AgNPs which reduces the toxicity. The synthesized AgNPs were tested for its antibacterial activity against the isolates by disc diffusion method. The obtained results confirmed that the E.officinalis fruit extract is a very good bioreductant for the synthesis of AgNPs. It was investigated that the synthesized AgNPs showed inhibition and had significant antibacterial against both gram-positive and gram-negative bacterial strains.

  18. Synthesis, characterizations and anti-bacterial activities of pure and Ag doped CdO nanoparticles by chemical precipitation method

    NASA Astrophysics Data System (ADS)

    Sivakumar, S.; Venkatesan, A.; Soundhirarajan, P.; Khatiwada, Chandra Prasad

    2015-02-01

    In the present study, synthesized pure and Ag (1%, 2%, and 3%) doped Cadmium Oxide (CdO) nanoparticles by chemical precipitation method. Then, the synthesized products were characterized by thermo gravimetric-differential thermal analysis (TG-DTA), X-ray diffraction (XRD) analysis, Fourier transform infrared (FT-IR) spectroscopy, Ultra violet-Vis diffused reflectance spectroscopy (UV-Vis-DRS), Scanning electron microscopy (SEM), Energy dispersive X-rays (EDX) spectroscopy, and anti-bacterial activities, respectively. The transition temperatures and phase transitions of Cd(OH)2 to CdO at 400 °C was confirmed by TG-DTA analysis. The XRD patterns show the cubic shape and average particle sizes are 21, 40, 34, and 37 nm, respectively for pure and Ag doped samples. FT-IR study confirmed the presence of CdO and Ag at 677 and 459 cm-1, respectively. UV-Vis-DRS study shows the variation on direct and indirect band gaps. The surface morphologies and elemental analysis have been confirmed from SEM and with EDX. In addition, the synthesized products have been characterized by antibacterial activities against Gram-positive and negative bacteria. Further, the present investigation suggests that CdO nanoparticles have the great potential applications on various industrial and medical fields of research.

  19. Synthesis and anti-bacterial activity of Cu, Ag and Cu-Ag alloy nanoparticles: A green approach

    SciTech Connect

    Valodkar, Mayur; Modi, Shefaly; Pal, Angshuman; Thakore, Sonal

    2011-03-15

    Research highlights: {yields} Synthesis of novel nanosized copper-silver alloys of different compositions. {yields} Completely green approach for synthesis of water soluble bimetallic nanoparticle. {yields} Interesting anti-bacterial activity of as synthesized metal and alloy nanoparticle. -- Abstract: Metallic and bimetallic nanoparticles of copper and silver in various proportions were prepared by microwave assisted chemical reduction in aqueous medium using the biopolymer, starch as a stabilizing agent. Ascorbic acid was used as the reducing agent. The silver and copper nanoparticles exhibited surface plasmon absorption resonance maxima (SPR) at 416 and 584 nm, respectively; while SPR for the Cu-Ag alloys appeared in between depending on the alloy composition. The SPR maxima for bimetallic nanoparticles changes linearly with increasing copper content in the alloy. Transmission electron micrograph (TEM) showed monodispersed particles in the range of 20 {+-} 5 nm size. Both silver and copper nanoparticles exhibited emission band at 485 and 645 nm, respectively. The starch-stabilized nanoparticles exhibited interesting antibacterial activity with both gram positive and gram negative bacteria at micromolar concentrations.

  20. Spectroscopic studies and antibacterial activities of pure and various levels of Cu-doped BaSO? nanoparticles.

    PubMed

    Sivakumar, S; Soundhirarajan, P; Venkatesan, A; Khatiwada, Chandra Prasad

    2015-12-01

    The present study was made to design the pure and various levels of Cu doped (0.025 M, 0.05 M and 0.075 M) BaSO4 NPs synthesized by chemical precipitation method. The synthesized products have been characterised by X-ray Diffractometer (XRD), Fourier transform infrared (FT-IR) spectrometer, thermogravimetric and differential thermal analysis (TG-DTA), UV-Vis-diffused reflectance spectroscopy (UV-Vis-DRS), field emission-scanning electron microscopy with energy dispersive spectroscopy (FE-SEM with EDS), transmission electron microscopy (TEM) and application oriented study like antibacterial activity also reported. The result determined from XRD was affirmed by the results obtained from electron microscopic measurements. XRD study revealed that the synthesized products were composed of orthorhombic structure and highly crystalline in nature. Furthermore, flaky like morphology of pure and Cu-BaSO4 nanoparticles have been observed from the images obtained from these studies. The existence of Cu(2+) was confirmed by EDS analysis. The functional groups of the synthesized samples were analysed by FT-IR study. The band gap energies of pure and doped samples were accomplished using UV-Vis-DRS analysis. Also, the kinetic parameters were evaluated and reported from the thermal stability of nanoparticles. Eventually, gram-negative bacteria shows the less antibacterial activities compared to gram-positive bacteria due to adsorption of BaSO4 nanoparticles on the surface of the used bacteria. PMID:26184475

  1. Antibacterial activities of surface modified electrospun poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) fibrous membranes

    NASA Astrophysics Data System (ADS)

    Yao, Chen; Li, Xinsong; Neoh, K. G.; Shi, Zhilong; Kang, E. T.

    2009-01-01

    Poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) membrane, with its excellent chemical and mechanical properties, has good potential for broad applications. However, due to its hydrophobic nature, microbial colonization is commonly encountered. In this work, electrospun PVDF-HFP fibrous membranes were surface modified by poly(4-vinyl- N-alkylpyridinium bromide) to achieve antibacterial activities. The membranes were first subjected to plasma pretreatment followed by UV-induced surface graft copolymerization of 4-vinylpyridine (4VP) and quaternization of the grafted pyridine groups with hexylbromide. The chemical composition of the surface modified PVDF-HFP electrospun membranes was studied by X-ray photoelectron spectroscopy (XPS). The morphology and mechanical properties of pristine and surface modified PVDF-HFP fibrous membranes were characterized by scanning electron microscopy (SEM) and tensile test, respectively. The antibacterial activities of the modified electrospun PVDF-HFP fibrous membranes were assessed against Gram-positive Staphylococcus aureus ( S. aureus) and Gram-negative Escherichia coli ( E. coli). The results showed that the PVDF-HFP fibrous membranes modified with quaternized pyridinium groups are highly effective against both bacteria with killing efficiency as high as 99.9999%.

  2. Enhanced solubility and antibacterial activity of lipophilic fluoro-substituted N-benzoyl-2-aminobenzothiazoles by complexation with ?-cyclodextrins.

    PubMed

    Trapani, A; De Laurentis, N; Armenise, D; Carrieri, A; Defrenza, I; Rosato, A; Mandracchia, D; Tripodo, G; Salomone, A; Capriati, V; Franchini, C; Corbo, F

    2016-01-30

    Some lipophilic fluoro-substituted N-benzoyl-2-aminobenzothiazole antibacterial agents have been evaluated for their activity in the presence of cyclodextrins (CDs) containing aqueous solutions where CDs are adopted as solubilizing excipients for improving the poor water solubility of these compounds. For such purpose both the natural ?-CD and one of FDA/EMA approved CDs for parenteral use (i.e. HP-?-CD) have been employed. The solubility rank order observed was accounted for by thermal analysis (Differential Scanning Calorimetry) and FT-IR spectroscopy. The most promising compound was subjected to further NMR spectroscopic studies and molecular modelling simulations to verify the interactions between the guest molecule and the CD cavity. The assessment of the antibacterial activity of such compounds against selected Gram positive and Gram negative bacterial strains clearly showed that their antimicrobial effectiveness may, quite in all instances, be positively affected by complexation with ?-CD and HP-?-CD. These results, which are in some ways in contrast with those already reported in the literature, are herein discussed on the basis of plausible mechanisms. Moreover, this investigation also reveals that the described methodology of complexing both lipophilic and hydrophilic antimicrobial agents with CDs may be an useful approach to enhance their effectiveness as well as a promising strategy to overcome even the microbial resistance problem. PMID:26611670

  3. Antibacterial activity and mechanism of Ag-ZnO nanocomposite on S. aureus and GFP-expressing antibiotic resistant E. coli.

    PubMed

    Matai, Ishita; Sachdev, Abhay; Dubey, Poornima; Kumar, S Uday; Bhushan, Bharat; Gopinath, P

    2014-03-01

    Emergence of multi-resistant organisms (MROs) leads to ineffective treatment with the currently available medications which pose a great threat to public health and food technology sectors. In this regard, there is an urgent need to strengthen the present therapies or to look over for other potential alternatives like use of "metal nanocomposites". Thus, the present study focuses on synthesis of silver-zinc oxide (Ag-ZnO) nanocomposites which will have a broad-spectrum antibacterial activity against Gram-positive and Gram-negative bacteria. Ag-ZnO nanocomposites of varied molar ratios were synthesized by simple microwave assisted reactions in the absence of surfactants. The crystalline behavior, composition and morphological analysis of the prepared powders were evaluated by X-ray diffraction, infrared spectroscopy, field emission scanning electron microscopy (FE-SEM) and atomic absorption spectrophotometry (AAS). Particle size measurements were carried out by transmission electron microscopy (TEM). Staphylococcus aureus and recombinant green fluorescent protein (GFP) expressing antibiotic resistant Escherichia coli were selected as Gram-positive and Gram-negative model systems respectively and the bactericidal activity of Ag-ZnO nanocomposite was studied. The minimum inhibitory concentration (MIC) and minimum killing concentration (MKC) of the nanocomposite against the model systems were determined by visual turbidity analysis and optical density analysis. Qualitative and quantitative assessments of its antibacterial effects were performed by fluorescent microscopy, fluorescent spectroscopy and Gram staining measurements. Changes in cellular morphology were examined by atomic force microscopy (AFM), FE-SEM and TEM. Finally, on the basis of the present investigation and previously published reports, a plausible antibacterial mechanism of Ag-ZnO nanocomposites was proposed. PMID:24412348

  4. Antiseptic mouthwashes: in vitro antibacterial activity.

    PubMed

    Watanabe, Evandro; Nascimento, Andresa P; Guerreiro-Tanomaru, Juliane M; Razaboni, Ana M; de Andrade, Denise; Tanomaru-Filho, Mário

    2015-08-01

    Mouthwashes are used as an adjunct to tooth brushing for improving breath and preventing oral diseases. The aim of this study was to compare the in vitro Maximum Inhibitory Dilution (MID) of 3 mouthwashes with different active ingredients against mutans streptococci (MS). The products analyzed were PeriogardR, CepacolR and PlaxR Fresh Mint. Their antibacterial activity was assessed in duplicate in 96-well microtiter plates against 36 clinical isolates of MS. Each mouthwash was submitted to a serial two-fold dilution (1/2.5 to 1/5120) using double concentration of Tryptose Soy Broth with 1.0% yeast extract. The final volume in each well was 100 mL plus 5 mL of a bacterial suspension, equivalent to 107 CFU/mL. They were incubated microaerobically at 37oC for 48 hours and the MIDs determined. MID was 1/320 for PeriogardR and CepacolR, and 1/20 for PlaxR. Statistical analysis revealed that the MID of PeriogardR MID did not differ from that of CepacolR (p>0.05), and was higher than that of PlaxR (p<0.05). In conclusion, the antiseptic mouthwashes containing chlorhexidine (PeriogardR) and cetylpyridinium chloride (CepacolR) had higher in vitroantibacterial activity (MID) against MS than the antiseptic mouthwash containing triclosan (PlaxR), according to microbiological method employed. PMID:26355890

  5. Biosynthesis of silver nanoparticles using ethanolic petals extract of Rosa indica and characterization of its antibacterial, anticancer and anti-inflammatory activities.

    PubMed

    Manikandan, Ramar; Manikandan, Beulaja; Raman, Thiagarajan; Arunagirinathan, Koodalingam; Prabhu, Narayanan Marimuthu; Jothi Basu, Muthuramalingam; Perumal, Muthulakshmi; Palanisamy, Subramanian; Munusamy, Arumugam

    2015-03-01

    The present study was aimed at biosynthesis of silver nanoparticles (AgNPs) using ethanolic extract of rose (Rosa indica) petals and testing their potential antibacterial activity using selective human pathogenic microbes, anticancer activity using human colon adenocarcinoma cancer cell line HCT 15 as well as anti-inflammatory activity using rat peritoneal macrophages in vitro. The biologically synthesized AgNPs were also characterized by UV-visible spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), energy-dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD). The characterized AgNPs showed an effective antibacterial activity against Gram negative (Escherichia coli, Klebsiella pneumoniae) than Gram positive (Streptococcus mutans, Enterococcus faecalis) bacteria. MTT assay, analysis of nuclear morphology, mRNA expression of Bcl-2, Bax and protein expression of caspase 3 as well as 9, indicated potential anticancer activity. In addition, green synthesized AgNPs also attenuated cytotoxicity, nuclear morphology and free radical generation (O2(-) and NO) by rat peritoneal macrophages in vitro. The results of our study show the potential green synthesis of silver nanoparticles in mitigating their toxicity while retaining their antibacterial activities. PMID:25481491

  6. The Effect of Substituent, Degree of Acetylation and Positioning of the Cationic Charge on the Antibacterial Activity of Quaternary Chitosan Derivatives

    PubMed Central

    Sahariah, Priyanka; Gaware, Vivek S.; Lieder, Ramona; Jónsdóttir, Sigríður; Hjálmarsdóttir, Martha Á.; Sigurjonsson, Olafur E.; Másson, Már

    2014-01-01

    A series of water-soluble cationic chitosan derivatives were prepared by chemoselective functionalization at the amino group of five different parent chitosans having varying degrees of acetylation and molecular weight. The quaternary moieties were introduced at different alkyl spacer lengths from the polymer backbone (C-0, C-2 and C-6) with the aid of 3,6-di-O-tert-butyldimethylsilyl protection of the chitosan backbone, thus allowing full (100%) substitution of the free amino groups. All of the derivatives were characterized using 1H-NMR, 1H-1H COSY and FT-IR spectroscopy, while molecular weight was determined by GPC. Antibacterial activity was investigated against Gram positive S. aureus and Gram negative E. coli. The relationship between structure and activity/toxicity was defined, considering the effect of the cationic group’s structure and its distance from the polymer backbone, as well as the degree of acetylation within a molecular weight range of 7–23 kDa for the final compounds. The N,N,N-trimethyl chitosan with 100% quaternization showed the highest antibacterial activity with moderate cytotoxicity, while increasing the spacer length reduced the activity. Trimethylammoniumyl quaternary ammonium moieties contributed more to activity than 1-pyridiniumyl moieties. In general, no trend in the antibacterial activity of the compounds with increasing molecular weight or degree of acetylation up to 34% was observed. PMID:25196937

  7. Biosynthesis of silver nanoparticles using ethanolic petals extract of Rosa indica and characterization of its antibacterial, anticancer and anti-inflammatory activities

    NASA Astrophysics Data System (ADS)

    Manikandan, Ramar; Manikandan, Beulaja; Raman, Thiagarajan; Arunagirinathan, Koodalingam; Prabhu, Narayanan Marimuthu; Jothi Basu, Muthuramalingam; Perumal, Muthulakshmi; Palanisamy, Subramanian; Munusamy, Arumugam

    2015-03-01

    The present study was aimed at biosynthesis of silver nanoparticles (AgNPs) using ethanolic extract of rose (Rosa indica) petals and testing their potential antibacterial activity using selective human pathogenic microbes, anticancer activity using human colon adenocarcinoma cancer cell line HCT 15 as well as anti-inflammatory activity using rat peritoneal macrophages in vitro. The biologically synthesized AgNPs were also characterized by UV-visible spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), energy-dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD). The characterized AgNPs showed an effective antibacterial activity against Gram negative (Escherichia coli, Klebsiella pneumoniae) than Gram positive (Streptococcus mutans, Enterococcus faecalis) bacteria. MTT assay, analysis of nuclear morphology, mRNA expression of Bcl-2, Bax and protein expression of caspase 3 as well as 9, indicated potential anticancer activity. In addition, green synthesized AgNPs also attenuated cytotoxicity, nuclear morphology and free radical generation (O2- and NO) by rat peritoneal macrophages in vitro. The results of our study show the potential green synthesis of silver nanoparticles in mitigating their toxicity while retaining their antibacterial activities.

  8. Gas chromatography-mass spectroscopy analysis of bioactive petalostigma extracts: Toxicity, antibacterial and antiviral activities

    PubMed Central

    Kalt, F. R.; Cock, I. E.

    2014-01-01

    Background: Petalostigma pubescens and Petalostigma triloculare were common components of pharmacopeia's of multiple Australian Aboriginal tribal groupings which traditionally inhabited the areas in which they grow. Among these groups, they had a myriad of medicinal uses in treating a wide variety of bacterial, fungal and viral infections. This study was undertaken to test P. pubescens and P. triloculare leaf and fruit extracts for the ability to inhibit bacterial and viral growth and thus validate Australian Aboriginal usage of these plants in treating bacterial and fungal diseases. Materials and Methods: P. pubescens, and P. triloculare leaves and fruit were extracted and tested for antimicrobial, antiviral activity and toxicity. The bioactive extracts were further examined by RP-HPLC and GC-MS to identify the component compounds. Results: The methanol, water and ethyl acetate leaf and fruit extracts of displayed potent antibacterial activity. The methanol and ethyl acetate extracts displayed the broadest specificity, inhibiting the growth of 10 of the 14 bacteria tested (71%) for the leaf extract and 9 of the 14 bacteria tested (64%) for the fruit extracts. The water extracts also had broad spectrum antibacterial activity, inhibiting the growth of 8 (57%) and 7 (50%) of the 14 bacteria tested, respectively. All antibacterial extracts were approximately equally effective against Gram-positive and Gram-negative bacteria, inhibiting the growth of 50-75% of the bacteria tested. The methanol, water and ethyl acetate extracts also displayed antiviral activity in the MS2 plaque reduction assay. The methanol and water extracts inhibited 26.6-49.0% and 85.4-97.2% of MS2 plaque formation, respectively, with the fruit extracts being more potent inhibitors. All ethyl acetate extracts inhibited 100% of MS2 plaque formation. All extracts were also non-toxic or of low toxicity. Analysis of these extracts by RP-HPLC showed that the P. triloculare ethyl acetate fruit extract was the least complex of the bioactive extracts. Subsequent analysis of this extract by GC-MS revealed that it contained 9 main compounds: acetic acid; 2,2-dimethoxybutane; 4-methyl-1,3-dioxane; decane; unadecane; 2-furanmethanol; 1,2-benzenediol; 1,2,3-benzenetriol; and benzoic acid. Conclusion: These studies validate Australian Aboriginal therapeutic usage of Petalostigma species and indicate their medicinal potential. PMID:24914307

  9. New eco-friendly 1-alkyl-3-(4-phenoxybutyl) imidazolium-based ionic liquids derivatives: a green ultrasound-assisted synthesis, characterization, antibacterial activity and POM analyses.

    PubMed

    Messali, Mouslim; Aouad, Mohamed R; El-Sayed, Wael S; Ali, Adeeb Al-Sheikh; Ben Hadda, Taibi; Hammouti, Belkheir

    2014-01-01

    In view of the emerging importance of the ILs as "green" materials with wide applications and our general interests in green processes, a series of a twenty five new 1-alkyl-3-(4-phenoxybutyl) imidazolium-based ionic liquids (ILs) derivatives is synthesized using a facile and green ultrasound-assisted procedure. Their structures were characterized by FT-IR, 1H-NMR, 13C-NMR, 11B, 19F, 31P, and mass spectrometry. Antimicrobial screens of some selected ILs were conducted against a panel of Gram-positive and Gram-negative bacteria. The antimicrobial activity of each compound was measured by determination of the minimal inhibitory concentration (MIC) yielding very interesting and promising results. Their antibacterial activities are reported, and, on the basis of the experimental and virtual POM screening data available, attempt is also made to elucidate the structure activity relationship. PMID:25153856

  10. Molecular cloning, expression of a galectin gene in Pacific white shrimp Litopenaeus vannamei and the antibacterial activity of its recombinant protein.

    PubMed

    Cha, Gui-Hong; Liu, Yuan; Peng, Ting; Huang, Ming-Zhu; Xie, Chen-Ying; Xiao, Yu-Chao; Wang, Wei-Na

    2015-10-01

    Galectins play crucial roles in innate immune responses in invertebrate by recognizing and eliminating microinvaders. In this study, a cDNA encoding a galectin in the Pacific white shrimp (L. vannamei) was identified and characterized. A recombinant variant of this lectin, rLvgalectin, was expressed in the model organism P. pastoris and its expression was confirmed by Western blot. Biochemical assays indicated that the recombinant protein antibacterial rLvgalectin activity and was expressed in all of the organism's tested tissues Injection of the bacterium V. alginolyticus into L. vannamei induced hemocytes upregulation of Lvgalectin. The recombinant Lvgalectin protein (rLvgalectin) could bind various microorganism including Gram-positive bacteria, Gram-negative bacteria and yeast. And it revealed antimicrobial activity against the test Gram-positive bacteria, Gram-negative bacteria, but did not inhibit the growth of fungus Pichia pastoris. Moreover, rLvgalectin could significantly enhance the clearance activity of V. alginolyticus in vivo. In vivo challenge experiments showed that the recombinant rLvgalectin protein can significantly reduce the mortalities of V. alginolyticus injection. Furthermore, Compared to their wild-type counterparts, Lvgalectin-silenced shrimp exhibited increased mortality and hemocyte apoptosis, decreased bacterial clearance ability and total hemocyte counts, and stronger expression of Lvp53, LvproPO, LvPEN3, and LvCrustin following V. alginolyticus challenge. Taken together, these results suggest that galectin is important in the innate immune response of shrimp to pathogens infection. PMID:26143399

  11. Proteolytically activated anti-bacterial hydrogel microspheres

    PubMed Central

    Buhrman, Jason S.; Cook, Laura C.; Rayahin, Jamie E.; Federle, Michael J.; Gemeinhart, Richard A.

    2013-01-01

    Hydrogels are finding increased clinical utility as advances continue to exploit their favorable material properties. Hydrogels can be adapted for many applications, including surface coatings and drug delivery. Anti-infectious surfaces and delivery systems that actively destroy invading organisms are alternative ways to exploit the favorable material properties offered by hydrogels. Sterilization techniques are commonly employed to ensure the materials are non-infectious upon placement, but sterilization is not absolute and infections are still expected. Natural, anti-bacterial proteins have been discovered which have the potential to act as anti-infectious agents; however, the proteins are toxic and need localized release to have therapeutic efficacy without toxicity. In these studies, we explore the use of the glutathione s-transferase (GST) to anchor the bactericidal peptide, melittin, to the surface of poly(ethylene glycol) diacrylate (PEGDA) hydrogel microspheres. We show that therapeutic levels of protein can be anchored to the surface of the microspheres using the GST anchor. We compared the therapeutic efficacy of recombinant melittin released from PEGDA microspheres to melittin. We found that, when released by an activating enzyme, thrombin, recombinant melittin efficiently inhibits growth of the pathogenic bacterium Streptococcus pyogenes as effectively as melittin created by solid phase peptide synthesis. We conclude that a GST protein anchor can be used to immobilize functional protein to PEGDA microspheres and the protein will remain immobilized under physiological conditions until the protein is enzymatically released. PMID:23816641

  12. Antibacterial activity and genotypic-phenotypic characteristics of bacteriocin-producing Bacillus subtilis KKU213: potential as a probiotic strain.

    PubMed

    Khochamit, Nalisa; Siripornadulsil, Surasak; Sukon, Peerapol; Siripornadulsil, Wilailak

    2015-01-01

    The antimicrobial activity and probiotic properties of Bacillus subtilis strain KKU213, isolated from local soil, were investigated. The cell-free supernatant (CFS) of a KKU213 culture containing crude bacteriocins exhibited inhibitory effects on Gram-positive bacteria, including Bacillus cereus, Listeria monocytogenes, Micrococcus luteus, and Staphylococcus aureus. The antibacterial activity of the CFS precipitated with 40% ammonium sulfate (AS) remained even after treatment at 60 and 100 °C, at pH 4 and 10 and with proteolytic enzymes, detergents and heavy metals. When analyzed by SDS-PAGE and overlaid with the indicator strains B. cereus and S. aureus, the 40% AS precipitate exhibited inhibitory activity on proteins smaller than 10 kDa. However, proteins larger than 25 kDa and smaller than 10 kDa were still observed on a native protein gel. Purified subtilosin A was prepared by Amberlite XAD-16 bead extraction and HPLC and analyzed by Nano-LC-QTOF-MS. Its molecular mass was found to be 3.4 kDa, and it retained its antibacterial activity. These results are consistent with the detection of the anti-listerial subtilosin A gene of the sbo/alb cluster in the KKU213 strain, which is 100% identical to that of B. subtilis subsp. subtilis 168. In addition to stable and cyclic subtilosin A, a mixture of many extracellular antibacterial peptides was also detected in the KKU213 culture. The KKU213 strain produced extracellular amylase, cellulase, lipase and protease, is highly acid-resistant (pH 2) when cultured in inulin and promotes health and reduces infection of intestinally colonized broiler chickens. Therefore, we propose that bacteriocin-producing B. subtilis KKU213 could be used as a potential probiotic strain or protective culture. PMID:25440998

  13. Antibacterial efficacy of raw and processed honey.

    PubMed

    Mohapatra, D P; Thakur, V; Brar, S K

    2011-01-01

    In vitro antibacterial activity of methanol, ethanol, and ethyl acetate extracts of raw and processed honey was tested against Gram-positive bacteria (Staphylococcus aureus, Bacillus subtilis, Bacillus cereus, Enterococcus faecalis, and Micrococcus luteus) and Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa, and Salmonella typhi). Both types of honey showed antibacterial activity against tested organisms with the zone of inhibition (ZOI) ranging from 6.94 to 37.94?mm, while E. coli, S. typhi, and P. aeruginosa showed that sensibility towards all the extracts with ZOI ranges between 13.09 to 37.94?mm. The methanol extract showed more potent activity than other organic extracts. Gram-negative bacteria were found to be more susceptible as compared to Gram-positive bacteria except E. faecalis. The broth microdilution assay gave minimum inhibitory concentrations (MIC) value of 625??g/mL, while the minimum bactericidal concentration (MBC) ranges between 625??g/mL 2500??g/mL. The study showed that honey has antibacterial activity (bacteriostatic and bactericidal effect), similar to antibiotics, against test organisms and provides alternative therapy against certain bacteria. PMID:21350671

  14. Biosynthesis characterization of silver nanoparticles using Cassia roxburghii DC. aqueous extract, and coated on cotton cloth for effective antibacterial activity.

    PubMed

    Balashanmugam, Pannerselvam; Kalaichelvan, Pudupalayam Thangavelu

    2015-01-01

    The present study reports the green synthesis of silver nanoparticles (AgNPs) from silver precursor using a plant biomaterial, Cassia roxburghii DC., aqueous extract. The AgNPs were synthesized from the shade-dried leaf extract and assessed for their stability; they elucidated characteristics under UV-visible spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy, high-resolution transmission electron microscopy, and energy dispersive X-ray spectroscopy. The synthesized AgNPs exhibited a maximum absorption at 430 nm, and the X-ray diffraction patterns showed that they were crystal in nature. Fourier transform infrared spectroscopy analysis confirmed the conversion of Ag(+) ions to AgNPs due to the reduction by capping material of plant extract. The HR-TEM analysis revealed that they are spherical ranging from 10 nm to 30 nm. The spot EDAX analysis showed the presence of silver atoms. In addition, AgNPs were evaluated for their antibacterial activity against six different pathogenic bacteria: three Gram-positive bacteria, Bacillus subtilis, Staphylococcus aureus, and Micrococcus luteus, and three Gram-negative bacteria, Pseudomonas aeruginosa, Escherichia coli, and Enterobacter aerogenes. They were highly sensitive to AgNPs, whereas less sensitive to AgNO3. Furthermore, the green synthesized AgNPs were immobilized on cotton fabrics and screened for antibacterial activity. The immobilized AgNPs on cotton cloth showed high antibacterial activity. Therefore, they could be a feasible alternative source in treating wounds or may help in replacing pharmaceutical band-aids. PMID:26491310

  15. Biosynthesis characterization of silver nanoparticles using Cassia roxburghii DC. aqueous extract, and coated on cotton cloth for effective antibacterial activity

    PubMed Central

    Balashanmugam, Pannerselvam; Kalaichelvan, Pudupalayam Thangavelu

    2015-01-01

    The present study reports the green synthesis of silver nanoparticles (AgNPs) from silver precursor using a plant biomaterial, Cassia roxburghii DC., aqueous extract. The AgNPs were synthesized from the shade-dried leaf extract and assessed for their stability; they elucidated characteristics under UV–visible spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy, high-resolution transmission electron microscopy, and energy dispersive X-ray spectroscopy. The synthesized AgNPs exhibited a maximum absorption at 430 nm, and the X-ray diffraction patterns showed that they were crystal in nature. Fourier transform infrared spectroscopy analysis confirmed the conversion of Ag+ ions to AgNPs due to the reduction by capping material of plant extract. The HR-TEM analysis revealed that they are spherical ranging from 10 nm to 30 nm. The spot EDAX analysis showed the presence of silver atoms. In addition, AgNPs were evaluated for their antibacterial activity against six different pathogenic bacteria: three Gram-positive bacteria, Bacillus subtilis, Staphylococcus aureus, and Micrococcus luteus, and three Gram-negative bacteria, Pseudomonas aeruginosa, Escherichia coli, and Enterobacter aerogenes. They were highly sensitive to AgNPs, whereas less sensitive to AgNO3. Furthermore, the green synthesized AgNPs were immobilized on cotton fabrics and screened for antibacterial activity. The immobilized AgNPs on cotton cloth showed high antibacterial activity. Therefore, they could be a feasible alternative source in treating wounds or may help in replacing pharmaceutical band-aids. PMID:26491310

  16. Synthesis and in vitro anti-bacterial evaluation of tetracyclic-ortho-fused 4H-naphtho[1',2'-5,6]pyrano[3,4-d](1,2,3)selenadiazole and its derivatives.

    PubMed

    Karnik, A V; Kulkarni, A M; Malviya, N J; Mourya, B R; Jadhav, B L

    2008-11-01

    Synthesis of new heterocyclic compounds 3a-e containing naphthopyran and selenadiazole as the heterocyclic sub-units in the molecule is achieved using high yielding synthetic protocol. These molecules 3a-e have shown moderate anti-bacterial activity against some gram-positive and gram-negative bacterias. PMID:18339454

  17. Injectable Bioadhesive Hydrogels with Innate Antibacterial Properties

    PubMed Central

    Giano, Michael C.; Ibrahim, Zuhaib; Medina, Scott H.; Sarhane, Karim A.; Christensen, Joani M.; Yamada, Yuji; Brandacher, Gerald; Schneider, Joel P.

    2014-01-01

    Surgical site infections cause significant postoperative morbidity and increased healthcare costs. Bioadhesives used to fill surgical voids and support wound healing are typically devoid of antibacterial activity. Here, we report novel syringe-injectable bioadhesive hydrogels with inherent antibacterial properties prepared from mixing polydextran aldehyde (PDA) and branched polyethylenimine (PEI). These adhesives kill both Gram-negative and Gram–positive bacteria, while sparing human erythrocytes. An optimal composition of 2.5 wt % oxidized dextran and 6.9 wt % PEI sets within seconds forming a mechanically rigid (~1700 Pa) gel offering a maximum adhesive stress of ~ 2.8 kPa. A murine infection model showed that the adhesive is capable of killing S. pyogenes introduced subcutaneously at the bioadhesive’s surface, with minimal inflammatory response. The adhesive was also effective in a cecal ligation and puncture model, preventing sepsis and significantly improving survival. These bioadhesives represent novel, inherently antibacterial materials for wound filling applications. PMID:24958189

  18. Inhibition of various gram-positive and gram- negative bacteria growth on selenium nanoparticle coated paper towels

    PubMed Central

    Wang, Qi; Larese-Casanova, Philip; Webster, Thomas J

    2015-01-01

    There are wide spread bacterial contamination issues on various paper products, such as paper towels hanging in sink splash zones or those used to clean surfaces, filter papers used in water and air purifying systems, and wrappings used in the food industry; such contamination may lead to the potential spread of bacteria and consequent severe health concerns. In this study, selenium nanoparticles were coated on normal paper towel surfaces through a quick precipitation method, introducing antibacterial properties to the paper towels in a healthy way. Their effectiveness at preventing biofilm formation was tested in bacterial assays involving Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, and Staphylococcus epidermidis. The results showed significant and continuous bacteria inhibition with about a 90% reduction from 24 to 72 hours for gram-positive bacteria including S. aureus and S. epidermidis. The selenium coated paper towels also showed significant inhibition of gram-negative bacteria like P. aeruginosa and E. coli growth at about 57% and 84%, respectively, after 72 hours of treatment. Therefore, this study established a promising selenium-based antibacterial strategy to prevent bacterial growth on paper products, which may lead to the avoidance of bacteria spreading and consequent severe health concerns. PMID:25926733

  19. Evaluation of the antibacterial potential of Petroselinum crispum and Rosmarinus officinalis against bacteria that cause urinary tract infections

    PubMed Central

    Petrolini, Fernanda Villas Boas; Lucarini, Rodrigo; de Souza, Maria Gorete Mendes; Pires, Regina Helena; Cunha, Wilson Roberto; Martins, Carlos Henrique Gomes

    2013-01-01

    In this study we evaluated the antibacterial activity of the crude hydroalcoholic extracts, fractions, and compounds of two plant species, namely Rosmarinus officinalis and Petroselinum crispum, against the bacteria that cause urinary tract infection. The microdilution method was used for determination of the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). The crude hydroalcoholic extract of R. officinalis displayed in vitro activity against Gram-positive bacteria, with satisfactory MBC for the clinical isolate S. saprophyticus. The fractions and the pure compound rosmarinic acid did not furnish promising results for Gram-negative bacteria, whereas fractions 2, 3, and 4 gave encouraging results for Gram-positive bacteria and acted as bactericide against S. epidermidis as well as E. faecalis (ATCC 29212) and its clinical isolate. R. officinalis led to promising results in the case of Gram-positive bacteria, resulting in a considerable interest in the development of reliable alternatives for the treatment of urinary infections. PMID:24516424

  20. Thermophilic Gram-Positive Biocatalysts for Biomass Conversion to Ethanol

    SciTech Connect

    Shanmugam, K.T.; Ingram, L.O.; Maupin-Furlow, J.A.; Preston, J.F.; Aldrich, H.C.

    2003-12-01

    Production of energy from renewable sources is receiving increased attention due to the finite nature of fossil fuels and the environmental impact associated with the continued large scale use of fossil energy sources. Biomass, a CO2-neutral abundant resource, is an attractive alternate source of energy. Biomass-derived sugars, such as glucose, xylose, and other minor sugars, can be readily fermented to fuel ethanol and commodity chemicals. Extracellular cellulases produced by fungi are commercially developed for depolymerization of cellulose in biomass to glucose for fermentation by appropriate biocatalysts in a simultaneous saccharification and fermentation (SSF) process. Due to the differences in the optimum conditions for the activity of the fungal cellulases and the growth and fermentation characteristics of the current industrial biocatalysts, SSF of cellulose is envisioned at conditions that are not optimal for the fungal cellulase activity leading to higher than required cost of cellulase in SSF. We have isolated bacterial biocatalysts whose growth and fermentation requirements match the optimum conditions for commercial fungal cellulase activity (pH 5.0 and 50 deg. C). These isolates fermented both glucose and xylose, major components of cellulose and hemicellulose, respectively, to L(+)-lactic acid. Xylose was metabolized through the pentose-phosphate pathway by these organisms as evidenced by the fermentation profile and analysis of the fermentation products of 13C1-xylose by NMR. As expected for the metabolism of xylose by the pentose-phosphate pathway, 13C-lactate accounted for more than 90% of the total 13C-labeled products. All three strains fermented crystalline cellulose to lactic acid with the addition of fungal cellulase (Spezyme CE) (SSF) at an optimum of about 10 FPU/g cellulose. These isolates also fermented cellulose and sugar cane bagasse hemicellulose acid hydrolysate simultaneously. Based on fatty acid profile and 16S rRNA sequence, these isolates cluster with Bacillus coagulans although B. coagulans type strain, ATCC 7050, failed to utilize xylose as a carbon source. For successful production of ethanol from pyruvate, both pyruvate decarboxylase (PDC) and alcohol dehydrogenase (AHD) need to be produced at optimal levels in these biocatalysts. A plasmid containing the S. ventriculi pdc gene and the adh gene from geobacillus stearothermophilus was constructed using plasmid pWH1520 that was successfully used for expression of pdc in B. megaterium. The resulting portable ethanol (PET) plasmid, pJAM423, was transformed into B. megaterium. After xylose induction, a significant fraction of cell cytoplasm was composed of the S. ventriculi PDC and G. stearothermophilus ADH proteins. In preliminary experiments, the amount of ethanol produced by b. megaterium with plasmid pJAM423 was about twice (20 mM) of the bacterium without the plasmid. These results show that the PET operon is functional in B. megaterium but high level ethanol production needs further genetic and metabolic engineering. A genetic transfer system for the second generation biocatalysts needs to be developed for transferring the plasmid pJAM423 and its derivatives for engineering these organisms for ethanol production from biomass derived sugars and cellulose to ethanol. One of the new biocatalysts, strain P4-102B was found to be transformable with plasmids and the method for introducing plasmid pJAM423 into this strain and expression of the encoded DNA is being optimized. These new second generation biocatalysts have the potential to reduce the cost of SSF by minimizing the amount of fungal cellulases, a significant cost component in the use of biomass as a renewable resource for production of fuels and chemicals.

