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

PubMed

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

2012-06-21

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).

Facile Synthesis of Efficient Antibacterial Agent as CoFe₂O₄/Ag Composite Material Against Both Gram-Negative Escherichia coli and Gram-Positive Bacillus subtilis Bacteria.

PubMed

Gankhuyag, Sukhbayar; Lee, Kyoung; Bae, Dong Sik

2018-09-01

We have suggested that a facile synthesis of CoFe2O4/Ag composite material as an antibacterial agent for substitution of a chlorination agent for microbial infected wastewater treatment. The CoFe2O4/Ag was synthesized by an impregnation method in assistance with trisodium citrate as a reducing agent. The as-prepared uncalcined CoFe2O4 (CFG), calcined CoFe2O4 (CFG600), and calcined CoFe2O4/Ag (CFG600/Ag) composites were characterized by X-ray diffraction (XRD), Field Emission Scanning Electron Microscope (FE-SEM) and Energy Dispersive X-ray (EDX) techniques. Antibacterial activities were also determined in liquid culture by measuring the minimum inhibitory concentrations (MIC) against Gram-negative Escherichia coli (E. coli) and Gram-positive Bacillus subtilis (B. subtilis) bacteria in vitro. Results showed that CFG600/Ag composites had an excellent antibacterial activity in comparison with CFG and CFG600 composites. The CFG600/Ag composites have completely inhibited the growth of both E. coli and B. subtilis bacteria from concentrations of more than 0.25 mg/ml. Furthermore, the FE-SEM study demonstrated the physical damage of bacteria when treated with CFG600/Ag composite material at a concentration of 0.10 mg/ml.

Preparation of active antibacterial LDPE surface through multistep physicochemical approach: I. Allylamine grafting, attachment of antibacterial agent and antibacterial activity assessment.

PubMed

Bílek, František; Křížová, Táňa; Lehocký, Marián

2011-11-01

Low-density polyethylene (LDPE) samples were treated in air plasma discharge, coated by polyallyamine brush thought copolymeric grafting surface-from reaction and deposited four common antibacterial agents (benzalkonium chloride, bronopol, chlorhexidine and triclosan) to gain material with active antibacterial properties. Surface characteristics were evaluated by static contact angle measurement with surface energy evaluation ATR-FTIR, X-ray Photoelectron Spectroscopy (XPS) and SEM analysis. Inhibition zone on agar was used as in vitro test of antibacterial properties on two representative gram positive Staphylococcus aureus (S. aureus) and gram negative Escherichia coli (E. coli) strains. It was confirmed, that after grafting of polyallyamine, more antibacterial agent is immobilized on the surface. The highest increase of antibacterial activity was observed by the sample containing triclosan. Samples covered by bronopol did not show significant antibacterial activity. Copyright © 2011 Elsevier B.V. All rights reserved.

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.

Zulu medicinal plants with antibacterial activity.

PubMed

Kelmanson, J E; Jäger, A K; van Staden, J

2000-03-01

Aqueous, methanolic and ethyl acetate extracts of 14 plants used in traditional Zulu medicine for treatment of ailments of an infectious nature were screened for antibacterial activity. Most of the activity detected was against gram-positive bacteria. Tuber bark extracts of Dioscorea sylvatica had activity against gram-negative Escherichia coli and extracts of Dioscorea dregeana, Cheilanthes viridis and Vernonia colorata were active against Pseudomonas aeruginosa. The highest antibacterial activity was found in extracts of C. viridis, D. dregeana, D. silvatica, Melianthus comosus and V. colorata. In general, methanolic extracts exhibited higher activity than aqueous and ethyl acetate extracts.

Synthesis and in vitro antibacterial activity of new steroidal thiosemicarbazone derivatives.

PubMed

Khan, Salman Ahmad; Kumar, Praveen; Joshi, Rajkumar; Iqbal, Prince F; Saleem, Kishwar

2008-09-01

We investigated the antibacterial activity of some new steroidal thiosemicarbazone derivatives, prepared from the reaction of cholest-5-en-7-one with thiosemicarbazides, in ethanol in the presence of a few drops of HCl at 80 degrees C in high yield. All the compounds have been characterized by means of elemental analyses, IR, 1H NMR and mass spectroscopic data, to find an effective antibacterial agent. The antibacterial activity was first tested in vitro by the disk diffusion assay against two Gram-positive and two Gram-negative bacteria, and then the minimum inhibitory concentration (MIC) of compounds was determined. The results showed that the steroidal thiosemicarbazones derivatives inhibit growth of both types of the bacteria (Gram-positive and Gram-negative). The acetoxy and chloro derivatives of cyclopentyl and cyclohexyl amine thiosemicarbazones were found to have more antibacterial activity than the other derivatives.

Phytochemical screening and antibacterial activity of Cyclamen persicum Mill tuber extracts.

PubMed

Alkowni, Raed; Jodeh, Shehdeh; Hussein, Fatima; Jaradat, Nidal

2018-01-01

The emerging drug resistance bacteria increased the demand on the discovery of antibiotics from natural sources. This research was aimed to study the antibacterial reactivity; as well as the phytochemicals, of the wild type of Cyclamen persicum, using nine different extraction methods where four solvents (Methanol, Ethanol, Hexane; and Water) were involved with varied extraction periods ranged from 2 up to 10 hours. The antibacterial activity of crude methanol extract (CME) was found as the best method of extraction, with particular emphasis on the method with prolonged extraction time of (10 hrs). The antibacterial activities of produced CME were determined by using agar diffusion method against two of gram-positive bacteria and two gram-negative ones. The CME treated Mueller-Hinton-Agar plates, were exhibited antibacterial effects against the gram-positive bacteria (Staphylococcus aureus and Bacillus subtilis) by showing of inhibition zone after overnight incubation, while nothing was noticed on those of gram negative ones (Pseudomonas aeruginosa and Escherichia coli). These results that proved the antibacterial activity of the Cyclamen persicum tubers were positively tested the Saponin glycosides from plant. In addition to that, methanol solvent could be the useful method for extractions of Cyclamen and can be used in any developing drugs against pathogenic gram positive bacteria.

Bio-fabricated silver nanoparticles preferentially targets Gram positive depending on cell surface charge.

PubMed

Mandal, Debasis; Kumar Dash, Sandeep; Das, Balaram; Chattopadhyay, Sourav; Ghosh, Totan; Das, Debasis; Roy, Somenath

2016-10-01

Recently bio-inspired experimental processes for synthesis of nanoparticles are receiving significant attention in nanobiotechnology. Silver nanoparticles (Ag NPs) have been used very frequently in recent times to the wounds, burns and bacterial infections caused by drug-resistant microorganisms. Though, the antibacterial effects of Ag NPs on some multi drug-resistant bacteria specially against Gram positive bacteria has been established, but further investigation is needed to elicit its effectiveness against Gram negatives and to identify the probable mechanism of action. Thus, the present study was conducted to synthesize Ag NPs using Andrographis paniculata leaf extract and to investigate its antibacterial efficacy. After synthesis process the biosynthesized nanoparticles were purified and characterized with the help of various physical measurement techniques which raveled their purity, stability and small size range. The antimicrobial activity of Ag NPs was determined against both Gram-positive Enterococcus faecalis and Gram-negative Proteus vulgaris. Results showed comparatively higher antibacterial efficacy of Ag NPs against Gram positive Enterococcus faecalis strains. It was found that greater difference in zeta potential values between Gram positive bacteria and Ag NPs triggers better internalization of the particles. Thus the cell surface charge played vital role in cell killing which was confirmed by surface zeta potential study. Finally it may be concluded that green synthesized Ag NPs using Andrographis paniculata leaf extract can be very useful against both multi drug resistant Gram-positive and Gram-negative bacteria. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Gram-Positive Bacterial Infections: Research Priorities, Accomplishments, and Future Directions of the Antibacterial Resistance Leadership Group.

PubMed

Doernberg, Sarah B; Lodise, Thomas P; Thaden, Joshua T; Munita, Jose M; Cosgrove, Sara E; Arias, Cesar A; Boucher, Helen W; Corey, G Ralph; Lowy, Franklin D; Murray, Barbara; Miller, Loren G; Holland, Thomas L

2017-03-15

Antimicrobial resistance in gram-positive bacteria remains a challenge in infectious diseases. The mission of the Gram-Positive Committee of the Antibacterial Resistance Leadership Group (ARLG) is to advance knowledge in the prevention, management, and treatment of these challenging infections to improve patient outcomes. Our committee has prioritized projects involving methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE) due to the scope of the medical threat posed by these pathogens. Approved ARLG projects involving gram-positive pathogens include (1) a pharmacokinetics/pharmacodynamics study to evaluate the impact of vancomycin dosing on patient outcome in MRSA bloodstream infection (BSI); (2) defining, testing, and validating innovative assessments of patient outcomes for clinical trials of MRSA-BSI; (3) testing new strategies for "step-down" antibiotic therapy for MRSA-BSI; (4) management of staphylococcal BSIs in neonatal intensive care units; and (5) defining the impact of VRE bacteremia and daptomycin susceptibility on patient outcomes. This article outlines accomplishments, priorities, and challenges for research of infections caused by gram-positive organisms. © The Author 2017. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail: journals.permissions@oup.com.

Preparation, characterization and antibacterial activity of oxidized κ-carrageenan.

PubMed

Zhu, Mingjin; Ge, Liming; Lyu, Yongbo; Zi, Yaxin; Li, Xinying; Li, Defu; Mu, Changdao

2017-10-15

The oxidized κ-carrageenans with different oxidation levels were prepared through the hydrogen peroxide and copper sulfate redox system. The oxidation level of oxidized κ-carrageenan was successfully controlled by adjusting the dosage of hydrogen peroxide. The results showed that the microtopography of oxidized κ-carrageenan changed from rough granules to smooth flakes, mainly resulting from the easily melting property of oxidized κ-carrageenan induced by introduced carboxyl and aldehyde groups. Especially, the antibacterial activity of oxidized κ-carrageenans against Gram-positive bacteria (Staphylococcus aureus and Listeria monocytogenes) and Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa) was systematically investigated. The results showed that the oxidized κ-carrageenan could damage the bacterial cell wall and cytoplasmic membrane and suppress the growth of both Gram-positive and Gram-negative bacteria. The oxidized κ-carrageenan possessed broad-spectrum antibacterial activity, which may be used as a new antibacterial agent. Copyright © 2017 Elsevier Ltd. All rights reserved.

Antiproliferative and antibacterial activity of some glutarimide derivatives.