  1. Antibacterial and catalytic activities of green synthesized silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Bindhu, M. R.; Umadevi, M.

    2015-01-01

    The aqueous beetroot extract was used as reducing agent for silver nanoparticles synthesis. The synthesized nanoparticles were characterized using UV-visible spectroscopy, X-ray diffraction (XRD) and transmission electron microscopy (TEM). The surface plasmon resonance peak of synthesized nanoparticles was observed at 438 nm. As the concentration of beetroot extract increases, absorption spectra shows blue shift with decreasing particle size. The prepared silver nanoparticles were well dispersed, spherical in shape with the average particle size of 15 nm. The prepared silver nanoparticles are effective in inhibiting the growth of both gram positive and gram negative bacteria. The prepared silver nanoparticles reveal faster catalytic activity. This natural method for synthesis of silver nanoparticles offers a valuable contribution in the area of green synthesis and nanotechnology avoiding the presence of hazardous and toxic solvents and waste.

  2. Antibacterial and catalytic activities of green synthesized silver nanoparticles.

    PubMed

    Bindhu, M R; Umadevi, M

    2015-01-25

    The aqueous beetroot extract was used as reducing agent for silver nanoparticles synthesis. The synthesized nanoparticles were characterized using UV-visible spectroscopy, X-ray diffraction (XRD) and transmission electron microscopy (TEM). The surface plasmon resonance peak of synthesized nanoparticles was observed at 438 nm. As the concentration of beetroot extract increases, absorption spectra shows blue shift with decreasing particle size. The prepared silver nanoparticles were well dispersed, spherical in shape with the average particle size of 15 nm. The prepared silver nanoparticles are effective in inhibiting the growth of both gram positive and gram negative bacteria. The prepared silver nanoparticles reveal faster catalytic activity. This natural method for synthesis of silver nanoparticles offers a valuable contribution in the area of green synthesis and nanotechnology avoiding the presence of hazardous and toxic solvents and waste. PMID:25093965

  3. Synthesis of novel selenium-containing sulfa drugs and their antibacterial activities.

    PubMed

    Abdel-Hafez, Sh H

    2010-01-01

    Synthesis of 3-[4-(N-substituted sulfamoyl)phenyl]-3,4-dihydro-4-oxo-7,9-dimethylpyrido[3',2':4,5]selenolo[3,2-d]pyrimidines, 7-[4-(N-substituted sulfamoyl)phenyl]-7,8-dihydro-8-oxo-3,4-diphenylpyrimido[4',5':4,5]selenolo [2,3-c]pyridazines and 1-[4-(N-substituted sulfamoyl)phenyl]-1,11-dihydro-11-oxo-4-methylpyrimido[4',5':4,5]selenolo[2,3-b]quinolines is reported. 4-Amino-N-pyrimidine-2-ylbenzene sulfonamide (a), 4-amino-N-(2,6-dimetnylpyrimidin-4-yl)benzene sulfonamide (b), N-[(4-aminophenyl)sulfonyl] acetamide (c) with N-ethoxymethyleneamino of selenolo pyridine, selenolo pyridazine and selenolo quinoline derivatives respectively were obtained starting from 1-amino-N-substituted sulfanilamides. Spectroscopic data (IR, (1)H NMR, (13)C NMR and Mass spectral) confirmed the structure of the newly synthesized compounds. Substituted pyrimidines, pyridazines and quinolines were screened for antibacterial activity against gram-positive and gram-negative bacteria. Selenolo derivative of N-[(4-aminophenyl)sulfonyl] acetamide (substitutent of sulfacetamide c) showed strong bactericidal effect against all the tested organisms. Selenolo[3,2-d]pyrimidin (substitutent a) showed a good bactericidal effect against Serratia marcescens, Staphylococcus aureus and Escherichia coli. Compounds Selenolo[2,3-c]pyridazine (substitutent b), Selenolo[2,3-b]quinoline(substitutents c)) exhibited a moderate bactericidal effect against Serratia marcescens. None of the synthesized selenopyridazines has a considerable antimicrobial activity against the tested organisms. The minimum inhibitory concentration (MIC) of the most active compound - 3-[4-(N-acetyl sulfamoyl)phenyl]-3,4-dihydro-4-oxo-7,9-dimethylpyrido[3',2':4,5]selenolo [3,2-d]pyrimidine was 10 mg mL(-1). PMID:20644596

  4. Antibacterial activity of garlic powder against Escherichia coli O-157.

    PubMed

    Sasaki, J; Kita, T; Ishita, K; Uchisawa, H; Matsue, H

    1999-12-01

    The antibacterial activity of garlic powder against O-157 was tested by using garlic bulbs post-harvested 1 y. O-157 at 10(6-7) cfu/mL perished after incubation for 24 h with a 1% solution of garlic powder. The use of powder from fresh garlic was more effective for antibacterial activity than that from old garlic; the 1% solution of fresh garlic powder eradicating the O-157 in 6 h. The antibacterial activity was resistant to heat treatment of 100 degrees C for 20 min. The water-soluble components of garlic powder were fractionated into three fractions (Fr. 1-3) by Sephadex G-100 column chromatography, among which Fr. 3 showed antibacterial activity against O-157 but the other fractions were scarce in activity. The antibacterial activity was also shown against other types of pathogenic bacteria such as methicillin-resistant Staphylococcus aureus (MRSA), Salmonella enteritidis, and Candida albicans. Thus, the practical use of garlic powder is expected to prevent bacteria-caused food poisoning. PMID:10737231

  5. An extreme-halophile archaebacterium possesses the interlock type of prephenate dehydratase characteristic of the Gram-positive eubacteria

    NASA Technical Reports Server (NTRS)

    Jensen, R. A.; d'Amato, T. A.; Hochstein, L. I.

    1988-01-01

    The focal point of phenylalanine biosynthesis is a dehydratase reaction which in different organisms may be prephenate dehydratase, arogenate dehydratase, or cyclohexadienyl dehydratase. Gram-positive, Gram-negative, and cyanobacterial divisions of the eubacterial kingdom exhibit different dehydratase patterns. A new extreme-halophile isolate, which grows on defined medium and is tentatively designated as Halobacterium vallismortis CH-1, possesses the interlock type of prephenate dehydratase present in Gram-positive bacteria. In addition to the conventional sensitivity to feedback inhibition by L-phenylalanine, the phenomenon of metabolic interlock was exemplified by the sensitivity of prephenate dehydratase to allosteric effects produced by extra-pathway (remote) effectors. Thus, L-tryptophan inhibited activity while L-tyrosine, L-methionine, L-leucine and L-isoleucine activated the enzyme. L-Isoleucine and L-phenylalanine were effective at micromolar levels; other effectors operated at mM levels. A regulatory mutant selected for resistance to growth inhibition caused by beta-2-thienylalanine possessed an altered prephenate dehydratase in which a phenomenon of disproportionately low activity at low enzyme concentration was abolished. Inhibition by L-tryptophan was also lost, and activation by allosteric activators was diminished. Not only was sensitivity to feedback inhibition by L-phenylalanine lost, but the mutant enzyme was now activated by this amino acid (a mutation type previously observed in Bacillus subtilis). It remains to be seen whether this type of prephenate dehydratase will prove to be characteristic of all archaebacteria or of some archaebacterial subgroup cluster.

  6. Synthesis, Characterization, Electrochemical Studies, and In Vitro Antibacterial Activity of Novel Thiosemicarbazone and Its Cu(II), Ni(II), and Co(II) Complexes

    PubMed Central

    Khan, Salman A.; Asiri, Abdullah M.; Al-Amry, Khalid; Malik, Maqsood Ahmad

    2014-01-01

    Metal complexes were prepared by the reaction of thiosemicarbazone with CuCl2, NiCl2, CoCl2, Cu(OAc)2, Ni(OAc)2, and Co(OAc)2. The thiosemicarbazone coordinates to metal through the thionic sulfur and the azomethine nitrogen. The thiosemicarbazone was obtained by the thiosemicarbazide with 3-acetyl-2,5-dimethylthiophene. The identities of these compounds were elucidated by IR, 1H, 13C-NMR, and GC-MS spectroscopic methods and elemental analyses. The antibacterial activity of these compounds was first tested in vitro by the disc diffusion assay against two Gram-positive and two Gram-negative bacteria, and then the minimum inhibitory concentration (MIC) was determined by using chloramphenicol as reference drug. The results showed that compound 1.1 is better inhibitor of both types of tested bacteria as compared to chloramphenicol. PMID:24523641

  7. Co-grafting of amino-poly(ethylene glycol) and Magainin I on a TiO2 surface: tests of antifouling and antibacterial activities.

    PubMed

    Peyre, Jessie; Humblot, Vincent; Méthivier, Christophe; Berjeaud, Jean-Marc; Pradier, Claire-Marie

    2012-11-29

    An antimicrobial peptide, Magainin I (Mag), was grafted to a titanium oxide surface, via an antiadhesive poly(ethylene glycol) (PEG) cross-linker. The latter plays a 2-fold part, being antiadhesive, and enabling the covalent immobilization of the peptide. The functionalization was characterized at each step by reflection absorption infrared spectroscopy (RAIRS) and X-ray photoelectron spectroscopy (XPS). The antiadhesive properties of PEG, and antibacterial activity of the anchored Magainin I, were individually tested toward adsorption of bovin serum albumin (BSA) proteins, and against Gram positive bacteria, Listeria ivanovii , respectively. The results reveal that adhesion of both proteins and bacteria have been considerably reduced, accompanied by an inhibition of the growth of remaining adhered bacteria. This work thus offers a novel approach to functionalize oxide surfaces against biofilms and to measure the so-obtained properties in each of the successive steps of a biofilm formation. PMID:22989370

  8. Isolation and identification of membrane vesicle-associated proteins in Gram-positive bacteria and mycobacteria

    PubMed Central

    Prados-Rosales, Rafael; Brown, Lisa; Casadevall, Arturo; Montalvo-Quirós, Sandra; Luque-Garcia, Jose L.

    2014-01-01

    Many intracellular bacterial pathogens naturally release membrane vesicles (MVs) under a variety of growth environments. For pathogenic bacteria there are strong evidences that released MVs are a delivery mechanism for the release of immunologically active molecules that contribute to virulence. Identification of membrane vesicle-associated proteins that can act as immunological modulators is crucial for opening up new horizons for understanding the pathogenesis of certain bacteria and for developing novel vaccines. In this protocol, we provide all the details for isolating MVs secreted by either mycobacteria or Gram-positive bacteria and for the subsequent identification of the protein content of the MVs by mass spectrometry. The protocol is adapted from Gram-negative bacteria and involves four main steps: (1) isolation of MVs from the culture media; (2) purification of MVs by density gradient ultrucentrifugation; (3) acetone precipitation of the MVs protein content and in-solution trypsin digestion and (4) mass spectrometry analysis of the generated peptides and protein identification. Our modifications are:•Growing Mycobacteria in a chemically defined media to reduce the number of unrelated bacterial components in the supernatant.•The use of an ultrafiltration system, which allows concentrating larger volumes.•In solution digestion of proteins followed by peptides purification by ziptip. PMID:26150943

  9. Synthesis and Antibacterial Activities of Antibacterial Peptides with a Spiropyran Fluorescence Probe

    PubMed Central

    Chen, Lei; Zhu, Yu; Yang, Danling; Zou, Rongfeng; Wu, Junchen; Tian, He

    2014-01-01

    In this report, antibacterial peptides1-3 were prepared with a spiropyran fluorescence probe. The probe exhibits a change in fluorescence when isomerized from a colorless spiro-form (spiropyran, Sp) to a colored open-form (merocyanine, Mc) under different chemical environments, which can be used to study the mechanism of antimicrobial activity. Peptides 1-3 exhibit a marked decrease in antimicrobial activity with increasing alkyl chain length. This is likely due to the Sp-Mc isomers in different polar environments forming different aggregate sizes in TBS, as demonstrated by time-dependent dynamic light scattering (DLS). Moreover, peptides 1-3 exhibited low cytotoxicity and hemolytic activity. These probe-modified peptides may provide a novel approach to study the effect of structural changes on antibacterial activity, thus facilitating the design of new antimicrobial agents to combat bacterial infection. PMID:25358905

  10. Plasmin digest of ?-casein as a source of antibacterial peptides.

    PubMed

    Sedaghati, Marjaneh; Ezzatpanah, Hamid; Boojar, Masoud Mashhadi Akbar; Ebrahimi, Maryam Tajabadi; Aminafshar, Mehdi

    2014-05-01

    This study investigated the antibacterial properties of plasmin, the plasmin hydrolysis of bovine ?-casein and the fractions (named ?C1, ?C2, ?C3, ?C4, and ?C5) liberated from it using RP-HPLC. The target bacteria were Escherichia coli, Staphylococcus aureus (pathogenic), Lactobacillus casei and Lactobacillus acidophilus (probiotic). Three peptides (kC1, kC3, and kC4) were found to have antibacterial activity, with ?C3 peptide being the most active. The plasmin digest of bovine ?-casein proved to be stronger than any of its fractions in terms of antibacterial potential. Measurement of the minimum inhibitory concentration (MIC) showed that Gram-positive bacteria are generally more sensitive to antibacterial activity than Gram-negative bacteria. The MIC of nisin, as a bacteriocin peptide, was also measured. The three antibacterial peptides were identified using LC-Mass. The molecular mass of kC1, kC3, and kC4 corresponded to the f(17-21), f(22-24), and f(1-3) of bovine ?-casein, respectively. It was also found that the positive charge and hydrophobicity of a peptide are not key factors in antibacterial activity. On the whole, the present study demonstrated that the plasmin digest of ?-casein has a high antibacterial potential and can be considered as a natural antibacterial agent in the food chain. PMID:24642261

  11. Acylated flavonol glycosides from Tagetes minuta with antibacterial activity

    PubMed Central

    Shahzadi, Irum; Shah, Mohammad M.

    2015-01-01

    Wild marigold (Tagetes minuta), a flowering plant of the family Asteraceae contains compounds of pharmaceutical and nutritional importance especially essential oils and flavonols. Identification, characterization of flavonols and determination of their antibacterial activity were major objectives of the current study. The isolation and purification of flavonols was accomplished using chromatographic techniques while structural elucidation was completed by LC–MS and NMR spectroscopy. The extracts and purified compounds were tested against various bacterial strains for antibacterial activity. A total of 19 flavonols were isolated from this species. Of these, 17 were of butanol and two of ethyl acetate extracts. Based on the concentration and purity, eight potential flavonols were selected and structurally elucidated. Four flavonols, 6-hydroxyquercetin 7-O-?-(6??-galloylglucopyranoside; 2), 6-hydroxykaempferol 7-O-?-glucopyranoside (5), 6-hydroxykaempferol 7-O-?-(6??-galloylglucopyranoside; 7), 6-hydroxyquercetin 7-O-?-(6??-caffeoylglucopyranoside; 9), were identified for the first time from T. minuta. Butanol and ethyl acetate extracts of flowers and seeds showed significant antibacterial activity against Micrococcus leteus, Staphylococcus aureus, Bacillus subtilis, and Pseudomonas pikettii. Among the isolated flavonols only 1, 2, and 18 were found to possess significant antibacterial activity against M. luteus. The extracts and purified flavonols from T. minuta can be potential candidates for antibacterial drug discovery and support to ethnopharmacological use. PMID:26441652

  12. Preparation, characterization, and antibacterial activity of ?-irradiated silver nanoparticles in aqueous gelatin

    NASA Astrophysics Data System (ADS)

    Darroudi, Majid; Ahmad, Mansor B.; Hakimi, Mohammad; Zamiri, Reza; Zak, Ali Khorsand; Hosseini, Hasan Ali; Zargar, Mohsen

    2013-04-01

    Colloidal silver nanoparticles (Ag-NPs) were obtained through ?-irradiation of aqueous solutions containing AgNO3 and gelatin as a silver source and stabilizer, respectively. The absorbed dose of ?-irradiation influences the particle diameter of the Ag-NPs, as evidenced from surface plasmon resonance (SPR) and transmission electron microscopy (TEM) images. When the ?-irradiation dose was increased (from 2 to 50 kGy), the mean particle size was decreased continuously as a result of ?-induced Ag-NPs fragmentation. The antibacterial properties of the Ag-NPs were tested against Methicillinresistant Staphylococcus aureus (MRSA) (Gram-positive) and Pseudomonas aeruginosa (P.a) (Gram-negative) bacteria. This approach reveals that the ?-irradiation-mediated method is a promising simple route for synthesizing highly stable Ag-NPs in aqueous solutions with good antibacterial properties for different applications.

  13. Antibacterial and antioxidant activities of Vaccinium corymbosum L. leaf extract

    PubMed Central

    Pervin, Mehnaz; Hasnat, Md Abul; Lim, Beong Ou

    2013-01-01

    Objective To investigate antibacterial and antioxidant activity of the leaf extract of tropical medicinal herb and food plant Vaccinium corymbosum L. (V. corymbosum). Methods Free radical scavenging activity on DPPH, ABTS, and nitrites were used to analyse phenoic and flavonoid contents of leaf extract. Other focuses included the determination of antioxidant enzymatic activity (SOD, CAT and GPx), metal chelating activity, reduction power, lipid peroxidation inhibition and the prevention of oxidative DNA damage. Antibacterial activity was determined by using disc diffusion for seven strains of bacteria. Results Results found that V. corymbosum leaf extract had significant antibacterial activity. The tested extract displayed the highest activity (about 23.18 mm inhibition zone) against Salmonella typhymurium and the lowest antibacterial activity was observed against Enterococcus faecalis (about 14.08 mm inhibition zone) at 10 mg/ disc. The IC50 values for DPPH, ABTS and radical scavenging activity were 0.120, 0.049 and 1.160 mg/mL, respectively. V. corymbosum leaf extract also showed dose dependent reduction power, lipid peroxidation, DNA damage prevention and significant antioxidant enzymatic activity. Conclusions These findings demonstrate that leaf extract of V. corymbosum could be used as an alternative therapy for antibiotic-resistant bacteria and help prevent various free radical related diseases.

  14. Molecular Characterization and Antibacterial Activity Analysis of Two Novel Penaeidin Isoforms from Pacific White Shrimp, Litopenaeus vannamei.

    PubMed

    Du, Zhi-Qiang; Jin, Yan-Hui

    2015-12-01

    Penaeidins were important immunity effector molecules, which played a crucial role in innate immunity system of penaeid shrimp. Here, we reported two penaeidin isoforms from Litopenaeus vannamei, which were named as Lva-PEN 2 and Lva-PEN 3 according to the respective structure features. The results of amino acid sequence multiple alignments showed that high similarities existed among these penaeidins. A signal peptide sequence and a cysteine-rich domain which contained six cysteine amino acid residues existed in each penaeidin at the same time. Besides, there was a proline-rich motif which was composed of eight proline residues existed in each penaeidin. After the expression profile analysis was studied, we found that both Lva-pen 2 and Lva-pen 3 transcripts were up-regulated at 48 h after bacteria challenge. Except for the antibacterial activity against Gram-positive bacteria like other penaeidins, these two penaeidins could strongly bind to bacteria and possessed antiproteinase activity. It was speculated that these two penaeidins could prevent bacteria pervasion through bacteria-binding activity and antiproteinase activity. Meantime, the proline-rich motif played a crucial role in these biological processes. PMID:26373944

  15. Pili in Gram-positive bacteria: assembly, involvement in colonization and biofilm development

    PubMed Central

    Mandlik, Anjali; Swierczynski, Arlene; Das, Asis; Ton-That, Hung

    2010-01-01

    Various cell-surface multisubunit protein polymers, known as pili or fimbriae, have a pivotal role in the colonization of specific host tissues by many pathogenic bacteria. In contrast to Gram-negative bacteria, Gram-positive bacteria assemble pili by a distinct mechanism involving a transpeptidase called sortase. Sortase crosslinks individual pilin monomers and ultimately joins the resulting covalent polymer to the cell-wall peptidoglycan. Here we review current knowledge of this mechanism and the roles of Gram-positive pili in the colonization of specific host tissues, modulation of host immune responses and the development of bacterial biofilms. PMID:18083568

  16. Pili in Gram-positive bacteria: assembly, involvement in colonization and biofilm development.

    PubMed

    Mandlik, Anjali; Swierczynski, Arlene; Das, Asis; Ton-That, Hung

    2008-01-01

    Various cell-surface multisubunit protein polymers, known as pili or fimbriae, have a pivotal role in the colonization of specific host tissues by many pathogenic bacteria. In contrast to Gram-negative bacteria, Gram-positive bacteria assemble pili by a distinct mechanism involving a transpeptidase called sortase. Sortase crosslinks individual pilin monomers and ultimately joins the resulting covalent polymer to the cell-wall peptidoglycan. Here we review current knowledge of this mechanism and the roles of Gram-positive pili in the colonization of specific host tissues, modulation of host immune responses and the development of bacterial biofilms. PMID:18083568

  17. Synthesis and Antibacterial Activity of Novel Quaternary Ammonium Pyridoxine Derivatives.

    PubMed

    Shtyrlin, Nikita V; Sapozhnikov, Sergey V; Koshkin, Sergey A; Iksanova, Alfiya G; Sabirov, Arthur H; Kayumov, Airat R; Nureeva, Aliya A; Zeldi, Marina I; Shtyrlin, Yurii G

    2015-01-01

    A series of 26 quaternary ammonium pyridoxine derivatives were synthesized and their cytotoxicity and antibacterial activities against clinically relevant bacterial strains were tested in vitro. The antibacterial activity of mono-ammonium salts increased with the rise of the lipophilicity and compound 3,3,5-trimethyl-8,8-dioctyl-1,7,8,9-tetrahydro-[1,3]dioxino[5,4-d]pyrrolo[3,4-b]pyridin-8- ium chloride (2d) reaches a maximum among them. Bis-ammonium salt of pyridoxine 4 with two dimethyloctylamine groups also demonstrated high antibacterial activity despite lower lipophilicity. The results of MTT assay indicated that HEK 293 cells were more sensitive than HSF to quaternary ammonium pyridoxine derivatives. Compounds 2d and 4 did not induce the damage of the DNA and might be of interest in the development of new antimicrobials. PMID:25938426

  18. Cytotoxic and antibacterial activities of the analogues of pogostone.

    PubMed

    Tang, Zheng-Wei; Peng, Cheng; Dai, Min; Han, Bo

    2015-10-01

    Six new (A5-A6, A8-A11) and six known (A1-A4, A7, PO) ?-pyrone compounds were synthesized with dehydroacetate and aldehydes in tetrahydrofuran at room temperature. And their structures were determined by (1)H-NMR, (13)C-NMR and mass spectroscopy. In the bioscreening experiments, ten compounds (A1-A5, PO, A7-A10) exhibited antibacterial activities against Staphylococcus aureus ATCC 25923 with minimum inhibitory concentration (MIC) values of 4-512mg/L, and nine compounds (A1-A5, PO, A7-A8, A10) exhibited antibacterial activities against Methicillin-resistant S. aureus (MRSA) ATCC 43300 with MIC values of 4-256mg/L. Moreover, compound A10 showed the highest antibacterial activity against S. aureus ATCC 25923 and MRSA with MIC values of 4mg/L, while the MIC values of Amoxicillin were 8mg/L and >256mg/L, respectively. Two compounds (A8 and PO) exhibited antibacterial activities against Escherichia coli ATCC 25922 with MIC values of 32-512mg/L. However, only one compound (A8) exhibited significant antibacterial activity against Pseudomonas aeruginosa CVCC 3360 with MIC value of 256mg/L. Moreover, A10 exhibited significant inhibition of proliferation in the four cell lines MCF-10, A549, A2780 and MFC, and showed stronger inhibitive activity of these four selected cell lines than cisplatin in the cytotoxic assay. Thus, this study suggests that pogostone analogues, especially A10, represented a kind of promising antibacterial and antineoplastic agents. PMID:26272659

  19. On the antibacterial activity of roots of Capparis spinosa L.

    PubMed

    Boga, Carla; Forlani, Luciano; Calienni, Rocco; Hindley, Teresa; Hochkoeppler, Alejandro; Tozzi, Silvia; Zanna, Nicola

    2011-02-01

    A decoction of Capparis spinosa L. roots, widely used in the traditional folk medicine of southern Italy, was prepared and submitted to antibacterial activity tests, which showed an interesting bacteriostatic activity on the growth of Deinococcus radiophilus. Heterocyclic compounds were also recovered from the chloroformic extract of the roots. PMID:21328135

  20. Antibacterial Activity of Long-Chain Polyunsaturated Fatty Acids against Propionibacterium acnes and Staphylococcus aureus

    PubMed Central

    Desbois, Andrew P.; Lawlor, Keelan C.

    2013-01-01

    New compounds are needed to treat acne and superficial infections caused by Propionibacterium acnes and Staphylococcus aureus due to the reduced effectiveness of agents used at present. Long-chain polyunsaturated fatty acids (LC-PUFAs) are attracting attention as potential new topical treatments for Gram-positive infections due to their antimicrobial potency and anti-inflammatory properties. This present study aimed to investigate the antimicrobial effects of six LC-PUFAs against P. acnes and S. aureus to evaluate their potential to treat infections caused by these pathogens. Minimum inhibitory concentrations were determined against P. acnes and S. aureus, and the LC-PUFAs were found to inhibit bacterial growth at 32–1024 mg/L. Generally, P. acnes was more susceptible to the growth inhibitory actions of LC-PUFAs, but these compounds were bactericidal only for S. aureus. This is the first report of antibacterial activity attributed to 15-hydroxyeicosapentaenoic acid (15-OHEPA) and 15-hydroxyeicosatrienoic acid (HETrE), while the anti-P. acnes effects of the six LC-PUFAs used herein are novel observations. During exposure to the LC-PUFAs, S. aureus cells were killed within 15–30 min. Checkerboard assays demonstrated that the LC-PUFAs did not antagonise the antimicrobial potency of clinical agents used presently against P. acnes and S. aureus. However, importantly, synergistic interactions against S. aureus were detected for combinations of benzoyl peroxide with 15-OHEPA, dihomo-?-linolenic acid (DGLA) and HETrE; and neomycin with 15-OHEPA, DGLA, eicosapentaenoic acid, ?-linolenic acid and HETrE. In conclusion, LC-PUFAs warrant further evaluation as possible new agents to treat skin infections caused by P. acnes and S. aureus, especially in synergistic combinations with antimicrobial agents already used clinically. PMID:24232668

  1. Antibacterial activity of long-chain polyunsaturated fatty acids against Propionibacterium acnes and Staphylococcus aureus.

    PubMed

    Desbois, Andrew P; Lawlor, Keelan C

    2013-11-01

    New compounds are needed to treat acne and superficial infections caused by Propionibacterium acnes and Staphylococcus aureus due to the reduced effectiveness of agents used at present. Long-chain polyunsaturated fatty acids (LC-PUFAs) are attracting attention as potential new topical treatments for Gram-positive infections due to their antimicrobial potency and anti-inflammatory properties. This present study aimed to investigate the antimicrobial effects of six LC-PUFAs against P. acnes and S. aureus to evaluate their potential to treat infections caused by these pathogens. Minimum inhibitory concentrations were determined against P. acnes and S. aureus, and the LC-PUFAs were found to inhibit bacterial growth at 32-1024 mg/L. Generally, P. acnes was more susceptible to the growth inhibitory actions of LC-PUFAs, but these compounds were bactericidal only for S. aureus. This is the first report of antibacterial activity attributed to 15-hydroxyeicosapentaenoic acid (15-OHEPA) and 15-hydroxyeicosatrienoic acid (HETrE), while the anti-P. acnes effects of the six LC-PUFAs used herein are novel observations. During exposure to the LC-PUFAs, S. aureus cells were killed within 15-30 min. Checkerboard assays demonstrated that the LC-PUFAs did not antagonise the antimicrobial potency of clinical agents used presently against P. acnes and S. aureus. However, importantly, synergistic interactions against S. aureus were detected for combinations of benzoyl peroxide with 15-OHEPA, dihomo-?-linolenic acid (DGLA) and HETrE; and neomycin with 15-OHEPA, DGLA, eicosapentaenoic acid, ?-linolenic acid and HETrE. In conclusion, LC-PUFAs warrant further evaluation as possible new agents to treat skin infections caused by P. acnes and S. aureus, especially in synergistic combinations with antimicrobial agents already used clinically. PMID:24232668

  2. Antibacterial activity of plant extracts from Brazilian southeast region.

    PubMed

    Oliveira, Denilson F; Pereira, Aline C; Figueiredo, Henrique C P; Carvalho, Douglas A; Silva, Greiciele; Nunes, Alexandro S; Alves, Dejane S; Carvalho, Hudson W P

    2007-02-01

    A screening was conducted with 26 plants collected in the Brazilian southeast region, to identify plant extracts with antibacterial properties against Aeromonas hydrophila, Bacillus subtilis, Pseudomonas aeruginosa and Staphylococcus aureus. Initially, the agar diffusion method was employed. Then, those extracts presenting activity were submitted to a broth microdilution assay to determine the minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC). It was observed that 13 of the tested extracts showed antibacterial activity. The best results were obtained with those from Lantana lilacina and Phyllanthus tenellus. PMID:17169500

  3. Synthesis, characterization, X-ray crystal structure, DFT calculation and antibacterial activities of new vanadium(IV, V) complexes containing chelidamic acid and novel thiourea derivatives.

    PubMed

    Farzanfar, Javad; Ghasemi, Khaled; Rezvani, Ali Reza; Delarami, Hojat Samareh; Ebrahimi, Ali; Hosseinpoor, Hona; Eskandari, Amir; Rudbari, Hadi Amiri; Bruno, Giuseppe

    2015-06-01

    Three new thiourea ligands derived from the condensation of aroyl- and aryl-isothiocyanate derivatives with 2,6-diaminopyridine, named 1,1'-(pyridine-2,6-diyl)bis(3-(benzoyl)thiourea) (L1), 1,1'-(pyridine-2,6-diyl)bis(3-(2-chlorobenzoyl)thiourea) (L2) and 1,1'-(pyridine-2,6-diyl)bis(3-(4-chlorophenyl)thiourea) (L3), their oxido-vanadium(IV) complexes, namely [VO(L1('))(H2O)] (C1), [VO(L2('))(H2O)] (C2) and [VO(L3('))(H2O)] (C3), and also, dioxo-vanadium(V) complex containing 4-hydroxy-2,6-pyridine dicarboxylic acid (chelidamic acid, H2dipic-OH) and metformin (N,N-dimethylbiguanide, Met), named [H2Met][VO2(dipic-OH)]2·H2O (C4), were synthesized and characterized by elemental analysis, FTIR and (1)H NMR and UV-visible spectroscopies. Proposed structures for free thiourea ligands and their vanadium complexes were corroborated by applying geometry optimization and conformational analysis. Solid state structure of complex [H2Met][VO2(dipic-OH)]2·H2O (triclinic, P?) was fully determined by single crystal X-ray diffraction analysis. In this complex, metformin is double protonated and acted as counter ion. The antibacterial properties of these compounds were investigated in vitro against standard Gram-positive and Gram-negative bacterial strains. The experiments showed that vanadium(IV) complexes had the superior antibacterial activities than novel thiourea derivatives and vanadium(V) complex against all Gram-positive and Gram-negative bacterial strains. PMID:25770009

  4. In vitro antibacterial activity of Tabernaemontana alternifolia (Roxb) stem bark aqueous extracts against clinical isolates of methicillin resistant Staphylococcus aureus

    PubMed Central

    2013-01-01

    Background The rise of antibiotic resistance among methicillin resistant Staphylococcus aureus (MRSA), have caused concerns for the treatment of MRSA infections. Hence, search for an alternative therapy for these infections is inevitable. Folk Indian medicine refers to the use of leaf and stem bark powder of Tabernaemontana alternifolia (Roxb) in treatment of skin infections, but no scientific report establishes its antibacterial activity. Methods Direct aqueous extracts and sequential aqueous extracts of the stem bark of T. alternifolia (using petroleum ether and ethyl acetate as other solvents) were prepared by soxhlet extraction. The antibiotic sensitivity profiles of the clinical isolates were determined against 18 antibiotics using disc diffusion method. The isolates were identified by 16S rRNA gene sequencing. The methicillin resistance among S. aureus (MRSA) was confirmed by PCR amplification of mecA gene. The disc diffusion method was used to determine the antibacterial activity of the extracts. The micro-dilution method was used to determine the minimum inhibitory concentration (MIC) of the extract against the test organism. To further evaluate the therapeutic potential of the extract, cell cytotoxicity was checked on Vero cells by MTT assay. Chemical profiling of the extract was done by HPTLC method. Results The aqueous extracts of T. alternifolia stem bark exhibited antibacterial activity against Gram-positive microorganisms, particularly against clinical isolates of MRSA and vancomycin resistant S. aureus (VRSA). The minimum inhibitory concentration (MIC) of extract against the isolates ranged from 600–800 ?g/ml. The extract did not exhibit cytotoxic activity against Vero cells even at the concentration of 4 mg/ml. The chemical profiling revealed presence of alkaloids, flavonoids, coumarins, saponins and steroids. Petroleum ether and ethyl acetate extracts did not exhibit antibacterial activity. Conclusion Our results offer a scientific basis for the traditional use of T. alternifolia in the treatment of skin infections, showing that the plant extract has an enormous potential as a prospective alternative therapy against MRSA skin infections. The present study lays the basis for future studies, to validate the possible use of T. alternifolia as a candidate in the treatment of MRSA infections. PMID:24066905

  5. Oligopolyphenylenevinylene-conjugated oligoelectrolyte membrane insertion molecules selectively disrupt cell envelopes of Gram-positive bacteria.

    PubMed

    Hinks, Jamie; Poh, Wee Han; Chu, Justin Jang Hann; Loo, Joachim Say Chye; Bazan, Guillermo C; Hancock, Lynn E; Wuertz, Stefan

    2015-03-01

    The modification of microbial membranes to achieve biotechnological strain improvement with exogenous small molecules, such as oligopolyphenylenevinylene-conjugated oligoelectrolyte (OPV-COE) membrane insertion molecules (MIMs), is an emerging biotechnological field. Little is known about the interactions of OPV-COEs with their target, the bacterial envelope. We studied the toxicity of three previously reported OPV-COEs with a selection of Gram-negative and Gram-positive organisms and demonstrated that Gram-positive bacteria are more sensitive to OPV-COEs than Gram-negative bacteria. Transmission electron microscopy demonstrated that these MIMs disrupt microbial membranes and that this occurred to a much greater degree in Gram-positive organisms. We used a number of mutants to probe the nature of MIM interactions with the microbial envelope but were unable to align the membrane perturbation effects of these compounds to previously reported membrane disruption mechanisms of, for example, cationic antimicrobial peptides. Instead, the data support the notion that OPV-COEs disrupt microbial membranes through a suspected interaction with diphosphatidylglycerol (DPG), a major component of Gram-positive membranes. The integrity of model membranes containing elevated amounts of DPG was disrupted to a greater extent by MIMs than those prepared from Escherichia coli total lipid extracts alone. PMID:25576607

  6. Transformations of the gram-positive honey bee pathogen, Paenibacillus larvae, by electroporation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In this study we developed an electrotransformation method for use with the Gram-positive bacterium Paenibacillus larvae—a deadly pathogen of honey bees. The method is substantially different from the only other electroporation method for a Paenibacillus species found in the literature. Using the ty...

  7. Identification of Surprisingly Diverse Type IV Pili, across a Broad Range of Gram-Positive Bacteria

    PubMed Central

    Roos, David S.; Pohlschröder, Mechthild

    2011-01-01

    Background In Gram-negative bacteria, type IV pili (TFP) have long been known to play important roles in such diverse biological phenomena as surface adhesion, motility, and DNA transfer, with significant consequences for pathogenicity. More recently it became apparent that Gram-positive bacteria also express type IV pili; however, little is known about the diversity and abundance of these structures in Gram-positives. Computational tools for automated identification of type IV pilins are not currently available. Results To assess TFP diversity in Gram-positive bacteria and facilitate pilin identification, we compiled a comprehensive list of putative Gram-positive pilins encoded by operons containing highly conserved pilus biosynthetic genes (pilB, pilC). A surprisingly large number of species were found to contain multiple TFP operons (pil, com and/or tad). The N-terminal sequences of predicted pilins were exploited to develop PilFind, a rule-based algorithm for genome-wide identification of otherwise poorly conserved type IV pilins in any species, regardless of their association with TFP biosynthetic operons (http://signalfind.org). Using PilFind to scan 53 Gram-positive genomes (encoding >187,000 proteins), we identified 286 candidate pilins, including 214 in operons containing TFP biosynthetic genes (TBG+ operons). Although trained on Gram-positive pilins, PilFind identified 55 of 58 manually curated Gram-negative pilins in TBG+ operons, as well as 53 additional pilin candidates in operons lacking biosynthetic genes in ten species (>38,000 proteins), including 27 of 29 experimentally verified pilins. False positive rates appear to be low, as PilFind predicted only four pilin candidates in eleven bacterial species (>13,000 proteins) lacking TFP biosynthetic genes. Conclusions We have shown that Gram-positive bacteria contain a highly diverse set of type IV pili. PilFind can be an invaluable tool to study bacterial cellular processes known to involve type IV pilus-like structures. Its use in combination with other currently available computational tools should improve the accuracy of predicting the subcellular localization of bacterial proteins. PMID:22216142

  8. Modified bamboo rayon-copper nanoparticle composites as antibacterial textiles.

    PubMed

    Teli, M D; Sheikh, Javed

    2013-10-01

    In the current study the bamboo rayon fabric grafted with acrylamide was utilized as a backbone to immobilize copper nanoprticles. The grafted bamboo rayon was first treated with CuSO4 followed by chemical reduction. The modified product was characterized using FTIR, TGA and SEM. The characteristic color developed after reduction was measured spectrophotometrically. The grafted bamboo rayon with Cu nanoparticles was then evaluated for antibacterial activity against both gram positive and gram negative bacteria and the durability of their antibacterial activity after washing. The product showed antibacterial activity against both types of bacterias which was found to be durable till 50 washes. The material can be claimed as suitable candidate for medical textile applications to prevent cross-infections. PMID:23916646

  9. Antibacterial Labdane Diterpenoids from Vitex vestita.

    PubMed

    Corlay, Nina; Lecsö-Bornet, Marylin; Leborgne, Erell; Blanchard, Florent; Cachet, Xavier; Bignon, Jérôme; Roussi, Fanny; Butel, Marie-Jose; Awang, Khalijah; Litaudon, Marc

    2015-06-26

    A large-scale in vitro screening of tropical plants using an antibacterial assay permitted the selection of several species with significant antibacterial activities. Bioassay-guided purification of the dichloromethane extract of the leaves of the Malaysian species Vitex vestita, led to the isolation of six new labdane-type diterpenoids, namely, 12-epivitexolide A (2), vitexolides B and C (3 and 4), vitexolide E (8), and vitexolins A and B (5 and 6), along with six known compounds, vitexolides A (1) and D (7), acuminolide (9), 3?-hydroxyanticopalic acid (10), 8?-hydroxyanticopalic acid (11), and 6?-hydroxyanticopalic acid (12). Their structures were elucidated on the basis of 1D and 2D NMR analyses and HRMS experiments. Both variable-temperature NMR spectroscopic studies and chemical modifications were performed to investigate the dynamic epimerization of the ?-hydroxybutenolide moiety of compounds 1-4. Compounds were assayed against a panel of 46 Gram-positive strains. Vitexolide A (1) exhibited the most potent antibacterial activity with minimal inhibitory concentration values ranging from 6 to 96 ?M, whereas compounds 2 and 6-9 showed moderate antibacterial activity. The presence of a ?-hydroxyalkyl-?-hydroxybutenolide subunit contributed significantly to antibacterial activity. Compounds 1-4 and 6-9 showed cytotoxic activities against the HCT-116 cancer cell line (1 < IC50s < 10 ?M) and human fetal lung fibroblast MRC5 cell line (1 < IC50s < 10 ?M for compounds 1, 2, 7, 8, and 9). PMID:26034885

  10. Enhancement of bismuth antibacterial activity with lipophilic thiol chelators.

    PubMed Central

    Domenico, P; Salo, R J; Novick, S G; Schoch, P E; Van Horn, K; Cunha, B A

    1997-01-01

    The antibacterial properties of bismuth are greatly enhanced when bismuth is combined with certain lipophilic thiol compounds. Antibacterial activity was enhanced from 25- to 300-fold by the following seven different thiols, in order of decreasing synergy: 1,3-propanedithiol, dimercaprol (BAL), dithiothreitol, 3-mercapto-2-butanol, beta-mercaptoethanol, 1-monothioglycerol, and mercaptoethylamine. The dithiols produced the greatest synergy with bismuth at optimum bismuth-thiol molar ratios of from 3:1 to 1:1. The monothiols were generally not as synergistic and required molar ratios of from 1:1 to 1:4 for optimum antibacterial activity. The most-active mono- or dithiols were also the most soluble in butanol. The intensity of the yellow formed by bismuth-thiol complexes reflected the degree of chelation and correlated with antibacterial potency at high molar ratios. The bismuth-BAL compound (BisBAL) was active against most bacteria, as assessed by broth dilution, agar diffusion, and agar dilution analyses. Staphylococci (MIC, 5 to 7 microM Bi3+) and Helicobacter pylori (MIC, 2.2 microM) were among the most sensitive bacteria. Gram-negative bacteria were sensitive (MIC, < 17 microM). Enterococci were relatively resistant (MIC, 63 microM Bi3+). The MIC range for anaerobes was 15 to 100 microM Bi3+, except for Clostridium difficile (MIC, 7.5 microM). Bactericidal activity averaged 29% above the MIC. Bactericidal activity increased with increasing pH and/or increasing temperature. Bismuth-thiol solubility, stability, and antibacterial activity depended on pH and the bismuth-thiol molar ratio. BisBAL was stable but ineffective against Escherichia coli at pH 4. Activity and instability (reactivity) increased with increasing alkalinity. BisBAL was acid soluble at a molar ratio of greater than 3:2 and alkaline soluble at a molar ratio of less than 2:3. In conclusion, certain lipophilic thiol compounds enhanced bismuth antibacterial activity against a broad spectrum of bacteria. The activity, solubility, and stability of BisBAL were strongly dependent on the pH, temperature, and molar ratio. Chelation of bismuth with certain thiol agents enhanced the solubility and lipophilicity of this cationic heavy metal, thereby significantly enhancing its potency and versatility as an antibacterial agent. PMID:9257744

  11. Antibacterial activity of Lawsonia inermis Linn (Henna) against Pseudomonas aeruginosa

    PubMed Central

    Habbal, O; Hasson, SS; El-Hag, AH; Al-Mahrooqi, Z; Al-Hashmi, N; Al-Bimani, Z; Al-Balushi, MS; Al-Jabri, AA

    2011-01-01

    Objective To investigate the antibacterial activity of henna (Lawsonia inermis Linn) obtained from different regions of Oman against a wide array of micro-organisms. Methods Fresh henna samples were obtained from different regions of Oman as leaves and seeds. 100 g fresh and dry leaves and 50 g of fresh and dry seeds were separately soaked in 500 mL of ethanol for three days, respectively, with frequent agitation. The mixture was filtered, and the crude extract was collected. The crude extract was then heated, at 48 °C in a water bath to evaporate its liquid content. The dry crude henna extract was then tested for its antibacterial activity using well-diffusion antibiotic susceptibility technique. Henna extracts were investigated for their antibacterial activity at different concentrations against a wide array of different micro-organisms including a laboratory standard bacterial strain of Pseudomonas aeruginosa (NCTC 10662) (P. aeruginosa) and eleven fresh clinical isolates of P. aeruginosa obtained from patients attending the Sultan Qaboos University Hospital (SQUH). 2-Hydroxy-p-Nathoqinone-Tech (2-HPNT, MW=174.16, C10H6O3) was included as control (at 50% concentration) along with the henna samples tested. Results Henna samples demonstrated antibacterial activity against all isolates but the highest susceptibility was against P. aeruginosa with henna samples obtained from Al-sharqyia region. Conclusions Omani henna from Al-sharqyia region demonstrates high in vitro anti-P. aeruginosa activity compared with many henna samples from different regions of Oman. PMID:23569753

  12. Functional and structural insights on self-assembled nanofiber-based novel antibacterial ointment from antimicrobial peptides, bacitracin and gramicidin S.

    PubMed

    Mandal, Santi M; Roy, Anupam; Mahata, Denial; Migliolo, Ludovico; Nolasco, Diego O; Franco, Octavio L

    2014-11-01

    A novel antibacterial ointment using bacitracin, specific for Gram-positive bacteria, and gramicidin S, a highly toxic antibacterial peptide, was here developed showing broad-spectrum antibacterial activities against pathogenic strains with less toxicity after self-assembly into nanofiber structures. Such structures were confirmed with scanning electron microscopy and CD analyses. In addition, in silico studies using docking associated with molecular dynamics were carried out to obtain information about fiber structural oligomerization. Thus, the bacitracin and gramicidin S-based self-assembled nanopeptide ribbon may be a successful ointment formulation for bacterial infection control. PMID:24894183

  13. Antibacterial activity of northern Ontario medicinal plant extracts

    E-print Network

    Qin, Wensheng

    University, 955 Oliver Road, Thunder Bay, Ontario, Canada P7B 5E1; and 2 Department of Chemistry, Lakehead University, 955 Oliver Road, Thunder Bay, Ontario Canada P7B 5E1. Received 7 August 2013, accepted 19. 94: 417Á424. In the present study, the antibacterial activity (in vitro) of the leaf and/or flower

  14. Antibacterial Activity of Fullerene Water Suspensions: Effects of

    E-print Network

    Alvarez, Pedro J.

    Antibacterial Activity of Fullerene Water Suspensions: Effects of Preparation Method and Particle and Department of Chemistry, Rice University, Houston, Texas 77005 Fullerene research in biological systems has to aggregate, forming stable fullerene water suspensions (FWS) whose properties differ from those of bulk solid

  15. Negligible Particle-Specific Antibacterial Activity of Silver Nanoparticles

    E-print Network

    Alvarez, Pedro J.

    -spectrum antimicrobial agent, silver nano- particles (AgNPs) are currently the most widely commercialized nanomaterial.1 of silver ions from the crystalline core of silver nanoparticles contribute to the toxicityNegligible Particle-Specific Antibacterial Activity of Silver Nanoparticles Zong-ming Xiu, Qing

  16. Antibacterial potential of garlic-derived allicin and its cancellation by sulfhydryl compounds.

    PubMed

    Fujisawa, Hiroyuki; Watanabe, Kazuhiro; Suma, Kaoru; Origuchi, Kana; Matsufuji, Hiroshi; Seki, Taiichiro; Ariga, Toyohiko

    2009-09-01

    Allicin (allyl 2-propenethiosulfinate), an antibacterial principle of garlic, has drawn much attention, since it has potent antimicrobial activity against a range of microorganisms, including methicillin-resistant Staphylococcus aureus. There have been many reports on the antibacterial properties of allicin, but no quantitative comparison of antibacterial activities between freshly prepared garlic extract and clinically useful antibiotics has been performed. To verify the substantial antibacterial effect of aqueous garlic extract, we compared it with those of allicin and several clinically useful antibiotics using two representative bacteria commonly found in the human environment, Gram-positive S. aureus and Gram-negative Escherichia coli. The garlic extract had more potent anti-staphylococcal activity than an equal amount of allicin. In terms of antibiotic potency against Gram-positive and Gram-negative bacteria, authentic allicin had roughly 1-2% of the potency of streptomycin (vs. S. aureus), 8% of that of vancomycin (vs. S. aureus), and only 0.2% of that of colistin (vs. E. coli). The antibacterial activity of allicin was completely abolished by cysteine, glutathione and coenzyme A, but not by non-SH-compounds. The oxygen in the structure (-S(=O)-S-) of allicin therefore functions to liberate the S-allyl moiety, which might be an offensive tool against bacteria. PMID:19734685

  17. Antibacterial, antifungal and antioxidant activities of honey collected from Timergara (Dir, Pakistan).

    PubMed

    Zahoor, Muhammad; Naz, Sumaira; Sangeen, Muhammad

    2014-01-01

    In this study honeys of Acacia modesta, Prunus persica, Zizyphus sativa and Isodon rogosus plants were tested against two Gram-positive bacterial strains (Staphylococcus aureus and Bacillus cereus), two Gram-negative bacterial strains (Klebsilla pneumonia and Escherichia coli) and two fungal strains (Alternaria alternata and Trichoderma harzianum) through Agar well diffusion method. The tested honeys showed high antimicrobial activities to the tested bacterial and fungal strains. All the tested honeys were more active against Gram-negative bacterial strains than the Gram-positive bacterial strains. They showed lower activity against the tested fungal strains as compared to all the tested bacterial strains. The given honeys showed free radical scavenging activity also. PMID:24374434

  18. Green synthesis of silver/montmorillonite/chitosan bionanocomposites using the UV irradiation method and evaluation of antibacterial activity

    PubMed Central

    Shameli, Kamyar; Ahmad, Mansor Bin; Yunus, Wan Md Zin Wan; Rustaiyan, Abdolhossein; Ibrahim, Nor Azowa; Zargar, Mohsen; Abdollahi, Yadollah

    2010-01-01

    In this study, silver nanoparticles (Ag-NPs) were synthesized using a green physical synthetic route into the lamellar space of montmorillonite (MMT)/chitosan (Cts) utilizing the ultraviolet (UV) irradiation reduction method in the absence of any reducing agent or heat treatment. Cts, MMT, and AgNO3 were used as the natural polymeric stabilizer, solid support, and silver precursor, respectively. The properties of Ag/MMT/Cts bionanocomposites (BNCs) were studied as the function of UV irradiation times. UV irradiation disintegrated the Ag-NPs into smaller sizes until a relatively stable size and size distribution were achieved. Meanwhile, the crystalline structure and d-spacing of the MMT interlayer, average size and size distribution, surface morphology, elemental signal peaks, functional groups, and surface plasmon resonance of Ag/MMT/Cts BNCs were determined by powder X-ray diffraction, transmission electron microscopy, scanning electron microscopy, energy dispersive X-ray fluorescence, Fourier transform infrared, and UV-visible spectroscopy. The antibacterial activity of Ag-NPs in MMT/Cts was investigated against Gram-positive bacteria, ie, Staphylococcus aureus and methicillin-resistant S. aureus and Gram-negative bacteria (ie, Escherichia coli) by the disk diffusion method on Muller–Hinton Agar at different sizes of Ag-NPs. All of the synthesized Ag/MMT/Cts BNCs were found to have high antibacterial activity. These results show that Ag/MMT/Cts BNCs can be useful in different biologic research and biomedical applications, such as surgical devices and drug delivery vehicles. PMID:21116328

  19. Synthesis and characterization of silver/montmorillonite/chitosan bionanocomposites by chemical reduction method and their antibacterial activity

    PubMed Central

    Shameli, Kamyar; Ahmad, Mansor Bin; Zargar, Mohsen; Yunus, Wan Md Zin Wan; Ibrahim, Nor Azowa; Shabanzadeh, Parvaneh; Moghaddam, Mansour Ghaffari

    2011-01-01

    Silver nanoparticles (AgNPs) of a small size were successfully synthesized using the wet chemical reduction method into the lamellar space layer of montmorillonite/chitosan (MMT/Cts) as an organomodified mineral solid support in the absence of any heat treatment. AgNO3, MMT, Cts, and NaBH4 were used as the silver precursor, the solid support, the natural polymeric stabilizer, and the chemical reduction agent, respectively. MMT was suspended in aqueous AgNO3/Cts solution. The interlamellar space limits were changed (d-spacing = 1.24–1.54 nm); therefore, AgNPs formed on the interlayer and external surface of MMT/Cts with d-average = 6.28–9.84 nm diameter. Characterizations were done using different methods, ie, ultraviolet-visible spectroscopy, powder X-ray diffraction, transmission electron microscopy, scanning electron microscopy, energy dispersive X-ray fluorescence spectrometry, and Fourier transform infrared spectroscopy. Silver/montmorillonite/chitosan bionanocomposite (Ag/MMT/Cts BNC) systems were examined. The antibacterial activity of AgNPs in MMT/Cts was investigated against Gram-positive bacteria, ie, Staphylococcus aureus and methicillin-resistant S. aureus and Gram-negative bacteria, ie, Escherichia coli, E. coli O157:H7, and Pseudomonas aeruginosa by the disc diffusion method using Mueller Hinton agar at different sizes of AgNPs. All of the synthesized Ag/MMT/Cts BNCs were found to have high antibacterial activity. These results show that Ag/MMT/Cts BNCs can be useful in different biological research and biomedical applications, including surgical devices and drug delivery vehicles. PMID:21499424

  20. Antibacterial gold nanoparticles-biomass assisted synthesis and characterization.

    PubMed

    Badwaik, Vivek D; Willis, Chad B; Pender, Dillon S; Paripelly, Rammohan; Shah, Monic; Kherde, Yogesh A; Vangala, Lakshmisri M; Gonzalez, Matthew S; Dakshinamurthy, Rajalingam

    2013-10-01

    Xylose is a natural monosaccharide found in biomass such as straw, pecan shells, cottonseed hulls, and corncobs. Using this monosaccharide, we report the facile, green synthesis and characterization of stable xylose encapsulated gold nanoparticles (Xyl-GNPs) with potent antibacterial activity. Xyl-GNPs were synthesized using the reduction property of xylose in an aqueous solution containing choloraurate anions carried out at room temperature and atmospheric pressure. These nanoparticles were stable and near spherical in shape with an average diameter of 15 +/- 5 nm. Microbiological assay results showed the concentration dependent antibacterial activity of these particles against both Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus epidermidis) bacteria. Thus the facile, environmentally friendly Xyl-GNPs have many potential applications in chemical and biomedical industries, particularly in the development of antibacterial agents in the field of biomedicine. PMID:24015501

  1. Susceptibilities of 428 gram-positive and -negative anaerobic bacteria to Bay y3118 compared with their susceptibilities to ciprofloxacin, clindamycin, metronidazole, piperacillin, piperacillin-tazobactam, and cefoxitin.

    PubMed

    Pankuch, G A; Jacobs, M R; Appelbaum, P C

    1993-08-01

    The susceptibilities of 428 gram-negative and gram-positive anaerobes (including selected cefoxitin-resistant strains) to Bay y3118 (a new fluoroquinolone), ciprofloxacin, clindamycin, metronidazole, cefoxitin, piperacillin, and piperacillin-tazobactam were tested. Organisms comprised 115 Bacteroides fragilis group, 116 non-B. fragilis Bacteroides, Prevotella, and Porphyromonas spp., 40 fusobacteria, 58 peptostreptococci, 48 gram-positive non-spore-forming rods, and 51 clostridia. beta-Lactamase production was demonstrated in 87% of the gram-negative rods but in none of the gram-positive organisms. Overall, Bay y3118 was the most active agent, with all organisms inhibited at an MIC of < or = 2.0 micrograms/ml (MICs for 50% [MIC50] and 90% [MIC90] of strains tested, 0.125 and 0.5 microgram/ml, respectively). By contrast, ciprofloxacin was much less active, with only 42% of strains susceptible at a breakpoint of 2.0 micrograms/ml (MIC50, 4.0 micrograms/ml; MIC90, 16.0 micrograms/ml). Metronidazole was active against all gram-negative rods, but 7% of peptostreptococci, 83% of gram-positive non-spore-forming rods, and 4% of non-Clostridium perfringens, non-Clostridium difficile clostridia were resistant to this agent (MICs, > 16.0 micrograms/ml). Clindamycin was active against 94% of Bacteroides, Prevotella, and Porphyromonas spp., 91% of peptostreptococci, and 100% of gram-positive non-spore-forming rods, but was active against only 70% of fusobacteria and 53% of clostridia. Cefoxitin was active against > or = 90% of all groups except the B. fragilis group and non-Propionibacterium acnes gram-positive non-spore-forming rods (both 85%) and C. difficile (20%). Significant enhancement of piperacillin by tazobactam was seen in all beta-lactamase-positive strains (99% susceptible; MIC90, 8.0 micrograms/ml), and all beta-lactamase-negative strains were susceptible to piperacillin (MIC90, 8.0 micrograms/ml). Clinical studies are required to delineate the role of Bay y3118 in the treatment of anaerobic infections. PMID:8215278

  2. Extracellular biosynthesis of CdTe quantum dots by the fungus Fusarium oxysporum and their anti-bacterial activity

    NASA Astrophysics Data System (ADS)

    Syed, Asad; Ahmad, Absar

    2013-04-01

    The growing demand for semiconductor [quantum dots (Q-dots)] nanoparticles has fuelled significant research in developing strategies for their synthesis and characterization. They are extensively investigated by the chemical route; on the other hand, use of microbial sources for biosynthesis witnessed the highly stable, water dispersible nanoparticles formation. Here we report, for the first time, an efficient fungal-mediated synthesis of highly fluorescent CdTe quantum dots at ambient conditions by the fungus Fusarium oxysporum when reacted with a mixture of CdCl2 and TeCl4. Characterization of these biosynthesized nanoparticles was carried out by different techniques such as Ultraviolet-visible (UV-Vis) spectroscopy, Photoluminescence (PL), X-ray Diffraction (XRD), X-ray Photoelectron spectroscopy (XPS), Transmission Electron Microscopy (TEM) and Fourier Transformed Infrared Spectroscopy (FTIR) analysis. CdTe nanoparticles shows antibacterial activity against Gram positive and Gram negative bacteria. The fungal based fabrication provides an economical, green chemistry approach for production of highly fluorescent CdTe quantum dots.

  3. Tunable ZnO spheres with high anti-biofilm and antibacterial activity via a simple green hydrothermal route.

    PubMed

    Patrinoiu, Greta; Calderón-Moreno, José Maria; Chifiriuc, Carmen Mariana; Saviuc, Crina; Birjega, Ruxandra; Carp, Oana

    2016-01-15

    A family of distinct ZnO morphologies - hollow, compartmented, core-shell and full solid ZnO spheres, dispersed or interconnected - is obtained by a simple hydrothermal route, in the presence of the starch biopolymer. The zinc-carbonaceous precursors were characterized by infrared spectroscopy, thermal analysis and scanning electron microscopy, while the ZnO spheres, obtained after the thermal processing, were investigated by X-ray diffraction, Raman spectroscopy, scanning electron microscopy, UV-VIS spectroscopy, photoluminescence measurements, antimicrobial, anti-biofilm and flow cytometry tests. The formation mechanism proposed for this versatile synthesis route is based on the gelling ability of amylose, one of the starch template constituents, responsible for the effective embedding of zinc cations into starch prior to its hydrothermal carbonization. The simple variation of the raw materials concentration dictates the type of ZnO spheres. The micro-sized ZnO spheres exhibit high antibacterial and anti-biofilm activity against Gram-positive (Staphylococcus aureus, Bacillus subtilis) and Gram-negative (Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa) reference and methicillin resistant clinical strains especially for Gram-negative biofilms (P. aeruginosa), demonstrating great potential for new ZnO anti-biofilm formulations. PMID:26433479

  4. Antimicrobial activity of the carnivorous plant Dionaea muscipula against food-related pathogenic and putrefactive bacteria.

    PubMed

    Ogihara, Hirokazu; Endou, Fumiko; Furukawa, Soichi; Matsufuji, Hiroshi; Suzuki, Kouichi; Anzai, Hiroshi

    2013-01-01

    Solvent extracts from the carnivorous plant Dionaea muscipula (Venus flytrap) were prepared using eight different organic solvents, and examined for antibacterial activity against food-related pathogenic and putrefactive bacteria. All solvent extracts showed higher antibacterial activity against gram positive bacteria than against gram negative bacteria. The TLC-bioautography analysis of the extracts revealed that a yellow spot was detected at Rf value of 0.85, which showed strong antibacterial activity. The UV, MS, and NMR analyses revealed that the antibacterial compound was plumbagin. PMID:24077538

  5. Antibacterial activity of Nymphaea nouchali (Burm. f) flower

    PubMed Central

    2013-01-01

    Background The present work aimed to find out the antibacterial activity of Nymphaea nouchali flower on human and plant pathogenic bacteria. Methods Antibacterial potency of methanol, acetone, ethyl acetate and petroleum spirit extracts of Nymphaea nouchali flower has been tested against four human pathogenic bacteria Bacillus subtilis (FO 3026) Escherichia coli (IFO 3007), Klebsiella pneumonia (ATTC 10031) and Sarcina lutea (IFO 3232) and one plant pathogenic bacterium Xanthomonas campestris (IAM 1671) by disc diffusion assay. Zone of inhibition produced by different extracts against the test bacteria was measured and compared with standard antibiotic disc. Results Methanol extract possessed better antibacterial activity against two pathogenic bacteria, B. subtilis (FO 3026) and S. lutea (IFO 3232) than commercial antibiotic nalidixic acid. Acetone extract showed moderate sensitivity whereas B. subtilis (FO 3026), S. lutea (IFO 3232) and X. campestris (IAM 1671) showed resistance to ethyl acetate and petroleum spirit extracts. The minimum inhibitory concentrations of various extracts were ranged between 128–2048 ?gml-1. Conclusions Nymphaea nouchali flower could be a potential candidate for future development of novel broad spectrum antibacterial herbal formulation. PMID:24099586

  6. Evaluation of the antibacterial activity of patchouli oil.

    PubMed

    Yang, Xian; Zhang, Xue; Yang, Shui-Ping; Liu, Wei-Qi

    2013-01-01

    In the present study, the antimicrobial tests of patchouli oil were studied by using molecular docking technology and antimicrobial test in vitro. Five biological macromolecule enzymes, required by the bacteria in the process of biosynthesis were selected as target molecules. Five antibiotics benzylpenicillin, sulfadiazine, trimethoprim, rifampicin and ciprofloxacin, which are generally acknowledged as antibacterial drugs, were selected as reference compounds. The 3 three-dimensional (3D) structures of the 5 reference compounds and 26 compounds from patchouli oil were established by using surflex-dock software (8.1). And the 3D structures of five biological macromolecule enzymes derived from Protein Data Bank (PDB). Molecular docking was carried out between the 31 chemical compounds (ligands) and the 5 enzymes (receptors) by using surflex-dock function. Furthermore, the antibacterial effects of 31 chemical compounds were investigated by the scoring function after molecular docking was completed. By comparing the scoring result of 26 compounds in patchouli oil with 5 compared components, we inferred antibacterial activity in about 26 compounds in patchouli oil. On the other hand, six frequently-used pathogenic bacteria were selected for antimicrobial test in vitro, patchouli oil and its two major compounds: (-)-patchouli alcohol and pogostone, which their contents exceeded 60% in patchouli oil samples, were selected antibacterial agents. Minimum inhibitory concentration (MIC) and Minimum bactericidal concentration (MBC) were also determined. Molecular docking technology and antimicrobial test in vitro proved that patchouli oil had strong antimicrobial effects. Particularly, pogostone and (-)-patchouli alcohol have potent antimicrobial activity. PMID:24250637

  7. Antimycobacterial and Antibacterial Activity of Allium sativum Bulbs

    PubMed Central

    Viswanathan, V.; Phadatare, A. G.; Mukne, Alka

    2014-01-01

    Tuberculosis is one of the major public health problems faced globally. Resistance of Mycobacterium tuberculosis to antitubercular agents has called for an urgent need to investigate newer drugs to combat tuberculosis. Garlic (Allium sativum) is an edible plant which has generated a lot of curiosity throughout human history as a medicinal plant. Garlic contains sulfur compounds like allicin, ajoene, allylmethyltrisulfide, diallyltrisulfide, diallyldisulphide and others which exhibit various biological properties like antimicrobial, anticancer, antioxidant, immunomodulatory, antiinflammatory, hypoglycemic, and cardiovascular effects. According to various traditional systems of medicine, garlic is one of the established remedies for tuberculosis. The objective of the current study was to investigate in vitro antimycobacterial activity as well as anti-bacterial activity of various extracts rich in specific phytoconstituents from garlic. Preparation of garlic extracts was done based on the chemistry of the constituents and their stability. The estimation of in vitro antimycobacterial activity of different garlic extracts was done using Resazurin microtire plate assay technique whereas activity of garlic oil was evaluated by colony count method. The antibacterial activity of extracts and oil was estimated by zone of inhibition method. Extracts of garlic rich in allicin and ajoene showed appreciable antimycobacterial activity as compared to standard drugs. Garlic oil demonstrated significant antibacterial activity, particularly against methicillin-resistant Staphylococcus aureus. PMID:25035540

  8. Antimycobacterial and Antibacterial Activity of Allium sativum Bulbs.

    PubMed

    Viswanathan, V; Phadatare, A G; Mukne, Alka

    2014-05-01

    Tuberculosis is one of the major public health problems faced globally. Resistance of Mycobacterium tuberculosis to antitubercular agents has called for an urgent need to investigate newer drugs to combat tuberculosis. Garlic (Allium sativum) is an edible plant which has generated a lot of curiosity throughout human history as a medicinal plant. Garlic contains sulfur compounds like allicin, ajoene, allylmethyltrisulfide, diallyltrisulfide, diallyldisulphide and others which exhibit various biological properties like antimicrobial, anticancer, antioxidant, immunomodulatory, antiinflammatory, hypoglycemic, and cardiovascular effects. According to various traditional systems of medicine, garlic is one of the established remedies for tuberculosis. The objective of the current study was to investigate in vitro antimycobacterial activity as well as anti-bacterial activity of various extracts rich in specific phytoconstituents from garlic. Preparation of garlic extracts was done based on the chemistry of the constituents and their stability. The estimation of in vitro antimycobacterial activity of different garlic extracts was done using Resazurin microtire plate assay technique whereas activity of garlic oil was evaluated by colony count method. The antibacterial activity of extracts and oil was estimated by zone of inhibition method. Extracts of garlic rich in allicin and ajoene showed appreciable antimycobacterial activity as compared to standard drugs. Garlic oil demonstrated significant antibacterial activity, particularly against methicillin-resistant Staphylococcus aureus. PMID:25035540

  9. When Ribonucleases Come into Play in Pathogens: A Survey of Gram-Positive Bacteria

    PubMed Central

    Jester, Brian C.; Romby, Pascale; Lioliou, Efthimia

    2012-01-01

    It is widely acknowledged that RNA stability plays critical roles in bacterial adaptation and survival in different environments like those encountered when bacteria infect a host. Bacterial ribonucleases acting alone or in concert with regulatory RNAs or RNA binding proteins are the mediators of the regulatory outcome on RNA stability. We will give a current update of what is known about ribonucleases in the model Gram-positive organism Bacillus subtilis and will describe their established roles in virulence in several Gram-positive pathogenic bacteria that are imposing major health concerns worldwide. Implications on bacterial evolution through stabilization/transfer of genetic material (phage or plasmid DNA) as a result of ribonucleases' functions will be covered. The role of ribonucleases in emergence of antibiotic resistance and new concepts in drug design will additionally be discussed. PMID:22550495

  10. Protein transport across the cell wall of monoderm Gram-positive bacteria

    PubMed Central

    Forster, Brian M.; Marquis, Hélène

    2012-01-01

    Summary In monoderm (single membrane) Gram-positive bacteria, the majority of secreted proteins are first translocated across the cytoplasmic membrane into the inner wall zone. For a subset of these proteins, final destination is within the cell envelope either as membrane-anchored or cell wall-anchored proteins, whereas another subset of proteins is destined to be transported across the cell wall into the extracellular milieu. Although the cell wall is a porous structure, there is evidence that, for some proteins, transport is a regulated process. This review aims at describing what is known about the mechanisms that regulate the transport of proteins across the cell wall of monoderm Gram-positive bacteria. PMID:22471582

  11. Cyclic-di-GMP signaling in the Gram-positive pathogen Clostridium difficile.

    PubMed

    Bordeleau, Eric; Burrus, Vincent

    2015-11-01

    The anaerobic Gram-positive bacterium Clostridium difficile causes intestinal infections responsible for symptoms ranging from mild diarrhea to fulminant colitis. Like other bacteria, C. difficile needs to sense and integrate environmental signals in order to adapt to changes and thrive in its environment. The second messenger cyclic diguanosine monophosphate (c-di-GMP) was recently recognized as a quasi-ubiquitous phenotype coordinator in bacteria. Mostly known to be involved in the transition from motile to sessile and multicellular behaviors in Gammaproteobacteria, c-di-GMP is now known to regulate many other phenotypes from cell morphogenesis to virulence, in many Gram-negative and a few Gram-positive bacteria. Herein, we review recent advances in our understanding of c-di-GMP signaling in the lifecycle of C. difficile. PMID:25800812

  12. Procalcitonin Levels in Gram-Positive, Gram-Negative, and Fungal Bloodstream Infections

    PubMed Central

    Ferranti, Marta; Moretti, Amedeo; Al Dhahab, Zainab Salim; Cenci, Elio; Mencacci, Antonella

    2015-01-01

    Procalcitonin (PCT) can discriminate bacterial from viral systemic infections and true bacteremia from contaminated blood cultures. The aim of this study was to evaluate PCT diagnostic accuracy in discriminating Gram-positive, Gram-negative, and fungal bloodstream infections. A total of 1,949 samples from patients with suspected bloodstream infections were included in the study. Median PCT value in Gram-negative (13.8?ng/mL, interquartile range (IQR) 3.4–44.1) bacteremias was significantly higher than in Gram-positive (2.1?ng/mL, IQR 0.6–7.6) or fungal (0.5?ng/mL, IQR 0.4–1) infections (P < 0.0001). Receiver operating characteristic analysis showed an area under the curve (AUC) for PCT of 0.765 (95% CI 0.725–0.805, P < 0.0001) in discriminating Gram-negatives from Gram-positives at the best cut-off value of 10.8?ng/mL and an AUC of 0.944 (95% CI 0.919–0.969, P < 0.0001) in discriminating Gram-negatives from fungi at the best cut-off of 1.6?ng/mL. Additional results showed a significant difference in median PCT values between Enterobacteriaceae and nonfermentative Gram-negative bacteria (17.1?ng/mL, IQR 5.9–48.5 versus 3.5?ng/mL, IQR 0.8–21.5; P < 0.0001). This study suggests that PCT may be of value to distinguish Gram-negative from Gram-positive and fungal bloodstream infections. Nevertheless, its utility to predict different microorganisms needs to be assessed in further studies. PMID:25852221

  13. Spectroscopic studies and antibacterial activities of some new 16-membered octaazamacrocyclic complexes derived from thiocarbohydrazide and pentane-2,4-dione

    NASA Astrophysics Data System (ADS)

    Singh, D. P.; Kumar, Krishan; Chopra, Rimpi Mehani ne'e.

    2011-02-01

    A series of macrocyclic complexes of the type [M(C 12H 20N 8S 2)X 2]; where M = Co(II), Ni(II), Cu(II), Zn(II); X = Cl -, NO 3-, CH 3COO - has been synthesized by template condensation of thiocarbohydrazide and pentane-2,4-dione in the presence of divalent metal salts in methanolic medium. The complexes have been characterized with the help of elemental analyses, conductance measurements, magnetic measurements, electronic, NMR, IR, EPR and MS spectral studies. The low value of molar conductance indicates them to be non-electrolytes. On the basis of various studies a distorted octahedral geometry may be proposed for all of these complexes. These metal complexes were also tested for their in vitro antibacterial activities against some Gram-positive bacterial strains, i.e., Bacillus subtilis, Bacillus stearothermophilus and two Gram-negative bacterial strains, i.e., Escherichia coli, Pseudomonas putida. The results obtained were compared with standard antibiotics, Chloramphenicol and Streptomycin and found that some of the synthesized complexes show good antibacterial activities as compared to the standard antibiotics.

  14. Employing carbon dots modified with vancomycin for assaying Gram-positive bacteria like Staphylococcus aureus.

    PubMed

    Zhong, Dan; Zhuo, Yan; Feng, Yuanjiao; Yang, Xiaoming

    2015-12-15

    By employing attractive performance of fluorescent carbon dots, we herein successfully established an assay for analyzing bacteria firstly. Specifically, carbon dots with blue fluorescence were initially synthesized according to a previous report, and modified with vancomycin on their surfaces. Subsequently, the prepared carbon dots were applied to detect Staphylococcus aureus accompanied with a linear range of 3.18×10(5)-1.59×10(8) cfu/mL as well as a detection limit of 9.40×10(4) cfu/mL. Compared with other regular methods, our method is more rapid and convenient in term of methodology. Meanwhile, the current strategy was applied for detection of other bacteria including Bacillus subtilis, Listeria monocytogenes, Salmonella, Pseudomonas aeruginosa and Escherichia coli, and the modified carbon dots showed obvious affinity with Gram-positive bacteria owing to the ligand-receptor interactions between vancomycin and the cell walls, suggesting its value for detecting Gram-positive bacteria. Additionally, the practicability of this sensing approach was validated by recovery experiments conducted in orange juice, confirming its potential to broaden avenues for detection of Gram-positive bacteria. PMID:26188677

  15. Antibacterial and antifungal activity of solvent extracts from Plumeria obtusa Linn.

    PubMed

    Ali, N; Junaid, M; Ahmad, D; urRahman, M; Ali, N; Katzenmeier, G

    2014-12-01

    Extracts of Plumeria obtusa are widely used in ethnomedicine and have been investigated for a variety of biological activities; however, the antimicrobial activity of P. obtusa flowers is poorly characterized. In this study, the antimicrobial activities of different solvents (petroleum ether, ethyl acetate, chloroform, isobutanol and ethanol) extracts from flowers of P. obtusa were investigated by a disc diffusion method against Gram-positive bacteria, Gram-negative bacteria and a fungus. All extracts exhibited growth inhibition of all microorganisms at variable degrees as measured by relative zones of inhibition, however, the petroleum ether extract was ineffective against Klebsiella pneumonia and ethyl acetate and isobutanol extracts were ineffective against Pseudomonas aeruginosa. The most susceptible Gram-positive bacterium was Bacillus subtilis while the most resistant Gram-positive bacterium was Staphylococcus aureus. Erwinia carotovora was the most susceptible Gram-negative bacterium while P. aeruginosa was highly resistant among the Gram-negative bacteria. In this study, for the first time, we investigated the antimicrobial activity of several different solvent extracts from flowers of P. obtusa against a broad spectrum of human-pathogenic microorganisms. These compounds warrant further investigation by isolation and structural elucidation with the aim to find novel and affordable bioactive compounds for the treatment of infectious diseases. PMID:25776586

  16. SK66-his, a novel glycine-rich peptide derived from Drosophila with antibacterial activity.

    PubMed

    Feng, Zhiguo; Liu, Huijuan; Lang, Jun; Li, Yanjiao; Shu, Muya; Chen, Zhengwang

    2009-03-23

    SK(66)-his, a novel glycine-rich peptide derived from the CG13551 gene of Drosophila, was directly expressed in Escherichia coli with the help of the glucose effect of the lac repressor and efficiently purified in high yield (10.063 mg/l). It showed significant activity against Gram-positive bacteria. We determined a MIC value of 9 microg ml(-1) with Bacillus thuringiensis. PMID:19270403

  17. Investigation of pseudo boehmite nanoparticles as an antibacterial agent

    NASA Astrophysics Data System (ADS)

    Chen, Zhi; Wu, Dudu; Chen, Jiaxi

    2015-06-01

    Pseudo boehmite nanoparticles were synthesized by using bovine serum albumin as the structure-directing agent. The morphology and crystal phase of the pseudo boehmite nanoparticles were determined by transmission electron microscopy, X-ray diffractograms and Fourier transform infrared spectroscopy. The antibacterial behaviors of pseudo boehmite nanoparticles were investigated using Escherichia coli (gram-negative) and Staphylococcus aureus (gram-positive) as model organisms. The results indicated that the synthesized pseudo boehmite nanoparticles showed high antibacterial activity when compared to plain aluminum oxide, which was assessed by measuring the growth inhibition and testing the zone of inhibition. The plausible mechanism of antibacterial behavior was attributed to the generation of reactive oxygen species by pseudo boehmite nanoparticles.