PubMed

Popović-Djordjević, Jelena B; Klaus, Anita S; Žižak, Željko S; Matić, Ivana Z; Drakulić, Branko J

2016-12-01

Antiproliferative and antibacterial activities of nine glutarimide derivatives (1-9) were reported. Cytotoxicity of compounds was tested toward three human cancer cell lines, HeLa, K562 and MDA-MB-453 by MTT assay. Compound 7 (2-benzyl-2-azaspiro[5.11]heptadecane-1,3,7-trione), containing 12-membered ketone ring, was found to be the most potent toward all tested cell lines (IC50 = 9-27 μM). Preliminary screening of antibacterial activity by a disk diffusion method showed that Gram-positive bacteria were more susceptible to the tested compounds than Gram-negative bacteria. Minimum inhibitory concentration (MIC) determined by a broth microdilution method confirmed that compounds 1, 2, 4, 6-8 and 9 inhibited the growth of all tested Gram-positive and some of the Gram-negative bacteria. The best antibacterial potential was achieved with compound 9 (ethyl 4-(1-benzyl-2,6-dioxopiperidin-3-yl)butanoate) against Bacillus cereus (MIC 0.625 mg/mL; 1.97 × 10(-3 )mol/L). Distinction between more and less active/inactive compounds was assessed from the pharmacophoric patterns obtained by molecular interaction fields.

Zn or O? An Atomic Level Comparison on Antibacterial Activities of Zinc Oxides.

PubMed

Yu, Fen; Fang, Xuan; Jia, Huimin; Liu, Miaoxing; Shi, Xiaotong; Xue, Chaowen; Chen, Tingtao; Wei, Zhipeng; Fang, Fang; Zhu, Hui; Xin, Hongbo; Feng, Jing; Wang, Xiaolei

2016-06-06

For the first time, the influence of different types of atoms (Zn and O) on the antibacterial activities of nanosized ZnO was quantitatively evaluated with the aid of a 3D-printing-manufactured evaluation system. Two different outermost atomic layers were manufactured separately by using an ALD (atomic layer deposition) method. Interestingly, we found that each outermost atomic layer exhibited certain differences against gram-positive or gram-negative bacterial species. Zinc atoms as outermost layer (ZnO-Zn) showed a more pronounced antibacterial effect towards gram-negative E. coli (Escherichia coli), whereas oxygen atoms (ZnO-O) showed a stronger antibacterial activity against gram-positive S. aureus (Staphylococcus aureus). A possible antibacterial mechanism has been comprehensively discussed from different perspectives, including Zn(2+) concentrations, oxygen vacancies, photocatalytic activities and the DNA structural characteristics of different bacterial species. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Screening of some Palestinian medicinal plants for antibacterial activity.

PubMed

Essawi, T; Srour, M

2000-06-01

Antibacterial activity of organic and aqueous extracts of 15 Palestinian medicinal plants were carried against eight different species of bacteria: Bacillus subtilis, two Escherichia coli species, Staphylococcus aureus (methicillin resistant), two S. aureus (methicillin sensitive) species, Pseudomonas aeruginosa, and Enterococcus fecalis. Of the 15 plants tested, eight showed antibacterial activity. Each plant species has unique against different bacteria. The most active antibacterial plants against both gram-positive and gram-negative bacteria were Thymus vulgaris and Thymus origanium. The organic and aqueous extract from the same plants showed different activities; the organic extract showed the same or greater activity than the aqueous extract. Finally, the hole-plate diffusion method showed larger activity than the disc diffusion method.

C8-Linked Pyrrolobenzodiazepine Monomers with Inverted Building Blocks Show Selective Activity against Multidrug Resistant Gram-Positive Bacteria.

PubMed

Andriollo, Paolo; Hind, Charlotte K; Picconi, Pietro; Nahar, Kazi S; Jamshidi, Shirin; Varsha, Amrit; Clifford, Melanie; Sutton, J Mark; Rahman, Khondaker Miraz

2018-02-09

Antimicrobial resistance has become a major global concern. Development of novel antimicrobial agents for the treatment of infections caused by multidrug resistant (MDR) pathogens is an urgent priority. Pyrrolobenzodiazepines (PBDs) are a promising class of antibacterial agents initially discovered and isolated from natural sources. Recently, C8-linked PBD biaryl conjugates have been shown to be active against some MDR Gram-positive strains. To explore the role of building block orientations on antibacterial activity and obtain structure activity relationship (SAR) information, four novel structures were synthesized in which the building blocks of previously reported compounds were inverted, and their antibacterial activity was studied. The compounds showed minimum inhibitory concentrations (MICs) in the range of 0.125-32 μg/mL against MDR Gram-positive strains with a bactericidal mode of action. The results showed that a single inversion of amide bonds reduces the activity while the double inversion restores the activity against MDR pathogens. All inverted compounds did not stabilize DNA and lacked eukaryotic toxicity. The compounds inhibit DNA gyrase in vitro, and the most potent compound was equally active against both wild-type and mutant DNA gyrase in a biochemical assay. The observed activity of the compounds against methicillin resistant S. aureus (MRSA) strains with equivalent gyrase mutations is consistent with gyrase inhibition being the mechanism of action in vivo, although this has not been definitively confirmed in whole cells. This conclusion is supported by a molecular modeling study showing interaction of the compounds with wild-type and mutant gyrases. This study provides important SAR information about this new class of antibacterial agents.

Antibacterial activity of propolins from Taiwanese green propolis.

PubMed

Chen, Yue-Wen; Ye, Siou-Ru; Ting, Chieh; Yu, Yu-Hsiang

2018-04-01

Taiwanese green propolis is a prenylated flavonoid rich honeybee product and propolins isolated from Taiwanese green propolis exert a broad spectrum of biological activities, such as anti-cancer and anti-oxidant. However, the anti-bacterial effects of Taiwanese green propolis or propolins are still poorly understood. In the current study, the antibacterial effects of Taiwanese green propolis and propolins were evaluated. Results show that the maximum dry matter yields of Taiwanese green propolis were observed in the 95% and 99.5% ethanol extracts compared to other extraction methods. Consistently, the highest concentration of propolins C, D, F and G from Taiwanese green propolis was obtained in 95% and 99.5% ethanol extracts. Propolins inhibited the growth of gram-positive bacterial strains (Staphylococcus aureus, Bacillus subtilis, Listeria monocytogenes and Paenibacillus larvae). The average minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of propolins from ethanol extracts were 20 μg/ml. Among the propolins, propolin C had the highest antibacterial activity. Furthermore, Taiwanese green propolis also showed antibacterial activity against methicillin-resistant S. aureus (MRSA). In conclusion, these results demonstrate that Taiwanese green propolis and propolins have significant antibacterial activity, particularly against gram-positive bacterial strains. Copyright © 2017. Published by Elsevier B.V.

[Antibacterial activity of sulopenem, a new parenteral penem antibiotic].

PubMed

Inoue, E; Komoto, E; Taniyama, Y; Mitsuhashi, S

1996-04-01

Sulopenem, a new penem antibiotic, was compared with other antibiotics with regard to in vitro antibacterial and bactericidal activities, stabilization against beta-lactamases, and effect on the release of lipopolysaccharide from Gram-negative bacteria. The results are summarized as follows. 1. Sulopenem showed more potent activities than other antibiotics against both Gram-positive and Gram-negative bacteria except Pseudomonas aeruginosa. 2. Sulopenem showed potent bactericidal activities (MIC/MBC) against both Gram-positive and Gram-negative bacteria. Time kill studies against Staphylococcus aureus, Escherichia coli, Enterobacter cloacae and Citrobacter freundii showed potent bactericidal activities of sulopenem. 3. Sulopenem was found to possess a stronger activity than other antibiotics against beta-lactamase-producing strains except P. aeruginosa and Stenotrophomonas maltophilia. 4. In particular, sulopenem was found to be more stable to the hydrolysis by various beta-lactamases produced by Gram-negative bacteria than any other antibiotics tested. Vmax/Km values of sulopenem were smaller than those of cefotiam for all tested beta-lactamases, which reflected a broad antibacterial spectrum of sulopenem. 5. E. coli ML4707 exposed to sulopenem and imipenem released less endotoxin than did controls at all concentration ranges tested. In contrast, the strain exposed to ceftazidime at bacteriostatic concentrations released a large amount of endotoxin.

Breaking barriers: expansion of the use of endolysins as novel antibacterials against Gram-negative bacteria.

PubMed

Briers, Yves; Lavigne, Rob

2015-01-01

The emergence and spread of antibiotic-resistant bacteria drives the search for novel classes of antibiotics to replenish our armamentarium against bacterial infections. This is particularly critical for Gram-negative pathogens, which are intrinsically resistant to many existing classes of antibiotics due to the presence of a protective outer membrane. In addition, the antibiotics development pipeline is mainly oriented to Gram-positive pathogens such as methicillin-resistant Staphylococcus aureus. A promising novel class of antibacterials is endolysins. These enzymes encoded by bacterial viruses hydrolyze the peptidoglycan layer with high efficiency, resulting in abrupt osmotic lysis and cell death. Their potential as novel antibacterials to treat Gram-positive bacteria has been extensively demonstrated; however, the Gram-negative outer membrane has presented a formidable barrier for the use of endolysins against Gram-negatives until recently. This review reports on the most recent advances in the development of endolysins to kill Gram-negative species with a special focus on endolysin-engineered Artilysins(®).

Synthesis and antibacterial activity of novel enolphosphate derivatives.

PubMed

Grison, Claude; Barthes, Nicolas; Finance, Chantal; Duval, Raphael E

2010-10-01

A new class of enolphosphates derivatives, the 1-alkenyldiphosphates, was designed and a rapid and efficient synthesis for these compounds was developed. These new molecules showed interesting in vitro antibacterial activities (MIC) against Gram-positive bacteria (Staphylococcus aureus) and Gram-negative pathogens including Pseudomonas aeruginosa and Escherichia coli. 2010 Elsevier Inc. All rights reserved.

Novel cajaninstilbene acid derivatives as antibacterial agents.

PubMed

Geng, Zhi-Zhong; Zhang, Jian-Jun; Lin, Jing; Huang, Mei-Yan; An, Lin-Kun; Zhang, Hong-Bin; Sun, Ping-Hua; Ye, Wen-Cai; Chen, Wei-Min

2015-07-15

Discovery of novel antibacterial agents with new structural scaffolds that combat drug-resistant pathogens is an urgent task. Cajaninstilbene acid, which is isolated from pigeonpea leaves, has shown antibacterial activity. In this study, a series of cajaninstilbene acid derivatives were designed and synthesized. The antibacterial activities of these compounds against gram-negative and gram-positive bacteria, as well as nine strains of methicillin-resistant staphylococcus aureus (MRSA) bacteria are evaluated，and the related structure-activity relationships are discussed. Assays suggest that some of the synthetic cajaninstilbene acid derivatives exhibit potent antibacterial activity against gram-positive bacterial strains and MRSA. Among these compounds, 5b, 5c, 5j and 5k show better antibacterial activity than the positive control compounds. The results of MTT assays illustrate the low cytotoxicity of the active compounds. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

Chemical Composition and Antibacterial Activity of Essential Oil of Cosmos bipinnatus Cav. Leaves from South Africa

PubMed Central

Olajuyigbe, Olufunmiso; Ashafa, Anofi

2014-01-01

The chemical composition of essential oils isolated from the leaves of Cosmos bipinnatus and its antibacterial activity were analyzed by GC-MS and microbroth dilution assay respectively. The essential oil extracted from this plant was predominantly composed of monoterpenes (69.62%) and sesquiterpenes (22.73%). The antibacterial assay showed that the oil had significant inhibitory effects against both Gram-negative and Gram-positive bacteria isolates. The MIC of Gram-positive strains ranged between 0.16 and 0.31 mg/mL while those of Gram-negative bacteria ranged between 0.31 and 0.63 mg/mL. The Gram-positive bacteria were more susceptible to the essential oil than the Gram-negative bacteria. Most of the major components of this oil in other plants have been reported for antimicrobial activities. The antibacterial activity can be attributed to effects of the combination of several components of the oil. The results indicate that the C. bipinnatus might be exploited as natural antibacterial agent and have application in the treatment of several infectious diseases caused by these bacteria. Since this species is endemic to the eastern Free State, the plant could be collected during its bloom and used efficiently in the management of bacterial infections in South Africa. PMID:25587332

Chemical Composition and Antibacterial Activity of Essential Oil of Cosmos bipinnatus Cav. Leaves from South Africa.

PubMed

Olajuyigbe, Olufunmiso; Ashafa, Anofi

2014-01-01

The chemical composition of essential oils isolated from the leaves of Cosmos bipinnatus and its antibacterial activity were analyzed by GC-MS and microbroth dilution assay respectively. The essential oil extracted from this plant was predominantly composed of monoterpenes (69.62%) and sesquiterpenes (22.73%). The antibacterial assay showed that the oil had significant inhibitory effects against both Gram-negative and Gram-positive bacteria isolates. The MIC of Gram-positive strains ranged between 0.16 and 0.31 mg/mL while those of Gram-negative bacteria ranged between 0.31 and 0.63 mg/mL. The Gram-positive bacteria were more susceptible to the essential oil than the Gram-negative bacteria. Most of the major components of this oil in other plants have been reported for antimicrobial activities. The antibacterial activity can be attributed to effects of the combination of several components of the oil. The results indicate that the C. bipinnatus might be exploited as natural antibacterial agent and have application in the treatment of several infectious diseases caused by these bacteria. Since this species is endemic to the eastern Free State, the plant could be collected during its bloom and used efficiently in the management of bacterial infections in South Africa.

Design, synthesis and structure-activity relationship evaluation of novel LpxC inhibitors as Gram-negative antibacterial agents.

PubMed

Ding, Shi; Dai, Rui-Yang; Wang, Wen-Ke; Cao, Qiao; Lan, Le-Fu; Zhou, Xian-Li; Yang, Yu-She

2018-01-15

LpxC inhibitors are new-type antibacterial agents developed in the last twenty years, mainly against Gram-negative bacteria infections. To develop novel LpxC inhibitors with good antibacterial activities and biological metabolism, we summarized the basic skeleton of reported LpxC inhibitors, designed and synthesized several series of compounds and tested their antibacterial activities against Escherichial coli and Pseudomonas aeruginosa in vitro. Structure-activity relationships have been discussed in this article. The metabolism stability of YDL-2, YDL-5, YDL-8, YDL-14, YDL-20-YDL-23 have been evaluated in liver microsomes, which indicated that the 2-amino isopropyl group may be a preferred structure than the 2-hydroxy ethyl group in the design of LpxC inhibitors. Copyright © 2017 Elsevier Ltd. All rights reserved.

Synthesis and study of antibacterial activities of antibacterial glycopeptide antibiotics conjugated with benzoxaboroles.

PubMed

Printsevskaya, S S; Reznikova, M I; Korolev, A M; Lapa, G B; Olsufyeva, E N; Preobrazhenskaya, M N; Plattner, J J; Zhang, Y K

2013-04-01

The ability of boron-containing compounds to undergo a number of novel binding interactions with drug target functional groups has recently been described. In an extension of this work, we have incorporated a boron-containing scaffold, the benzoxaborole, into several glycopeptides antibiotics. The aim of this work is to exploit the inherent reactivity of boron to gain additional interactions with the bacterial cell wall components to improve binding affinity and to thereby overcome resistance. Three antibacterial glycopeptides (vancomycin, eremomycin and teicoplanin aglycone) have been selected for the construction of a series of 12 new benzoxaborole-glycopeptide conjugates. The hybrid antibiotics, in which the benzoxaborole and glycopeptide moieties were separated by a linker, exhibited excellent antibacterial activity against Gram-positive bacteria, including those with intermediate susceptibility to glycopeptides. Some analogs also demonstrated activity against vancomycin-resistant enterococci. Conjugation of antibiotics with benzoxaborole derivatives provides antibiotics with new and useful properties. Teicoplanin aglycone-benzoxaborole derivatives overcome resistance of Gram-positive bacteria to vancomycin.

Antibacterial activity of head-to-head bis-benzimidazoles.

PubMed

Moreira, Joao B; Mann, John; Neidle, Stephen; McHugh, Timothy D; Taylor, Peter W

2013-10-01

Symmetric bis-benzimidazole (BBZ) conjugates were profiled for activity against a range of Gram-positive and Gram-negative bacteria. para-Substituted ethoxy, amino and methoxy derivatives displayed potent bacteriostatic activity against meticillin-resistant Staphylococcus aureus, vancomycin-resistant enterococci, streptococci and Listeria monocytogenes. Moderate to good activity was also found against mycobacteria; two compounds were strongly active against logarithmic phase and hypoxia-induced latent Mycobacterium tuberculosis. No compound displayed significant activity towards Gram-negative bacteria. Only high concentrations of antibacterial BBZs showed cytotoxic effects towards fibroblasts, and the most active compound was well tolerated by zebrafish embryos. Copyright © 2013 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved.

[Post-marketing surveillance of antibacterial activities of cefozopran against various clinical isolates--II. Gram-negative bacteria].

PubMed

Igari, Jun; Oguri, Toyoko; Hiramatsu, Nobuyoshi; Akiyama, Kazumitsu; Koyama, Tsuneo

2003-10-01

As a post-marketing surveillance, the in vitro antibacterial activities of cefozopran (CZOP), an agent of cephems, against various clinical isolates were yearly evaluated and compared with those of other cephems, oxacephems, carbapenems, monobactams, and penicillins. Changes in CZOP susceptibility among bacteria were also evaluated with the bacterial resistance ratio calculated from the breakpoint MIC. Twenty-five species (4,154 strains) of Gram-negative bacteria were isolated from the clinical materials annually collected from 1996 to 2001, and consisted of Moraxella (Branhamella) catarrhalis, Haemophilus influenzae, Escherichia coli, Klebsiella pneumoniae, Klebsiella oxytoca, Enterobacter cloacae, Enterobacter aerogenes, Serratia marcescens, Serratia liquefaciens, Citrobacter freundii, Citrobacter koseri, Proteus mirabilis, Proteus vulgaris, Morganella morganii, Providencia spp., Pseudomonas aeruginosa, Pseudomonas fluorescens, Pseudomonas putida, Acinetobacter baumannii, Acinetobacter Iwoffii, Burkholderia cepacia, Stenotrophomonas maltophilia, Bacteroides fragilis group, and Prevotella/Porphyromonas. CZOP preserved its antibacterial activity against M. (B.) catarrhalis (MIC90: 4 micrograms/mL) and showed comparable activity to carbapenems against H. influenzae (MIC90: 1 microgram/mL). The antibacterial activity of CZOP against E. coli was preferable (MIC90: 0.125 microgram/mL) and comparable to those of cefpirome (CPR), cefepime (CFPM), and imipenem (IPM). The MIC90 of CZOP against K. pneumoniae and K. oxytoca was 1 and 0.25 microgram/mL, respectively. The MIC90 of CZOP against E. cloacae increased during 6 years (32 to 128 micrograms/mL). The antibacterial activity of CZOP against E. aerogenes was preferable (MIC90: 1 microgram/mL). The antibacterial activities of CZOP against S. marcescens and S. liquefaciens were relatively potent (MIC90: 0.5 and 0.25 microgram/mL) and comparable to those of CPR, CFPM, and carumonam. CZOP preserved comparable antibacterial

Antibacterial and cytotoxic activities of the sesquiterpene lactones cnicin and onopordopicrin.

PubMed

Bach, Sandra M; Fortuna, Mario A; Attarian, Rodgoun; de Trimarco, Juliana T; Catalán, César A N; Av-Gay, Yossef; Bach, Horacio

2011-02-01

The antimicrobial and cytotoxic activities of chloroform extracts from the weeds Centaurea tweediei and C. diffusa, and the main sesquiterpene lactones isolated from these species, onopordopicrin and cnicin, respectively, were assayed. Results show that the chloroform extracts from both Centaurea species possess antibacterial activities against a panel of Gram-positive and Gram-negative bacteria. Remarkable antibacterial activity against methicillin-resistant Staphylococcus aureus was also measured. Both the extracts and the purified sesquiterpene lactones show high cytotoxicity against human-derived macrophages. Despite this cytotoxicity, C. diffusa chloroform extract and cnicin are attractive candidates for evaluation as antibiotics in topical preparations against skin-associated pathogens.

In Vitro Antibacterial Activity of Several Plant Extracts and Oils against Some Gram-Negative Bacteria

PubMed Central

Al-Mariri, Ayman; Safi, Mazen

2014-01-01

Background: Medicinal plants are considered new resources for producing agents that could act as alternatives to antibiotics in the treatment of antibiotic-resistant bacteria. The aim of this study was to evaluate the antibacterial activity of 28 plant extracts and oils against four Gram-negative bacterial species. Methods: Experimental, in vitro, evaluation of the activities of 28 plant extracts and oils as well as some antibiotics against E. coli O157:H7, Yersinia enterocolitica O9, Proteus spp., and Klebsiella pneumoniae was performed. The activity against 15 isolates of each bacterium was determined by disc diffusion method at a concentration of 5%. Microdilution susceptibility assay was used in order to determine the minimal inhibitory concentrations (MICs) of the plant extracts, oils, and antibiotics. Results: Among the evaluated herbs, only Origanum syriacum L., Thymus syriacus Boiss., Syzygium aromaticum L., Juniperus foetidissima Wild, Allium sativum L., Myristica fragrans Houtt, and Cinnamomum zeylanicum L. essential oils and Laurus nobilis L. plant extract showed anti-bacterial activity. The MIC50 values of these products against the Gram-negative organisms varied from 1.5 (Proteus spp. and K. pneumoniae( and 6.25 µl/ml (Yersinia enterocolitica O9 ) to 12.5 µl/ml (E. coli O:157). Conclusion: Among the studied essential oils, O. syriacum L., T. syriacus Boiss., C. zeylanicum L., and S. aromaticum L. essential oils were the most effective. Moreover, Cephalosporin and Ciprofloxacin were the most effective antibiotics against almost all the studied bacteria. Therefore, O. syriacum L., T. syriacus Boiss., C. zeylanicum L., and S. aromaticum L. could act as bactericidal agents against Gram-negative bacteria. PMID:24453392

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. Copyright © 2013 Elsevier B.V. All rights reserved.