  18. Type I and Type II mechanisms of antimicrobial photodynamic therapy: An in vitro study on Gram-negative and Gram-positive bacteria

    PubMed Central

    Huang, Liyi; Xuan, Yi; Koide, Yuichiro; Zhiyentayev, Timur; Tanaka, Masamitsu; Hamblin, Michael R.

    2012-01-01

    Background and Objectives Antimicrobial photodynamic therapy (APDT) employs a nontoxic photosensitizer (PS) and visible light, which in the presence of oxygen produce reactive oxygen species (ROS), such as singlet oxygen (1O2, produced via Type II mechanism) and hydroxyl radical (HO•, produced via Type I mechanism). This study examined the relative contributions of 1O2 and HO• to APDT killing of Gram-positive and Gram-negative bacteria. Study Design/Materials and Methods Fluorescence probes, 3'-(p-hydroxyphenyl)-fluorescein (HPF) and singlet oxygen sensor green reagent (SOSG) were used to determine HO• and 1O2 produced by illumination of two PS: tris-cationic-buckminsterfullerene (BB6) and a conjugate between polyethylenimine and chlorin(e6) (PEI–ce6). Dimethylthiourea is a HO• scavenger, while sodium azide (NaN3) is a quencher of 1O2. Both APDT and killing by Fenton reaction (chemical generation of HO•) were carried out on Gram-positive bacteria (Staphylococcus aureus and Enteroccoccus fecalis) and Gram-negative bacteria (Escherichia coli, Proteus mirabilis and Pseudomonas aeruginosa. Results Conjugate PEI-ce6 mainly produced 1O2 (quenched by NaN3), while BB6 produced HO• in addition to 1O2 when NaN3 potentiated probe activation. NaN3 also potentiated HPF activation by Fenton reagent. All bacteria were killed by Fenton reagent but Gram-positive bacteria needed a higher concentration than Gram-negatives. NaN3 potentiated Fenton-mediated killing of all bacteria. The ratio of APDT killing between Gram-positive and Gram-negative bacteria was 2 or 4:1 for BB6 and 25:1 for conjugate PEI-ce6. There was a NaN3 dose dependent inhibition of APDT killing using both PEI-ce6 and BB6 against Gram-negative bacteria while NaN3 almost failed to inhibit killing of Gram-positive bacteria. Conclusion Azidyl radicals may be formed from NaN3 and HO•. It may be that Gram-negative bacteria are more susceptible to HO• while Gram-positive bacteria are more susceptible to 1O2. The differences in NaN3 inhibition may reflect differences in the extent of PS binding to bacteria (microenvironment) or differences in penetration of NaN3 into cell walls of bacteria. PMID:22760848

  19. In vitro antibacterial activity of different pulp capping materials

    PubMed Central

    Beltrami, Riccardo; Colombo, Marco; Ceci, Matteo; Dagna, Alberto; Chiesa, Marco

    2015-01-01

    Background Direct pulp capping involves the application of a dental material to seal communications between the exposed pulp and the oral cavity (mechanical and carious pulp exposures) in an attempt to act as a barrier, protect the dental pulp complex and preserve its vitality. The aim of this study was to evaluate and compare, by the agar disc diffusion test, the antimicrobial activity of six different pulp-capping materials: Dycal (Dentsply), Calcicur (Voco), Calcimol LC (Voco), TheraCal LC (Bisco), MTA Angelus (Angelus), Biodentine (Septodont). Material and Methods Streptococcus salivarius, Streptococcus sanguis and Streptococcus mutans strains were selected to evaluate the antimicrobial activity by the agar disc diffusion test of different pulp capping materials. Paper disks were impregnated whit each pulp capping materials and placed onto culture agar-plates pre-adsorbed with bacterial cells and further incubated for 24 h at 37°C. The growth inhibition zones around each pulp capping materials were recorded and compared for each bacterial strain. Results For the investigation of the antibacterial properties the ANOVA showed the presence of significant differences among the various materials. Tukey test showed that MTA-based materials induced lower growth inhibition zones. Conclusions MTA-based products show a discrete antibacterial activity varying from calcium hydroxide-based materials which present an higher antibacterial activity. Key words:Agar disc diffusion test, antimicrobial activity, calcium hydroxide, MTA, pulp capping materials. PMID:26644833

  20. Mechanism of antibacterial activity of copper nanoparticles

    NASA Astrophysics Data System (ADS)

    Chatterjee, Arijit Kumar; Chakraborty, Ruchira; Basu, Tarakdas

    2014-04-01

    In a previous communication, we reported a new method of synthesis of stable metallic copper nanoparticles (Cu-NPs), which had high potency for bacterial cell filamentation and cell killing. The present study deals with the mechanism of filament formation and antibacterial roles of Cu-NPs in E. coli cells. Our results demonstrate that NP-mediated dissipation of cell membrane potential was the probable reason for the formation of cell filaments. On the other hand, Cu-NPs were found to cause multiple toxic effects such as generation of reactive oxygen species, lipid peroxidation, protein oxidation and DNA degradation in E. coli cells. In vitro interaction between plasmid pUC19 DNA and Cu-NPs showed that the degradation of DNA was highly inhibited in the presence of the divalent metal ion chelator EDTA, which indicated a positive role of Cu2+ ions in the degradation process. Moreover, the fast destabilization, i.e. the reduction in size, of NPs in the presence of EDTA led us to propose that the nascent Cu ions liberated from the NP surface were responsible for higher reactivity of the Cu-NPs than the equivalent amount of its precursor CuCl2; the nascent ions were generated from the oxidation of metallic NPs when they were in the vicinity of agents, namely cells, biomolecules or medium components, to be reduced simultaneously.

  1. Antibacterial Activity of a Cardanol from Thai Apis mellifera Propolis

    PubMed Central

    Boonsai, Pattaraporn; Phuwapraisirisan, Preecha; Chanchao, Chanpen

    2014-01-01

    Background: Propolis is a sticky, dark brown resinous residue made by bees that is derived from plant resins. It is used to construct and repair the nest, and in addition possesses several diverse bioactivities. Here, propolis from Apis mellifera from Nan province, Thailand, was tested for antibacterial activity against Gram+ve (Staphylococcus aureus and Paenibacillus larvae) and Gram-ve (Escherichia coli) bacteria. Materials and methods: The three bacterial isolates were confirmed for species designation by Gram staining and analysis of the partial sequence of 16S rDNA. Propolis was sequentially extracted by methanol, dichloromethane and hexane. The antibacterial activity was determined by agar well diffusion and microbroth dilution assays using streptomycin as a positive control. The most active crude extract was further purified by quick column and adsorption chromatography. The apparent purity of each bioactive fraction was tested by thin layer chromatography. The chemical structure of the isolated bioactive compound was analyzed by nuclear magnetic resonance (NMR). Results: Crude methanol extract of propolis showed the best antibacterial activity with a minimum inhibition concentration (MIC) value of 5 mg/mL for S. aureus and E. coli and 6.25 mg/mL for P. larvae. After quick column chromatography, only three active fractions were inhibitory to the growth of S. aureus and E. coli with MIC values of 6.25 and 31.3 µg/mL, respectively. Further adsorption chromatography yielded one pure bioactive fraction (A1A) with an IC50 value of 0.175 µg/mL for E. coli and 0.683 µg/mL for P. larvae, and was determined to be cardanol by NMR analysis. Scanning and transmission electron microscopy analysis revealed unusual shaped (especially in dividing cells), damaged and dead cells in cardanol-treated E. coli. Conclusion: Thai propolis contains a promising antibacterial agent. PMID:24578609

  2. Isolation and Characterization of Gram-Positive Biosurfactant-Producing Halothermophilic Bacilli From Iranian Petroleum Reservoirs

    PubMed Central

    Zargari, Saeed; Ramezani, Amin; Ostvar, Sassan; Rezaei, Rasool; Niazi, Ali; Ayatollahi, Shahab

    2014-01-01

    Background: Petroleum reservoirs have long been known as the hosts of extremophilic microorganisms. Some of these microorganisms are known for their potential biotechnological applications, particularly production of extra and intracellular polymers and enzymes. Objectives: Here, 14 petroleum liquid samples from southern Iranian oil reservoirs were screened for presence of biosurfactant?producing halothermophiles. Materials and Methods: Mixture of the reservoir fluid samples with a minimal growth medium was incubated under an N2 atmosphere in 40°C; 0.5 mL samples were transferred from the aqueous phase to agar plates after 72 hours of incubation; 100 mL cell cultures were prepared using the MSS-1 (mineral salt solution 1) liquid medium with 5% (w/v) NaCl. The time-course samples were analyzed by recording the absorbance at 600 nm using a spectrophotometer. Incubation was carried out in 40°C with mild shaking in aerobic conditions. Thermotolerance was evaluated by growing the isolates at 40, 50, 60 and 70°C with varying NaCl concentrations of 5% and 10% (w/v). Halotolerance was evaluated using NaCl concentrations of 5%, 10%, 12.5% and 15% (w/v) and incubating them at 40°C under aerobic and anaerobic conditions. Different phenotypic characteristics were evaluated, as outlined in Bergey's manual of determinative bacteriology. Comparing 16S rDNA sequences is one of the most powerful tools for classification of microorganisms. Results: Among 34 isolates, 10 demonstrated biosurfactant production and growth at temperatures between 40°C and 70°C in saline media containing 5%?15% w/v NaCl. Using partial 16S rDNA sequencing (and amplified ribosomal DNA restriction analysis [ARDRA]) and biochemical tests (API tests 20E and 50 CHB), all the 10 isolates proved to be facultative anaerobic, Gram-positive moderate thermohalophiles of the genus Bacillus (B. thermoglucosidasius, B. thermodenitrificans, B. thermoleovorans, B. stearothermophilus and B. licheniformis), exhibiting surface-active behaviors. Conclusions: General patterns include decreasing the thermotolerance with increasing the salt concentrations and also more halotolerance in the aerobic environment compared with anaerobic conditions. The results demonstrated that Iranian petroleum reservoirs enjoy a source of indigenous extremophilic microorganisms with potential applications in microbial enhanced oil recovery and commercial enzyme production. PMID:25485045

  3. The mechanism of antibacterial activity of tetrandrine against Staphylococcus aureus.

    PubMed

    Lee, Young-Seob; Han, Sin-Hee; Lee, Su-Hwan; Kim, Young-Guk; Park, Chung-Berm; Kang, Ok-Hwa; Keum, Joon-Ho; Kim, Sung-Bae; Mun, Su-Hyun; Seo, Yun-Soo; Myung, Noh-Yil; Kwon, Dong-Yeul

    2012-08-01

    Tetrandrine (TET) is a bis-benzylisoquinoline alkaloid derived from the radix of Stephania tetrandra S. Moore. TET performs a wide spectrum of biological activities. The radix of S. tetrandrae has been used traditionally in Asia, including Korea, to treat congestive circulatory disorders and inflammatory diseases. The aim of this study was to examine the mechanism of antibacterial activity of tetrandrine against Staphylococcus aureus. The mechanism was investigated by studying the effects of TET in combination with detergent or membrane potential un-couplers. In addition, the direct involvement of peptidoglycan (PGN) was assessed in titration assays. TET activity against S. aureus was 125-250??g/mL, and the minimum inhibitory concentration (MIC) of the two reference strains was 250??g/mL. The OD(600) of each suspension treated with a combination of ethylenediaminetetraacetic acid (EDTA), tris(hydroxymethyl) aminomethane (TRIS), and Triton X-100 (TX) with TET (0.25×MIC) had been reduced from 43% to 96%. Additional structure-function studies on the antibacterial activity of TET in combination with other agents may lead to the discovery of more effective antibacterial agents. PMID:22845553

  4. Current Concepts in Antimicrobial Therapy Against Select Gram-Positive Organisms: Methicillin-Resistant Staphylococcus aureus, Penicillin-Resistant Pneumococci, and Vancomycin-Resistant Enterococci

    PubMed Central

    Rivera, Ana Maria; Boucher, Helen W.

    2011-01-01

    Gram-positive bacteria cause a broad spectrum of disease in immunocompetent and immunocompromised hosts. Despite increasing knowledge about resistance transmission patterns and new antibiotics, these organisms continue to cause significant morbidity and mortality, especially in the health care setting. Methicillin-resistant Staphylococcus aureus poses major problems worldwide as a cause of nosocomial infection and has emerged as a cause of community-acquired infections. This change in epidemiology affects choices of empirical antibiotics for skin and skin-structure infections and community-acquired pneumonia in many settings. Throughout the world, the treatment of community-acquired pneumonia and other respiratory tract infections caused by penicillin-resistant Streptococcus pneumoniae has been complicated by resistance to ?-lactam and macrolide antibacterial drugs. Vancomycin-resistant enterococci are a major cause of infection in the hospital setting and remain resistant to treatment with most standard antibiotics. Treatment of diseases caused by resistant gram-positive bacteria requires appropriate use of available antibiotics and stewardship to prolong their effectiveness. In addition, appropriate and aggressive infection control efforts are vital to help prevent the spread of resistant pathogens. PMID:22134942

  5. Antibacterial activity of Citrus limonum fruit juice extract.

    PubMed

    Okeke, Malachy Ifeanyi; Okoli, Arinze Stanley; Eze, Edith Nneka; Ekwume, Grace Chinwe; Okosa, Evangelin Uchena; Iroegbu, Christian Ukwuoma

    2015-09-01

    The fruit juice extract of Citrus limonum was investigated for antibacterial activity. The antibacterial activity of the extract on ten strains of bacteria was determined by both agar well diffusion and macro-broth dilution methods. The extract was variously bacteriostatic and bactericidal against Bacillussubtilis ATCC 6051, Staphylococcus aureus ATCC 12600, Escherichia coli ATCC 11775, Pseudomonas aeruginosa ATCC 10145 as well as locally isolated clinical strains of the above bacteria and Salmonella kintambo (Human: 13, 23: mt:-), Salmonella typhi and Proteus sp. The MICs ranged from 0.78 mg/ml to 50mg/ml; MBCs, 25.0mg/ml to >100mg/ml and MBC/MIC ratios 2.0 to >16.0. These results provide scientific justification for the medicinal use of Citrus limonum fruit juice by Nigerian herbalists in the treatment of diseases in which strains of the test organisms have been implicated as etiologic agents. PMID:26408878

  6. In vitro antibacterial activity of concentrated polyethylene glycol 400 solutions.

    PubMed Central

    Chirife, J; Herszage, L; Joseph, A; Bozzini, J P; Leardini, N; Kohn, E S

    1983-01-01

    It was found that concentrated polyethylene glycol 400 (PEG 400) solutions have significant antibacterial activity against various pathogenic bacteria, including Klebsiella pneumoniae, Pseudomonas aeruginosa, Escherichia coli, and Staphylococcus aureus. This effect might be attributed to two effects: lowering of water activity and, superimposed on this, the specific action of PEG-400 molecules on bacterial cells. Phase-contrast microscopic observations of cells placed in contact with PEG 400 revealed clumping and morphological changes of bacterial cells. The larger changes in appearance were evidenced by the species which were more rapidly killed by PEG 400. The results obtained suggested that concentrated PEG 400 solutions may have a potential value in medicine as a topical antibacterial agent. The feasibility of this application is the subject of present investigation. Images PMID:6638996

  7. Synergistic Antibacterial and Anti-Inflammatory Activity of Temporin A and Modified Temporin B In Vivo

    PubMed Central

    Capparelli, Rosanna; Romanelli, Alessandra; Iannaccone, Marco; Nocerino, Nunzia; Ripa, Raffaella; Pensato, Soccorsa; Pedone, Carlo; Iannelli, Domenico

    2009-01-01

    Temporins are antimicrobial peptides secreted by the granular glands of the European red frog (Rana temporaria). They are 10–14 amino acid long polypeptides active prevalently against gram positive bacteria. This study shows that a synthetic temporin B analogue (TB-YK), acquires the capacity to act in synergism with temporin A and to exert antimicrobial and anti-inflammatory activity in vivo against gram positive and gram negative bacteria. Administration of 3.4 mg/Kg of temporin A (TA)+1.6 mg/Kg TB-YK, given to individual mice concurrently with a lethal dose of bacteria (gram positive or negative), rescued 100% of the animals. More importantly, the same doses of temporins, administered one week after experimental infection with a sub lethal dose of bacteria, sterilized 100% of the animals within 3–6 days. Also, it is described an animal model based on the use of sub lethal doses of bacteria, which closely mimics bacterial infection in humans. The model offers the possibility to test in a preclinical setting the true potential of TA and TB-YK in combination as antimicrobial and anti-inflammatory agents. PMID:19784377

  8. Effects of antibacterial agents on in vitro ovine ruminal biotransformation of the hepatotoxic pyrrolizidine alkaloid jacobine.

    PubMed

    Wachenheim, D E; Blythe, L L; Craig, A M

    1992-08-01

    Ingestion of pyrrolizidine alkaloids, naturally occurring plant toxins, causes illness and death in a number of animal species. Senecio jacobaea pyrrolizidine alkaloids cause significant economic losses due to livestock poisoning, particularly in the Pacific Northwest. Some sheep are resistant to pyrrolizidine alkaloid poisoning, because ovine ruminal biotransformation detoxifies free pyrrolizidine alkaloids in digesta. Antibacterial agents modify ruminal fermentation. Pretreatment with antibacterial agents may account for some animal variability in resistance to pyrrolizidine alkaloid toxicosis, and antibacterial agents can also be used for characterizing ruminal pyrrolizidine alkaloid-biotransforming microflora. The objective of this study was to evaluate the effects of antibacterial agents on biotransformation of a predominant S. jacobaea pyrrolizidine alkaloid, jacobine, in ovine ruminal contents. Ovine ruminal jacobine biotransformation was tested in vitro with 20 independent antibacterial agents. Low amounts of rifampin and erythromycin prevented jacobine biotransformation. Chlortetracycline, lasalocid, monensin, penicillin G, and tetracycline were slightly less effective at inhibiting jacobine biotransformation. Bacitracin, crystal violet, kanamycin, and neomycin were moderately inhibitory against jacobine biotransformation. Brilliant green, chloramphenicol, gramicidin, nalidixic acid, polymyxin B SO4, sodium azide, streptomycin, sulfisoxazole, and vancomycin had little to no effect on jacobine biotransformation. The antibiotics that were most effective at inhibiting biotransformation were those that are active against gram-positive bacteria. Therefore, gram-positive bacteria are most likely critical members of the jacobine-biotransforming consortia. PMID:1514802

  9. (Aminophosphane)gold(I) and silver(I) complexes as antibacterial agents.

    PubMed

    Ortego, Lourdes; Gonzalo-Asensio, Jesús; Laguna, Antonio; Villacampa, M Dolores; Gimeno, M Concepción

    2015-05-01

    This manuscript describes the synthesis of new Au(I) and Ag(I) complexes with aminophosphane ligands and a study of their antibacterial activity against Gram-negative Salmonella enterica serovar typhimurium and Escherichia coli and Gram-positive Listeria monocytogenes and Staphylococcus aureus. The bactericidal assays revealed the effectiveness of these compounds on paradigm Gram-negative and Gram-positive pathogens, showing a moderate antimicrobial activity, comparable with the antibiotics of reference, for all gold(I) complexes and the silver(I) complexes without coordinated PPh3 groups. For those complexes that were found to show inhibitory activity, serial dilutions in liquid broth method were performed for determination of MIC (minimum inhibitory concentration) and MBC (minimum bactericidal concentration). PMID:25706322

  10. Chitosan coated cotton gauze for antibacterial water filtration.

    PubMed

    Ferrero, Franco; Periolatto, Monica; Vineis, Claudia; Varesano, Alessio

    2014-03-15

    Communicable diseases can be transmitted by contaminated water. Water decontamination process is fundamental to eliminate microorganisms. In this work, cotton gauzes were coated with chitosan using an UV-curing process or cationized by introduction of quaternary ammonium groups and tested, in static and dynamic conditions, as water filter for biological disinfection against both Gram-negative and Gram-positive bacteria. Both materials showed good antibacterial activity, in static assessment, instead in dynamic conditions, chitosan treated gauze showed a high antimicrobial efficiency in few seconds of contact time. This composite could be a good candidate for application as biological filter. PMID:24528721

  11. Modulating the activity of short arginine-tryptophan containing antibacterial peptides with N-terminal metallocenoyl groups

    PubMed Central

    Albada, H Bauke; Chiriac, Alina-Iulia; Wenzel, Michaela; Penkova, Maya; Bandow, Julia E; Sahl, Hans-Georg

    2012-01-01

    Summary A series of small synthetic arginine and tryptophan containing peptides was prepared and analyzed for their antibacterial activity. The effect of N-terminal substitution with metallocenoyl groups such as ferrocene (FcCO) and ruthenocene (RcCO) was investigated. Antibacterial activity in different media, growth inhibition, and killing kinetics of the most active peptides were determined. The toxicity of selected derivatives was determined against erythrocytes and three human cancer cell lines. It was shown that the replacement of an N-terminal arginine residue with a metallocenoyl moiety modulates the activity of WRWRW-peptides against Gram-positive and Gram-negative bacteria. MIC values of 2–6 µM for RcCO-W(RW)2 and 1–11 µM for (RW)3 were determined. Interestingly, W(RW)2-peptides derivatized with ferrocene were significantly less active than those derivatized with ruthenocene which have similar structural but different electronic properties, suggesting a major influence of the latter. The high activities observed for the RcCO-W(RW)2- and (RW)3-peptides led to an investigation of the origin of activity of these peptides using several important activity-related parameters. Firstly, killing kinetics of the RcCO-W(RW)2-peptide versus killing kinetics of the (RW)3 derivative showed faster reduction of the colony forming units for the RcCO-W(RW)2-peptide, although MIC values indicated higher activity for the (RW)3-peptide. This was confirmed by growth inhibition studies. Secondly, hemolysis studies revealed that both peptides did not lead to significant destruction of erythrocytes, even up to 500 µg/mL for (RW)3 and 250 µg/mL for RcCO-W(RW)2. In addition, toxicity against three human cancer cell lines (HepG2, HT29, MCF7) showed that the (RW)3-peptide had an IC50 value of ~140 µM and the RcW(RW)2 one of ~90 µM, indicating a potentially interesting therapeutic window. Both the killing kinetics and growth inhibition studies presented in this work point to a membrane-based mode of action for these two peptides, each having different kinetic parameters. PMID:23209509

  12. Antibacterial activities of persimmon extracts relate with their hydrogen peroxide concentration.

    PubMed

    Arakawa, Hidetoshi; Takasaki, Makiko; Tajima, Noriko; Fukamachi, Haruka; Igarashi, Takeshi

    2014-01-01

    Persimmon, a deciduous tree of the family Ebenaceae, is found throughout East Asia and contains high levels of tannins. This class of natural compounds exhibit favorable toxicity profiles along with bactericidal activity without the emergence of resistant bacteria, suggesting potential medical applications. Consistent with these observations, persimmon leaves show antibacterial activity. However, the mechanism of persimmon antibacterial activity remains unknown. In the present work, we demonstrate that the antibacterial activity of persimmon reflects the generation of reactive oxygen from tannins. The identification and quantification of reactive oxygen generated from persimmon and the level of antibacterial activity were determined. PMID:24805207

  13. Desulfotomaculum spp. and related gram-positive sulfate-reducing bacteria in deep subsurface environments

    PubMed Central

    Aüllo, Thomas; Ranchou-Peyruse, Anthony; Ollivier, Bernard; Magot, Michel

    2013-01-01

    Gram-positive spore-forming sulfate reducers and particularly members of the genus Desulfotomaculum are commonly found in the subsurface biosphere by culture based and molecular approaches. Due to their metabolic versatility and their ability to persist as endospores. Desulfotomaculum spp. are well-adapted for colonizing environments through a slow sedimentation process. Because of their ability to grow autotrophically (H2/CO2) and produce sulfide or acetate, these microorganisms may play key roles in deep lithoautotrophic microbial communities. Available data about Desulfotomaculum spp. and related species from studies carried out from deep freshwater lakes, marine sediments, oligotrophic and organic rich deep geological settings are discussed in this review. PMID:24348471

  14. Actinopyga lecanora Hydrolysates as Natural Antibacterial Agents

    PubMed Central

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

    2012-01-01

    Actinopyga lecanora, a type of sea cucumber commonly known as stone fish with relatively high protein content, was explored as raw material for bioactive peptides production. Six proteolytic enzymes, namely alcalase, papain, pepsin, trypsin, bromelain and flavourzyme were used to hydrolyze A. lecanora at different times and their respective degrees of hydrolysis (DH) were calculated. Subsequently, antibacterial activity of the A. lecanora hydrolysates, against some common pathogenic Gram positive bacteria (Bacillus subtilis and Staphylococcus aureus) and Gram negative bacteria (Escherichia coli, Pseudomonas aeruginosa, and Pseudomonas sp.) were evaluated. Papain hydrolysis showed the highest DH value (89.44%), followed by alcalase hydrolysis (83.35%). Bromelain hydrolysate after one and seven hours of hydrolysis exhibited the highest antibacterial activities against Pseudomonas sp., P. aeruginosa and E. coli at 51.85%, 30.07% and 30.45%, respectively compared to the other hydrolysates. Protein hydrolysate generated by papain after 8 h hydrolysis showed maximum antibacterial activity against S. aureus at 20.19%. The potent hydrolysates were further fractionated using RP-HPLC and antibacterial activity of the collected fractions from each hydrolysate were evaluated, wherein among them only three fractions from the bromelain hydrolysates exhibited inhibitory activities against Pseudomonas sp., P. aeruginosa and E. coli at 24%, 25.5% and 27.1%, respectively and one fraction of papain hydrolysate showed antibacterial activity of 33.1% against S. aureus. The evaluation of the relationship between DH and antibacterial activities of papain and bromelain hydrolysates revealed a meaningful correlation of four and six order functions. PMID:23222684

  15. Effects of fractionation and combinatorial evaluation of Tamarindus indica fractions for antibacterial activity.

    PubMed

    Nwodo, Uchechukwu U; Iroegbu, Christian U; Ngene, Augustine A; Chigor, Vincent N; Okoh, Anthony I

    2011-01-01

    Six fractions, named TiA - TiF, were obtained by fractionating the crude ethanol extract of the stem bark of Tamarindus indica using column chromatographic techniques. On TLC, fraction TiB showed five bands, TiC three bands, while TiD and TiE showed two bands each. TiC, TiD and TiE were re-eluted with different solvent systems to yield two fractions each, while TiB yielded four. These subfractions were designated B1-B4; C1-C2; D1-D2 and E1-E2, respectively. Tannins, flavonoids and alkaloids, among other components, were detected, albeit in different proportions with respect to fractions and subfractions and were compartmentalized with respect to the solvent systems used. The in vitro antibacterial activity of fractions and subfractions was tested separately and in combinations using the agar well diffusion technique. The susceptibly of test strains (expressed as %) were: 83.3% (TiA and TiB), 75.0% (crude extract and TiC), 66.7% (TiD), 50.0% (TiE) and 16.7% (TiF) when used singly, whereas in combination, the corresponding susceptibilities were 100% (CE), 83.3% (DE), 66.7% (AB, AF, BC, BD, DE and EF), 50% (AC and CD), 33.3% (BE and BF) and 16.7% (AD) against Gram negative bacteria strains and 100% (EF), 80% (DE), 60% (AB, BC and CE), 40% (AC, BD, BF, CF and DF) and 20% (AE, AF, BE and CD) against Gram positive strains. Percentage susceptibility with combinatorial use of re-fractions ranged from 85.7-57.1% and 60-40% against Gram negative and positive strains (TiB subfractions), respectively, 100-85.7% and 40-0% against Gram negative and positive strains (TiC, TiD and TiE sub-fractions). PMID:21659967

  16. Antibacterial activity from Penicillium corylophilum Dierckx.

    PubMed

    Silva, Marley Garcia; Furtado, Niege Araçari Jacometti Cardoso; Pupo, Mônica Tallarico; Fonseca, Maria José Vieira; Said, Suraia; da Silva Filho, Ademar Alves; Bastos, Jairo Kenupp

    2004-01-01

    A strain of Penicillium corylophilum isolated from Brazilian soil sample was submitted to different culture conditions to investigate the production of secondary metabolites with antimicrobial activity. The largest number of conidia was obtained after 5 days of incubation in oat medium and the highest level of antimicrobial activity was produced when the fungus culture was developed in the Czapek medium. The activity against Staphylococcus aureus was found only in the chloroform extract from Czapek culture broth, which also showed activity against Micrococcus luteus. Fumiquinozoline F was isolated from the active chloroform extract by using chromatographic methods. The minimal inhibitory concentration (MIC) values for M. luteus and S. aureus were 99 microg/ mL and 137microg/mL, respectively. PMID:15646377

  17. Surfaces of Fluorinated Pyridinium Block Copolymers with Enhanced Antibacterial Activity

    SciTech Connect

    Krishnan,S.; Ward, R.; Hexemer, A.; Sohn, K.; Lee, K.; Angert, E.; Fischer, D.; Kramer, E.; Ober, C.

    2006-01-01

    Polystyrene-b-poly(4-vinylpyridine) copolymers were quaternized with 1-bromohexane and 6-perfluorooctyl-1-bromohexane. Surfaces prepared from these polymers were characterized by contact angle measurements, near-edge X-ray absorption fine structure spectroscopy and X-ray photoelectron spectroscopy. The fluorinated pyridinium surfaces showed enhanced antibacterial activity compared to their nonfluorinated counterparts. Even a polymer with a relatively low molecular weight pyridinium block showed high antimicrobial activity. The bactericidal effect was found to be related to the molecular composition and organization in the top 2-3 nm of the surface and increased with increasing hydrophilicity and pyridinium concentration of the surface.

  18. In vitro antibacterial effect of wasp (Vespa orientalis) venom

    PubMed Central

    2014-01-01

    Background The emergence of antibacterial resistance against several classes of antibiotics is an inevitable consequence of drug overuse. As antimicrobial resistance spreads throughout the globe, new substances will always be necessary to fight against multidrug-resistant microorganisms. Venoms of many animals have recently gained attention in the search for new antimicrobials to treat infectious diseases. Thefore, the present study aimed to study the antibacterial effects of wasp (Vespa orientalis) crude venom. Two gram-positive bacteria (Staphylococcus aureus and Bacillus subtilis) and two gram-negative ones (Escherichia coli and Klesiella pneumonia) were compared for their sensitivity to the venom by determining the inhibition zone (Kirby-Bauer method) and minimum inhibitory concentration (MIC). A microbroth kinetic system based on continuous monitoring of changes in the optical density of bacterial growth was also used for determination of antimicrobial activity. Results The venom exhibited a well-recognized antimicrobial property against the tested bacterial strains. The inhibition zones were determined to be 12.6, 22.7, 22.4 and 10.2 mm for S. aureus, B. subtilis, E. coli and K. pneumonia, respectively. The corresponding MIC values were determined to be 64, 8, 64 and 128 ?g/mL, respectively. The MIC50 and MIC90 values of the venom were respectively determined to be 63.6 and 107 ?g/mL for S. aureus, 4.3 and 7.0 ?g/mL for B. subtilis, 45.3 and 65.7 ?g/mL for E. coli and 74.4 and 119.2 ?g/mL for K. pneumonia. Gram-positive bacteria were generally more sensitive to the venom than gram-negative ones. Conclusions Results revealed that the venom markedly inhibits the growth of both gram-positive and gram-negative bacteria and could be considered a potential source for developing new antibacterial drugs. PMID:24955088

  19. Overview of resistant gram-positive pathogens in the surgical patient.

    PubMed

    Rapp, R P

    2000-01-01

    Staphylococci and enterococci are the most common pathogens in surgical-site and bloodstream infections. The emergence of drug resistance among these gram-positive bacteria thus poses a substantial threat to patients with surgical infections. Resistance to methicillin/oxacillin is frequently observed in Staphylococcus aureus isolates and is often accompanied by multidrug resistance. Vancomycin is usually the treatment of choice for infections caused by methicillin-resistant S. aureus (MRSA), so the recent appearance of S. aureus isolated with intermediate sensitivity to vancomycin is cause for concern. Vancomycin resistance has already appeared in most species of enterococci. Infections caused by vancomycin-resistant enterococci (VRE) are associated with increased mortality compared to infections caused by vancomycin-sensitive isolates. Measures for preventing vancomycin resistance include reducing the use of vancomycin and other agents that appear to be associated with VRE, including third-generation cephalosporins and anti-anaerobic drugs. Third-generation cephalosporins have also been implicated in the increased prevalence of MRSA infections. Prudent use of existing antibiotics is an essential strategy for combating the rising tide of drug-resistant gram-positive pathogens. PMID:12594908

  20. The Mechanisms of Virulence Regulation by Small Noncoding RNAs in Low GC Gram-Positive Pathogens

    PubMed Central

    Pitman, Stephanie; Cho, Kyu Hong

    2015-01-01

    The discovery of small noncoding regulatory RNAs (sRNAs) in bacteria has grown tremendously recently, giving new insights into gene regulation. The implementation of computational analysis and RNA sequencing has provided new tools to discover and analyze potential sRNAs. Small regulatory RNAs that act by base-pairing to target mRNAs have been found to be ubiquitous and are the most abundant class of post-transcriptional regulators in bacteria. The majority of sRNA studies has been limited to E. coli and other gram-negative bacteria. However, examples of sRNAs in gram-positive bacteria are still plentiful although the detailed gene regulation mechanisms behind them are not as well understood. Strict virulence control is critical for a pathogen’s survival and many sRNAs have been found to be involved in that process. This review outlines the targets and currently known mechanisms of trans-acting sRNAs involved in virulence regulation in various gram-positive pathogens. In addition, their shared characteristics such as CU interaction motifs, the role of Hfq, and involvement in two-component regulators, riboswitches, quorum sensing, or toxin/antitoxin systems are described. PMID:26694351

  1. Fluorescence studies of gram-positive and gram-negative bacteria

    NASA Astrophysics Data System (ADS)

    Blust, Brittni

    2012-02-01

    Autofluorescence is a relatively unexplored technique for identification. It is nondestructive, noncontact, fast, and has the potential to be integrated in small handheld devices. On the other hand, the autofluorescent signal is sometimes very week, or it can be overwhelmed by the emission of a surrounding medium. We are exploring the possibility to develop an optical method for identification of the Gram-type of bacterial cultures based on the autofluorescence. We have enhanced the detectivity of a standard fluorimeter using combination of bandpass and long pass filters. In this particular study, we are investigating if the previously observed difference in the autofluorescent spectra of Gram-positive and Gram-negative bacteria is dependent on the age of the culture. We have selected two types of bacteria, Kocuria rhizophila and Alcagenes faecalis, and we have monitored in equal time intervals of their development the autofluorescence spectra. The stages of development were monitored separately by measuring the turbidity and creating a growth curve. The goal of this study is to find out if the previously observed difference in the autofluorescence spectra of Gram-positive and Gram-negative bacteria is dependent on the stage of the development of the bacterial culture.

  2. Identification of gram-negative and gram-positive bacteria by fluorescence studies

    NASA Astrophysics Data System (ADS)

    Demchak, Jonathan; Calabrese, Joseph; Tzolov, Marian

    2011-03-01

    Several type strains of bacteria including Vibrio fischeri, Azotobacter vinelandii, Enterobacter cloacae, and Corynebacterium xerosis, were cultured in the laboratory following standard diagnostic protocol based on their individual metabolic strategies. The bacterial cultures were not further treated and they were studied in their pristine state (pure culture - axenic). The fluorescent studies were applied using a continuous wave and a pulsed excitation light sources. Emission and excitation spectra were recorded for the continuous wave excitation and they all show similar spectral features with the exception of the gram positive bacteria showing vibronic structures. The vibrational modes involved in these vibronic bands have energy typical for carbon-carbon vibrations. The fluorescence is quenched in addition of water, even a very thin layer, which confirms that the observed spectral features originate from the outer parts of the bacteria. These results allow to conclude that the fluorescence spectroscopy can be used as a method for studying the membranes of the bacteria and eventually to discriminate between gram positive and gram negative bacteria. The pulsed experiments show that the fluorescence lifetime is in the sub-microsecond range. The results indicate that the observed spectra are superposition of the emission with different lifetimes.