Size-dependent bacterial growth inhibition and mechanism of antibacterial activity of zinc oxide nanoparticles.

PubMed

Raghupathi, Krishna R; Koodali, Ranjit T; Manna, Adhar C

2011-04-05

The antibacterial properties of zinc oxide nanoparticles were investigated using both gram-positive and gram-negative microorganisms. These studies demonstrate that ZnO nanoparticles have a wide range of antibacterial activities toward various microorganisms that are commonly found in environmental settings. The antibacterial activity of the ZnO nanoparticles was inversely proportional to the size of the nanoparticles in S. aureus. Surprisingly, the antibacterial activity did not require specific UV activation using artificial lamps, rather activation was achieved under ambient lighting conditions. Northern analyses of various reactive oxygen species (ROS) specific genes and confocal microscopy suggest that the antibacterial activity of ZnO nanoparticles might involve both the production of reactive oxygen species and the accumulation of nanoparticles in the cytoplasm or on the outer membranes. Overall, the experimental results suggest that ZnO nanoparticles could be developed as antibacterial agents against a wide range of microorganisms to control and prevent the spreading and persistence of bacterial infections.

Silver enhances antibiotic activity against gram-negative bacteria.

PubMed

Morones-Ramirez, J Ruben; Winkler, Jonathan A; Spina, Catherine S; Collins, James J

2013-06-19

A declining pipeline of clinically useful antibiotics has made it imperative to develop more effective antimicrobial therapies, particularly against difficult-to-treat Gram-negative pathogens. Silver has been used as an antimicrobial since antiquity, yet its mechanism of action remains unclear. We show that silver disrupts multiple bacterial cellular processes, including disulfide bond formation, metabolism, and iron homeostasis. These changes lead to increased production of reactive oxygen species and increased membrane permeability of Gram-negative bacteria that can potentiate the activity of a broad range of antibiotics against Gram-negative bacteria in different metabolic states, as well as restore antibiotic susceptibility to a resistant bacterial strain. We show both in vitro and in a mouse model of urinary tract infection that the ability of silver to induce oxidative stress can be harnessed to potentiate antibiotic activity. Additionally, we demonstrate in vitro and in two different mouse models of peritonitis that silver sensitizes Gram-negative bacteria to the Gram-positive-specific antibiotic vancomycin, thereby expanding the antibacterial spectrum of this drug. Finally, we used silver and antibiotic combinations in vitro to eradicate bacterial persister cells, and show both in vitro and in a mouse biofilm infection model that silver can enhance antibacterial action against bacteria that produce biofilms. This work shows that silver can be used to enhance the action of existing antibiotics against Gram-negative bacteria, thus strengthening the antibiotic arsenal for fighting bacterial infections.

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

Antibacterial activity evaluation of bioactive glass and biphasic calcium phosphate nanopowders mixtures

NASA Astrophysics Data System (ADS)

Nazemi, Zahra; Mehdikhani-Nahrkhalaji, Mehdi; Haghbin-Nazarpak, Masoumeh; Staji, Hamid; Kalani, Mohammad Mehdi

2016-12-01

The aim of this work was to evaluate the antibacterial activity of bioactive glass (BG) and biphasic calcium phosphate (BCP) nanopowders mixtures for the first time. 37S BG and BCP (50% HA-50% β-TCP) nanopowders were prepared via sol-gel technique. Characterization techniques such as X-ray diffraction, scanning electron microscopy, transition electron microscopy, and X-ray fluorescent. The antibacterial activity was studied using Escherichia coli and Salmonella typhi as gram-negative, and Staphylococcus aureus as gram-positive bacteria. The antibacterial effect of BG, BCP nanopowders, and their mixtures was evaluated at different concentrations. The 37S BG nanopowders showed minimum bactericidal concentration at 25 mg/ml. At broth concentrations below 300 mg/ml, BCP showed no antibacterial activity. BCP and BG nanopowders mixture (M2) with 60/40 ratio of BCP/BG showed noticeable antibacterial effect. It was concluded that BCP and 37S BG nanopowders mixture could be used as a good candidate for dental and orthopedic applications.

Comparative antibacterial activity of hexachlorophane in different formulations used for skin disinfection

PubMed Central

Gibson, J. W.

1969-01-01

Two formulations of hexachlorophane have been compared for their antibacterial effects in respect of skin disinfection. It was found that the activity of hexachlorophane is dependent upon its vehicle of formulation. A 2·5% soap gel possesses broad-spectrum bactericidal activity with remarkable speed of kill, whereas a 3% detergent formulation has no bactericidal action against Gram-negative bacteria and only a very slow action against Gram-positive bacteria. In practice the rapid action of the 2·5% soap gel against both Gram-negative and Gram-positive transient skin bacteria can be achieved by correctly applying the preparation directly to the dry hands. It appears that the 2·5% soap gel does not need to rely on mechanical removal of transient organisms as does the 3% detergent. The 2·5% soap gel is more dependable in its action on the resident bacteria than the 3% detergent. It controlled the resident flora in the skin of all subjects tested whereas the latter appeared to be potentiated on the skin of certain individuals only. It has been possible to distinguish between the antibacterial effect on the resident organisms and the mere removal of transient bacteria by mechanical action of the 3% detergent as opposed to antibacterial effect on residents and rapid antibacterial effect on transients by the 2·5% soap gel. PMID:5784696

A Nanocomposite Hydrogel with Potent and Broad-Spectrum Antibacterial Activity.

PubMed

Dai, Tianjiao; Wang, Changping; Wang, Yuqing; Xu, Wei; Hu, Jingjing; Cheng, Yiyun

2018-05-02

Local bacterial infection is a challenging task and still remains a serious threat to human health in clinics. Systemic administration of antibiotics has only short-term antibacterial activity and usually causes adverse effects and bacterial resistance. A bioadhesive hydrogel with broad-spectrum and on-demand antibiotic activity is highly desirable. Here, we designed a pH-responsive nanocomposite hydrogel via a Schiff base linkage between oxidized polysaccharides and cationic dendrimers encapsulated with silver nanoparticles. The antibacterial components, both the cationic dendrimers and silver species, could be released in response to the acidity generated by growing bacteria. The released cationic polymer and silver exhibited a synergistic effect in antibacterial activity, and thus, the nanocomposite hydrogel showed potent antibacterial activity against both Gram-negative ( Escherichia coli and Pseudomonas aeruginosa) and Gram-positive bacteria ( Staphylococcus epidermidis and Staphylococcus aureus). The gel showed superior in vivo antibacterial efficacy against S. aureus infection compared with a commercial silver hydrogel at the same silver concentration. In addition, no obvious hemolytic toxicity, cytotoxicity, and tissue and biochemical toxicity were observed for the antibacterial hydrogel after incubation with cells or implantation. This study provides a facile and promising strategy to develop smart hydrogels to treat local bacterial infections.

Structure-Activity and Lipophilicity Relationships of Selected Antibacterial Natural Flavones and Flavanones of Chilean Flora.

PubMed

Echeverría, Javier; Opazo, Julia; Mendoza, Leonora; Urzúa, Alejandro; Wilkens, Marcela

2017-04-10

In this study, we tested eight naturally-occurring flavonoids-three flavanones and five flavones-for their possible antibacterial properties against four Gram-positive and four Gram-negative bacteria. Flavonoids are known for their antimicrobial properties, and due their structural diversity; these plant-derived compounds are a good model to study potential novel antibacterial mechanisms. The lipophilicity and the interaction of antibacterial compounds with the cell membrane define the success or failure to access its target. Therefore, through the determination of partition coefficients in a non-polar/aqueous phase, lipophilicity estimation and the quantification of the antibacterial activity of different flavonoids, flavanones, and flavones, a relationship between these parameters was assessed. Active flavonoids presented diffusion coefficients between 9.4 × 10 -10 and 12.3 × 10 -10 m²/s and lipophilicity range between 2.0 to 3.3. Active flavonoids against Gram-negative bacteria showed a narrower range of lipophilicity values, compared to active flavonoids against Gram-positive bacteria, which showed a wide range of lipophilicity and cell lysis. Galangin was the most active flavonoid, whose structural features are the presence of two hydroxyl groups located strategically on ring A and the absence of polar groups on ring B. Methylation of one hydroxyl group decreases the activity in 3- O -methylgalangin, and methylation of both hydroxyl groups caused inactivation, as shown for 3,7- O -dimethylgalangin. In conclusion, the amphipathic features of flavonoids play a crucial role in the antibacterial activity. In these compounds, hydrophilic and hydrophobic moieties must be present and could be predicted by lipophilicity analysis.

18β-Glycyrrhetinic Acid Derivatives Possessing a Trihydroxylated A Ring Are Potent Gram-Positive Antibacterial Agents.

PubMed

Huang, Li-Rong; Hao, Xiao-Jiang; Li, Qi-Ji; Wang, Dao-Ping; Zhang, Jian-Xin; Luo, Heng; Yang, Xiao-Sheng

2016-04-22

The oleanane-type triterpene 18β-glycyrrhetinic acid (1) was modified chemically through the introduction of a trihydroxylated A ring and an ester moiety at C-20 to enhance its antibacterial activity. Compounds 22, 23, 25, 28, 29, 31, and 32 showed more potent inhibitory activity against Streptomyces scabies than the positive control, streptomycin. Additionally, the inhibitory activity of the most potent compound, 29, against Bacillus subtilis, Staphylococcus aureus, and methicillin-resistant Staphylococcus aureus was greater than that of the positive controls. The antibacterial mode of action of the active derivatives involved the regulation of the expression of genes associated with peptidoglycans, the respiratory metabolism, and the inherent virulence factors found in bacteria, as determined through a quantitative real-time reverse transcriptase PCR assay.

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.

Screening for fractions of Oxytropis falcata Bunge with antibacterial activity.

PubMed

Jiang, H; Hu, J R; Zhan, W Q; Liu, X

2009-01-01

Preliminary studies with the four extracts of Oxytropis falcate Bunge exhibited that the chloroform and ethyl acetate extracts showed stronger antibacterial activities against the nine tested Gram-positive and Gram-negative bacteria. The HPLC-scanned and bioassay-guided fractionation led to the isolation and identification of the main flavonoid compounds, i.e. rhamnocitrin, kaempferol, rhamnetin, 2',4'-dihydroxychalcone and 2',4',beta-trihydroxy-dihydrochalcon. Except 2',4',beta-trihydroxy-dihydrochalcon, four other compounds had good antibacterial activities. The minimal inhibitory concentrations (MICs) and minimal bactericidal concentrations (MBCs) of the four compounds ranged between 125 and 515 microg mL(-1). Staphylococcus aureus was the most susceptible to these compounds, with MIC and MBC values from 125 to 130 microg mL(-1). This is the first report of antibacterial activity in O. falcate Bunge. In this study, evidence to evaluate the biological functions of O. falcate Bunge is provided, which promote the rational use of this herb.