  3. Antibacterial activity of aqueous extracts of selected chewing sticks.

    PubMed

    Ndukwe, Kizito Chioma; Okeke, Iruka N; Lamikanra, Adebayo; Adesina, Simeon K; Aboderin, Oliadipo

    2005-08-15

    This aim of this study was to determine the antibacterial activity in extracts obtained from various Nigerian chewing sticks. Aqueous extracts from seventeen chewing sticks and the fruit of C. ferruginea, one fruit used in oral hygiene in Nigeria, were screened for antibacterial activity against type cultures of Staphylococcus aureus, Bacillus subtilis, Escherichia coli, and Pseudomonas aeruginosa. Eleven of the test extracts showed activity against at least two of these referenced organisms. Minimum inhibitory concentrations (MIC) of these eleven extracts against clinical isolates from orofacial infection were determined. All the extracts demonstrated activity against Staphylococcal and Streptococcal isolates. Over half of the extracts were active against Enterobacteriaceae and obligate anaerobic isolates, including Prevotella melaninogenica, Porphyromonas gigivalis, Fusobacterium nucleatum, and Peptostreptococcus prevotii. Extracts of the Vitellaria paradoxa root, Bridellia ferruginea stem and twigs, Garcinia cola stem, Terminalia glaucescens root, Morinda lucida root, and Cnestis ferruginea fruit showed appreciable activity against all classes of bacterial isolates. The extracts of these plants may serve as sources for chemotherapeutic agents for the management of orofacial infections. PMID:16127476

  4. The Gram-positive bacterium Streptococcus pyogenes is also known as group A Streptococcus (GAS) and is

    E-print Network

    Nizet, Victor

    The Gram-positive bacterium Streptococcus pyogenes is also known as group A Streptococcus (GAS streptococcal pharyngitis6 and invasive diseases worldwide2,7 , and the resurgence of severe invasive GAS

  5. Antibacterial, antidiarrhoeal, and cytotoxic activities of methanol extract and its fractions of Caesalpinia bonducella (L.) Roxb leaves

    PubMed Central

    2013-01-01

    Background Caesalpinia bonducella is an important medicinal plant for its traditional uses against different types of diseases. Therefore, the present study investigated the antimicrobial, antidiarrhoeal, and cytotoxic activities of the methanol extract and ethyl acetate, chloroform, and petroleum ether (pet. ether) fractions of C. bonducella leaves. Methods The antibacterial potentialities of methanol extract and its fractions of C. bonducella leaves were investigated by the disc diffusion method against four gram-positive and five gram-negative bacteria at 300, 500 and 800 ?g/disc. Kanamycin (30 ?g/disc) was used as the standard drug. Antidiarrhoeal activities of leaf extracts were evaluated at two doses (200 and 400 mg/kg) and compared with loperamide in a castor oil-induced diarrhoeal model in rat. The fractions were subjected to a brine shrimp lethality test to evaluate their cytotoxicity. Results The methanol extract and other three fractions exhibited better activities at higher concentrations. Amongst, the chloroform fraction showed maximum activity at all three concentrations (300, 500, and 800 ?g/disc) against almost all bacteria. S. aureus and P. aeruginosa showed better sensitivities to all extracts at all three concentrations excluding the pet. ether fraction. Bacillus megaterium and Klebsiella spp. were two bacteria amongst nine that showed lowest sensitivity to the extracts. Maximum zone of inhibition (25-mm) was obtained by the methanol extract at an 800 ?g/disc concentration against S. aureus. In the antidiarrhoeal test, all fractions exhibited dose-dependent actions, which were statistically significant (p?antibacterial activities along with moderate cytotoxicities that may lead to new drug development. PMID:23663985

  6. Synthesis of Fe3O4 nanoparticles and its antibacterial application

    NASA Astrophysics Data System (ADS)

    Prabhu, Y. T.; Rao, K. Venkateswara; Kumari, B. Siva; Kumar, Vemula Sesha Sai; Pavani, Tambur

    2015-02-01

    The Present work outlines the antibacterial activity of Fe3O4 nanoparticles synthesized through chemical combustion method where ferric nitrate is used as precursor material and urea as fuel with the assistant of Tween 80, a non-ionic surfactant. The obtained Fe3O4 nanoparticles were characterized by X-ray diffraction, differential thermal analysis/thermo gravimetric analysis (DTA/TGA), particle size analyzer, SEM with EDAX and TEM. Various parameters such as dislocation density, micro strain, analysis of weight loss and surface morphological studies were calculated. The particle size was calculated from XRD and it was found to be 33-40 nm. Using well diffusion method antibacterial activity of Fe3O4 nanoparticles was tested against gram-positive and gram-negative Staphylococus aureus, Xanthomonas, Escherichia coli and Proteus vulgaris. Fe3O4 nanoparticles exhibited strong antibacterial activity against bacterial species.

  7. Nanotechnology approaches for antibacterial drug delivery: Preparation and microbiological evaluation of fusogenic liposomes carrying fusidic acid.

    PubMed

    Nicolosi, Daria; Cupri, Sarha; Genovese, Carlo; Tempera, Gianna; Mattina, Roberto; Pignatello, Rosario

    2015-06-01

    Many antibacterial drugs have some difficulty passing through the bacterial cell membrane, especially if they have a high molecular weight or large spatial structure. Consequently, intrinsic resistance is shown by some bacterial strains. Reduced cell membrane permeability is one of the mechanisms of resistance known for fusidic acid (FUS), a bacteriostatic steroidal compound with activity limited to Gram-positive bacteria. Moreover, the lipophilic character of FUS has been shown to cause drug retention inside the bilayers of cell membranes, preventing its diffusion towards target sites inside the cytoplasm. Targeting antimicrobial agents by means of liposomes may be a valid strategy in the treatment of infections refractory to conventional routes of antimicrobial treatment. On this basis, loading of FUS in fusogenic liposomes (FLs) was planned in this study. Fusogenic small unilamellar vesicles loaded with FUS were produced to evaluate their influence on improving the cell penetration and antibacterial activity of the antibiotic. The produced carriers were technologically characterised and were subjected to an in vitro microbiological assay against several strains of Gram-negative and Gram-positive bacteria. The experimental results showed that encapsulating FUS in a liposomal carrier can improve antimicrobial efficacy and reduce the effective concentration required, probably through putative mechanisms of increased diffusion through the bacterial cell membrane. In fact, whilst free FUS was active only on the tested Gram-positive strains, incubation of FUS-loaded FLs exhibited growth inhibitory activity both against Gram-positive and Gram-negative strains. The lowest MICs were obtained against Staphylococcus epidermidis (?0.15 ?g/mL) and Acinetobacter baumannii (37.5 ?g/mL) clinical strains. PMID:25816979

  8. Molecular cloning, expression, purification and characterization of vitellogenin in scallop Patinopecten yessoensis with special emphasis on its antibacterial activity.

    PubMed

    Wu, Biao; Liu, Zhihong; Zhou, Liqing; Ji, Guangdong; Yang, Aiguo

    2015-04-01

    Vitellogenin (Vg), the major precursor of the egg-yolk proteins, has been found to play an immune role in fish and protochordate amphioxus, however, no study on the immune function of Vg in invertebrates has ever been studied before. In this study, the complete cDNA of Vg was identified from the scallop Patinopecten yessoensis (termed PyVg). The cDNA contained an open reading frame (ORF) of 6888?bp, encoding a polypeptide of 2295 amino acid protein, which had an N-terminal signal peptide followed by the mature Vg. The mature Vg had the domains Vitellogenin_N, domain of unknown function 1943 (DUF1943) and von Willebrand factor type D domain (VWD) as well as the consensus cleavage site (R-X-R/K-R) and conserved motif (KTIGNAG). Tissue distribution assay revealed that PyVg transcripts were predominantly present in the ovary and hepatopancreas, and its expression profile in ovary well reflected the annual cycle of vitellogenesis. Interestingly, bacterial challenge caused a significant change in PyVg expression, hinting an involvement of PyVg in the acute phase response in P. yessoensis. Consistently, recombinant DUF1943 and VWD domains both could interact with LTA and LPS on bacterial wall, and purified native PyVg displayed a broad-spectrum antibacterial activity against both Gram-negative (Escherichia coli and Vibrio anguillarum) and Gram-positive bacteria (Staphylococcus aureus). Overall, these data indicate that Vg is a pattern recognition molecule with bacterial growth-inhibiting activity in the scallop. PMID:25499034

  9. Identification of Multiple Soluble Fe(III) Reductases in Gram-Positive Thermophilic Bacterium Thermoanaerobacter indiensis BSB-33

    PubMed Central

    Pal, Subrata

    2014-01-01

    Thermoanaerobacter indiensis BSB-33 has been earlier shown to reduce Fe(III) and Cr(VI) anaerobically at 60°C optimally. Further, the Gram-positive thermophilic bacterium contains Cr(VI) reduction activity in both the membrane and cytoplasm. The soluble fraction prepared from T. indiensis cells grown at 60°C was found to contain the majority of Fe(III) reduction activity of the microorganism and produced four distinct bands in nondenaturing Fe(III) reductase activity gel. Proteins from each of these bands were partially purified by chromatography and identified by mass spectrometry (MS) with the help of T. indiensis proteome sequences. Two paralogous dihydrolipoamide dehydrogenases (LPDs), thioredoxin reductase (Trx), NADP(H)-nitrite reductase (Ntr), and thioredoxin disulfide reductase (Tdr) were determined to be responsible for Fe(III) reductase activity. Amino acid sequence and three-dimensional (3D) structural similarity analyses of the T. indiensis Fe(III) reductases were carried out with Cr(VI) reducing proteins from other bacteria. The two LPDs and Tdr showed very significant sequence and structural identity, respectively, with Cr(VI) reducing dihydrolipoamide dehydrogenase from Thermus scotoductus and thioredoxin disulfide reductase from Desulfovibrio desulfuricans. It appears that in addition to their iron reducing activity T. indiensis LPDs and Tdr are possibly involved in Cr(VI) reduction as well. PMID:25180173

  10. Antibacterial activities and antioxidant capacity of Aloe vera

    PubMed Central

    2013-01-01

    Background The aim of this study was to identify, quantify, and compare the phytochemical contents, antioxidant capacities, and antibacterial activities of Aloe vera lyophilized leaf gel (LGE) and 95% ethanol leaf gel extracts (ELGE) using GC-MS and spectrophotometric methods. Results Analytically, 95% ethanol is less effective than ethyl acetate/diethyl ether or hexane (in the case of fatty acids) extractions in separating phytochemicals for characterization purposes. However, although fewer compounds are extracted in the ELGE, they are approximately 345 times more concentrated as compared to the LGE, hence justifying ELGE use in biological efficacy studies in vivo. Individual phytochemicals identified included various phenolic acids/polyphenols, phytosterols, fatty acids, indoles, alkanes, pyrimidines, alkaloids, organic acids, aldehydes, dicarboxylic acids, ketones, and alcohols. Due to the presence of the antioxidant polyphenols, indoles, and alkaloids, the A. vera leaf gel shows antioxidant capacity as confirmed by ORAC and FRAP analyses. Both analytical methods used show the non-flavonoid polyphenols to contribute to the majority of the total polyphenol content. Three different solvents such as aqueous, ethanol, and acetone were used to extract the bioactive compounds from the leaves of A. vera to screen the antibacterial activity selected human clinical pathogens by agar diffusion method. The maximum antibacterial activities were observed in acetone extracts (12 ± 0.45, 20 ± 0.35, 20 ± 0.57, and 15 ± 0.38 nm) other than aqueous and ethanol extracts. Conclusion Due to its phytochemical composition, A. vera leaf gel may show promise in alleviating symptoms associated with/or prevention of cardiovascular diseases, cancer, neurodegeneration, and diabetes. PMID:23870710

  11. A biotemplated nickel nanostructure: Synthesis, characterization and antibacterial activity

    SciTech Connect

    Ashtari, Khadijeh; Fasihi, Javad; Mollania, Nasrin; Khajeh, Khosro

    2014-02-01

    Highlights: • Nickel nanostructure-encapsulated bacteria were prepared using electroless deposition. • Bacterium surface was activated by red-ox reaction of its surface amino acids. • Interfacial changes at cell surfaces were investigated using fluorescence spectroscopy. • TEM and AFM depicted morphological changes. • Antibacterial activity of nanostructure was examined against different bacteria strains. - Abstract: Nickel nanostructure-encapsulated bacteria were prepared using the electroless deposition procedure and activation of bacterium cell surface by red-ox reaction of surface amino acids. The electroless deposition step occurred in the presence of Ni(II) and dimethyl amine boran (DMAB). Interfacial changes at bacteria cell surfaces during the coating process were investigated using fluorescence spectroscopy. Fluorescence of tryptophan residues was completely quenched after the deposition of nickel onto bacteria surfaces. Transmission electron microscopy (TEM) and atomic force microscopy (AFM) depicted morphological changes on the surface of the bacterium. It was found that the Ni coated nanostructure was mechanically stable after ultrasonication for 20 min. Significant increase in surface roughness of bacteria was also observed after deposition of Ni clusters. The amount of coated Ni on the bacteria surface was calculated as 36% w/w. The antibacterial activity of fabricated nanostructure in culture media was examined against three different bacteria strains; Escherichia coli, Bacillus subtilis and Xantomonas campestris. The minimum inhibitory concentrations (MIC) were determined as 500 mg/L, 350 mg/L and 200 mg/L against bacteria, respectively.

  12. Ciprofloxacin-Induced Antibacterial Activity Is Attenuated by Phosphodiesterase Inhibitors

    PubMed Central

    Masadeh, Majed M.; Alzoubi, Karem H.; Khabour, Omar F.; Al-Azzam, Sayer I.

    2014-01-01

    Background Ciprofloxacin is a commonly used antibiotic for urinary tract infection that interacts with bacterial topoisomerases leading to oxidative radicals generation and bacterial cell death. Phosphodiesterase inhibitors (PDEis), on the other hand, are commonly used drugs for the management of erectile dysfunction. The group includes agents such as sildenafil, vardenafil, and tadalafil. Objectives We investigated whether PDEi could interfere with the antibacterial activity of ciprofloxacin. Methods PDEis were tested in several reference bacteria, including Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Staphylococcus epidermidis, Acinetobacter baumannii, Proteus mirabilis, and Klebsiella pneumoniae utilizing a standard disc diffusion method and measuring both zones of inhibition and MIC. Results Results from both assays indicated that ciprofloxacin demonstrates potent activity against the tested reference bacteria. Additionally, when bacteria were treated with a combination of ciprofloxacin and sildenafil, tadalafil, or vardenafil, the zones of the combination inhibition were significantly reduced, whereas the MIC values were significantly greater than those of ciprofloxacin alone for all tested bacterial strains. In an attempt to examine the mechanism by which PDEis interfere with the action of ciprofloxacin, we utilized the in vitro E coli DNA gyrase cleavage assay. The results showed that PDEi drugs had no effect on ciprofloxacin’s inhibition of E coli gyrase activity. Conclusions Pretreatment of various reference bacterial cells with PDEis largely inhibited the antibacterial activity of ciprofloxacin.

  13. Lithocholic acid and derivatives: Antibacterial activity.

    PubMed

    do Nascimento, Patrícia G G; Lemos, Telma L G; Almeida, Macia C S; de Souza, Juliana M O; Bizerra, Ayla M C; Santiago, Gilvandete M P; da Costa, José G M; Coutinho, Henrique D M

    2015-12-01

    In order to develop bioactive lithocholic acid derivatives, we prepared fifteen semi-synthetic compounds through modification at C-3 and/or C-24. The reactions showed yields ranging from 37% to 100%. The structures of all compounds obtained were identified on the basis of their spectral data (IR, MS, 1D- and 2D-NMR). The activity of lithocholic acid and derivatives was evaluated against the growth of Escherichia coli, Staphylococcus aureus, Bacillus cereus and Pseudomonas aeruginosa. The derivative 3?-formyloxy-5?-cholan-24-oic acid (LA-06) showed the best activity, with MIC values of 0.0790mM against E. coli (Ec 27) and B. cereus in both cases, and 0.0395mM against S. aureus (ATCC 12692). Lithocholic acid and the derivatives with MIC?1.2mM were evaluated on the susceptibility of some bacterial pathogens to the aminoglycoside antibiotics neomycin, amikacin and gentamicin was evaluated. There are no previously reported studies about these compounds as modifiers of the action of antibiotics or any other drugs. PMID:26216208

  14. One-pot synthesis of porous Fe3O4 shell/silver core nanocomposites used as recyclable magnetic antibacterial agents

    NASA Astrophysics Data System (ADS)

    Fang, Weijun; Zheng, Jun; Chen, Cheng; Zhang, Huabing; Lu, Yunxia; Ma, Ling; Chen, Guangjun

    2014-05-01

    Porous Fe3O4 shell/silver core nanocomposites featuring sustainable and recyclable antibacterial activity have been successfully prepared via a facile one-pot hydrothermal method. The unique structural feature of the Ag@Fe3O4 nanocomposites with Ag embedded in porous Fe3O4 shell endows them with the ability of sustained-release of silver ions. Their antimicrobial activity studies were investigated on both Gram negative Escherichia coli and Gram positive Bacillus subtilis, which demonstrate that the nanocomposites are highly toxic to microorganisms and exhibit sustainable antibacterial activity. Besides, the Ag@Fe3O4 nanocomposites can be separated easily from the medium by a small magnet, which provided an effective way to eliminate the residual nanosilver from the surroundings. We finally demonstrate that the recovered nanocomposites exhibit recyclable antibacterial activity, acting as an ideal long-acting antibacterial agent.

  15. Repromicin derivatives with potent antibacterial activity against Pasteurella multocida.

    PubMed

    McFarland, J W; Hecker, S J; Jaynes, B H; Jefson, M R; Lundy, K M; Vu, C B; Glazer, E A; Froshauer, S A; Hayashi, S F; Kamicker, B J; Reese, C P; Olson, J A

    1997-03-14

    Reductive amination of repromicin with polyfunctional amines has led to new macrolide antibacterial agents, some of which are highly potent against the Gram-negative pathogen Pasteurella multocida both in vitro and in a mouse infection model. A key element in this discovery was the recognition that among certain known macrolides increasing lipophilicity results in diminished in vivo activity. One repromicin derivative, 20-[N-[3-(dimethylamino)-propyl]-N-L-alanylamino]-20-deoxorepro micin (35), was selected for advanced evaluation. At 5 mg/kg, a single subcutaneous dose was found to control induced pasteurellosis in swine and induced respiratory disease in cattle. PMID:9083494

  16. Interconverting flavonostilbenes with antibacterial activity from Sophora alopecuroides.

    PubMed

    Wan, Chuan-Xing; Luo, Jian-Guang; Ren, Xiao-Pu; Kong, Ling-Yi

    2015-08-01

    Five flavonostilbenes (alopecurones H, I, J, K and L) and five known ones were isolated from roots of Sophora alopecuroides, in addition to ten other phenolic compounds. A non-enzymatic interconversion of the lavandulyl-substituted flavonostilbenes was observed among alopecurones A, H, I, and K through a Wessely-Moser rearrangement reaction; this was proven by 1D and 2D NMR, HPLC-CD-PDA and HRMS analyses. Bioassay results suggested that flavonostilbenes exhibit significant antibacterial and anti-biofilm formation activities against Staphylococcus epidermidis with MIC values ranging from 3.1 to 12.5?g/mL. PMID:25813880

  17. Antibacterial activity of silver-killed bacteria: the "zombies" effect

    NASA Astrophysics Data System (ADS)

    Wakshlak, Racheli Ben-Knaz; Pedahzur, Rami; Avnir, David

    2015-04-01

    We report a previously unrecognized mechanism for the prolonged action of biocidal agents, which we denote as the zombies effect: biocidally-killed bacteria are capable of killing living bacteria. The concept is demonstrated by first killing Pseudomonas aeruginosa PAO1 with silver nitrate and then challenging, with the dead bacteria, a viable culture of the same bacterium: Efficient antibacterial activity of the killed bacteria is observed. A mechanism is suggested in terms of the action of the dead bacteria as a reservoir of silver, which, due to Le-Chatelier's principle, is re-targeted to the living bacteria. Langmuirian behavior, as well as deviations from it, support the proposed mechanism.

  18. Facile, one-pot synthesis, and antibacterial activity of mesoporous silica nanoparticles decorated with well-dispersed silver nanoparticles.

    PubMed

    Tian, Yue; Qi, Juanjuan; Zhang, Wei; Cai, Qiang; Jiang, Xingyu

    2014-08-13

    In this study, we exploit a facile, one-pot method to prepare MCM-41 type mesoporous silica nanoparticles decorated with silver nanoparticles (Ag-MSNs). Silver nanoparticles with diameter of 2-10 nm are highly dispersed in the framework of mesoporous silica nanoparticles. These Ag-MSNs possess an enhanced antibacterial effect against both Gram-positive and Gram-negative bacteria by preventing the aggregation of silver nanoparticles and continuously releasing silver ions for one month. The cytotoxicity assay indicates that the effective antibacterial concentration of Ag-MSNs shows little effect on human cells. This report describes an efficient and economical route to synthesize mesoporous silica nanoparticles with uniform silver nanoparticles, and these nanoparticles show promising applications as antibiotics. PMID:25050635

  19. Synthesis, characterization, antibacterial activities and carbonic anhydrase enzyme inhibitor effects of new arylsulfonylhydrazone and their Ni(II), Co(II) complexes

    NASA Astrophysics Data System (ADS)

    Özdemir, Ümmühan Özmen; Arslan, Fatma; Hamurcu, Fatma

    2010-01-01

    Ethane sulfonic acide hydrazide ( esh: CH 3CH 2SO 2NHNH 2) derivatives as 5-methylsalicyl-aldehydeethanesulfonylhydrazone ( 5msalesh), 5-methyl-2-hydroxyacetophenoneethane sulfonylhydrazone ( 5mafesh) and their Ni(II), Co(II) complexes have been synthesized for the first time. The structure of these compounds has been investigated by elemental analysis, FT-IR, 1H NMR, 13C NMR, LC/MS, UV-vis spectrophotometric method, magnetic susceptibility, thermal studies and conductivity measurements. The antibacterial activities of synthesized compounds were studied against Gram positive bacteria; Staphylococcus aureus, Bacillus subtilis, Bacillus magaterium and Gram negative bacteria; Salmonella enteritidis, Escherichia coli by using the microdilution broth method. The biological activity screening showed that ligands have more activity than complexes against the tested bacteria. The inhibition activities of these compounds on carbonic anhydrase II (CA II) have been investigated by comparing IC 50 and Ki values and it has been found that 5msalesh and its complexes have more enzyme inhibition efficiency than other compounds.

  20. Evaluation of substituted methyl cyclohexanone hybrids for anti-tubercular, anti-bacterial and anti-fungal activity: Facile syntheses under catalysis by ionic liquids.

    PubMed

    Ghatole, Ajay M; Lanjewar, Kushal R; Gaidhane, Mahesh K; Hatzade, Kishor M

    2015-12-01

    An library of unresolved racemic Mannich bases incorporating two stereogenic carbon centers was evaluated for antibacterial activity against clinically isolated Gram-positive bacteria i.e. Staphylococcus aureus, Gram-negative bacteria Escherichia coli and Pseudomonas aeruginosa and for antifungal activity against Candida albicans strains. Additionally, the susceptibility of microorganisms to Mannich bases prompted us to evaluate the potential for anti-tubercular activity against clinically isolated Mycobacterium tuberculosis and virulent H37Rv strains. All compounds showed potent activity against M. tuberculosis strains at MIC ranging from 50 ?g/mL to 6.25 ?g/mL of concentration. Facile one pot Mannich type syntheses of rac-(2S)-2-[(R)-[(4-substituted phenyl){[4-(4-substituted phenyl)-1,3-thiazol-2-yl]amino}methyl]cyclohexanone derivatives were achieved by reactions of various 2-amino-4-aryl-thiazoles, appropriately substituted aromatic aldehydes and cyclohexanone in Bronsted acidic quaternary ammonium sulfated ionic liquids serving as dual solvents and catalysts. PMID:26162339

  1. Antibacterial activity of large-area monolayer graphene film manipulated by charge transfer

    NASA Astrophysics Data System (ADS)

    Li, Jinhua; Wang, Gang; Zhu, Hongqin; Zhang, Miao; Zheng, Xiaohu; di, Zengfeng; Liu, Xuanyong; Wang, Xi

    2014-03-01

    Graphene has attracted increasing attention for potential applications in biotechnology due to its excellent electronic property and biocompatibility. Here we use both Gram-positive Staphylococcus aureus (S. aureus) and Gram-negative Escherichia coli (E. coli) to investigate the antibacterial actions of large-area monolayer graphene film on conductor Cu, semiconductor Ge and insulator SiO2. The results show that the graphene films on Cu and Ge can surprisingly inhibit the growth of both bacteria, especially the former. However, the proliferation of both bacteria cannot be significantly restricted by the graphene film on SiO2. The morphology of S. aureus and E. coli on graphene films further confirms that the direct contact of both bacteria with graphene on Cu and Ge can cause membrane damage and destroy membrane integrity, while no evident membrane destruction is induced by graphene on SiO2. From the viewpoint of charge transfer, a plausible mechanism is proposed here to explain this phenomenon. This study may provide new insights for the better understanding of antibacterial actions of graphene film and for the better designing of graphene-based antibiotics or other biomedical applications.

  2. Antibacterial activity of large-area monolayer graphene film manipulated by charge transfer

    PubMed Central

    Li, Jinhua; Wang, Gang; Zhu, Hongqin; Zhang, Miao; Zheng, Xiaohu; Di, Zengfeng; Liu, Xuanyong; Wang, Xi

    2014-01-01

    Graphene has attracted increasing attention for potential applications in biotechnology due to its excellent electronic property and biocompatibility. Here we use both Gram-positive Staphylococcus aureus (S. aureus) and Gram-negative Escherichia coli (E. coli) to investigate the antibacterial actions of large-area monolayer graphene film on conductor Cu, semiconductor Ge and insulator SiO2. The results show that the graphene films on Cu and Ge can surprisingly inhibit the growth of both bacteria, especially the former. However, the proliferation of both bacteria cannot be significantly restricted by the graphene film on SiO2. The morphology of S. aureus and E. coli on graphene films further confirms that the direct contact of both bacteria with graphene on Cu and Ge can cause membrane damage and destroy membrane integrity, while no evident membrane destruction is induced by graphene on SiO2. From the viewpoint of charge transfer, a plausible mechanism is proposed here to explain this phenomenon. This study may provide new insights for the better understanding of antibacterial actions of graphene film and for the better designing of graphene-based antibiotics or other biomedical applications. PMID:24619247

  3. Mechanism of action of recombinant Acc-royalisin from royal jelly of Chinese honeybee against gram-positive bacteria

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The antibacterial activity of royalisin, an antimicrobial peptide from the royal jelly produced by honeybees has been addressed extensively. However, its mechanism of action remains unclear. In this study, a recombinant royalisin, RAcc-royalisin from the royal jelly of Chinese honeybee Apis cerana...

  4. Efficient synthesis of anacardic acid analogues and their antibacterial activities.

    PubMed

    Mamidyala, Sreeman K; Ramu, Soumya; Huang, Johnny X; Robertson, Avril A B; Cooper, Matthew A

    2013-03-15

    Anacardic acid derivatives exhibit a broad range of biological activities. In this report, an efficient method for the synthesis of anacardic acid derivatives was explored, and a small set of salicylic acid variants synthesised retaining a constant hydrophobic element (a naphthyl tail). The naphthyl side chain was introduced via Wittig reaction and the aldehyde installed using directed ortho-metalation reaction of the substituted o-anisic acids. The failure of ortho-metalation using unprotected carboxylic acid group compelled us to use directed ortho-metalation in which a tertiary amide was used as a strong ortho-directing group. In the initial route, tertiary amide cleavage during final step was challenging, but cleaving the tertiary amide before Wittig reaction was beneficial. The Wittig reaction with protected carboxylic group (methyl ester) resulted in side-products whereas using sodium salt resulted in higher yields. The novel compounds were screened for antibacterial activity and cytotoxicity. Although substitution on the salicylic head group enhanced antibacterial activities they also enhanced cytotoxicity. PMID:23416004

  5. Antibacterial alkaloids from Artabotrys crassifolius Hook.f. & Thomson.

    PubMed

    Tan, Kok Kwan; Khoo, Teng Jing; Rajagopal, Mogana; Wiart, Christophe

    2015-12-01

    Chloroform extract of bark of Artabotrys crassifolius Hook.f. & Thomson exhibited antibacterial activities against both American Type Culture Collection and clinical bacterial strains in vitro with zones of inhibition ranging from 7 to 14 mm. Further analysis of this extract yielded artabotrine, liridine, lysicamine and atherospermidine. Artabotrine displayed a broad array of antibacterial activity mostly against Gram-positive bacteria with minimum inhibitory concentration (MIC) values ranging from 1.25 ?g/mL to 5 ?g/mL. Of note, artabotrine, liridine and lysicamine are bactericidal against Gram-negative extended-spectrum beta-lactamase-producing Klebsiella with MIC values equal 2.5, 2.5 and 10 ?g/mL, respectively, and minimum bactericidal concentrations values equal to 2.5, 5 and 20 ?g/mL. PMID:25738993

  6. The antibacterial activity of phytochemically characterised fractions from Folium Syringae.

    PubMed

    Zhou, Zhengyuan; Han, Na; Liu, Zhihui; Wang, Jinling; Xia, Huanzhang; Miao, Dezu; Li, Wei; Yin, Jun

    2014-01-01

    To identify the most active antimicrobial fraction of Folium Syringae, four common pathogens were used in an in vitro screening. The results indicated that the combination of the 30% and 60% ethanol fraction (FSC) obtained from the water extraction was the most active fraction with a minimal inhibitory concentration of 0.65 mg mL(-1). FSC was also found to be able to protect mice from a lethal infection of Staphylococcus aureus at clinical dosage (0.2 g kg(-1)) with a survival rate of 83.3%. The antibacterial activity of FSC was then tested using the serum pharmacology method which revealed that FSC exhibits a more long-lasting activity than the positive control (levofloxacin hydrochloride). The main components were confirmed to be iridoid glycosides and flavones by HPLC-MS analysis. PMID:24805057

  7. Antibacterial activities of oxyprenylated chalcones and napthtoquinone against Helicobacter pylori.

    PubMed

    Bodet, Charles; Burucoa, Christophe; Rouillon, Steeve; Bellin, Nicolas; Taddeo, Vito Alessandro; Fiorito, Serena; Genovese, Salvatore; Epifano, Francesco

    2014-09-01

    In this study, we synthesized and characterized the antibacterial activity of three naturally occurring oxyprenylated chalcones {xinjiachalcone A (1), (2E)-1-{2,6-dihydroxy-4-[(3-methylbut-2-enyl)oxy]phenyl}-3-(4-hydroxyphenyl)prop-2-en-1-one (2), (2E)-1-{2,6-dihydroxy-4-[(3-methylbut-2-enyl)oxy]phenyl}-3-phenylprop-2-en-1-one (3), and lawsone 2-isopentenyl ether (4)}. Using several strains of Helicobacter pylori, including clinical ones, minimum inhibitory concentration (MIC) values and bactericidal activities of these compounds were determined. Xinjiachalcone A (1), active principle of Glycyrrhiza inflata Batalin, was the most effective compound, showing both a low MIC and a strong bactericidal activity against H. pylori. This study suggests that these compounds represent potential natural molecules for the prevention and treatment of H. pylori associated diseases. PMID:25918797

  8. Antibacterial activity of xanthones from Garcinia mangostana (L.) and their structure-activity relationship studies.

    PubMed

    Dharmaratne, H R W; Sakagami, Yoshikazu; Piyasena, K G P; Thevanesam, Vasanthi

    2013-01-01

    Antibacterial activities of prenylated xanthones from Garcinia mangostana and their synthetic analogues were investigated, and their structure-activity relationships have been studied. ?-Mangostin has shown antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA), methicillin sensitive Staphylococcus aureus (MSSA), vancomycin-resistant Enterococcus (VRE) and vancomycin-sensitive Enterococcus (VSE) strains at MICs 3.13, 6.25, 6.25 and 6.25 µg mL(-1), respectively. In these experiments, gentamicin was used as the positive control. Further, some analogues of ?-mangostin and ?-mangostin were synthesised and their activity was tested against MRSA and VRE strains. The analysis of the bioassay results above indicated that, the combination of C-6 and C-3 hydroxyl groups along with the prenyl side chain at C-2 in the 1,3,6,7-tetraoxygenated xanthones from G. mangostana is essential to have a high antibacterial activity. PMID:22494050

  9. Selective Inactivation of Resistant Gram-Positive Pathogens with a Light-Driven Hybrid Nanomaterial.

    PubMed

    Grüner, Malte; Tuchscherr, Lorena; Löffler, Bettina; Gonnissen, Dominik; Riehemann, Kristina; Staniford, Mark C; Kynast, Ulrich; Strassert, Cristian A

    2015-09-23

    Herein, we present a straightforward strategy to disperse highly insoluble photosensitizers in aqueous environments, without major synthetic efforts and keeping their photosensitizing abilities unaffected. A layered nanoclay was employed to adsorb and to solubilize a highly efficient yet hydrophobic Si(IV) phthalocyaninate in water. The aggregation of the photoactive dye was correlated with its photophysical properties, particularly with the ability to produce highly cytotoxic singlet oxygen. Moreover, the resulting hybrid nanomaterial is able to selectively photoinactivate Gram-positive pathogens, due to local interactions between the bacterial membranes and the negatively charged nanodiscs. Nanotoxicity assays confirmed its innocuousness toward eukaryotic cells, showing that it constitutes a new class of "phototriggered magic bullet" for the inactivation of pathogens in phototherapy, as well as in the development of coatings for self-disinfecting surfaces. PMID:26360157

  10. Subcellular localization for Gram positive and Gram negative bacterial proteins using linear interpolation smoothing model.

    PubMed

    Saini, Harsh; Raicar, Gaurav; Dehzangi, Abdollah; Lal, Sunil; Sharma, Alok

    2015-12-01

    Protein subcellular localization is an important topic in proteomics since it is related to a protein?s overall function, helps in the understanding of metabolic pathways, and in drug design and discovery. In this paper, a basic approximation technique from natural language processing called the linear interpolation smoothing model is applied for predicting protein subcellular localizations. The proposed approach extracts features from syntactical information in protein sequences to build probabilistic profiles using dependency models, which are used in linear interpolation to determine how likely is a sequence to belong to a particular subcellular location. This technique builds a statistical model based on maximum likelihood. It is able to deal effectively with high dimensionality that hinders other traditional classifiers such as Support Vector Machines or k-Nearest Neighbours without sacrificing performance. This approach has been evaluated by predicting subcellular localizations of Gram positive and Gram negative bacterial proteins. PMID:26386142

  11. Acylprolinamides: a new class of peptide deformylase inhibitors with in vivo antibacterial activity.

    PubMed

    Axten, Jeffrey M; Medina, Jesús R; Blackledge, Charles W; Duquenne, Céline; Grant, Seth W; Bobko, Mark A; Peng, Tony; Miller, William H; Pinckney, Theresa; Gallagher, Timothy F; Kulkarni, Swarupa; Lewandowski, Thomas; Van Aller, Glenn S; Zonis, Rimma; Ward, Paris; Campobasso, Nino

    2012-06-15

    A new class of PDF inhibitor with potent, broad spectrum antibacterial activity is described. Optimization of blood stability and potency provided compounds with improved pharmacokinetics that were suitable for in vivo experiments. Compound 5c, which has robust antibacterial activity, demonstrated efficacy in two respiratory tract infection models. PMID:22579486

  12. sRNAdb: A small non-coding RNA database for gram-positive bacteria

    PubMed Central

    2012-01-01

    Background The class of small non-coding RNA molecules (sRNA) regulates gene expression by different mechanisms and enables bacteria to mount a physiological response due to adaptation to the environment or infection. Over the last decades the number of sRNAs has been increasing rapidly. Several databases like Rfam or fRNAdb were extended to include sRNAs as a class of its own. Furthermore new specialized databases like sRNAMap (gram-negative bacteria only) and sRNATarBase (target prediction) were established. To the best of the authors’ knowledge no database focusing on sRNAs from gram-positive bacteria is publicly available so far. Description In order to understand sRNA’s functional and phylogenetic relationships we have developed sRNAdb and provide tools for data analysis and visualization. The data compiled in our database is assembled from experiments as well as from bioinformatics analyses. The software enables comparison and visualization of gene loci surrounding the sRNAs of interest. To accomplish this, we use a client–server based approach. Offline versions of the database including analyses and visualization tools can easily be installed locally on the user’s computer. This feature facilitates customized local addition of unpublished sRNA candidates and related information such as promoters or terminators using tab-delimited files. Conclusion sRNAdb allows a user-friendly and comprehensive comparative analysis of sRNAs from available sequenced gram-positive prokaryotic replicons. Offline versions including analysis and visualization tools facilitate complex user specific bioinformatics analyses. PMID:22883983

  13. The unique regulation of iron-sulfur cluster biogenesis in a Gram-positive bacterium

    PubMed Central

    Santos, Joana A.; Alonso-García, Noelia; Macedo-Ribeiro, Sandra; Pereira, Pedro José Barbosa

    2014-01-01

    Iron-sulfur clusters function as cofactors of a wide range of proteins, with diverse molecular roles in both prokaryotic and eukaryotic cells. Dedicated machineries assemble the clusters and deliver them to the final acceptor molecules in a tightly regulated process. In the prototypical Gram-negative bacterium Escherichia coli, the two existing iron-sulfur cluster assembly systems, iron-sulfur cluster (ISC) and sulfur assimilation (SUF) pathways, are closely interconnected. The ISC pathway regulator, IscR, is a transcription factor of the helix-turn-helix type that can coordinate a [2Fe-2S] cluster. Redox conditions and iron or sulfur availability modulate the ligation status of the labile IscR cluster, which in turn determines a switch in DNA sequence specificity of the regulator: cluster-containing IscR can bind to a family of gene promoters (type-1) whereas the clusterless form recognizes only a second group of sequences (type-2). However, iron-sulfur cluster biogenesis in Gram-positive bacteria is not so well characterized, and most organisms of this group display only one of the iron-sulfur cluster assembly systems. A notable exception is the unique Gram-positive dissimilatory metal reducing bacterium Thermincola potens, where genes from both systems could be identified, albeit with a diverging organization from that of Gram-negative bacteria. We demonstrated that one of these genes encodes a functional IscR homolog and is likely involved in the regulation of iron-sulfur cluster biogenesis in T. potens. Structural and biochemical characterization of T. potens and E. coli IscR revealed a strikingly similar architecture and unveiled an unforeseen conservation of the unique mechanism of sequence discrimination characteristic of this distinctive group of transcription regulators. PMID:24847070

  14. Study of the antibacterial activity of ZnO nanoparticles

    NASA Astrophysics Data System (ADS)

    Surti, Arjuman; Radha, S.; Garje, S. S.

    2013-02-01

    This study focuses on the antibacterial activity of the ZnO nanoparticles against organisms causing skin and wound infections. The nanoparticles were synthesized by a wet chemical route. The method was quick and nanoparticles were obtained in 3 days of incubation in dark. Characterization of the nanoparticles was done by X-Ray Diffraction and UV-Visible Spectrophotometry. It was observed that the UV-Visible spectrum peak was obtained at 357 nm corresponding to the Plasmon absorbance of Zinc oxide. X-Ray diffraction exhibited the 2? values corresponding to Zinc oxide and the particle size was estimated to be 20 nm. The antibacterial effect of nanoparticles was observed against Staphylococcus spp and Bacillus spp. The significance of the bactericidal activity of the nanoparticles lies in the reduction of using antibiotics against nosocomial infections, especially in prolonged treatments. The bandage material used in wound dressing was coated with ZnO nanoparticles by adsorption method. The textile was found to be efficient in inhibiting the growth of these organisms. The effect of adverse storage conditions on the coated bandage material was also studied. On comparing the results obtained at extreme pH and temperature and those obtained at optimum conditions, it was seen that the nanoparticles were less effective at these extreme conditions.

  15. Sexual ornamentation reflects antibacterial activity of ejaculates in mallards

    PubMed Central

    Rowe, Melissah; Czirják, Gábor Árpád; McGraw, Kevin J.; Giraudeau, Mathieu

    2011-01-01

    Bacteria present in ejaculates can impair sperm function and reduce male reproductive success. Thus, selection should favour the evolution of antimicrobial defences to limit the detrimental effects of sperm-associated bacteria. Additionally, current hypotheses suggest that ornamental traits may signal information about the infection status of an individual or the ability of an individual to resist bacterial-induced sperm damage. However, despite the evolutionary implications of ejaculate antimicrobials, and the putative importance of pathogens for the evolution of male ornamentation, tests of these hypotheses are lacking. We examined the antibacterial activity of semen from mallard ducks (Anas platyrhynchos) and tested whether the bactericidal capacity of semen was associated with bill coloration, a sexually selected trait. We show that mallard semen exhibits significant antibacterial activity, as measured by the in vitro capacity to kill Escherichia coli and Staphylococcus aureus. Furthermore, we demonstrate that males with more colourful bills have semen with superior bacterial-killing ability. These results suggest that females could use male phenotypic traits to avoid sexually transmitted pathogens and acquire partners whose sperm suffer less bacteria-induced damage. PMID:21490006

  16. MRJP1-containing glycoproteins isolated from honey, a novel antibacterial drug candidate with broad spectrum activity against multi-drug resistant clinical isolates

    PubMed Central

    Brudzynski, Katrina; Sjaarda, Calvin; Lannigan, Robert

    2015-01-01

    The emergence of extended- spectrum ?-lactamase (ESBL) is the underlying cause of growing antibiotic resistance among Gram-negative bacteria to ?-lactam antibiotics. We recently reported the discovery of honey glycoproteins (glps) that exhibited a rapid, concentration-dependent antibacterial activity against both Gram-positive Bacillus subtilis and Gram-negative Escherichia coli that resembled action of cell wall-active ?-lactam drugs. Glps showed sequence identity with the Major Royal Jelly Protein 1 (MRJP1) precursor that harbors three antimicrobial peptides: Jelleins 1, 2, and 4. Here, we used semi-quantitative radial diffusion assay and broth microdilution assay to evaluate susceptibility of a number of multi-drug resistant (MDR) clinical isolates to the MRJP1-contaning honey glycoproteins. The MDR bacterial strains comprised three methicillin-resistant Staphylococcus aureus (MRSA), four Pseudomonas aeruginosa, two Klebsiella pneumoniae, two vancomycin-resistant Enterococci (VRE), and five ESBL identified as one Proteus mirabilis, three E. coli, and one E. coli NDM. Their resistance to different classes of antibiotics was confirmed using automated system Vitek 2. MDR isolates differed in their susceptibility to glps with MIC90 values ranging from 4.8 ?g/ml against B. subtilis to 14.4 ?g/ml against ESBL K. pneumoniae, Klebsiella spp. ESBL and E. coli and up to 33 ?g/ml against highly resistant strains of P. aeruginosa. Glps isolated from different honeys showed a similar ability to overcome bacterial resistance to ?-lactams suggesting that (a) their mode of action is distinct from other classes of ?-lactams and that (b) the common glps structure was the lead structure responsible for the activity. The results of the current study together with our previous evidence of a rapid bactericidal activity of glps demonstrate that glps possess suitable characteristics to be considered a novel antibacterial drug candidate. PMID:26217333

  17. Evaluation of antibacterial properties of Barium Zirconate Titanate (BZT) nanoparticle

    PubMed Central

    Mohseni, Simin; Aghayan, Mahdi; Ghorani-Azam, Adel; Behdani, Mohammad; Asoodeh, Ahmad

    2014-01-01

    So far, the antibacterial activity of some organic and inorganic compounds has been studied. Barium zirconate titanate [Ba(ZrxTi1-x)O3] (x = 0.05) nanoparticle is an example of inorganic materials. In vitro studies have provided evidence for the antibacterial activity of this nanoparticle. In the current study, the nano-powder was synthesized by sol-gel method. X-ray diffraction showed that the powder was single-phase and had a perovskite structure at the calcination temperature of 1000 °C. Antibacterial activity of the desired nanoparticle was assessed on two gram-positive (Staphylococcus aureus PTCC1431 and Micrococcus luteus PTCC1625) and two gram-negative (Escherichia coli HP101BA 7601c and clinically isolated Klebsiella pneumoniae) bacteria according to Radial Diffusion Assay (RDA). The results showed that the antibacterial activity of BZT nano-powder on both gram-positive and gram-negative bacteria was acceptable. The minimum inhibitory concentration of this nano-powder was determined. The results showed that MIC values for E. coli, K. pneumoniae, M. luteus and S. aureus were about 2.3 ?g/mL, 7.3 ?g/mL, 3 ?g/mL and 12 ?g/mL, respectively. Minimum bactericidal concentration (MBC) was also evaluated and showed that the growth of E. coli, K. pneumoniae, M. luteus and S. aureus could be decreased at 2.3, 14, 3 and 18 ?g/mL of BZT. Average log reduction in viable bacteria count in time-kill assay ranged between 6 Log10 cfu/mL to zero after 24 h of incubation with BZT nanoparticle. PMID:25763046

  18. Larvicidal activity of synthetic disinfectants and antibacterial soaps against mosquito, Culex quinquefasciatus (Diptera: Culicidae).

    PubMed

    Xue, Rui-De; Qualls, Whitney A

    2013-01-01

    Seven commercial synthetic disinfectant and antibacterial soap products were evaluated as mosquito larvicides against Culex quinquefasciatus Say in the laboratory. Three aerosol disinfectant products, at 0.01% concentration resulted in 58-76% mortality of laboratory-reared fourth instar mosquito larvae at 24 h posttreatment. Four antibacterial soap products at 0.0001% concentration resulted in 88-100% larval mortality at 24 h posttreatment. The active ingredient of the antibacterial soap products, triclosan (0.1%) resulted in 74% larval mortality. One of the antibacterial soap products, Equate caused the highest mosquito larval mortality in the laboratory. Equate antibacterial soap at the application rate of 0.000053 ppm resulted in 90% mortality of the introduced fourth instar larvae of Cx. quinquesfasicatus in the outdoor pools. In laboratory and field bioassays, the antibacterial soap resulted in significant larval mosquito mortality. PMID:23427662

  19. Investigation of antibacterial activity of cotton fabric incorporating nano silver colloid

    NASA Astrophysics Data System (ADS)

    Thanh, Ngo Vo Ke; Thi Phuong Phong, Nguyen

    2009-09-01

    In this work, silver nanoparticles were prepared by polyol process with microwave heating and incorporated on cotton fabric surfaces. The antibacterial performance of the antibacterial cotton fabric was tested for different concentration of nano-sized silver colloid, contact time germs, and washing times. It was found that antibacterial activity increased with the increasing concentration of nano-sized silver colloid. The antibacterial fabric with 758 mg/kg of silver nanoparticles on surface cotton was highly effective in killing test bacteria and had excellent water resisting property.

  20. Dual Mode Antibacterial Activity of Ion Substituted Calcium Phosphate Nanocarriers for Bone Infections

    PubMed Central

    Sampath Kumar, T. S.; Madhumathi, K.; Rubaiya, Y.; Doble, Mukesh

    2015-01-01

    Nanotechnology has tremendous potential for the management of infectious diseases caused by multi-drug resistant bacteria, through the development of newer antibacterial materials and efficient modes of antibiotic delivery. Calcium phosphate (CaP) bioceramics are commonly used as bone substitutes due to their similarity to bone mineral and are widely researched upon for the treatment of bone infections associated with bone loss. CaPs can be used as local antibiotic delivery agents for bone infections and can be substituted with antibacterial ions in their crystal structure to have a wide spectrum, sustained antibacterial activity even against drug resistant bacteria. In the present work, a dual mode antibiotic delivery system with antibacterial ion substituted calcium deficient hydroxyapatite (CDHA) nanoparticles has been developed. Antibacterial ions such as zinc, silver, and strontium have been incorporated into CDHA at concentrations of 6, 0.25–0.75, and 2.5–7.5 at. %, respectively. The samples were found to be phase pure, acicular nanoparticles of length 40–50?nm and width 5–6?nm approximately. The loading and release profile of doxycycline, a commonly used antibiotic, was studied from the nanocarriers. The drug release was studied for 5?days and the release profile was influenced by the ion concentrations. The release of antibacterial ions was studied over a period of 21?days. The ion substituted CDHA samples were tested for antibacterial efficacy on Staphylococcus aureus and Escherichia coli by MIC/MBC studies and time-kill assay. AgCDHA and ZnCDHA showed high antibacterial activity against both bacteria, while SrCDHA was weakly active against S. aureus. Present study shows that the antibiotic release can provide the initial high antibacterial activity, and the sustained ion release can provide a long-term antibacterial activity. Such dual mode antibiotic and antibacterial ion release offers an efficient and potent way to treat an incumbent drug resistant infection. PMID:25984512

  1. Antibacterial activity and mechanism of berberine against Streptococcus agalactiae

    PubMed Central

    Peng, Lianci; Kang, Shuai; Yin, Zhongqiong; Jia, Renyong; Song, Xu; Li, Li; Li, Zhengwen; Zou, Yuanfeng; Liang, Xiaoxia; Li, Lixia; He, Changliang; Ye, Gang; Yin, Lizi; Shi, Fei; Lv, Cheng; Jing, Bo

    2015-01-01

    The antibacterial activity and mechanism of berberine against Streptococcus agalactiae were investigated in this study by analyzing the growth, morphology and protein of the S. agalactiae cells treated with berberine. The antibacterial susceptibility test result indicated minimum inhibition concentration (MIC) of berberine against Streptococcus agalactiae was 78 ?g/mL and the time-kill curves showed the correlation of concentration-time. After the bacteria was exposed to 78 ?g/mL berberine, the fragmentary cell membrane and cells unequal division were observed by the transmission electron microscopy (TEM), indicating the bacterial cells were severely damaged. Sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) study demonstrated that berberine could damage bacterial cells through destroying cellular proteins. Meanwhile, Fluorescence microscope revealed that berberine could affect the synthesis of DNA. In conclusion, these results strongly suggested that berberine may damage the structure of bacterial cell membrane and inhibit synthesis of protein and DNA, which cause Streptococcus agalactiae bacteria to die eventually. PMID:26191220

  2. Antibacterial activity of caffeine against plant pathogenic bacteria.

    PubMed

    Sledz, Wojciech; Los, Emilia; Paczek, Agnieszka; Rischka, Jacek; Motyka, Agata; Zoledowska, Sabina; Piosik, Jacek; Lojkowska, Ewa

    2015-01-01

    The objective of the present study was to evaluate the antibacterial properties of a plant secondary metabolite - caffeine. Caffeine is present in over 100 plant species. Antibacterial activity of caffeine was examined against the following plant-pathogenic bacteria: Ralstonia solanacearum (Rsol), Clavibacter michiganesis subsp. sepedonicus (Cms), Dickeya solani (Dsol), Pectobacterium atrosepticum (Pba), Pectobacterium carotovorum subsp. carotovorum (Pcc), Pseudomonas syringae pv. tomato (Pst), and Xanthomonas campestris subsp. campestris (Xcc). MIC and MBC values ranged from 5 to 20 mM and from 43 to 100 mM, respectively. Caffeine increased the bacterial generation time of all tested species and caused changes in cell morphology. The influence of caffeine on the synthesis of DNA, RNA and proteins was investigated in cultures of plant pathogenic bacteria with labelled precursors: [(3)H]thymidine, [(3)H]uridine or (14)C leucine, respectively. RNA biosynthesis was more affected than DNA or protein biosynthesis in bacterial cells treated with caffeine. Treatment of Pba with caffeine for 336 h did not induce resistance to this compound. Caffeine application reduced disease symptoms caused by Dsol on chicory leaves, potato slices, and whole potato tubers. The data presented indicate caffeine as a potential tool for the control of diseases caused by plant-pathogenic bacteria, especially under storage conditions. PMID:26307771

  3. Synthesis, spectroscopic characterisation, DNA cleavage, superoxidase dismutase activity and antibacterial properties of some transition metal complexes of a novel bidentate Schiff base derived from isatin and 2-aminopyrimidine

    NASA Astrophysics Data System (ADS)

    Nitha, L. P.; Aswathy, R.; Mathews, Niecy Elsa; Sindhu kumari, B.; Mohanan, K.

    2014-01-01

    Complexes of manganese(II), cobalt(II), nickel(II), copper(II) and zinc(II) with a Schiff base, formed by the condensation of isatin with 2-aminopyrimidine have been synthesised and characterised through elemental analysis, molar conductance measurements, magnetic susceptibility, IR, UV-Vis, 1HNMR, FAB mass and EPR spectral studies. The spectral data revealed that the ligand acts as neutral bidentate, coordinating to the metal ion through the carbonyl oxygen and azomethine nitrogen. Molar conductance values adequately support the electrolytic nature of the complexes. On the basis of the above observations the complexes have been formulated as [M(ISAP)2]X2, where M = Mn(II), Co(II), Ni(II), Cu(II) and Zn(II); X = Cl, OAc; ISAP = 2-[N-indole-2-one]aminopyrimidine. The ligand and copper(II) complex were subjected to X-ray diffraction studies. The DNA cleavage study was monitored by gel electrophoresis method. The superoxide dismutase (SOD) mimetic activities of the ligand and the metal complexes were checked using NBT assay. The in vitro antibacterial activity of the synthesized compounds has been tested against gram negative and gram positive bacteria.

  4. Impact of chain length on antibacterial activity and hemocompatibility of quaternary N-alkyl and n,n-dialkyl chitosan derivatives.

    PubMed

    Sahariah, Priyanka; Benediktssdóttir, Berglind E; Hjálmarsdóttir, Martha Á; Sigurjonsson, Olafur E; Sørensen, Kasper K; Thygesen, Mikkel B; Jensen, Knud J; Másson, Már

    2015-05-11

    A highly efficient method for chemical modification of chitosan biopolymers by reductive amination to yield N,N-dialkyl chitosan derivatives was developed. The use of 3,6-O-di-tert-butyldimethylsilylchitosan as a precursor enabled the first 100% disubstitution of the amino groups with long alkyl chains. The corresponding mono N-alkyl derivatives were also synthesized, and all the alkyl compounds were then quaternized using an optimized procedure. These well-defined derivatives were studied for antibacterial activity against Gram positive S. aureus, E. faecalis, and Gram negative E. coli, P. aeruginosa, which could be correlated to the length of the alkyl chain, but the order was dependent on the bacterial strain. Toxicity against human red blood cells and human epithelial Caco-2 cells was found to be proportional to the length of the alkyl chain. The most active chitosan derivatives were found to be more selective for killing bacteria than the quaternary ammonium disinfectants cetylpyridinium chloride and benzalkonium chloride, as well as the antimicrobial peptides melittin and LL-37. PMID:25830631

  5. Synthesis of silver nanoparticles using Solanum trilobatum fruits extract and its antibacterial, cytotoxic activity against human breast cancer cell line MCF 7

    NASA Astrophysics Data System (ADS)

    Ramar, Manikandan; Manikandan, Beulaja; Marimuthu, Prabhu Narayanan; Raman, Thiagarajan; Mahalingam, Anjugam; Subramanian, Palanisamy; Karthick, Saravanan; Munusamy, Arumugam

    2015-04-01

    In the present study, we have synthesized silver nanoparticles by a simple and eco-friendly method using unripe fruits of Solanum trilobatum. The aqueous silver ions when exposed to unripe fruits extract were reduced and stabilized over long time resulting in biosynthesis of surface functionalized silver nanoparticles. The bio-reduced silver nanoparticles were characterized by UV-visible spectroscopy, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive spectroscopy (EDX) and X-ray diffraction (XRD). These biologically synthesized silver nanoparticles were tested for its antibacterial activity against few human pathogenic bacteria including Gram-positive (Streptococcus mutans, Enterococcus faecalis) and Gram-negative (Escherichia coli, Klebsiella pneumoniae) bacteria. In addition, we also demonstrated anticancer activity of these nanoparticles in vitro against human breast cancer cell line (MCF 7) using MTT, nuclear morphology assay, Western blot and RT-PCR expression. These results taken together show the potential applications of biosynthesized silver nanoparticles using S. trilobatum fruits.

  6. Synthesis of silver nanoparticles using Solanum trilobatum fruits extract and its antibacterial, cytotoxic activity against human breast cancer cell line MCF 7.

    PubMed

    Ramar, Manikandan; Manikandan, Beulaja; Marimuthu, Prabhu Narayanan; Raman, Thiagarajan; Mahalingam, Anjugam; Subramanian, Palanisamy; Karthick, Saravanan; Munusamy, Arumugam

    2015-04-01

    In the present study, we have synthesized silver nanoparticles by a simple and eco-friendly method using unripe fruits of Solanum trilobatum. The aqueous silver ions when exposed to unripe fruits extract were reduced and stabilized over long time resulting in biosynthesis of surface functionalized silver nanoparticles. The bio-reduced silver nanoparticles were characterized by UV-visible spectroscopy, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive spectroscopy (EDX) and X-ray diffraction (XRD). These biologically synthesized silver nanoparticles were tested for its antibacterial activity against few human pathogenic bacteria including Gram-positive (Streptococcus mutans, Enterococcus faecalis) and Gram-negative (Escherichia coli, Klebsiella pneumoniae) bacteria. In addition, we also demonstrated anticancer activity of these nanoparticles in vitro against human breast cancer cell line (MCF 7) using MTT, nuclear morphology assay, Western blot and RT-PCR expression. These results taken together show the potential applications of biosynthesized silver nanoparticles using S. trilobatum fruits. PMID:25613692

  7. Influence of glucosamine on oligochitosan solubility and antibacterial activity.

    PubMed

    Blagodatskikh, Inesa V; Kulikov, Sergey N; Vyshivannaya, Oxana V; Bezrodnykh, Evgeniya A; Yamskov, Igor A; Tikhonov, Vladimir E

    2013-11-15

    Light scattering studies indicate that oligochitosan (short-chain chitosan) solutions contain aggregates at pH values below the critical pH of phase separation, while at or above this point the gel phase coexists with the aggregate solution. This work demonstrates for the first time that the presence of D-glucosamine in an oligochitosan solution shifts the critical pH to a higher value and improves the oligochitosan antibacterial activity against Escherichia coli, Staphylococcus aureus, and Staphylococcus epidermis in neutral and slightly alkaline aqueous media. By comparing the results of light scattering studies and antimicrobial assays one can conclude that the antimicrobial activity of oligochitosan is dependent on its unimolecular form, not its supramolecular structures. The widening of the homogeneity region of an oligochitosan solution could lead to promising biomedical applications. PMID:24056011

  8. Use of Enzyme Tests in Characterization and Identification of Aerobic and Facultatively Anaerobic Gram-Positive Cocci

    PubMed Central

    Bascomb, Shoshana; Manafi, Mammad

    1998-01-01

    The contribution of enzyme tests to the accurate and rapid routine identification of gram-positive cocci is introduced. The current taxonomy of the genera of aerobic and facultatively anaerobic cocci based on genotypic and phenotypic characterization is reviewed. The clinical and economic importance of members of these taxa is briefly summarized. Tables summarizing test schemes and kits available for the identification of staphylococci, enterococci, and streptococci on the basis of general requirements, number of tests, number of taxa, test classes, and completion times are discussed. Enzyme tests included in each scheme are compared on the basis of their synthetic moiety. The current understanding of the activity of enzymes important for classification and identification of the major groups, methods of testing, and relevance to the ease and speed of identification are reviewed. Publications describing the use of different identification kits are listed, and overall identification successes and problems are discussed. The relationships between the results of conventional biochemical and rapid enzyme tests are described and considered. The use of synthetic substrates for the detection of glycosidases and peptidases is reviewed, and the advantages of fluorogenic synthetic moieties are discussed. The relevance of enzyme tests to accurate and meaningful rapid routine identification is discussed. PMID:9564566

  9. Systematic Review of Membrane Components of Gram-Positive Bacteria Responsible as Pyrogens for Inducing Human Monocyte/Macrophage Cytokine Release

    PubMed Central

    Rockel, Christoph; Hartung, Thomas

    2012-01-01

    Fifty years after the elucidation of lipopolysaccharides (LPS, endotoxin) as the principal structure of Gram-negative bacteria activating the human immune system, its Gram-positive counterpart is still under debate. Pyrogen tests based on the human monocyte activation have been validated for LPS detection as an alternative to the rabbit test and, increasingly, the limulus amebocyte lysate test. For full replacement, international validations with non-endotoxin pyrogens are in preparation. Following evidence-based medicine approaches, a systematic review of existing evidence as to the structural nature of the Gram-positive pyrogen was undertaken. For the three major constituents suggested, i.e., peptidoglycan, lipoteichoic acids (LTA), and bacterial lipoproteins (LP), the questions to be answered and a search strategy for relevant literature was developed, starting in MedLine. The evaluation was based on the Koch–Dale criteria for a mediator of an effect. A total of 380 articles for peptidoglycan, 391 for LP, and 285 for LTA were retrieved of which 12, 8, and 24, respectively, fulfilled inclusion criteria. The compiled data suggest that for peptidoglycan two Koch–Dale criteria are fulfilled, four for LTA, and two for bacterial LP. In conclusion, based on the best currently available evidence, LTA is the only substance that fulfills all criteria. LTA has been isolated from a large number of bacteria, results in cytokine release patterns inducible also with synthetic LTA. Reduction in bacterial cytokine induction with an inhibitor for LTA was shown. However, this systematic review cannot exclude the possibility that other stimulatory compounds complement or substitute for LTA in being the counterpart to LPS in some Gram-positive bacteria. PMID:22529809

  10. Studies on Properties of Rice Straw/Polymer Nanocomposites Based on Polycaprolactone and Fe3O4 Nanoparticles and Evaluation of Antibacterial Activity

    PubMed Central

    Khandanlou, Roshanak; Ahmad, Mansor B.; Shameli, Kamyar; Saki, Elnaz; Kalantari, Katayoon

    2014-01-01

    Modified rice straw/Fe3O4/polycaprolactone nanocomposites (ORS/Fe3O4/PCL-NCs) have been prepared for the first time using a solution casting method. The RS/Fe3O4-NCs were modified with octadecylamine (ODA) as an organic modifier. The prepared NCs were characterized by using X-ray powder diffraction (XRD), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), Thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FT-IR). The XRD results showed that as the intensity of the peaks decreased with the increase of ORS/Fe3O4-NCs content in comparison with PCL peaks, the Fe3O4-NPs peaks increased from 1.0 to 60.0 wt. %. The TEM and SEM results showed a good dispersion of ORS/Fe3O4-NCs in the PCL matrix and the spherical shape of the NPs. The TGA analysis indicated thermal stability of ORS/Fe3O4-NCs increased after incorporation with PCL but the thermal stability of ORS/Fe3O4/PCL-NCs decreased with the increase of ORS/Fe3O4-NCs content. Tensile strength was improved with the addition of 5.0 wt. % of ORS/Fe3O4-NCs. The antibacterial activities of the ORS/Fe3O4/PCL-NC films were examined against Gram-negative bacteria (Escherichia coli) and Gram-positive bacteria (Staphylococcus aureus) by diffusion method using nutrient agar. The results indicated that ORS/Fe3O4/PCL-NC films possessed a strong antibacterial activity with the increase in the percentage of ORS/Fe3O4-NCs in the PCL. PMID:25318051

  11. Studies on properties of rice straw/polymer nanocomposites based on polycaprolactone and Fe?O? nanoparticles and evaluation of antibacterial activity.

    PubMed

    Khandanlou, Roshanak; Ahmad, Mansor B; Shameli, Kamyar; Saki, Elnaz; Kalantari, Katayoon

    2014-01-01

    Modified rice straw/Fe3O4/polycaprolactone nanocomposites (ORS/Fe3O4/ PCL-NCs) have been prepared for the first time using a solution casting method. The RS/Fe3O4-NCs were modified with octadecylamine (ODA) as an organic modifier. The prepared NCs were characterized by using X-ray powder diffraction (XRD), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), Thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FT-IR). The XRD results showed that as the intensity of the peaks decreased with the increase of ORS/Fe3O4-NCs content in comparison with PCL peaks, the Fe3O4-NPs peaks increased from 1.0 to 60.0 wt. %. The TEM and SEM results showed a good dispersion of ORS/Fe3O4-NCs in the PCL matrix and the spherical shape of the NPs. The TGA analysis indicated thermal stability of ORS/Fe3O4-NCs increased after incorporation with PCL but the thermal stability of ORS/Fe3O4/PCL-NCs decreased with the increase of ORS/Fe3O4-NCs content. Tensile strength was improved with the addition of 5.0 wt. % of ORS/Fe3O4-NCs. The antibacterial activities of the ORS/Fe3O4/PCL-NC films were examined against Gram-negative bacteria (Escherichia coli) and Gram-positive bacteria (Staphylococcus aureus) by diffusion method using nutrient agar. The results indicated that ORS/Fe3O4/PCL-NC films possessed a strong antibacterial activity with the increase in the percentage of ORS/Fe3O4-NCs in the PCL. PMID:25318051

  12. Generation and characterization of the antibacterial activity of a novel hybrid

    E-print Network

    Lowenberger, Carl

    Generation and characterization of the antibacterial activity of a novel hybrid antimicrobial. Key words: hybrid antimicrobial peptides, cecropin, antimicrobial activity, fusion expression. Re. Murray, and Carl A. Lowenberger Abstract: The search for new antimicrobial compounds involves finding

  13. Effect of Cu content on the antibacterial activity of titanium-copper sintered alloys.

    PubMed

    Liu, Jie; Li, Fangbing; Liu, Cong; Wang, Hongying; Ren, Baorui; Yang, Ke; Zhang, Erlin

    2014-02-01

    The phase constitution and the microstructure Ti-x Cu (x=2, 5, 10 and 25 wt.%) sintered alloys were investigated by XRD and SEM and the antibacterial activity was assessed in order to investigate the effect of the Cu content on the antibacterial activity. The results have shown that Ti2Cu was synthesized as a main secondary phase in all Ti-Cu alloys while Cu-rich phase was formed in the alloys with 5 wt.% or more copper. Antibacterial tests have showed that the Cu content influences the antibacterial rate seriously and only the alloys with 5 wt.% or high Cu have a strong and stable antibacterial rate, which indicates that the Cu content in Ti-Cu alloys must be at least 5 wt.% to obtain strong and stable antibacterial property. The Cu content also influenced the Cu ion release behavior. High Cu ion release concentration and high Cu ion release rate were observed for Ti-Cu alloys with high Cu content. It was concluded that the Cu content affects the Cu existence and the Cu ion release behavior, which in turn influences the antibacterial property. It was thought that the Cu-rich phase should play an important role in the strong antibacterial activity. PMID:24411393

  14. Biological Activity of Some Magnesium(II) Complexes of Quinolones

    PubMed Central

    Šonc, Andrej; Zupan?i?, Marija; Sep?i?, Kristina; Turk, Tom

    2000-01-01

    A new magnesium complex of quinolone antibacterial agent was prepared. This new complex as well as a previously isolated complex of magnesium with ciprofloxacin were tested against various Gram positive and Gram negative microorganisms. Antimicrobial activities were evaluated using the agar diffusion test. The results have shown that all magnesium complexes are significantly less active than the parent quinolone drugs. It was also found that the activity of quinolones is reduced when the solutions of quinolones are titrated with magnesium ions. PMID:18475931

  15. Antibacterial activity of silver-killed bacteria: the "zombies" effect.

    PubMed

    Wakshlak, Racheli Ben-Knaz; Pedahzur, Rami; Avnir, David

    2015-01-01

    We report a previously unrecognized mechanism for the prolonged action of biocidal agents, which we denote as the zombies effect: biocidally-killed bacteria are capable of killing living bacteria. The concept is demonstrated by first killing Pseudomonas aeruginosa PAO1 with silver nitrate and then challenging, with the dead bacteria, a viable culture of the same bacterium: Efficient antibacterial activity of the killed bacteria is observed. A mechanism is suggested in terms of the action of the dead bacteria as a reservoir of silver, which, due to Le-Chatelier's principle, is re-targeted to the living bacteria. Langmuirian behavior, as well as deviations from it, support the proposed mechanism. PMID:25906433

  16. Sensing and antibacterial activity of imidazolium-based conjugated polydiacetylenes.

    PubMed

    Lee, Songyi; Cheng, Hua; Chi, Meiying; Xu, Qingling; Chen, Xiaoqiang; Eom, Chi-Yong; James, Tony D; Park, Sungsu; Yoon, Juyoung

    2016-03-15

    In the current study, we report the first example of polydiacetylenes (PDAs), where our PDA-based system acts as both a sensing probe and killer for bacteria. The contact of imidazolium and imidazole-derived PDA with various bacterial strains including MRSA (methicillin-resistant Staphylococcus aureus) and ESBL-EC (extended-spectrum ?-lactamase-producing Escherichia coli) results in a distinct blue-to-red colorimetric change of the solution as well as a rapid disruption of the bacterial membrane, which is demonstrated by transmission electron microscopy and confocal microscopy. Zeta potential analysis supports that antibacterial activity of the PDA solution originates from an electrostatic interaction between the negatively charged bacterial cell surface and the positively charged polymers. These results suggest that the PDA has a great potential to carry out the dual roles of a probe and killer for bacteria. PMID:26547428

  17. Synthesis of Silver Polymer Nanocomposites and Their Antibacterial Activity

    NASA Astrophysics Data System (ADS)

    Gavade, Chaitali; Shah, Sunil; Singh, N. L.

    2011-07-01

    PVA (Polyvinyl Alcohol) silver nanocomposites of different sizes were prepared by chemical reduction method. Silver nitrate was taken as the metal precursor and amine hydrazine as a reducing agent. The formation of the silver nanoparticles was noticed using UV- visible absorption spectroscopy. The UV-visible spectroscopy revealed the formation of silver nanoparticles by exhibiting the surface plasmon resonance. The bactericidal activity due to silver release from the surface was determined by the modification of conventional diffusion method. Salmonella typhimurium, Serratia sps and Shigella sps were used as test bacteria which are gram-negative type bacteria. Effect of the different sizes of silver nano particles on antibacterial efficiency was discussed. Zones of inhibition were measured after 24 hours of incubation at 37 °C which gave 20 mm radius for high concentration of silver nanoparticles.

  18. Gramicidin D enhances the antibacterial activity of fluoride.

    PubMed

    Nelson, James W; Zhou, Zhiyuan; Breaker, Ronald R

    2014-07-01

    Fluoride is a toxic anion found in many natural environments. One of the major bacterial defenses against fluoride is the cell envelope, which limits passage of the membrane-impermeant fluoride anion. Accordingly, compounds that enhance the permeability of bacterial membranes to fluoride should also enhance fluoride toxicity. In this study, we demonstrate that the pore-forming antibiotic gramicidin D increases fluoride uptake in Bacillus subtilis and that the antibacterial activity of this compound is potentiated by fluoride. Polymyxin B, another membrane-targeting antibiotic with a different mechanism of action, shows no such improvement. These results, along with previous findings, indicate that certain compounds that destabilize bacterial cell envelopes can enhance the toxicity of fluoride. PMID:24857543

  19. Gramicidin D enhances the antibacterial activity of fluoride

    PubMed Central

    Breaker, Ronald R.

    2014-01-01

    Fluoride is a toxic anion found in many natural environments. One of the major bacterial defenses against fluoride is the cell envelope, which limits passage of the membrane-impermeant fluoride anion. Accordingly, compounds that enhance the permeability of bacterial membranes to fluoride should also enhance fluoride toxicity. In this study, we demonstrate that the pore-forming antibiotic gramicidin D increases fluoride uptake in B. subtilis and that the antibacterial activity of this compound is potentiated by fluoride. Polymyxin B, another membrane-targeting antibiotic with a different mechanism of action, shows no such improvement. These results, along with previous findings, indicate that certain compounds that destabilize bacterial cell envelopes can enhance the toxicity of fluoride. PMID:24857543

  20. Antibacterial activity of extracts of Parmotrema praesorediosum, Parmotrema rampoddense, Parmotrema tinctorum and Parmotrema reticulatum

    NASA Astrophysics Data System (ADS)

    Rajan, Vinoshene Pillai; Gunasekaran, Saranyapiriya; Ramanathan, Surash; Murugaiyah, Vikneswaran; Samsudin, Mohd. Wahid; Din, Laily B.

    2015-09-01

    The present study was carried out to evaluate the antibacterial potential of acetone and methanol extracts of lichens of Parmotrema praesorediosum, P. rampoddense, P. tinctorum and P. reticulatum. Antibacterial activity was evaluated using broth dilution method. The acetone extracts (except for P. reticulatum) showed good inhibitory activity against Staphylococcus aureus and Bacillus subtilis with MIC values ranging from 125 - 500 ?g/mL, whereas, no activity was observed for the methanol extracts. None of the extracts exhibited inhibitory activity against Escherichia coli.

  1. Preparation of bio-deep eutectic solvent triggered cephalopod shaped silver chloride-DNA hybrid material having antibacterial and bactericidal activity.

    PubMed

    Bhatt, Jitkumar; Mondal, Dibyendu; Bhojani, Gopal; Chatterjee, Shruti; Prasad, Kamalesh

    2015-11-01

    2.5% w/w DNA (Salmon testes) was solubilized in a bio-deep eutectic solvent [(bio-DES), obtained by the complexation of choline chloride and ethylene glycol at 1:2 molar ratio] containing 1% w/w of silver chloride (AgCl) to yield a AgCl decorated DNA based hybrid material. Concentration dependent formation of AgCl crystals in the DES was observed and upon interaction with DNA it gave formation of a cephalopod shaped hybrid material. DNA was found to maintain its chemical and structural stability in the material. Further, AgCl microstructures were found to have orderly self assembled on the DNA helices indicating the electrostatic interaction between Ag(+) and phosphate side chain of DNA as a driving force for the formation of the material with ordered microstructural distribution of AgCl. Furthermore, the functionalized material exhibited excellent antibacterial and bactericidal activity against both Gram negative and Gram positive pathogenic bacteria. PMID:26249573

  2. Synthesis, antimycobacterial and antibacterial activity of fluoroquinolone derivatives containing an 3-alkoxyimino-4-(cyclopropylanimo)methylpyrrolidine moiety.

    PubMed

    Zhang, Tingting; Shen, Weiyi; Liu, Mingliang; Zhang, Rui; Wang, Minghua; Li, Linhu; Wang, Bin; Guo, Huiyuan; Lu, Yu

    2015-11-01

    A series of novel fluoroquinolone derivatives containing an 3-alkoxyimino-4-(cyclopropylanimo)methylpyrrolidine moiety were designed, synthesized and evaluated for their biological activity. Our results revealed that 19b2 shows good activity against MTB H37Rv ATCC 27294 (MIC: <0.25 ?g/mL) and MDR-MTB 6133 clinical isolate (MIC: 0.11 ?g/mL). Most of them have potent potency against Gram-positive strains, although they are generally poor active against Gram-negative strains. Especially, compounds 22b1 and 23a3 (MICs: <0.008-8 ?g/mL) were found to 2-128 times more potent than ciprofloxacin and levofloxacin against all of the tested Gram-positive strains including quinolone-resistant MRSA, MRSE, Enterococcus faecium and Enterococcus faecalis. PMID:26435513

  3. Population biology of Gram-positive pathogens: high-risk clones for dissemination of antibiotic resistance

    PubMed Central

    Willems, Rob J. L.; Hanage, William P; Bessen, Debra E.; Feil, Edward J.