Report: Studies on antibacterial activity of some traditional medicinal plants used in folk medicine.

PubMed

Israr, Fozia; Hassan, Fouzia; Naqvi, Baqir Shyum; Azhar, Iqbal; Jabeen, Sabahat; Hasan, S M Farid

2012-07-01

Ethanolic extracts of eight medicinal plants commonly used in folk medicine were tested for their antibacterial activity against four Gram positive strains (Bacillus subtilis, Staphylococcus aureus, Staphylococcus epidermidis and, Streptococcus pneumoniae) and six Gram negative strains (Escherichia coli, Proteus vulgaris, Proteus mirabilis. Salmonella typhi para A, Salmonella typhi para B and Shigella dysenteriae) that were obtained from different pathological laboratories located in Karachi, Pakistan. Disc diffusion method was used to analyze antibacterial activity. Out of eight, five medicinal plants showed antibacterial activity against two or more than two microbial species. The most effective antimicrobial plant found to be Punica granatum followed by Curcuma zedoaria Rosc, Grewia asiatica L and Carissa carandas L, Curcuma caesia Roxb respectively. From these results, it is evident that medicinal plants could be used as a potential source of new antibacterial agents.

Potent antibacterial, antioxidant and toxic activities of extracts from Passiflora suberosa L. leaves

PubMed Central

Bandara, Kumudu R.V.; Padumadasa, Chayanika

2018-01-01

Passiflora suberosa L. belonging to the family Passifloraceae is an important medicinal plant used in traditional medicinal system in Sri Lanka to treat diabetes, hypertension and skin diseases. We extracted P. suberosa leaves under reflux conditions using different solvents (hexane, chloroform, methanol and water), then subjected to phytochemical screening. Alkaloids, flavonoids and saponins and saponins and anthraquinones were present in hexane and chloroform extracts. Alkaloids, unsaturated sterols, triterpenes, saponins, flavonoids and tannins were observed in both methanol and aqueous extracts. Proanthocyanidins were observed only in the aqueous extract. Hence, aqueous and methanol extracts with most classes of phytochemicals present were subjected to antimicrobial, antioxidant, antihaemolytic activities and Brine shrimp lethality studies. Antibacterial activity and minimum inhibition concentrations were evaluated using three Gram-positive (Bacillus subtilis, Staphylococcus aureus and Enterococcus faecium) and three Gram-negative bacteria (Pseudumonas aeruginosa, Salmonella typhimuriam and Escherichia coli). The results indicated that only the methanol extract of P. suberosa exhibited antibacterial activities against all the strains of Gram-negative and Gram-positive bacterial with stronger activity against Gram-negative bacteria. DPHH (2,2-diphenyl-1-picrylhydrazy) scavenging assay was adopted to evaluate antioxidant properties while antihaemolytic and toxic activities were studied respectively using cow blood and Brine shrimp lethality assay. The IC50 values of the aqueous extract in both antioxidant and antihaemolytic assays were significantly lower than the standard ascorbic acid. Similar results were observed in the Brine shrimp lethality assay. In conclusion both aqueous and methanol extracts of P. suberosa leaves showed the presence of majority of phytochemicals including proanthocyanidins. Antibacterial activity was obtained only for methanol extract

Antibacterial activity of 2-alkynoic fatty acids against multidrug resistant bacteria

PubMed Central

Sanabria-Ríos, David J.; Rivera-Torres, Yaritza; Maldonado-Domínguez, Gamalier; Domínguez, Idializ; Ríos, Camille; Díaz, Damarith; Rodríguez, José W.; Altieri-Rivera, Joanne S.; Ríos-Olivares, Eddy; Cintrón, Gabriel; Montano, Nashbly; Carballeira, Néstor M.

2014-01-01

The first study aimed at determining the structural characteristics needed to prepare antibacterial 2-alkynoic fatty acids (2-AFAs) was accomplished by synthesizing several 2-AFAs and other analogues in 18-76% overall yields. Among all the compounds tested, the 2-hexadecynoic acid (2-HDA) displayed the best overall antibacterial activity against Gram-positive Staphylococcus aureus (MIC = 15.6 μg/mL), Staphylococcus saprophyticus (MIC = 15.5 μg/mL), and Bacillus cereus (MIC = 31.3 μg/mL), as well as against the Gram-negative Klebsiella pneumoniae (7.8 μg/mL) and Pseudomonas aeruginosa (MIC = 125 μg/mL). In addition, 2-HDA displayed significant antibacterial activity against methicillin-resistant S. aureus (MRSA) ATCC 43300 (MIC = 15.6 μg/mL) and clinical isolates of MRSA (MIC = 3.9 μg/mL). No direct relationship was found between the antibacterial activity of 2-AFAs and their critical micelle concentration (CMC) suggesting that the antibacterial properties of these fatty acids are not mediated by micelle formation. It was demonstrated that the presence of a triple bond at C-2 as well as the carboxylic acid moiety in 2-AFAs are important for their antibacterial activity. 2-HDA has the potential to be further evaluated for use in antibacterial formulations. PMID:24365283

Antibacterial activity of 2-alkynoic fatty acids against multidrug-resistant bacteria.

PubMed

Sanabria-Ríos, David J; Rivera-Torres, Yaritza; Maldonado-Domínguez, Gamalier; Domínguez, Idializ; Ríos, Camille; Díaz, Damarith; Rodríguez, José W; Altieri-Rivera, Joanne S; Ríos-Olivares, Eddy; Cintrón, Gabriel; Montano, Nashbly; Carballeira, Néstor M

2014-02-01

The first study aimed at determining the structural characteristics needed to prepare antibacterial 2-alkynoic fatty acids (2-AFAs) was accomplished by synthesizing several 2-AFAs and other analogs in 18-76% overall yields. Among all the compounds tested, the 2-hexadecynoic acid (2-HDA) displayed the best overall antibacterial activity against Gram-positive Staphylococcus aureus (MIC=15.6 μg/mL), Staphylococcus saprophyticus (MIC=15.5 μg/mL), and Bacillus cereus (MIC=31.3 μg/mL), as well as against the Gram-negative Klebsiella pneumoniae (7.8 μg/mL) and Pseudomonas aeruginosa (MIC=125 μg/mL). In addition, 2-HDA displayed significant antibacterial activity against methicillin-resistant S. aureus (MRSA) ATCC 43300 (MIC=15.6 μg/mL) and clinical isolates of MRSA (MIC=3.9 μg/mL). No direct relationship was found between the antibacterial activity of 2-AFAs and their critical micelle concentration (CMC) suggesting that the antibacterial properties of these fatty acids are not mediated by micelle formation. It was demonstrated that the presence of a triple bond at C-2 and the carboxylic acid moiety in 2-AFAs are important for their antibacterial activity. 2-HDA has the potential to be further evaluated for use in antibacterial formulations. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

1-(2-aminophenyl)-1H-1,2,3-triazole-4-carboxylic acid: activity against Gram-positive and Gram-negative pathogens including Vibrio cholerae

NASA Astrophysics Data System (ADS)

Maji, Krishnendu; Haldar, Debasish

2017-10-01

We report a new synthetic aromatic ε-amino acid containing a triazole moiety with antimicrobial potential against Gram-positive, Gram-negative and pathogenic bacteria including Vibrio cholerae. Structure-property relationship studies revealed that all the functional groups are essential to enhance the antimicrobial activity. The 1-(2-aminophenyl)-1H-1,2,3-triazole-4-carboxylic acid was synthesized by click chemistry. From X-ray crystallography, the amino acid adopts a kink-like structure where the phenyl and triazole rings are perpendicular to each other and the amine and acid groups maintain an angle of 60°. The agar diffusion test shows that the amino acid has significant antibacterial activity. The liquid culture test exhibits that the minimum inhibitory concentration (MIC) value for Bacillus subtilis and Vibrio cholerae is 59.5 µg ml-1. FE-SEM experiments were performed to study the morphological changes of bacterial shape after treatment with compound 1. The antimicrobial activity of the amino acid was further studied by DNA binding and degradation study, protein binding, dye-binding assay and morphological analysis. Moreover, the amino acid does not have any harmful effect on eukaryotes.

Antioxidant Content, Antioxidant Activity, and Antibacterial Activity of Five Plants from the Commelinaceae Family

PubMed Central

Tan, Joash Ban Lee; Yap, Wei Jin; Tan, Shen Yeng; Lim, Yau Yan; Lee, Sui Mae

2014-01-01

Commelinaceae is a family of herbaceous flowering plants with many species used in ethnobotany, particularly in South America. However, thus far reports of their bioactivity are few and far between. The primary aim of this study was to quantify the antioxidant and antibacterial activity of five Commelinaceae methanolic leaf extracts. The antioxidant content was evaluated by the total phenolic content (TPC), total tannin content (TTC), and total flavonoid content (TFC) assays. The antioxidant activities measured were DPPH free radical scavenging (FRS), ferric reducing power (FRP), and ferrous ion chelating (FIC); of the five plants, the methanolic leaf extract of Tradescantia zebrina showed the highest antioxidant content and activity, and exhibited antibacterial activity against six species of Gram-positive and two species of Gram-negative bacteria in a range of 5–10 mg/mL based on the broth microdilution method. PMID:26785239

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. PMID:26733995

Functional synergy of α-helical antimicrobial peptides and traditional antibiotics against Gram-negative and Gram-positive bacteria in vitro and in vivo.

PubMed

Feng, Q; Huang, Y; Chen, M; Li, G; Chen, Y

2015-01-01

In this study, the antimicrobial activities based on the synergistic effects of traditional antibiotics (imipenem, cefepime, levofloxacin hydrochloride and vancomycin) and antimicrobial peptides (AMPs; PL-5, PL-31, PL-32, PL-18, PL-29 and PL-26), alone or in combination, against three Gram-positive bacteria (Staphylococcus aureus, Streptococcus pneumoniae and Staphylococcus epidermidis) and three Gram-negative bacteria (Pseudomonas aeruginosa, Escherichia coli and Klebsiella pneumoniae) were investigated. In addition, the antimicrobial activity that was based on the synergistic effects of levofloxacin hydrochloride and PL-5 against Staphylococcus aureus in vivo was explored in a mouse infection model. Traditional antibiotics and AMPs showed significant synergistic effects on the antibacterial activities against the different Gram-positive and Gram-negative bacteria in vitro. A strong synergistic effect in the PL-5 and levofloxacin hydrochloride combination against Staphylococcus aureus was observed in the mouse infection model in vivo. The mechanism of synergistic action was due to the different targets of AMPs and traditional antibiotics. The combination of AMPs and traditional antibiotics can dramatically enhance antimicrobial activity and may help prevent or delay the emergence of antibiotic resistance. Thus, this combination therapy could be a promising approach to treat bacterial infections, particularly mixed infections and multi-antibiotic-resistant infections, in the clinics.