    2011-01-01

    Infections caused by multi-resistant Gram positive bacteria represent a major health burden in the community as well as in hospitalized patients. Staphylococcus aureus, Enterococcus faecalis and Enterococcus faecium are well-known pathogens of hospitalized patients, frequently linked with resistance against multiple antibiotics, compromising effective therapy. Streptococcus pneumoniae and Streptococcus pyogenes are important pathogens in the community and S. aureus has recently emerged as an important community-acquired pathogen. Population genetic studies reveal that recombination prevails as a driving force of genetic diversity in E. faecium, E. faecalis, S. pneumoniae, and S. pyogenes and thus, these species are weakly clonal. Although recombination has a relatively modest role driving the genetic variation of the core genome of S. aureus, the horizontal acquistion of resistance and virulence genes plays a key role in the emergence of new clinically relevant clones in this species. In this review we discuss the population genetics of E. faecium, E. faecalis, S. pneumoniae, S. pyogenes, and S. aureus. Knowledge of the population structure of these pathogens is not only highly relevant for (molecular) epidemiological research but also for identifying the genetic variation that underlies changes in clinical behaviour, to improve our understanding of the pathogenic behaviour of particular clones and to identify novel targets for vaccines or immunotherapy. PMID:21658083

  4. A role for glycosylated Serine-rich repeatproteins in Gram-positive bacterial pathogenesis

    PubMed Central

    Lizcano, Anel; Sanchez, Carlos J.; Orihuela, Carlos J.

    2012-01-01

    Summary Bacterial attachment to host surfaces is a pivotal event in the biological and infectious processes of both commensal and pathogenic bacteria, respectively. Serine-rich Repeat Proteins (SRRPs) are a family of adhesins in Gram-Positive bacteria that mediate attachment to a variety of host and bacterial surfaces. As such, they contribute towards a wide-range of diseases including sub-acute bacterial endocarditis, community-acquired pneumonia, and meningitis. SRRPs are unique in that they are glycosylated, require a non-canonical Sec-translocase for transport, and are largely composed of a domain containing hundreds of alternating serine residues. These serine-rich repeats are thought to extend a unique non-repeat (NR) domain outward away from the bacterial surface to mediate adhesion. Thus far, NR domains have been determined to bind to sialic acid moieties, keratins, or other NR domains of a similar SRRP. This review summarizes how this important family of bacterial adhesins mediates bacterial attachment to host and bacterial cells, contributes to disease pathogenesis, and might be targeted for pharmacological intervention or used as novel protective vaccine antigens. This review also highlights recent structural findings on the NR domains of these proteins. PMID:22759311

  5. [Isolation of Gram-positive bacteria from raw milk with antimicrobial residues].

    PubMed

    Faría Reyes, José; García Urdaneta, Aleida; Izquierdo Corser, Pedro; Allara Cagnasso, María; Valero Leal, Kutchynskaya

    2002-03-01

    Two hundred samples of raw milk were collected at the receiving plants located in three areas of high milk production in Zulia state, Venezuela. The CTT test and trial disk were used in order to detect the presence of antimicrobials. The positive samples were inoculated in tripticase soy broth, human blood agar and manitol salt agar in order to isolate Gram-positive bacteria. The identification of species was performed through biochemical tests. It was found that 45 samples (22.5%) of analyzed milk contained antimicrobials, and bacterial growth was obtained in 35 of them. 100 strains were isolated namely: 44 Staphylococcus, 19 Streptococcus, 17 Enterococcus, 9 Bacillus, 4 Micrococcus, 4 Corynebacterium and 3 Lactococcus. The most frequently isolated specie was S. aureus, the main producing agent of bovine mastitis in Zulia state, a microorganism frequently associated in the country to food-borne intoxications, associated to cheese processed from raw milk. It is recommended to apply control programs for the use of antibiotics. PMID:12214550

  6. Biofilms affecting progression of mild steel corrosion by Gram positive Bacillus sp.

    PubMed

    Lin, Johnson; Madida, Bafana B

    2015-10-01

    The biodeterioration of metals have detrimental effects on the environment with economic implications. The deterioration of metals is of great concern to industry. In this study, mild steel coupons which were immersed in a medium containing Gram-positive Bacillus spp. and different nutrient sources were compared with the control in sterile deionized water. The weight loss of the coupons in the presence of Bacillus spp. alone was lower than the control and was further reduced when additional carbon sources, especially fructose, were added. The level of metal corrosion was significantly increased in the presence of nitrate with or without bacteria. There was a significant strong correlation between the weight loss and biofilm level (r?= ?0.64; p?

  7. Quorum-sensing regulators in Gram-positive bacteria: 'cherchez le peptide'.

    PubMed

    Monnet, V; Gardan, R

    2015-07-01

    Gram-positive bacteria can regulate gene expression at the population level via a mechanism known as quorum sensing. Oligopeptides serve as the signaling molecules; they are secreted and then are either detected at the bacterial surface by two-component systems or reinternalized via an oligopeptide transport system. In the latter case, imported peptides interact with cognate regulators (phosphatases or transcriptional regulators) that modulate the expression of target genes. These regulators help control crucial functions such as virulence, persistence, conjugation and competence and have been reported in bacilli, enterococci and streptococci. They form the rapidly growing RRNPP group. In this issue of Molecular?Microbiology, Hoover et?al. (2015) highlight the group's importance: they have identified a new family of regulators, Tprs (Transcription factor regulated by a Phr peptide), which work with internalized Phr-like peptides. The mechanisms underlying the expression of the genes that encode these internalized peptides are poorly documented. However, Hoover et?al. (2015) have provided a new insight: an environmental molecule, glucose, can inhibit expression of the Phr-like peptide gene via catabolic repression. This previously undescribed regulatory pathway, controlling the production of a bacteriocin, might influence Streptococcus pneumonia's fitness in the nasopharynx, where galactose is present. PMID:25988215

  8. Production of acylated homoserine lactone by gram-positive bacteria isolated from marine water.

    PubMed

    Biswa, Pramal; Doble, Mukesh

    2013-06-01

    Acylated homoserine lactone (AHL)-based quorum sensing (QS) has been reported to be present only in Gram-negative microorganisms. Isolation of a novel Gram-positive microorganism from sea water, capable of producing AHL, is reported here. The isolate (GenBank: JF915892, designated as MPO) belonging to the Exiguobacterium genera is capable of inducing the AHL bioreporters, namely Chromobacterium violaceum CV026, Agrobacterium tumefaceins A136, and E. coli JM 109(psb1075). This inducer is characterized as C3-oxo-octanoyl homoserine lactone (OOHL), and its production reaches a maximum of 15.6 ?g L(-1), during the stationary growth phase of the organism. MPO extract when exogenously added inhibits the formation of biofilm for the same organism and lowers the extracellular polymeric substances, indicating an AHL-associated phenotypic trait. The isolated sequence of a probable LuxR homolog from MPO (designated as ExgR) shows similar functional domains and contains conserved residues in LuxR from other known bacterial QS LuxR regulators. Also present immediately downstream to ExgR was found a sequence showing homology to known LuxI synthase of Pseudomonas putida. qPCR analysis suggests an increment in exgR mRNA on addition of AHL, further proving the role of ExgR as a QS regulator. PMID:23489290

  9. ?, a New Subunit of RNA Polymerase Found in Gram-Positive Bacteria

    PubMed Central

    Keller, Andrew N.; Yang, Xiao; Wiedermannová, Jana; Delumeau, Olivier; Krásný, Libor

    2014-01-01

    RNA polymerase in bacteria is a multisubunit protein complex that is essential for gene expression. We have identified a new subunit of RNA polymerase present in the high-A+T Firmicutes phylum of Gram-positive bacteria and have named it ?. Previously ? had been identified as a small protein (?1) that copurified with RNA polymerase. We have solved the structure of ? by X-ray crystallography and show that it is not an ? subunit. Rather, ? bears remarkable similarity to the Gp2 family of phage proteins involved in the inhibition of host cell transcription following infection. Deletion of ? shows no phenotype and has no effect on the transcriptional profile of the cell. Determination of the location of ? within the assembly of RNA polymerase core by single-particle analysis suggests that it binds toward the downstream side of the DNA binding cleft. Due to the structural similarity of ? with Gp2 and the fact they bind similar regions of RNA polymerase, we hypothesize that ? may serve a role in protection from phage infection. PMID:25092033

  10. Sortases and the Art of Anchoring Proteins to the Envelopes of Gram-Positive Bacteria

    PubMed Central

    Marraffini, Luciano A.; DeDent, Andrea C.; Schneewind, Olaf

    2006-01-01

    The cell wall envelopes of gram-positive bacteria represent a surface organelle that not only functions as a cytoskeletal element but also promotes interactions between bacteria and their environment. Cell wall peptidoglycan is covalently and noncovalently decorated with teichoic acids, polysaccharides, and proteins. The sum of these molecular decorations provides bacterial envelopes with species- and strain-specific properties that are ultimately responsible for bacterial virulence, interactions with host immune systems, and the development of disease symptoms or successful outcomes of infections. Surface proteins typically carry two topogenic sequences, i.e., N-terminal signal peptides and C-terminal sorting signals. Sortases catalyze a transpeptidation reaction by first cleaving a surface protein substrate at the cell wall sorting signal. The resulting acyl enzyme intermediates between sortases and their substrates are then resolved by the nucleophilic attack of amino groups, typically provided by the cell wall cross bridges of peptidoglycan precursors. The surface protein linked to peptidoglycan is then incorporated into the envelope and displayed on the microbial surface. This review focuses on the mechanisms of surface protein anchoring to the cell wall envelope by sortases and the role that these enzymes play in bacterial physiology and pathogenesis. PMID:16524923

  11. Can procalcitonin differentiate Staphylococcus aureus from coagulase-negative staphylococci in clustered gram-positive bacteremia?

    PubMed

    Shomali, William; Hachem, Ray; Chaftari, Anne-Marie; Bahu, Ramez; Helou, Gilbert El; Jiang, Ying; Hanania, Alex; Reitzel, Ruth; Raad, Issam

    2013-06-01

    Procalcitonin (PCT) and pro-adrenomedullin (ProADM) have been proposed as diagnostic and prognostic biomarkers of infection. Between July 2009 and January 2012, we studied the role of these biomarkers in 163 patients with clustered gram-positive and gram-negative bacteremia. PCT levels were significantly higher in patients with Staphylococcus aureus and gram-negative bacteremia than those with coagulase-negative staphylococci (CoNS) isolated from blood cultures (P = 0.29 and <0.001, respectively). ProADM levels were only significantly higher in patients with gram-negative bacteremia (median 1.46 nmol/L) than those with CoNS (median 1.01 nmol/L) (P = 0.04). Among patients with CoNS, PCT, and ProADM, levels failed to differentiate blood contamination (medians 0.24 ng/mL and 0.97 nmol/L) from true bacteremia (medians 0.26 ng/mL and 1.14 nmol/L) (P = 0.51 and 0.57, respectively). In cancer patients, PCT (and to a lesser extent, ProADM) was useful in differentiating CoNS from S. aureus and gram-negative bacteremia. PMID:23578976

  12. Antibacterial activity of medicinal plant extracts against periodontopathic bacteria.

    PubMed

    Iauk, L; Lo Bue, A M; Milazzo, I; Rapisarda, A; Blandino, G

    2003-06-01

    This study was performed to evaluate the antibacterial activity of Althaea officinalis L. roots, Arnica montana L. flowers, Calendula officinalis L. flowers, Hamamelis virginiana L. leaves, Illicium verum Hook. fruits and Melissa officinalis L. leaves, against anaerobic and facultative aerobic periodontal bacteria: Porphyromonas gingivalis, Prevotella spp., Fusobacterium nucleatum, Capnocytophaga gingivalis, Veilonella parvula, Eikenella corrodens, Peptostreptococcus micros and Actinomyces odontolyticus. The methanol extracts of H. virginiana and A. montana and, to a lesser extent, A. officinalis were shown to possess an inhibiting activity (MIC < or = 2048 mg/L) against many of the species tested. In comparison, M. officinalis and C. officinalis extracts had a lower inhibiting activity (MIC > or = 2048 mg/L) against all the tested species with the exception of Prevotella sp. Illicium verum methanol extract was not very active though it had a particular good activity against E. corrodens. The results suggest the use of the alcohol extracts of H. virginiana, A. montana and A. officinalis for topical medications in periodontal prophylactics. PMID:12820224

  13. Antibacterial Optimization of 4-Aminothiazolyl Analogues of the Natural Product GE2270 A: Identification of the Cycloalkylcarboxylic Acids

    SciTech Connect

    LaMarche, Matthew J.; Leeds, Jennifer A.; Amaral, Kerri; Brewer, Jason T.; Bushell, Simon M.; Dewhurst, Janetta M.; Dzink-Fox, JoAnne; Gangl, Eric; Goldovitz, Julie; Jain, Akash; Mullin, Steve; Neckermann, Georg; Osborne, Colin; Palestrant, Deborah; Patane, Michael A.; Rann, Elin M.; Sachdeva, Meena; Shao, Jian; Tiamfook, Stacey; Whitehead, Lewis; Yu, Donghui

    2012-11-09

    4-Aminothiazolyl analogues of the antibiotic natural product GE2270 A (1) were designed, synthesized, and optimized for their activity against Gram positive bacterial infections. Optimization efforts focused on improving the physicochemical properties (e.g., aqueous solubility and chemical stability) of the 4-aminothiazolyl natural product template while improving the in vitro and in vivo antibacterial activity. Structure-activity relationships were defined, and the solubility and efficacy profiles were improved over those of previous analogues and 1. These studies identified novel, potent, soluble, and efficacious elongation factor-Tu inhibitors, which bear cycloalkylcarboxylic acid side chains, and culminated in the selection of development candidates amide 48 and urethane 58.

  14. A novel application of quaternary ammonium compounds as antibacterial hybrid coating on glass surfaces.

    PubMed

    Saif, Muhammad Jawwad; Anwar, Jamil; Munawar, Munawar Ali

    2009-01-01

    A hybrid coating is prepared on a glass surface by a sol-gel process using tetraethoxysilane (TEOS) and Q(4)N(+)-Si(OR)(3). Transparent coatings with smooth surfaces were investigated against both Gram-positive (Escherichia coli) and Gram-negative bacteria (Staphylococcus aureus). A rapid decrease of the count for both strains was observed within 72 h. A significant correlation has been observed between the concentration of Q(4)N(+)-Si(OR)(S) and the antibacterial activity which has been thoroughly investigated. PMID:19115872

  15. Antibacterial and Antibiofilm Activities of Tryptoquivalines and Meroditerpenes Isolated from the Marine-Derived Fungi Neosartorya paulistensis, N. laciniosa, N. tsunodae, and the Soil Fungi N. fischeri and N. siamensis

    PubMed Central

    Gomes, Nelson M.; Bessa, Lucinda J.; Buttachon, Suradet; Costa, Paulo M.; Buaruang, Jamrearn; Dethoup, Tida; Silva, Artur M.S.; Kijjoa, Anake

    2014-01-01

    A new meroditerpene, sartorypyrone C (5), was isolated, together with the known tryptoquivalines l (1a), H (1b), F (1c), 3?-(4-oxoquinazolin-3-yl) spiro[1H-indole-3,5?]-2,2?-dione (2) and 4(3H)-quinazolinone (3), from the culture of the marine sponge-associated fungus Neosartorya paulistensis (KUFC 7897), while reexamination of the fractions remaining from a previous study of the culture of the diseased coral-derived fungus N. laciniosa (KUFC 7896) led to isolation of a new tryptoquivaline derivative tryptoquivaline T (1d). Compounds 1a–d, 2, 3, and 5, together with aszonapyrones A (4a) and B (4b), chevalones B (6) and C (7a), sartorypyrones B (7b) and A (8), were tested for their antibacterial activity against four reference strains (Staphylococcus aureus, Bacillus subtilis, Escherichia coli, and Pseudomonas aeruginosa), as well as the environmental multidrug-resistant isolates. Only aszonapyrone A (4a) and sartorypyrone A (8) exhibited significant antibacterial activity as well as synergism with antibiotics against the Gram-positive multidrug-resistant strains. Antibiofilm assays of aszonapyrone A (4a) and sartorypyrone A (8) showed that practically no biofilm was formed in the presence of their 2× MIC and MIC. However, the presence of a sub-inhibitory concentration of ½ MIC of 4a and 8 was found to increase the biofilm production in both reference strain and the multidrug-resistant isolates of S. aureus. PMID:24477284

  16. Synthesis, crystal structure, antibacterial activity and theoretical studies on a novel mononuclear cobalt(II) complex based on 2,4,6-tris(2-pyridyl)-1,3,5-triazine ligand

    NASA Astrophysics Data System (ADS)

    Maghami, Mahboobeh; Farzaneh, Faezeh; Simpson, Jim; Ghiasi, Mina; Azarkish, Mohammad

    2015-08-01

    A cobalt complex was prepared from CoCl2·6H2O and 2,4,6-tris(2-pyridyl)-1,3,5-triazine (tptz) in methanol and designated as [Co(tptz)(CH3OH)Cl2]·CH3OH·0.5H2O (1). It was characterized by several techniques including TGA analysis and FT-IR, UV-Vis and 1H NMR spectral studies. The crystal structure of 1 was determined by single-crystal X-ray diffraction. The Co(II) metal center in 1 is six coordinated with a distorted octahedral geometry. The tptz ligand is tridentate and coordinates to the cobalt through coplanar nitrogen atoms from the triazine and two pyridyl rings. Two chloride anions and a methanol molecule complete the inner coordination sphere of the metal ion. The optimized geometrical parameters obtained by DFT calculation are in good agreement with single XRD data. The in vitro antibacterial activity of various tptz complexes of Co(II), Ni(II), Cu(II), Mn(II) and Rh(III) were evaluated against Gram-positive (Bacillus subtilis, Staphylococcus aureus and Gram-negative (Escherichia coli and Pseudomonas aeruginosa) bacteria. Whereas all complexes exhibited good activity in comparison to standard antibacterial drugs, the inhibitory effects of complexes were found to be more than that of the parent ligand. Overall, the obtained results strongly suggest that the cobalt(II) complex is a suitable candidate for counteracting antibiotic resistant microorganisms.

  17. Dustborne and airborne gram-positive and gram-negative bacteria in high versus low ERMI homes

    EPA Science Inventory

    The study aimed at investigating Gram-positive and Gram-negative bacteria in moldy and non-moldy homes, as defined by the home's Environmental Relative Moldiness Index (ERMI) value. The ERMI values were determined from floor dust samples in 2010 and 2011 and homes were classified...

  18. Tuberculosis (TB) is caused by gram-positive bac-teria known as the Mycobacterium tuberculosis complex

    E-print Network

    Tuberculosis (TB) is caused by gram-positive bac- teria known as the Mycobacterium tuberculosis and, more rarely, wild animal species. We report an M. tuberculosis strain isolated from a wild of the biology and evolutionary history of this widespread infectious disease. Tuberculosis (TB) is caused

  19. Draft Genome Sequence of the Gram-Positive Thermophilic Iron Reducer Thermincola ferriacetica Strain Z-0001T.

    PubMed

    Lusk, Bradley G; Badalamenti, Jonathan P; Parameswaran, Prathap; Bond, Daniel R; Torres, Cesar I

    2015-01-01

    A 3.19-Mbp draft genome of the Gram-positive thermophilic iron-reducing Firmicutes isolate from the Peptococcaceae family, Thermincola ferriacetica Z-0001, was assembled at ~100× coverage from 100-bp paired-end Illumina reads. The draft genome contains 3,274 predicted genes (3,187 protein coding genes) and putative multiheme c-type cytochromes. PMID:26404602

  20. Draft Genome Sequence of the Gram-Positive Thermophilic Iron Reducer Thermincola ferriacetica Strain Z-0001T

    PubMed Central

    Badalamenti, Jonathan P.; Parameswaran, Prathap; Bond, Daniel R.

    2015-01-01

    A 3.19-Mbp draft genome of the Gram-positive thermophilic iron-reducing Firmicutes isolate from the Peptococcaceae family, Thermincola ferriacetica Z-0001, was assembled at ~100× coverage from 100-bp paired-end Illumina reads. The draft genome contains 3,274 predicted genes (3,187 protein coding genes) and putative multiheme c-type cytochromes. PMID:26404602

  1. Shape-dependent bactericidal activity of copper oxide nanoparticle mediated by DNA and membrane damage

    SciTech Connect

    Laha, Dipranjan; Pramanik, Arindam; Laskar, Aparna; Jana, Madhurya; Pramanik, Panchanan; Karmakar, Parimal

    2014-11-15

    Highlights: • Spherical and sheet shaped copper oxide nanoparticles were synthesized. • Physical characterizations of these nanoparticles were done by TEM, DLS, XRD, FTIR. • They showed shape dependent antibacterial activity on different bacterial strain. • They induced both membrane damage and ROS mediated DNA damage in bacteria. - Abstract: In this work, we synthesized spherical and sheet shaped copper oxide nanoparticles and their physical characterizations were done by the X-ray diffraction, fourier transform infrared spectroscopy, transmission electron microscopy and dynamic light scattering. The antibacterial activity of these nanoparticles was determined on both gram positive and gram negative bacterial. Spherical shaped copper oxide nanoparticles showed more antibacterial property on gram positive bacteria where as sheet shaped copper oxide nanoparticles are more active on gram negative bacteria. We also demonstrated that copper oxide nanoparticles produced reactive oxygen species in both gram negative and gram positive bacteria. Furthermore, they induced membrane damage as determined by atomic force microscopy and scanning electron microscopy. Thus production of and membrane damage are major mechanisms of the bactericidal activity of these copper oxide nanoparticles. Finally it was concluded that antibacterial activity of nanoparticles depend on physicochemical properties of copper oxide nanoparticles and bacterial strain.

  2. Antibacterial activities in various tissues of the horse mussel, Modiolus modiolus.

    PubMed

    Haug, Tor; Stensvåg, Klara; Olsen M, Ørjan M; Sandsdalen, Erling; Styrvold, Olaf B

    2004-02-01

    A search for antibacterial activity in different organs/tissues of the horse mussel, Modiolus modiolus, was conducted. Dried samples were extracted with 60% (v/v) acetonitrile, containing 0.1% (v/v) trifluoroacetic acid. Due to high salt content, two liquid phases were obtained; an acetonitrile-rich phase (ACN extract) and an aqueous phase. The aqueous phase was further subjected to solid phase extraction (SPE). Eluates from SPE and ACN extracts were tested for antibacterial, lysozyme, and toxic activity. Antibacterial activity was demonstrated in extracts from several tissues, including plasma, haemocytes, labial palps, byssus, mantle, and gills. Some of the extracts were sensitive to proteinase K treatment, indicating antibacterial peptides and/or proteins. Lysozyme-like activity and toxic activity against Artemia salina nauplii was detected in fractions from the gills, mantle, muscle, and haemocytes. Results from this study indicate that M. modiolus is a promising source for identifying novel drug lead compounds. PMID:15050841

  3. Flow cytometric evaluation of physico-chemical impact on Gram-positive and Gram-negative bacteria

    PubMed Central

    Fröhling, Antje; Schlüter, Oliver

    2015-01-01

    Since heat sensitivity of fruits and vegetables limits the application of thermal inactivation processes, new emerging inactivation technologies have to be established to fulfill the requirements of food safety without affecting the produce quality. The efficiency of inactivation treatments has to be ensured and monitored. Monitoring of inactivation effects is commonly performed using traditional cultivation methods which have the disadvantage of the time span needed to obtain results. The aim of this study was to compare the inactivation effects of peracetic acid (PAA), ozonated water (O3), and cold atmospheric pressure plasma (CAPP) on Gram-positive and Gram-negative bacteria using flow cytometric methods. E. coli cells were completely depolarized after treatment (15 s) with 0.25% PAA at 10°C, and after treatment (10 s) with 3.8 mg l?1 O3 at 12°C. The membrane potential of CAPP treated cells remained almost constant at an operating power of 20 W over a time period of 3 min, and subsequently decreased within 30 s of further treatment. Complete membrane permeabilization was observed after 10 s O3 treatment, but treatment with PAA and CAPP did not completely permeabilize the cells within 2 and 4 min, respectively. Similar results were obtained for esterase activity. O3 inactivates cellular esterase but esterase activity was detected after 4 min CAPP treatment and 2 min PAA treatment. L. innocua cells and P. carotovorum cells were also permeabilized instantaneously by O3 treatment at concentrations of 3.8 ± 1 mg l?1. However, higher membrane permeabilization of L. innocua and P. carotovorum than of E. coli was observed at CAPP treatment of 20 W. The degree of bacterial damage due to the inactivation processes is highly dependent on treatment parameters as well as on treated bacteria. Important information regarding the inactivation mechanisms can be obtained by flow cytometric measurements and this enables the definition of critical process parameters. PMID:26441874

  4. Infections caused by Gram-positive bacteria: a review of the global challenge.

    PubMed

    Woodford, Neil; Livermore, David M

    2009-09-01

    Infections caused by multidrug-resistant Gram-positive bacteria represent a major public health burden, not just in terms of morbidity and mortality, but also in terms of increased expenditure on patient management and implementation of infection control measures. Staphylococcus aureus and Enterococcus spp. are established pathogens in the hospital environment, and their frequent multidrug resistance complicates therapy. The archetypal hospital "superbug", methicillin-resistant S. aureus (MRSA), regularly attracts mass-media interest and, in many countries, there is political pressure to reduce MRSA infection rates, with some progress now being made in the United Kingdom and the United States. To compound these established problems, we have witnessed the emergence and spread of virulent clones of MRSA in the community, and of Clostridium difficile in hospitals. Multidrug-resistant Streptococcus pneumoniae clones are major community pathogens in many parts of the world, but are now being challenged by new conjugate vaccines. Using combinations of molecular epidemiological tools, which characterize the resistant isolates and their resistance determinants, scientists can track highly successful bacterial strains at local, national, and international levels. These methods have provided new insights into the evolution of key pathogens, and this information may aid the design of control strategies and vaccines. In addition, the development of new antimicrobials including oxazolidinones, lipopeptides, glycylcyclines, ketolides, and new generations of fluoroquinolones, antistaphylococcal b-lactams, and glycopeptides must remain a high priority for the continued effective treatment of infections caused by resistant strains. So far, resistance to these newer agents is identified rarely in surveillance programs, but occasional reports of resistance causing therapeutic failure (e.g., with linezolid, daptomycin, telithromycin, or newer fluoroquinolones) give cause for concern. The emergence of antibiotic resistance is inevitable, but we must seek to decrease its impact and prolong the effectiveness of the agents available to us. PMID:19766888

  5. Acyl Enzyme Intermediates in Sortase-Catalyzed Pilus Morphogenesis in Gram-Positive Bacteria?

    PubMed Central

    Guttilla, Irene K.; Gaspar, Andrew H.; Swierczynski, Arlene; Swaminathan, Anu; Dwivedi, Prabhat; Das, Asis; Ton-That, Hung

    2009-01-01

    In gram-positive bacteria, covalently linked pilus polymers are assembled by a specific transpeptidase enzyme called pilus-specific sortase. This sortase is postulated to cleave the LPXTG motif of a pilin precursor between threonine and glycine and to form an acyl enzyme intermediate with the substrate. Pilus polymerization is believed to occur through the resolution of this intermediate upon specific nucleophilic attack by the conserved lysine located within the pilin motif of another pilin monomer, which joins two pilins with an isopeptide bond formed between threonine and lysine. Here, we present evidence for sortase reaction intermediates in Corynebacterium diphtheriae. We show that truncated SrtA mutants that are loosely bound to the cytoplasmic membrane form high-molecular-weight complexes with SpaA polymers secreted into the extracellular milieu. These complexes are not formed with SpaA pilin mutants that have alanine substitutions in place of threonine in the LPXTG motif or lysine in the pilin motif. The same phenotype is observed with alanine substitutions of either the conserved cysteine or histidine residue of SrtA known to be required for catalysis. Remarkably, the assembly of SpaA pili, or the formation of intermediates, is abolished with a SrtA mutant missing the membrane-anchoring domain. We infer that pilus polymerization involves the formation of covalent pilin-sortase intermediates, which occurs within a molecular platform on the exoplasmic face of the cytoplasmic membrane that brings together both sortase and its cognate substrates in close proximity to each other, likely surrounding a secretion apparatus. We present electron microscopic data in support of this picture. PMID:19592583

  6. Health economics assessment study of teicoplanin versus vancomycin in Gram-positive infections.

    PubMed

    Portolés, A; Palau, E; Puerro, M; Vargas, E; Picazo, J J

    2006-03-01

    The objective of this study, conducted at Hospital Clínico San Carlos, Madrid, Spain, was to compare the cost of treatment of Gram-positive infections with teicoplanin and vancomycin under normal conditions. Using a prospective observational study design for drug utilization and economic assessment, we evaluated the comparability of the sample, adverse events, features of treatment with teicoplanin/vancomycin and factors influencing the consumption of resources until the end of glycopeptide treatment or discharge (whichever occurred later) using Health System perspective. Costs were assigned using the hospital's evaluation at the time of the study. Analyses made: multivariate, sensitivity (by modifying staff or acquisition costs) and simulation of reduction of stay by early discharge in the teicoplanin group. Study participants included 201 patients who had been using teicoplanin (n=100) or vancomycin (n=101) for at least four days. Data collected daily outside morning work timetable. Costs of acquisition, administration and monitoring by course of treatment (mean+/-SD, in euros) were lower in the vancomycin group (teicoplanin euro647.62+/-euro572.75 vs. vancomycin euro378.11+/-euro225.90); when total costs (including hospital stay) were considered, no differences were found (teicoplanin euro4,432.04+/-euro3,383.46 vs. vancomycin euro4,364.44+/-euro2,734.24). Conditions of use and results were similar for both antibiotics. The economic results of acquisition, administration and monitoring were advantageous for vancomycin; when global costs of care were taken into account, these differences were not evident. Tolerability was significantly advantageous in the teicoplanin group (with regard to phlebitis and elevation of creatininemia), without differences in clinical or economic outcomes. The formulation of teicoplanin did not take advantage of its potential benefits of administration. PMID:16688294

  7. Comparative post-antibiotic effect of five antibiotics against ten aerobic gram-positive cocci.

    PubMed

    Drabu, Y J; Blakemore, P H

    1990-01-01

    The post-antibiotic effect (PAE) is the persistent suppression of bacterial growth after a short antibiotic exposure. It is well documented with a variety of antibiotics and micro-organisms and may have important therapeutic implications. The authors have evaluated the PAE produced by teicoplanin, fucidin, gentamicin, rifampicin and ciprofloxacin against a total of ten Gram-positive organisms (S. aureus (2), MRSA (2), S. epidermis (2) S. haemolyticus (2) and E. faecalis (2)). All the organisms were clinical isolates with variable sensitivity patterns confirmed by disc and MIC testing. MICs were performed by the broth dilution method using a final inoculum of 10 x 5 cfu/ml. The PAE was estimated by adding 5 x MIC of each antibiotic to a log phase of growth of approximately 10 x 7 cfu/ml, and incubating at 37 degrees C for 1 h. Antibiotic was removed by 1000-fold dilution in nutrient broth, and total viable counts were carried out hourly by the Miles and Misra method for a further 9 h. All the antibiotics tested showed a PAE against the organisms tested, except for fucidin and ciprofloxacin against the enterococci. Overall, teicoplanin showed a maximum PAE of 5 h against MSRA and a minimum of 0.6 h against E. faecalis. Gentamicin, rifampicin and ciprofloxacin also showed a variable range. Fucidin showed the least PAE against the ten organisms, ranging from 0-1.3 h, except for S. epidermidis (FUC-R) which had a PAE of up to 4.5 h. The duration of PAE of each antibiotic/organism combination varied and was associated with the sensitivity pattern of the organism.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2151661

  8. Isolation and Characterization of Gram-Positive Piezophilic Bacteria from Deep Marine Subsurface Sediment

    NASA Astrophysics Data System (ADS)

    Runko, G. M.; Fang, J.; Kato, C.

    2014-12-01

    The marine deep biosphere remains as the least studied of all of Earth's habitats and is inadequately understood, but is extremely important to understand the impacts that microbes have on global biogeochemical cycles. Sediment samples were obtained during IODP Expedition 337 in the western Pacific Ocean, from 1,498 meters below the seafloor (mbsf; samples 6R3), 1,951-1,999 mbsf (19R1), and 2,406 mbsf (29R7). These samples were initially mixed with marine broth and cultivated under anaerobic conditions at pressure of 35 MPa (megapascal) and temperatures of 35° C, 45° C, and 55° C for 3 months on board the Chikyu. Single colonies were isolated via plating on marine broth. Then, six strains of bacteria were identified, 6R3-1, 6R3-15, 19R1-5, 29R7-12B, 29R7-12M, and 29R7-12S. The six strains were then examined for optimal growth temperature and pressure. These organisms are Gram-positive, spore-forming, facultative anaerobic piezophilic bacteria. Major fatty acids are anteiso-15:0, anteiso-17:0 and iso-15:0. Phylogenetic analysis of 16S rRNA gene sequences revealed that the isolates are closely related to Virgibacillus pantothenticus, Robinsoniella peoriensis, and Bacillus subtilis. Because of their abundance in the deep marine subsurface, these microorganisms likely play an important role in sustaining the deep microbial ecosystem and influencing biogeochemical cycles in the deep biosphere.

  9. Isolation and Characterization of Four Gram-Positive Nickel-Tolerant Microorganisms from Contaminated Sediments

    SciTech Connect

    Van Nostrand, J. D.; Khijniak, T. V.; Gentry, T. J.; Novak, M. T.; Sowder, A. G.; Zhou, J. Z.; Bertsch, P. M.; Morris, P. J.

    2007-01-01

    Microbial communities from riparian sediments contaminated with high levels of Ni and U were examined for metal-tolerant microorganisms. Isolation of four aerobic Ni-tolerant, Gram-positive heterotrophic bacteria indicated selection pressure from Ni. These isolates were identified as Arthrobacter oxydans NR-1, Streptomyces galbus NR-2, Streptomyces aureofaciens NR-3, and Kitasatospora cystarginea NR-4 based on partial 16S rDNA sequences. A functional gene microarray containing gene probes for functions associated with biogeochemical cycling, metal homeostasis, and organic contaminant degradation showed little overlap among the four isolates. Fifteen of the genes were detected in all four isolates with only two of these related to metal resistance, specifically to tellurium. Each of the four isolates also displayed resistance to at least one of six antibiotics tested, with resistance to kanamycin, gentamycin, and ciprofloxacin observed in at least two of the isolates. Further characterization of S. aureofaciens NR-3 and K. cystarginea NR-4 demonstrated that both isolates expressed Ni tolerance constitutively. In addition, both were able to grow in higher concentrations of Ni at pH 6 as compared with pH 7 (42.6 and 8.5 mM Ni at pH 6 and 7, respectively). Tolerance to Cd, Co, and Zn was also examined in these two isolates; a similar pH-dependent metal tolerance was observed when grown with Co and Zn. Neither isolate was tolerant to Cd. These findings suggest that Ni is exerting a selection pressure at this site for metal-resistant actinomycetes.

  10. Synergistic antibacterial activity of the essential oil of aguaribay (Schinus molle L.).

    PubMed

    de Mendonça Rocha, Pedro M; Rodilla, Jesus M; Díez, David; Elder, Heriberto; Guala, Maria Silvia; Silva, Lúcia A; Pombo, Eunice Baltazar

    2012-01-01

    Schinus molle L. (aguaribay, aroeira-falsa, "molle", family Anacardiaceae), a native of South America, produces an active antibacterial essential oil extracted from the leaves and fruits. This work reports a complete study of its chemical composition and determines the antibacterial activity of Schinus molle L. essential oil and its main components. The results showed that the crude extract essential oil has a potent antibacterial effect on Staphylococcus aureus ATCC 25923, a strong/moderate effect on Escherichia coli ATCC 25922 and moderate/weak one on Pseudomonas aeruginosa ATCC 27853. PMID:23085653

  11. pH-Dependent Metal Ion Toxicity Influences the Antibacterial Activity of Two Natural Mineral Mixtures

    PubMed Central

    Cunningham, Tanya M.; Koehl, Jennifer L.; Summers, Jack S.; Haydel, Shelley E.

    2010-01-01

    Background Recent studies have demonstrated that several mineral products sold for medicinal purposes demonstrate antimicrobial activity, but little is known about the physicochemical properties involved in antibacterial activity. Methodology/Principal Findings Using in vitro mineral suspension testing, we have identified two natural mineral mixtures, arbitrarily designated BY07 and CB07, with antibacterial activity against a broad-spectrum of bacterial pathogens. Mineral-derived aqueous leachates also exhibited antibacterial activity, revealing that chemical, not physical, mineral characteristics were responsible for the observed activity. The chemical properties essential for bactericidal activity against Escherichia coli were probed by testing antibacterial activity in the presence of metal chelators, the hydroxyl radical scavenger, thiourea, and varying pH levels. Chelation of the BY07 minerals with EDTA or desferrioxamine eliminated or reduced BY07 toxicity, respectively, suggesting a role of an acid-soluble metal species, particularly Fe3+ or other sequestered metal cations, in mineral toxicity. This conclusion was supported by NMR relaxation data, which indicated that BY07 and CB07 leachates contained higher concentrations of chemically accessible metal ions than leachates from non-bactericidal mineral samples. Conclusions/Significance We conclude that the acidic environment of the hydrated minerals significantly contributes to antibacterial activity by increasing the availability and toxicity of metal ions. These findings provide impetus for further investigation of the physiological effects of mineral products and their applications in complementary antibacterial therapies. PMID:20209160

  12. Bacillus spp. produce antibacterial activities against lactic acid bacteria that contaminate fuel ethanol plants

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Lactic acid bacteria (LAB) frequently contaminate commercial fuel ethanol fermentations, reducing yields and decreasing profitability of biofuel production. Microorganisms from environmental sources in different geographic regions of Thailand were tested for antibacterial activity against LAB. Fou...

  13. Restriction of the Conformational Dynamics of the Cyclic Acyldepsipeptide Antibiotics Improves Their Antibacterial Activity

    E-print Network

    Carney, Daniel W.

    The cyclic acyldepsipeptide (ADEP) antibiotics are a new class of antibacterial agents that kill bacteria via a mechanism that is distinct from all clinically used drugs. These molecules bind and dysregulate the activity ...

  14. DRUG DISCOVERY AND RESISTANCE Antibacterial activities of dendritic amphiphiles against nontuberculous

    E-print Network

    Falkinham, Joseph

    DRUG DISCOVERY AND RESISTANCE Antibacterial activities of dendritic amphiphiles against November 2011 Accepted 4 December 2011 Keywords: Dendritic amphiphiles Nontuberculous mycobacteria Anti of nine series of dicarboxyl and tricarboxyl dendritic amphiphiles with one alkyl, two alkyl

  15. Preparation and antibacterial activity of quaternized chitosan with iodine.

    PubMed

    Tang, Yang; Xie, Linlin; Sai, Mingze; Xu, Ningning; Ding, Derun

    2015-03-01

    Chitosan (CTS) is a natural polymer with active groups such as -NH2 which can be functionalized to introduce new positively charged N-atoms and protonated amino group for better use. In this study, to improve the stability of iodine, a novel complex (CTS-CTA-I2) was prepared by mixing N-(2-hydroxy) propyl-3-trimethylammonium chitosan chloride (CTS-CTA) with iodine in ethanol solution. The CTS-CTA-I2 was characterized by Fourier transform infrared spectra (FTIR), Ultraviolet and visible (UV-vis) spectra and thermal gravimetric analysis (TG). Besides, the interaction of iodine with CTS-CTA was also studied. The mole ratio of CTS-CTA with iodine was measured by iodometric titration method and the max mole ratio of CTS-CTA with iodine was 1:1.33. The antimicrobial activity of CTS, CTS-CTA and CTS-CTS-I2 complexes was investigated against Escherichia coli and Staphylococcus aureus and the antibacterial property of CTS-CTA-I2 was superior to CTS-CTA. PMID:25579889

  16. Antioxidant, Antibacterial, and Cytoprotective Activity of Agathi Leaf Protein

    PubMed Central

    Zarena, A. S.; Gopal, Shubha; Vineeth, R.

    2014-01-01

    In the present study a protein termed agathi leaf protein (ALP) from Sesbania grandiflora Linn. (agathi) leaves was isolated after successive precipitation with 65% ammonium sulphate followed by purification on Sephadex G 75. The column chromatography of the crude protein resulted in four peaks of which Peak I (P I) showed maximum inhibition activity against hydroxyl radical. SDS-PAGE analysis of P I indicated that the molecular weight of the protein is ?29?kDa. The purity of the protein was 98.4% as determined by RP-HPLC and showed a single peak with a retention time of 19.9?min. ALP was able to reduce oxidative damage by scavenging lipid peroxidation against erythrocyte ghost (85.50 ± 6.25%), linolenic acid (87.67 ± 3.14%) at 4.33??M, ABTS anion (88 ± 3.22%), and DNA damage (83 ± 4.20%) at 3.44??M in a dose-dependent manner. The purified protein offered significant protection to lymphocyte (72% at 30?min) induced damage by t-BOOH. In addition, ALP showed strong antibacterial activity against Pseudomonas aeruginosa (20 ± 3.64?mm) and Staphylococcus aureus (19 ± 1.53?mm) at 200??g/mL. The safety assessment showed that ALP does not induce cytotoxicity towards human lymphocyte at the tested concentration of 0.8?mg/mL. PMID:24616824

  17. Synthesis, optimization, and characterization of silver nanoparticles from Acinetobacter calcoaceticus and their enhanced antibacterial activity when combined with antibiotics

    PubMed Central

    Singh, Richa; Wagh, Priyanka; Wadhwani, Sweety; Gaidhani, Sharvari; Kumbhar, Avinash; Bellare, Jayesh; Chopade, Balu Ananda

    2013-01-01

    Background The development of nontoxic methods of synthesizing nanoparticles is a major step in nanotechnology to allow their application in nanomedicine. The present study aims to biosynthesize silver nanoparticles (AgNPs) using a cell-free extract of Acinetobacter spp. and evaluate their antibacterial activity. Methods Eighteen strains of Acinetobacter were screened for AgNP synthesis. AgNPs were characterized using various techniques. Reaction parameters were optimized, and their effect on the morphology of AgNPs was studied. The synergistic potential of AgNPs on 14 antibiotics against seven pathogens was determined by disc-diffusion, broth-microdilution, and minimum bactericidal concentration assays. The efficacy of AgNPs was evaluated as per the minimum inhibitory concentration (MIC) breakpoints of the Clinical and Laboratory Standards Institute (CLSI) guidelines. Results Only A. calcoaceticus LRVP54 produced AgNPs within 24 hours. Monodisperse spherical nanoparticles of 8–12 nm were obtained with 0.7 mM silver nitrate at 70°C. During optimization, a blue-shift in ultraviolet-visible spectra was seen. X-ray diffraction data and lattice fringes (d =0.23 nm) observed under high-resolution transmission electron microscope confirmed the crystallinity of AgNPs. These AgNPs were found to be more effective against Gram-negative compared with Gram-positive microorganisms. Overall, AgNPs showed the highest synergy with vancomycin in the disc-diffusion assay. For Enterobacter aerogenes, a 3.8-fold increase in inhibition zone area was observed after the addition of AgNPs with vancomycin. Reduction in MIC and minimum bactericidal concentration was observed on exposure of AgNPs with antibiotics. Interestingly, multidrug-resistant A. baumannii was highly sensitized in the presence of AgNPs and became susceptible to antibiotics except cephalosporins. Similarly, the vancomycin-resistant strain of Streptococcus mutans was also found to be susceptible to antibiotic treatment when AgNPs were added. These biogenic AgNPs showed significant synergistic activity on the ?-lactam class of antibiotics. Conclusion This is the first report of synthesis of AgNPs using A. calcoaceticus LRVP54 and their significant synergistic activity with antibiotics resulting in increased susceptibility of multidrug-resistant bacteria evaluated as per MIC breakpoints of the CLSI standard. PMID:24235826

  18. Antibacterial Activity of Various Plants Extracts Against Antibiotic-resistant Aeromonas hydrophila

    PubMed Central

    Al Laham, Shaza Anwar; Al Fadel, Frdoos Mohammad

    2014-01-01

    Background: Aeromonas hydrophila cause one of the most important diseases in fishes and lead to economic losses, and may be contaminated human beings. Objectives: The current research aimed to investigate the anti-bacterial activity shown by the extracts prepared from different parts of Olea europea, Myrtus communis, Thymus vulgaris, Rosmarinuis officinalis, and Achillea falcata that grow in Syria against A. hydrophila that causes the most dangerous bacterial diseases in fish. Materials and Methods: The study was performed in four stages: First of all, the presence of A. hydrophila was investigated in 450 Samples of Cyprinus Carpio fish using blood agar, Trypticase soya agar, and Analytical Profile Index (API20E). Secondly, the plants extract was obtained using water, absolute alcohol, then ether using Soxhlet extraction apparatus and rotary vacuum evaporator. Thirdly, the antibacterial activity of some antibiotics on these bacteria was evaluated by disk diffusion method. Finally, the antibacterial effect of the extracts was determined by disk diffusion method. Results: The studied antibiotics showed no antibacterial activity against these bacteria, except amikacin which had an acceptable effectiveness. However, the ethanol extracts of the studied plants revealed different antibacterial effects against A. hydrophila which showed antibiotic resistant. T. vulgaris extract had the strongest effect, whereas O. europea extract had the weakest activity. The water and ether petroleum extracts had no antibacterial activities. Conclusions: Ethanol extracts of the studied plants had different antibacterial effects against antibiotic-resistant A. hydrophila. T. vulgaris had the highest activity, R. officinalis had the second, and M. communis and A. falcate were in the third place, while the O. europea had the weakest antibacterial activity. PMID:25368797

  19. Total synthesis of albicidin: a lead structure from Xanthomonas albilineans for potent antibacterial gyrase inhibitors.

    PubMed

    Kretz, Julian; Kerwat, Dennis; Schubert, Vivien; Grätz, Stefan; Pesic, Alexander; Semsary, Siamak; Cociancich, Stéphane; Royer, Monique; Süssmuth, Roderich D

    2015-02-01

    The peptide antibiotic albicidin, which is synthesized by the plant pathogenic bacterium Xanthomonas albilineans, displays remarkable antibacterial activity against various Gram-positive and Gram-negative microorganisms. The low amounts of albicidin obtainable from the producing organism or through heterologous expression are limiting factors in providing sufficient material for bioactivity profiling and structure-activity studies. Therefore, we developed a convergent total synthesis route toward albicidin. The unexpectedly difficult formation of amide bonds between the aromatic amino acids was achieved through a triphosgene-mediated coupling strategy. The herein presented synthesis of albicidin confirms the previously determined chemical structure and underlines the extraordinary antibacterial activity of this compound. The synthetic protocol will provide multigram amounts of albicidin for further profiling of its drug properties. PMID:25504839

  20. Antibacterial properties of L-amino acid oxidase: mechanisms of action and perspectives for therapeutic applications.

    PubMed

    Kasai, Kosuke; Ishikawa, Takashi; Nakamura, Toshiya; Miura, Tomisato

    2015-10-01

    Venom, the mucus layer covering the body surface, ink glands, mammary glands, milk, and various animal secretory functions as both a physical and chemical defense barrier against bacteria and virus infections. Previously, several studies reported that L-amino acid oxidases (LAAOs) present in animal secretary fluids have strong antimicrobial activities and selective cytotoxic activities against Gram-positive and Gram-negative bacteria, various pathogenic bacteria, viruses, and parasite species. These LAAOs catalyze oxidative deamination of an L-amino acid substrate with the generation of hydrogen peroxide. The antibacterial activity of LAAOs is completely inhibited by catalase; thus, LAAOs kill bacteria by the hydrogen peroxide generated from the oxidation of L-amino acid substrates. This review focuses on the selective, specific, and local antibacterial actions of various LAAOs that may be used as novel therapeutic agents against infectious diseases. LAAOs that are suitable leads for combating multidrug-resistant bacterial infections are also studied. PMID:26243056

  1. Genetic determinants of antimicrobial resistance in Gram positive bacteria from organic foods.

    PubMed

    Fernández-Fuentes, Miguel Angel; Abriouel, Hikmate; Ortega Morente, Elena; Pérez Pulido, Rubén; Gálvez, Antonio

    2014-02-17

    Bacterial biocide resistance is becoming a matter of concern. In the present study, a collection of biocide-resistant, Gram-positive bacteria from organic foods (including 11 isolates from genus Bacillus, 25 from Enterococcus and 10 from Staphylococcus) were analyzed for genes associated to biocide resistance efflux pumps and antibiotic resistance. The only qac-genes detected were qacA/B (one Bacillus cereus isolate) and smr (one B. cereus and two Staphylococcus saprophyticus isolates). Efflux pump genes efrA and efrB genes were detected in Staphylococcus (60% of isolates), Bacillus (54.54%) and Enterococcus (24%); sugE was detected in Enterococcus (20%) and in one Bacillus licheniformis; mepA was detected in Staphylococcus (60%) and in one Enterococcus isolate (which also carried mdeA), and norE gene was detected only in one Enterococcus faecium and one S. saprophyticus isolate. An amplicon for acrB efflux pump was detected in all but one isolate. When minimal inhibitory concentrations (MICs) were determined, it was found that the addition of reserpine reduced the MICs by eight fold for most of the biocides and isolates, corroborating the role of efflux pumps in biocide resistance. Erythromycin resistance gene ermB was detected in 90% of Bacillus isolates, and in one Staphylococcus, while ereA was detected only in one Bacillus and one Staphyloccus, and ereB only in one Staphylococcus. The ATP-dependent msrA gene (which confers resistance to macrolides, lincosamides and type B streptogramins) was detected in 60% of Bacillus isolates and in all staphylococci, which in addition carried msrB. The lincosamide and streptogramin A resistance gene lsa was detected in Staphylococcus (40%), Bacillus (27.27%) and Enterococcus (8%) isolates. The aminoglycoside resistance determinant aph (3_)-IIIa was detected in Staphylococcus (40%) and Bacillus (one isolate), aph(2_)-1d in Bacillus (27.27%) and Enterococcus (8%), aph(2_)-Ib in Bacillus (one isolate), and the bifunctional aac(6_)1e-aph(2_)-Ia in Staphylococcus (20%), Enterococcus (8%) and Bacillus (one isolate). Chloramphenicol resistance cat gene was detected in Enterococcus (8%) and Staphylococcus (20%), and blaZ only in Staphylococcus (20%). All other antibiotic or biocide resistance genes investigated were not detected in any isolate. Isolates carrying multiple biocide and antibiotic determinants were frequent among Bacillus (36.36%) and Staphylococcus (50%), but not Enterococcus. These results suggest that biocide and antibiotic determinants may be co-selected. PMID:24361832

  2. Genome-wide gene order distances support clustering the gram-positive bacteria

    PubMed Central

    House, Christopher H.; Pellegrini, Matteo; Fitz-Gibbon, Sorel T.

    2015-01-01

    Initially using 143 genomes, we developed a method for calculating the pair-wise distance between prokaryotic genomes using a Monte Carlo method to estimate the conservation of gene order. The method was based on repeatedly selecting five or six non-adjacent random orthologs from each of two genomes and determining if the chosen orthologs were in the same order. The raw distances were then corrected for gene order convergence using an adaptation of the Jukes-Cantor model, as well as using the common distance correction D? = ?ln(1-D). First, we compared the distances found via the order of six orthologs to distances found based on ortholog gene content and small subunit rRNA sequences. The Jukes-Cantor gene order distances are reasonably well correlated with the divergence of rRNA (R2 = 0.24), especially at rRNA Jukes-Cantor distances of less than 0.2 (R2 = 0.52). Gene content is only weakly correlated with rRNA divergence (R2 = 0.04) over all distances, however, it is especially strongly correlated at rRNA Jukes-Cantor distances of less than 0.1 (R2 = 0.67). This initial work suggests that gene order may be useful in conjunction with other methods to help understand the relatedness of genomes. Using the gene order distances in 143 genomes, the relations of prokaryotes were studied using neighbor joining and agreement subtrees. We then repeated our study of the relations of prokaryotes using gene order in 172 complete genomes better representing a wider-diversity of prokaryotes. Consistently, our trees show the Actinobacteria as a sister group to the bulk of the Firmicutes. In fact, the robustness of gene order support was found to be considerably greater for uniting these two phyla than for uniting any of the proteobacterial classes together. The results are supportive of the idea that Actinobacteria and Firmicutes are closely related, which in turn implies a single origin for the gram-positive cell. PMID:25653643

  3. Silver nanoparticles synthesised using plant extracts show strong antibacterial activity.

    PubMed

    Kumari, Avnesh; Guliani, Anika; Singla, Rubbel; Yadav, Ramdhan; Yadav, Sudesh Kumar

    2015-06-01

    In this study, three plants Populus alba, Hibiscus arboreus and Lantana camara were explored for the synthesis of silver nanoparticles (SNPs). The effect of reaction temperature and leaf extract (LE) concentration of P. alba, H. arboreus and L. camara was evaluated on the synthesis and size of SNPs. The SNPs were characterised by ultra-violet-visible spectroscopy, scanning electron microscopy and atomic force microscopy. The synthesis rate of SNPs was highest with LE of L. camara followed by H. arboreus and P. alba under similar conditions. L. camara LE showed maximum potential of smaller size SNPs synthesis, whereas bigger particles were formed by H. arboreous LE. The size and shape of L. camara LE synthesised SNPs were analysed by transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDX). TEM analysis revealed the formation of SNPs of average size 17±9.5 nm with 5% LE of L. camara. The SNPs synthesised by LE of L. camara showed strong antibacterial activity against Escherichia coli. The results document that desired size SNPs can be synthesised using these plant LEs at a particular temperature for applications in the biomedical field. PMID:26023158

  4. A new antibacterial compound produced by an indigenous marine bacteria--fermentation, isolation, and biological activity.

    PubMed

    Uzair, Bushra; Ahmed, Nuzhat; Ahmad, Viqar Uddin; Kousar, Farzana

    2006-12-01

    The use of microorganisms for biological purpose has become an effective alternative to control pathogens. A marine bacterium Pseudomonas aeruginosa was isolated from Eal fish of Baluchistan coast of Pakistan. This strain produced a bactericidal antibiotic against environmental and clinical isolates. In this study, we purified bactericidal antibiotic from the ethyl acetate extract of the cells of P. aeruginosa and analyzed its chemical structure. Based on spectrometric analysis, this compound 1 is proposed to be 1-methyl-1,4 dihydroquinoline and is active against methicillin-resistant Staphylococcus aureus (MRSA), methicillin-sensitive S. aureus (MSSA), Salmonella typhi, Shigella flexneri, Escherichia coli, Proteus mirabilis, Vibrio aliginolyticus, Micrococcus luteus, Enterococcus faecalis, Enterobacter faecium but it is not active against G streptococci, Candida albicans, Aspergillus niger. Minimal inhibitory concentration for Gram-positive bacteria was between 50 and 75 microg mL(-1) and for Gram-negative bacteria 75-100 microg mL(-1). PMID:17393659

  5. Antibacterial activity of aqueous extracts of Indian chewing sticks on dental plaque: An in vitro study

    PubMed Central

    Rao, Dola Srinivasa; Penmatsa, Tanuja; Kumar, Alapati Kranthi; Reddy, M. Narendra; Gautam, Nalam Sai; Gautam, Nalam Radhika

    2014-01-01

    The anti-microbial efficacy of aqueous extracts of Indian chewing sticks against different kinds of plaque bacteria in vitro was investigated. Supra-gingival plaque is cultured and subjected to the antibacterial activity of the aqueous extracts of chewing sticks (Neem, Acacia, Pongamia glabra, Achyranthes aspera, Streblus asper) separately. The results of the study demonstrate that all the five chewing sticks under study possess inhibitory potential against bacteria present in dental plaque mainly on aerobes. The antibacterial efficacy of aqueous extracts has antibacterial effects and could be used as a therapeutic agent and therefore, it appears to be potent anti-microbial agents that could be considered as a medicinal plant. Results of this study showed chewing sticks contained antibacterial agents, but the concentration and composition of the active substances differed among the plants. PMID:25210357

  6. New antibacterial agents derived from the DNA gyrase inhibitor cyclothialidine.

    PubMed

    Angehrn, Peter; Buchmann, Stefan; Funk, Christoph; Goetschi, Erwin; Gmuender, Hans; Hebeisen, Paul; Kostrewa, Dirk; Link, Helmut; Luebbers, Thomas; Masciadri, Raffaello; Nielsen, Joergen; Reindl, Peter; Ricklin, Fabienne; Schmitt-Hoffmann, Anne; Theil, Frank-Peter

    2004-03-11

    Cyclothialidine (1, Ro 09-1437) is a potent DNA gyrase inhibitor that was isolated from Streptomyces filipinensis NR0484 and is a member of a new family of natural products. It acts by competitively inhibiting the ATPase activity exerted by the B subunit of DNA gyrase but barely exhibits any growth inhibitory activity against intact bacterial cells, presumably due to insufficient permeation of the cytoplasmic membrane. To explore the antibacterial potential of 1, we developed a flexible synthetic route allowing for the systematic modification of its structure. From a first set of analogues, structure-activity relationships (SAR) were established for different substitution patterns, and the 14-hydroxylated, bicyclic core (X) of 1 seemed to be the structural prerequisite for DNA gyrase inhibitory activity. The variation of the lactone ring size, however, revealed that activity can be found among 11- to 16-membered lactones, and even seco-analogues were shown to maintain some enzyme inhibitory properties, thereby reducing the minimal structural requirements to a rather simple, hydroxylated benzyl sulfide (XI). On the basis of these "minimal structures" a modification program afforded a number of inhibitors that showed in vitro activity against Gram-positive bacteria. The best activities were displayed by 14-membered lactones, and representatives of this subclass exhibit excellent and broad in vitro antibacterial activity against Gram-positive pathogens, including Staphylococcus aureus, Streptococcus pyogenes, and Enterococcus faecalis, and overcome resistance against clinically used drugs. By improving the pharmacokinetic properties of the most active compounds (94, 97), in particular by lowering their lipophilic properties, we were able to identify congeners of cyclothialidine (1) that showed efficacy in vivo. PMID:14998336

  7. Characterization of saltern based Streptomyces sp. and statistical media optimization for its improved antibacterial activity

    PubMed Central

    Rajeswari, Pandiyan; Jose, Polpass Arul; Amiya, Richa; Jebakumar, Solomon Robinson David

    2015-01-01

    A moderately halotolerant Streptomyces strain, designated JAJ13 was characterized and a culture medium was statistically optimized to improve its antibacterial activity. Based on the phenotypic and molecular characteristics, strain JAJ13 was identified as a moderately halotolerant Streptomyces sp. JAJ13. Novelty of the strain JAJ13 in production of antibacterial compound was assessed by sequence analysis of KS? gene and LC-MS analysis of the active compound. Optimization of the culture medium for antibacterial compound production by the strain JAJ13 was performed with statistical methodology based on experimental designs. Initially, a starch based basal production medium was selected out of eight different production media screened for antibacterial compound production by Streptomyces sp. JAJ13. Plackett-Burman design was employed to screen the influential media components affecting the antibacterial compound production. Subsequently, statistical optimization of selected medium components was performed by employing the response surface methodology (RSM) with Box-Behnken design. The optimum initial level of CuSO4.5H2O, (NH4)2SO4 and K2HPO4 for the highest antibacterial activity was determined to be at 4.45 mg, 1.96 g, and 1.15 g in 1 L of distilled H2O, respectively. PBD and RSM guided design of experiments resulted in a maximum antibacterial activity of 23.37 ± 2.08 mm, which is a 78.8% increase in comparison with that obtained in the unoptimized medium. This study points the success of statistical model in developing an optimized production media for enhanced antibacterial compound production by Streptomyces sp. JAJ13. PMID:25653640

  8. Antibacterial activity of Phyllantus emblica, Coriandrum sativum, Culinaris medic, Lawsonia alba and Cucumis sativus.

    PubMed

    Khan, Dawood Ali; Hassan, Fouzia; Ullah, Hanif; Karim, Sabiha; Baseer, Abdul; Abid, Mobasher Ali; Ubaidi, Muhammad; Khan, Shujaat Ali; Murtaza, Ghulam

    2013-01-01

    Present study deals with the demonstration of the antibacterial activity of very common medicinal plants of Pakistani origin i.e., Phyllantus emblica, Coriandrum sativum, Culinaris medic, Lawsonia alba and Cucumis sativus. The extracts were prepared in crude form by the use of hydro-alcoholic solution and were screened for antibacterial activity against various bacterial species by disk diffusion method. Assay was performed using clinical isolates of B. cereus, S. aureus, P. aeruginosa and E. coli. Crude extract of Phyllantus emblica fruit exhibited strong activity against standard cultures of all studied bacteria. Lawsonia alba showed good activity against standard cultures of all the used microorganisms. Coriandrum sativum was effective only against Bacillus cereus, while Cucumis sativus and Culinaris medic showed poor activity against Pseudomonas aeruginosa only. Hence, Phyllantus emblica exhibited strong antibacterial activity against a wide range of bacteria it means that Phyllantus emblica extract contains some compounds which have broad spectrum of bactericidal activity. PMID:24147363

  9. Potent antibacterial nanoparticles for pathogenic bacteria.

    PubMed

    Lai, Hong-Zheng; Chen, Wei-Yu; Wu, Ching-Yi; Chen, Yu-Chie

    2015-01-28

    Antibiotic-resistant bacteria have emerged because of the prevalent use of antibacterial agents. Thus, new antibacterial agents and therapeutics that can treat bacterial infections are necessary. Vancomycin is a potent antibiotic. Unfortunately, some bacterial strains have developed their resistance toward vancomycin. Nevertheless, it has been demonstrated that vancomycin-immobilized nanoparticles (NPs) are capable to be used in inhibition of the cell growth of vancomycin-resistant bacterial strains through multivalent interactions. However, multistep syntheses are usually necessary to generate vancomycin-immobilized NPs. Thus, maintaining the antibiotic activity of vancomycin when the drug is immobilized on the surface of NPs is challenging. In this study, a facile approach to generate vancomycin immobilized gold (Van-Au) NPs through one-pot stirring of vancomycin with aqueous tetrachloroauric acid at pH 12 and 25 °C for 24 h was demonstrated. Van-Au NPs (8.4 ± 1.3 nm in size) were readily generated. The generated Van-Au NPs maintained their antibiotic activities and inhibited the cell growth of pathogens, which included Gram-positive and Gram-negative bacteria as well as antibiotic-resistant bacterial strains. Furthermore, the minimum inhibitory concentration of the Van-Au NPs against bacteria was lower than that of free-form vancomycin. Staphylococcus aureus-infected macrophages were used as the model samples to examine the antibacterial activity of the Van-Au NPs. Macrophages have the tendency to engulf Van-Au NPs through endocytosis. The results showed that the cell growth of S. aureus in the macrophages was effectively inhibited, suggesting the potential of using the generated Van-Au NPs as antibacterial agents for bacterial infectious diseases. PMID:25584802

  10. Relevance of GC content to the conservation of DNA polymerase III/mismatch repair system in Gram-positive bacteria

    PubMed Central

    Akashi, Motohiro; Yoshikawa, Hirofumi

    2013-01-01

    The mechanism of DNA replication is one of the driving forces of genome evolution. Bacterial DNA polymerase III, the primary complex of DNA replication, consists of PolC and DnaE. PolC is conserved in Gram-positive bacteria, especially in the Firmicutes with low GC content, whereas DnaE is widely conserved in most Gram-negative and Gram-positive bacteria. PolC contains two domains, the 3?-5?exonuclease domain and the polymerase domain, while DnaE only possesses the polymerase domain. Accordingly, DnaE does not have the proofreading function; in Escherichia coli, another enzyme DnaQ performs this function. In most bacteria, the fidelity of DNA replication is maintained by 3?-5? exonuclease and a mismatch repair (MMR) system. However, we found that most Actinobacteria (a group of Gram-positive bacteria with high GC content) appear to have lost the MMR system and chromosomes may be replicated by DnaE-type DNA polymerase III with DnaQ-like 3?-5? exonuclease. We tested the mutation bias of Bacillus subtilis, which belongs to the Firmicutes and found that the wild type strain is AT-biased while the mutS-deletant strain is remarkably GC-biased. If we presume that DnaE tends to make mistakes that increase GC content, these results can be explained by the mutS deletion (i.e., deletion of the MMR system). Thus, we propose that GC content is regulated by DNA polymerase and MMR system, and the absence of polC genes, which participate in the MMR system, may be the reason for the increase of GC content in Gram-positive bacteria such as Actinobacteria. PMID:24062730

  11. Antibacterial activity and reusability of CNT-Ag and GO-Ag nanocomposites

    NASA Astrophysics Data System (ADS)

    Kim, Ji Dang; Yun, Hyosuk; Kim, Gwui Cheol; Lee, Chul Won; Choi, Hyun Chul

    2013-10-01

    A facile approach to the synthesis of novel CNT-Ag and GO-Ag antibacterial materials, in which thiol groups are utilized as linkers to secure silver (Ag) nanoparticles to the CNT and GO surfaces without agglomeration, is reported. The resulting CNT-Ag and GO-Ag samples were characterized by performing TEM, XRD, Auger, XPS, and Raman measurements, which revealed that in these antibacterial materials size-similar and quasi-spherical Ag nanoparticles are anchored to the CNT and GO surfaces. The Ag nanoparticles in CNT-Ag and GO-Ag have narrow size distributions with average diameters of 2.6 and 3.5 nm respectively. The antibacterial activities of CNT-Ag and GO-Ag against Escherichia coli were assessed with the paper-disk diffusion method and by determining the minimal inhibitory concentrations (MICs). CNT-Ag was found to have higher antibacterial activity than the reference Ag colloid. Moreover, both CNT-Ag and GO-Ag retain more than 50% of their original antibacterial activities after 20 washes with detergent, which indicates their potential as antibacterial materials for laboratory and medical purposes.

  12. Antibacterial properties of poly (octanediol citrate)/gallium-containing bioglass composite scaffolds.

    PubMed

    Zeimaran, Ehsan; Pourshahrestani, Sara; Djordjevic, Ivan; Pingguan-Murphy, Belinda; Kadri, Nahrizul Adib; Wren, Anthony W; Towler, Mark R

    2016-01-01

    Bioactive glasses may function as antimicrobial delivery systems through the incorporation and subsequent release of therapeutic ions. The aim of this study was to evaluate the antimicrobial properties of a series of composite scaffolds composed of poly(octanediol citrate) with increased loads of a bioactive glass that releases zinc (Zn(2+)) and gallium (Ga(3+)) ions in a controlled manner. The antibacterial activity of these scaffolds was investigated against both Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria. The ability of the scaffolds to release ions and the subsequent ingress of these ions into hard tissue was evaluated using a bovine bone model. Scaffolds containing bioactive glass exhibited antibacterial activity and this increased in vitro with higher bioactive glass loads; viable cells decreased to about 20 % for the composite scaffold containing 30 % bioactive glass. The Ga(3+) release rate increased as a function of time and Zn(2+) was shown to incorporate into the surrounding bone. PMID:26676864

  13. Spectral, morphological and antibacterial studies of ?-cyclodextrin stabilized silver - Chitosan nanocomposites

    NASA Astrophysics Data System (ADS)

    Punitha, N.; Ramesh, P. S.; Geetha, D.

    2015-02-01

    The aim of the study is to investigate the antibacterial properties and characterization of ?-cyclodextrin (?-CD) stabilized silver - chitosan nanocomposite (Ag-Cts NCs). An effective and eco-friendly technique for the synthesis of Ag-Cts NCs in the presence of a strong stabilizing agent ?-CD is described. The well formed nanocomposites were characterized by the Ultraviolet Visible spectroscopy (UV-Vis), X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), Photoluminescence spectroscopy (PL), Scanning electron microscope (SEM/EDS), Atomic force microscope (AFM), High resolution transmission electron microscope (HR-TEM) and Zeta potential measurement (ZP). The results confirmed that the poly dispersed Ag-Cts NCs are less than 15 nm in size with spherical shape and show good stability. The antibacterial activity was also investigated and ?-CD coated Ag-Cts NCs showed a promising bacterial activity against gram negative Escherichia coli (E. coli) and gram positive Staphylococcus aureus (S. aureus) micro-organism.

  14. Development of a Treatment Algorithm for Streptococci and Enterococci from Positive Blood Cultures Identified with the Verigene Gram-Positive Blood Culture Assay

    PubMed Central

    Alby, Kevin; Daniels, Lindsay M.; Weber, David J.

    2013-01-01

    Seventy-eight blood cultures with a Gram stain result of Gram-positive cocci in pairs and/or chains were evaluated with the Nanosphere Verigene Gram-positive blood culture (BC-GP) assay. The overall concordance of the assay with culture was 89.7% (70/78 cultures), allowing for the development of a targeted treatment algorithm. PMID:23985910

  15. Determination of the gram-positive bacterial content of soils and sediments by analysis of teichoic acid components

    NASA Technical Reports Server (NTRS)

    Gehron, M. J.; Davis, J. D.; Smith, G. A.; White, D. C.

    1984-01-01

    Many gram-positive bacteria form substituted polymers of glycerol and ribitol phosphate esters known as teichoic acids. Utilizing the relative specificity of cold concentrated hydrofluoric acid in the hydrolysis of polyphosphate esters it proved possible to quantitatively assay the teichoic acid-derived glycerol and ribitol from gram-positive bacteria added to various soils and sediments. The lipids are first removed from the soils or sediments with a one phase chloroform-methanol extraction and the lipid extracted residue is hydrolyzed with cold concentrated hydrofluoric acid. To achieve maximum recovery of the teichoic acid ribitol, a second acid hydrolysis of the aqueous extract is required. The glycerol and ribitol are then acetylated after neutralization and analyzed by capillary gas-liquid chromatography. This technique together with measures of the total phospholipid, the phospholipid fatty acid, the muramic acid and the hydroxy fatty acids of the lipopolysaccharide lipid A of the gram-negative bacteria makes it possible to describe the community structure environmental samples. The proportion of gram-positive bacteria measured as the teichoic acid glycerol and ribitol is higher in soils than in sediments and increases with depth in both.

  16. Thermal inactivation of antimicrobial-resistant Gram-positive cocci in chicken meat: D and Z value determinations.

    PubMed

    Bertolatti, D; Munyard, S J; Grubb, W B; Binns, C W

    2001-09-01

    Antimicrobial-resistance in Gram-positive bacteria is reported with increasing frequency in strains isolated from food animals. Their isolation from commercial poultry carcasses and meat products constitute a potential risk that resistant strains or resistance genes might spread to humans via the food chain. As bacterial inactivation by thermal process is a critical control point in the safe preparation of many ready-to-eat foods, it is important to determine the thermal resistance of these organisms. The present study was undertaken to investigate the thermal tolerance (D and Z values) of antimicrobial-resistant, Gram-positive cocci in ground chicken meat. The antimicrobial-resistant, Gram-positive cocci for this study were isolated from two poultry processing plants in Western Australia. D and Z value data indicate that these isolates do not exhibit enhanced thermal resistant characteristics. The estimated lethal effect of the cooking process for chicken meat indicates that an internal temperature of 70 degrees C for 2.1 min would provide a 7-log reduction of all cell suspensions tested. PMID:11672482

  17. Antibacterial Activity of Biosecur® Citrus Extract Surface Cleaner Against Vibrio Vulnificus

    PubMed Central

    Cormier, Jiemin; Scott, Ronson; Janes, Marlene

    2013-01-01

    This study evaluated the antibacterial activity of Biosecur® citrus extract surface cleaner against Vibrio vulnificus using plate count method. Two concentrations, 0.5% and 2% of Biosecur® surface cleaner were plated on Vibrio vulnificus Agar (VVA) and tested for reduction of Vibrio vulnificus. In order to investigate the lasting residual activity of Biosecur®, antibacterial activity tests were also performed at time intervals up to 2.5 h after Biosecur® was plated on VVA. Biosecur® showed 6-log reduction of Vibrio vulnificus at 2%, and 3-log reduction of Vibrio vulnificus at 0.5%. The antibacterial activity of 2% Biosecur® against Vibrio vulnificus was shown to be equivalent to that of tetracycline. The residual activity of 2% Biosecur® was shown to maintain for at least 2.5 h after application. This study confirmed the high activity and long lasting residual effect of a safe, non-toxic organic food grade surface cleaner. PMID:24302976

  18. Synthesis, characterization and antibacterial activity of new sulfonyl hydrazone derivatives and their nickel(II) complexes

    NASA Astrophysics Data System (ADS)

    Özmen, Ümmühan Özdemir; Olgun, Gülçin

    2008-08-01

    Prophane sulfonic acid hydrazide (psh: CH 3CH 2CH 2SO 2NHNH 2) derivatives as salicylaldehydeprophanesulfonylhydrazone (salpsh), 5-methylsalicylaldehydeprophanesulfonylhydrazone (5-msalpsh), 2-hydroxyacetophenoneprophanesulfonylhydrazone (afpsh), 5-methyl-2-hydroxyacetophenoneprophanesulfonylhydrazone (5-mafpsh) and their Ni(II) complexes have been synthesized. The structure of these compounds has been investigated by using elemental analysis, FTIR, 1H NMR, LC/MS, UV-vis spectrophotometric method, magnetic susceptibility and conductivity measurements. The complexes were found to have general compositions [NiL2]. Square-planer structures are proposed for the Ni(II) complexes on the basis of magnetic evidence, electronic spectra and TGA data. Bacterial activities of sulfonyl hydrazone compounds were studied against gram-positive bacteria: Staphylococcus aureus, Bacillus subtilis, Bacillus magaterium and gram-negative bacteria: Salmonella enteritidis, Escherichia coli by using minimum inhibitory concentrations (MICs) method.

  19. A new antibacterial benzophenone glycoside from Psidium guajava (Linn.) leaves.

    PubMed

    Ukwueze, Stanley E; Osadebe, Patience O; Okoye, Festus B C

    2015-01-01

    Bioactivity-guided fractionation of methanol extract from the leaves of Psidium guajava L. (Myrtaceae) yielded a new benzophenone glycoside, Guajaphenone A (2) together with two known compounds, Garcimangosone D (1) and Guaijaverin (3). Their structures were elucidated by analysis of spectroscopic data including 1D and 2D NMR and electrospray ionisation mass spectrometry (ESI-MS). The isolated compounds were screened against standard strains of Gram-positive and Gram-negative bacteria using broth dilution assay method, and the MIC values determined and compared with reference antibiotic ceftriaxone. They were found to have significant antibacterial activities against Escherichia coli and Staphylococcus aureus with all of them showing better activities against S. aureus, but displaying weaker activities, in comparison to ceftriaxone. However, despite reduced effect of these compounds against the organisms, this work opens the perspective to use these molecules as 'leads' for the design of novel and selective drug candidates for some tropical infectious diseases. PMID:25631395

  20. Helvolic acid, an antibacterial nortriterpenoid from a fungal endophyte, Xylaria sp. of orchid Anoectochilus setaceus endemic to Sri Lanka

    PubMed Central

    Ratnaweera, Pamoda B.; Williams, David E.; de Silva, E. Dilip; Wijesundera, Ravi L.C.; Dalisay, Doralyn S.; Andersen, Raymond J.

    2014-01-01