Phytochemical screening, cytotoxicity and antibacterial activities of two Bangladeshi medicinal plants.

PubMed

Roy, Ajoy; Biswas, Subrata Kumar; Chowdhury, Anusua; Shill, Manik Chandra; Raihan, Sheikh Zahir; Muhit, Md Abdul

2011-10-01

The objectives of the present study were to investigate phytochemical screening and to assay cytotoxicity and antibacterial activities of ethanolic extracts of leaves of two medicinal plants, Aglaonema hookerianum Schott (Family: Araceae) and Lannea grandis Engl. (Family: Anacardiaceae) available in Bangladesh. The brine shrimp lethality bioassay showed that the ethanolic extracts of Aglaonema hookerianum and Lannea grandis possessed cytotoxic activities with LC50 5.25 (microg mL(-1)) and 5.75 (microg mL(-1)) and LC90 10.47 (microg mL(-1)) and 9.55 (microg mL(-1)), respectively. Two extracts obtained from leaves were examined for their antibacterial activities against some gram positive bacteria such as Bacillus subtilis, Bacillus megaterium and Staphylococcus aureus, also gram negative strains of Pseudomonas aeruginosa, Escherichia coli, Shigella dysenteriae, Salmonella typhi, Salmonella paratyphi and Vibrio cholerae. Agar disc diffusion method was applied to observe the antibacterial efficacy of the extracts. Results indicated that both plant extracts (500 microg disc(-1)) displayed antibacterial activity against all of the tested microorganisms. These results were also compared with the zones of inhibition produced by commercially available standard antibiotic, Amoxicillin at concentration of 10 microg disc(-1). Observed antibacterial properties of the ethanolic extract of Aglaonema hookerianum Schott and Lannea grandis Engl. showed that both plants might be useful sources for the development of new potent antibacterial agents.

Comparative activity of ceftobiprole against Gram-positive and Gram-negative isolates from Europe and the Middle East: the CLASS study.

PubMed

Rossolini, Gian M; Dryden, Matthew S; Kozlov, Roman S; Quintana, Alvaro; Flamm, Robert K; Läuffer, Jörg M; Lee, Emma; Morrissey, Ian; CLASS Study Group

2011-01-01

to assess the in vitro activity of ceftobiprole and comparators against a recent collection of Gram-positive and Gram-negative pathogens, in order to detect potential changes in susceptibility patterns, and to evaluate the Etest assay for ceftobiprole susceptibility testing. contemporary Gram-positive and Gram-negative isolates (excluding extended-spectrum β-lactamase-producing isolates) from across Europe and the Middle East were collected, and their susceptibility to ceftobiprole, vancomycin, teicoplanin, linezolid, ceftazidime and cefepime was assessed using the Etest method. Quality testing [using Etest and broth microdilution (BMD)] was conducted at a central reference laboratory. some 5041 Gram-positive and 4026 Gram-negative isolates were included. Against Gram-positive isolates overall, ceftobiprole had the lowest MIC50 (0.5 mg/L), compared with 1 mg/L for its comparators (vancomycin, teicoplanin and linezolid). Against methicillin-resistant Staphylococcus aureus, all four agents had a similar MIC90 (2 mg/L), but ceftobiprole had a 4-fold better MIC90 (0.5 mg/L) against methicillin-susceptible strains. Only 38 Gram-positive isolates were confirmed as ceftobiprole resistant. Among Gram-negative strains, 86.9%, 91.7% and 95.2% were susceptible to ceftobiprole, ceftazidime and cefepime, respectively. Pseudomonas aeruginosa was less susceptible to all three antimicrobials than any other Gram-negative pathogen. There was generally good agreement between local Etest results and those obtained at the reference laboratory (for ceftobiprole: 86.8% with Gram-negatives; and 94.7% with Gram-positives), as well as between results obtained by BMD and Etest methods (for ceftobiprole: 98.2% with Gram-negatives; and 98.4% with Gram-positives). ceftobiprole exhibits in vitro activity against a wide range of Gram-positive and Gram-negative pathogens, including multidrug-resistant strains. No changes in its known susceptibility profile were identified.

Thieno[2,3-d]pyrimidinedione derivatives as antibacterial agents

PubMed Central

Dewal, Mahender B.; Wani, Amit S.; Vidaillac, Celine; Oupicky, David; Rybak, Michael J.

2012-01-01

Several thieno[2,3-d]pyrimidinediones have been synthesized and examined for antibacterial activity against a range of Gram-positive and Gram-negative pathogens. Two compounds displayed potent activity (2–16 mg/L) against multi-drug resistant Gram-positive organisms, including methicillin, vancomycin-intermediate, and vancomycin-resistant Staphylococcus aureus (MRSA, VISA, VRSA) and vancomycin-resistant enterococci (VRE). Only one of these agents possessed moderate activity (16–32 mg/L) against Gram-negative strains. An examination of the cytotoxicity of these agents revealed that they displayed low toxicity (40–50 mg/L) against mammalian cell and very low hemolytic activity (2–7%). Taken together, these studies suggest that thieno[2,3-d]pyrimidinediones are interesting scaffolds for the development of novel Gram-positive antibacterial agents. PMID:22405289

Novel semisynthetic antibiotics from caprazamycins A-G: caprazene derivatives and their antibacterial activity.

PubMed

Takahashi, Yoshiaki; Igarashi, Masayuki; Miyake, Toshiaki; Soutome, Hiromi; Ishikawa, Kanae; Komatsuki, Yasuhiro; Koyama, Yoshiko; Nakagawa, Naoko; Hattori, Seiko; Inoue, Kunio; Doi, Norio; Akamatsu, Yuzuru

2013-03-01

Acidic treatment of a mixture of caprazamycins (CPZs) A-G isolated from a screen of novel antimycobacterial agents gave caprazene, a core structure of CPZs, in high yield. Chemical modification of the resulting caprazene was performed to give its various derivatives. The structure-activity relationships of the caprazene derivatives against several mycobacterial species and pathogenic Gram-positive and Gram-negative bacteria were studied. Although caprazene showed no antibacterial activity, the antibacterial activity was restored for its 1'''-alkylamide, 1'''-anilide and 1'''-ester derivatives. Compounds 4b (CPZEN-45), 4d (CPZEN-48), 4f and 4g (CPZEN-51) exhibited more potent activities against Mycobacterium tuberculosis and M. avium complex strains than CPZ-B. These results suggest that caprazene would be a good precursor from which novel semisynthetic antibacterial antibiotics can be designed for the treatment of mycobacterial diseases such as tuberculosis and M. avium complex infection.

Synthesis, antibacterial and anti-MRSA activity, in vivo toxicity and a structure-activity relationship study of a quinoline thiourea.

PubMed

Dolan, Niamh; Gavin, Declan P; Eshwika, Ahmed; Kavanagh, Kevin; McGinley, John; Stephens, John C

2016-01-15

We report the synthesis, antibacterial evaluation of a series of thiourea-containing compounds. 1-(3,5-Bis(trifluoromethyl)phenyl)-3-((S)-(6-methoxyquinolin-4-yl)-((1S,2S,4S,5R)-5-vinylquinuclidin-2-yl)methyl)thiourea 5, was the most active against a range of Gram-positive and Gram-negative bacteria, and exhibited bacteriostatic activity against methicillin resistant Staphylococcus aureus (MRSA) comparable to that of the well-known antibacterial agent vancomycin. Quinoline thiourea 5 was subjected to a detailed structure-activity relationship study, with 5 and its derivatives evaluated for their bacteriostatic activity against both Gram-negative and Gram-positive bacteria. A number of structural features important for the overall activity of quinoline thiourea 5 have been identified. A selection of compounds, including 5, was also evaluated for their in vivo toxicity using the larvae of the Greater wax moth, Galleria mellonella. Compound 5, and a number of derivatives, were found to be non-toxic to the larvae of Galleria mellonella. A new class of antibiotic can result from the further development of this family of compounds. Copyright © 2015 Elsevier Ltd. All rights reserved.

Antibacterial assay-guided isolation of active compounds from Artocarpus heterophyllus heartwoods.

PubMed

Septama, Abdi Wira; Panichayupakaranant, Pharkphoom

2015-01-01

Preparations from Artocarpus heterophyllus Lam. (Moraceae) heartwoods are used in the traditional folk medicine for the treatment of inflammation, malarial fever, and to prevent bacterial and fungal infections. The objective of this study was to isolate pure antibacterial compounds from A. heterophyllus heartwoods. The dried and powdered A. heterophyllus heartwoods were successively extracted with the following solvents: hexane, ethyl acetate, and methanol. Each of the extracts was screened for their antibacterial activities using a disc diffusion method (10 mg/disc). Their minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) were determined using a broth microdilution method. The extract that showed the strongest antibacterial activities was fractionated to isolate the active compounds by an antibacterial assay-guided isolation process. The ethyl acetate extract exhibited the strongest antibacterial activities against Streptococcus mutans, S. pyogenes, and Bacillus subtilis with MIC values of 78, 39, and 9.8 µg/mL, respectively. Based on an antibacterial assay-guided isolation, four antibacterial compounds: cycloartocarpin (1), artocarpin (2), artocarpanone (3), and cyanomaclurin (4) were purified. Among these isolated compounds, artocarpin exhibited the strongest antibacterial activity against Gram-positive bacteria, including S. mutans, S. pyogenes, B. subtilis, Staphylococcus aureus, and S. epidermidis with MICs of 4.4, 4.4, 17.8, 8.9, and 8.9 µM, respectively, and MBCs of 8.9, 8.9, 17.8, 8.9, and 8.9 µM, respectively, while artocarpanone showed the strongest activity against Escherichia coli, a Gram-negative bacteria with MIC and MBC values of 12.9 and 25.8 µM, respectively. Only artocarpin showed inhibitory activity against Pseudomonas aeruginosa with an MIC of 286.4 µM.

Gold(I) NHC Complexes: Antiproliferative Activity, Cellular Uptake, Inhibition of Mammalian and Bacterial Thioredoxin Reductases, and Gram-Positive Directed Antibacterial Effects.

PubMed

Schmidt, Claudia; Karge, Bianka; Misgeld, Rainer; Prokop, Aram; Franke, Raimo; Brönstrup, Mark; Ott, Ingo

2017-02-03

Gold complexes with N-heterocyclic carbene (NHC) ligands represent a promising class of metallodrugs for the treatment of cancer or infectious diseases. In this report, the synthesis and the biological evaluation of halogen-containing NHC-Au I -Cl complexes are described. The complexes 1 and 5 a-5 f displayed good cytotoxic activity against tumor cells, and cellular uptake studies suggested that an intact Au-NHC fragment is essential for the accumulation of high amounts of both the metal and the NHC ligand. However, the bioavailability was negatively affected by serum components of the cell culture media and was influenced by likely transformations of the complex. One example (5 d) efficiently induced apoptosis in vincristine- and daunorubicin-resistant P-glycoprotein overexpressing Nalm-6 leukemia cells. Cellular uptake studies with this compound showed that both the wild-type and resistant Nalm-6 cells accumulated comparable amounts of gold, indicating that the gold drug was not excreted by P-glycoprotein or other efflux transporters. The effective inhibition of mammalian and bacterial thioredoxin reductases (TrxR) was confirmed for all of the gold complexes. Antibacterial screening of the gold complexes showed a particularly high activity against Gram-positive strains, reflecting their high dependence on an intact Trx/TrxR system. This result is of particular interest as the inhibition of bacterial TrxR represents a relatively little explored mechanism of new anti-infectives. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

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.

Synthesis and in vitro antibacterial activity of oxazolidine LBM-415 analogs as peptide deformylase inhibitors.

PubMed

Yu, Linliang; Zhou, Weicheng; Wang, Zhenyu

2011-03-01

The drug resistant bacteria pose a severe threat to human health. The increasing resistance of those pathogens to traditional antibacterial therapy renders the identification of new antibacterial agents with novel antibacterial mechanisms an urgent need. In this study, a series of (2S)-N-substituted-1-[(formyhydroxyamino)methyl]-1-oxohexyl]-2-oxazolidinecarboxamides were designed, synthesized and evaluated for in vitro antibacterial activity. Most of these compounds displayed good activities against Gram-positive organisms comparable to reference agent LBM-415. Crown Copyright © 2010. Published by Elsevier Ltd. All rights reserved.

Traditional medicine in north Côte-d'Ivoire: screening of 50 medicinal plants for antibacterial activity.

PubMed

Koné, W M; Atindehou, K Kamanzi; Terreaux, C; Hostettmann, K; Traoré, D; Dosso, M

2004-07-01

Sixty-seven crude ethanol extracts from 50 plants (31 families), which are used in North Côte-d'Ivoire as traditional remedies for bacterial diseases, were screened for in vitro activity against Gram negative (Escherichia coli and Pseudomonas aeruginosa) and Gram positive (Staphylococcus aureus, Enterococcus faecalis, Streptococcus pyogenes and Bacillus subtilis) bacteria. Thirty-one extracts showed antibacterial activity only on Gram positive bacteria. Of these, 10 extracts from 10 plant species had a promising level of activity against bacteria including strains resistant to antibiotics such as aminosides, penicillin M, macrolides, lincosamide and streptrogramin B. The most active was Erythrina senegalensis DC (Fabaceae) followed by Bobgunnia madagascariensis (Desv.) J.H. Kirkbr. & Wiersema (Caesalpinaceae), Waltheria lanceolata R. Br. ex Mast. (Sterculiaceae), Uapaca togoensis Pax. (Euphorbiaceae), Ximenia americana L. (Olacaceae), Khaya senegalensis (Ders.) A. Juss. (Meliaceae), Lannea acida A. Rich. (Anacardiaceae), Cissus populnea Guill. & Perr. (Vitaceae), Keetia hispida (Benth.) Bridson (Rubiaceae) and Ficus thonningii (Miq.) A. Rich. (Moraceae). This is the first report of the antibacterial potency of these 10 plant species on a range of bacteria. The results provided evidence that some of the studied plants might indeed be potential sources of new antibacterial agents, also against some antibiotic-resistant strains.

Synthesis and antibacterial activity of 5-methylphenanthridium derivatives as FtsZ inhibitors.

PubMed

Liu, Fang; Venter, Henrietta; Bi, Fangchao; Semple, Susan J; Liu, Jingru; Jin, Chaobin; Ma, Shutao

2017-08-01

5-Methylphenanthridium derivatives were designed, synthesized and evaluated for their in vitro antibacterial activity and cell division inhibitory activity against various Gram-positive and -negative bacteria. Among them, compounds 5A2, 5B1, 5B2, 5B3, 5C1 and 5C2 displayed the best on-target antibacterial activity with an MIC value of 4µg/mL against B. subtilis ATCC9372 and S. pyogenes PS, showing over 2-fold better activity than sanguinarine. The SARs showed that the 5-methylphenanthridium derivatives with the alkyl side chains at the 2-postion, especially the straight alkyl side chains exerted better on-target antibacterial activity. Copyright © 2017 Elsevier Ltd. All rights reserved.

Isolation, morphological identification and in vitro antibacterial activity of endophytic bacteria isolated from Azadirachta indica (neem) leaves

PubMed Central

Singh, Ankit Kumar; Sharma, Rajesh Kumar; Sharma, Varsha; Singh, Tanmay; Kumar, Rajesh; Kumari, Dimple

2017-01-01

Aim: The objective of this study was to isolate endophytic bacteria from Azadirachta indica (neem) leaves, their identification and investigate their antibacterial activity against three Gram-positive bacteria, Staphylococcus aureus, Streptococcus pyogenes and Bacillus cereus and Gram-negative bacteria Escherichia coli, Salmonella Typhimurium and Klebsiella pneumoniae. Materials and Methods: Fresh leaves of A. indica (neem) was procured from the Department of Botany, JNKVV, Jabalpur. Five samples were taken, and each sample was divided into five subsamples and separated for further isolation of endophytic bacteria. For sterilization leaves were treated with double distilled water, 0.1% sodium hypochlorite, 0.01% bavistin, 0.05% and 70% ethanol. Sterilized leaves of the plants were embedded in Kings B (KB) petri plates and incubated at 37°C for 24 h. Characterization of the bacteria was done according to its morphology and by Gram-staining. After that, a single colony was transferred into brain heart infusion (BHI) broth and incubated at 37°C for 24 h. The antibacterial effect was studied by the disk diffusion method with known antibiotic ciprofloxacin (Ci) as standard. Results: A total of 25 bacterial isolates from A. indica (neem) were obtained and identified morphologically. Most of the samples on KB media depicted irregular shape, flat elevation, undulated, rough, opaque, and white in color. Most of the samples on blood agar showed irregular, raise elevation, undulated, smooth, opaque and all the isolates were nonhemolytic and nonchromogenic. The growth of endophytic bacteria in BHI broth were all isolates showed turbidity. The microscopic examination revealed that maximum isolates were Gram-positive and rod shaped. Good antibacterial activity was observed against S. aureus, Streptococcus pyogenes, E. coli, Salmonella Typhimurium, and K. pneumoniae. Conclusions: Endophytic bacteria are present in leaves of A. indica (neem) and it possesses antibacterial

Antibacterial activity of antipsychotic agents, their association with lipid nanocapsules and its impact on the properties of the nanocarriers and on antibacterial activity.

PubMed

Nehme, Hassan; Saulnier, Patrick; Ramadan, Alyaa A; Cassisa, Viviane; Guillet, Catherine; Eveillard, Matthieu; Umerska, Anita

2018-01-01

Bacterial antibiotic resistance is an emerging public health problem worldwide; therefore, new therapeutic strategies are needed. Many studies have described antipsychotic compounds that present antibacterial activity. Hence, the aims of this study were to evaluate the in vitro antibacterial activity of antipsychotics belonging to different chemical families, to assess the influence of their association with lipid nanocapsules (LNCs) on their antimicrobial activity as well as drug release and to study the uptake of LNCs by bacterial cells. Antibacterial activity was evaluated against Gram-positive Staphylococcus aureus and Gram negative Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae and Acinetobacter baumannii by minimum inhibitory concentration (MIC) assay, and the capability of killing tested microorganisms was evaluated by time kill assay. LNCs were prepared by phase inversion method, and the antipsychotic agents were incorporated using pre-loading and post-loading strategies. Only phenothiazines and thioxanthenes showed antibacterial activity, which was independent of antibiotic-resistance patterns. Loading the nanocarriers with the drugs affected the properties of the former, particularly their zeta potential. The release rate depended on the drug and its concentration-a maximum of released drug of less than 40% over 24 hours was observed for promazine. The influence of the drug associations on the antibacterial properties was concentration-dependent since, at low concentrations (high nanocarrier/drug ratio), the activity was lost, probably due to the high affinity of the drug to nanocarriers and slow release rate, whereas at higher concentrations, the activity was well maintained for the majority of the drugs. Chlorpromazine and thioridazine increased the uptake of the LNCs by bacteria compared with blank LNCs, even below the minimum inhibitory concentration.

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

New Potent Membrane-Targeting Antibacterial Peptides from Viral Capsid Proteins

PubMed Central

Dias, Susana A.; Freire, João M.; Pérez-Peinado, Clara; Domingues, Marco M.; Gaspar, Diana; Vale, Nuno; Gomes, Paula; Andreu, David; Henriques, Sónia T.; Castanho, Miguel A. R. B.; Veiga, Ana S.

2017-01-01

The increasing prevalence of multidrug-resistant bacteria urges the development of new antibacterial agents. With a broad spectrum activity, antimicrobial peptides have been considered potential antibacterial drug leads. Using bioinformatic tools we have previously shown that viral structural proteins are a rich source for new bioactive peptide sequences, namely antimicrobial and cell-penetrating peptides. Here, we test the efficacy and mechanism of action of the most promising peptides among those previously identified against both Gram-positive and Gram-negative bacteria. Two cell-penetrating peptides, vCPP 0769 and vCPP 2319, have high antibacterial activity against Staphylococcus aureus, MRSA, Escherichia coli, and Pseudomonas aeruginosa, being thus multifunctional. The antibacterial mechanism of action of the two most active viral protein-derived peptides, vAMP 059 and vCPP 2319, was studied in detail. Both peptides act on both Gram-positive S. aureus and Gram-negative P. aeruginosa, with bacterial cell death occurring within minutes. Also, these peptides cause bacterial membrane permeabilization and damage of the bacterial envelope of P. aeruginosa cells. Overall, the results show that structural viral proteins are an abundant source for membrane-active peptides sequences with strong antibacterial properties. PMID:28522994

Antibacterial Activity of Mother Tinctures of Cholistan Desert Plants in Pakistan

PubMed Central

Ahmad, M.; Ghafoor, Nazia; Aamir, M. N.

2012-01-01

The mother tinctures of desert were screened for antibacterial activity against bacterial strains of Gram-positive and Gram-negative bacteria. Mother tinctures were prepared by maceration process and antibacterial activity of different plants was evaluated and compared by measuring their zones of inhibition. The results indicated that Boerrhavia diffusa mother tincture had excellent activity only against Escherichia coli. Mother tincture of Chorozophora plicata showed highly effective results against Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa whereas Echinops echinatus mother tincture showed highly effectiveness only against Salmonella typhi. Heliotropium europaeum mother tincture exhibited highly effective results against Bacillus subtilis in all concentrations. Tamrix aphylla presented maximum activity only against Bacillus subtilis in all three concentrations. Among the selected species Heliotropium europaeum, Chorozophora plicata and Tamrix aphylla were more effective plants against many microorganisms. However, Boerrhavia diffusa and Echinops echinatus were less effective plants against tested pathogenic bacteria. PMID:23716878

Antioxidant, antibacterial, and anti-inflammatory activities of standardized brazilin-rich Caesalpinia sappan extract.

PubMed

Nirmal, Nilesh Prakash; Panichayupakaranant, Pharkphoom

2015-01-01

Brazilin is a major active principle of Caesalpinia sappan L. (Leguminosae or Fabaceae). For industry aspects, brazilin-rich extract (BRE) has been prepared and standardized to contain 39% w/w brazilin. BRE may have more advantages than brazilin in term of a lower-cost production process. To investigate the antioxidant, antibacterial, and anti-inflammatory activities of BRE. BRE was prepared by a simple one-step purification of the crude ethanol extract of C. sappan heartwood (CSE) using a Diaion® HP-20 column. The antioxidant activities were determined using three methods, including DPPH radical scavenging, reducing power, and β-carotene bleaching assays, at concentration ranges of 1-10, 10-100, and 10-100 µg/mL, respectively. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of BRE (15.6-1000 µg/mL) against Gram-positive and Gram-negative bacteria were determined by the broth microdilution method. Anti-inflammatory activity of BRE (0.1-5 µg/mL) was evaluated as anti-denaturation activity using bovine serum albumin as a substrate. On the basis of β-carotene bleaching assay, BRE showed antioxidant activity with an EC50 value of 60.5 µg/mL, which was almost equal to that of pure brazilin (52.1 µg/mL). Gram-positive bacteria were more sensitive to all tested samples than Gram-negative bacteria. BRE possessed higher antibacterial activities than CSE, but lower than brazilin. MIC/MBC values of 62.5-125/125 and 250-500/250-500 µg/mL were obtained for BRE against Gram-positive and Gram-negative bacteria, respectively. A low concentration (0.1 µg/mL) of brazilin, BRE, and CSE showed anti-inflammatory activity by inhibiting protein denaturation up to 46.8, 54.1, and 61.9%, respectively.

In vitro and bactericidal activities of ABT-492, a novel fluoroquinolone, against Gram-positive and Gram-negative organisms.

PubMed

Almer, Laurel S; Hoffrage, Jennifer B; Keller, Erika L; Flamm, Robert K; Shortridge, Virginia D

2004-07-01

In vitro activities of ABT-492, ciprofloxacin, levofloxacin, trovafloxacin, moxifloxacin, gatifloxacin, and gemifloxacin were compared. ABT-492 was more potent against quinolone-susceptible and -resistant gram-positive organisms, had activity similar to that of ciprofloxacin against certain members of the family Enterobacteriaceae, and had comparable activity against quinolone-susceptible, nonfermentative, gram-negative organisms. Bactericidal activity of ABT-492 was also evaluated.

In Vitro and Bactericidal Activities of ABT-492, a Novel Fluoroquinolone, against Gram-Positive and Gram-Negative Organisms

PubMed Central

Almer, Laurel S.; Hoffrage, Jennifer B.; Keller, Erika L.; Flamm, Robert K.; Shortridge, Virginia D.

2004-01-01

In vitro activities of ABT-492, ciprofloxacin, levofloxacin, trovafloxacin, moxifloxacin, gatifloxacin, and gemifloxacin were compared. ABT-492 was more potent against quinolone-susceptible and -resistant gram-positive organisms, had activity similar to that of ciprofloxacin against certain members of the family Enterobacteriaceae, and had comparable activity against quinolone-susceptible, nonfermentative, gram-negative organisms. Bactericidal activity of ABT-492 was also evaluated. PMID:15215148

Oligomerization of esculin improves its antibacterial activity and modulates antibiotic resistance.

PubMed

Mokdad-Bzeouich, Imen; Mustapha, Nadia; Chaabane, Fadwa; Ghedira, Zied; Ghedira, Kamel; Ghoul, Mohamed; Chebil, Latifa; Chekir-Ghedira, Leila

2015-03-01

In this particular study, the antibacterial activity of esculin and oligomer fractions was assessed. MIC values of esculin and its oligomer fractions as well as of some antibiotics against Gram-positive and Gram-negative strains and against Escherichia coli multiresistant variants were determined by the standard broth microdilution method. Both esculin and oligoesculin fractions exhibited antibacterial effect against reference strains; Staphylococcus aureus, Enterococcus faecalis, Salmonella enteritidis and Salmonella typhimurium. It appears that E3 oligomer fraction had the greatest antibacterial activity against these reference strains. Besides, as E2 and E3 revealed the best antibacterial effect against multiresistant variants of E. coli, we decided to test the effect of each, combined to the antibiotic against which the variants were resistant. In the interaction study, E2 and E3 oligoesculin fractions were found to be effective in reducing the resistance of E. coli 6574 to ofloxacin and the resistance of E. coli 6228 to amoxicillin. Only E3 oligoesculin fraction showed a synergetic interaction with amoxicillin and tetracyclin against E. coli 6708, but no interaction was found either with E2 or E3 fractions against E. coli 6234. Our study allowed us to conclude that oligomerization of esculin increases its antibacterial potential, according to the degree of polymerization.

Antibacterial and Antioxidant Activities of Novel Actinobacteria Strain Isolated from Gulf of Khambhat, Gujarat.

PubMed

Dholakiya, Riddhi N; Kumar, Raghawendra; Mishra, Avinash; Mody, Kalpana H; Jha, Bhavanath

2017-01-01

Bacterial secondary metabolites possess a wide range of biologically active compounds including antibacterial and antioxidants. In this study, a Gram-positive novel marine Actinobacteria was isolated from sea sediment which showed 84% 16S rRNA gene sequence (KT588655) similarity with Streptomyces variabilis (EU841661) and designated as Streptomyces variabilis RD-5. The genus Streptomyces is considered as a promising source of bioactive secondary metabolites. The isolated novel bacterial strain was characterized by antibacterial characteristics and antioxidant activities. The BIOLOG based analysis suggested that S. variabilis RD-5 utilized a wide range of substrates compared to the reference strain. The result is further supported by statistical analysis such as AWCD (average well color development), heat-map and PCA (principal component analysis). The whole cell fatty acid profiling showed the dominance of iso/anteiso branched C15-C17 long chain fatty acids. The identified strain S. variabilis RD-5 exhibited a broad spectrum of antibacterial activities for the Gram-negative bacteria ( Escherichia coli NCIM 2065, Shigella boydii NCIM, Klebsiella pneumoniae, Enterobacter cloacae, Pseudomonas sp. NCIM 2200 and Salmonella enteritidis NCIM), and Gram-positive bacteria ( Bacillus subtilis NCIM 2920 and Staphylococcus aureus MTCC 96). Extract of S. variabilis strain RD-5 showed 82.86 and 89% of 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging and metal chelating activity, respectively, at 5.0 mg/mL. While H 2 O 2 scavenging activity was 74.5% at 0.05 mg/mL concentration. Furthermore, polyketide synthases (PKSs types I and II), an enzyme complex that produces polyketides, the encoding gene(s) detected in the strain RD-5 which may probably involve for the synthesis of antibacterial compound(s). In conclusion, a novel bacterial strain of Actinobacteria , isolated from the unexplored sea sediment of Alang, Gulf of Khambhat (Gujarat), India showed promising

Antibacterial and Antioxidant Activities of Novel Actinobacteria Strain Isolated from Gulf of Khambhat, Gujarat

PubMed Central

Dholakiya, Riddhi N.; Kumar, Raghawendra; Mishra, Avinash; Mody, Kalpana H.; Jha, Bhavanath

2017-01-01

Bacterial secondary metabolites possess a wide range of biologically active compounds including antibacterial and antioxidants. In this study, a Gram-positive novel marine Actinobacteria was isolated from sea sediment which showed 84% 16S rRNA gene sequence (KT588655) similarity with Streptomyces variabilis (EU841661) and designated as Streptomyces variabilis RD-5. The genus Streptomyces is considered as a promising source of bioactive secondary metabolites. The isolated novel bacterial strain was characterized by antibacterial characteristics and antioxidant activities. The BIOLOG based analysis suggested that S. variabilis RD-5 utilized a wide range of substrates compared to the reference strain. The result is further supported by statistical analysis such as AWCD (average well color development), heat-map and PCA (principal component analysis). The whole cell fatty acid profiling showed the dominance of iso/anteiso branched C15–C17 long chain fatty acids. The identified strain S. variabilis RD-5 exhibited a broad spectrum of antibacterial activities for the Gram-negative bacteria (Escherichia coli NCIM 2065, Shigella boydii NCIM, Klebsiella pneumoniae, Enterobacter cloacae, Pseudomonas sp. NCIM 2200 and Salmonella enteritidis NCIM), and Gram-positive bacteria (Bacillus subtilis NCIM 2920 and Staphylococcus aureus MTCC 96). Extract of S. variabilis strain RD-5 showed 82.86 and 89% of 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging and metal chelating activity, respectively, at 5.0 mg/mL. While H2O2 scavenging activity was 74.5% at 0.05 mg/mL concentration. Furthermore, polyketide synthases (PKSs types I and II), an enzyme complex that produces polyketides, the encoding gene(s) detected in the strain RD-5 which may probably involve for the synthesis of antibacterial compound(s). In conclusion, a novel bacterial strain of Actinobacteria, isolated from the unexplored sea sediment of Alang, Gulf of Khambhat (Gujarat), India showed promising

Antibacterial metabolites synthesized by psychrotrophic bacteria isolated from cold-freshwater environments.

PubMed

Barros, Javier; Becerra, José; González, Carlos; Martínez, Miguel

2013-03-01

The ability of three psychrotrophic Gram-negative bacilli isolated from Chilean Patagonian cold freshwater rivers to produce bioactive metabolites was evaluated. The strains were isolated from cold waters rivers and identified by their biochemical properties and 16S rRNA gene analysis. The metabolites fractions showing antibacterial activity were obtained by solvent extraction and partially characterized by gas-mass chromatography (GC-MS). Antibacterial activity of the fractions was evaluated by an agar-well diffusion test upon 14 bacterial strains, both Gram positive and Gram negative. Thermal and proteolytic resistances of the antibacterial metabolites fractions were also evaluated. Molecular analysis allows the identification of the three Patagonian strains as Pseudomonas sp. RG-6 (Pseudomonas brenneri 99.6 % identity), Pseudomonas sp. RG-8 (Pseudomonas trivialis 99.6 % identity) and Yersinia sp. RP-3 (Yersinia aldovae 99.5 % identity). These extracts were able to inhibit both Gram-positive and Gram-negative bacteria but not Listeria monocytogenes. The antibacterial activity of the filtrated supernatants was lost at temperatures ≥60 °C, and was not affected by proteinase K treatment. The chemical structure of the active molecule remains to be elucidated, although the GC-MS analysis of the filtrates suggests that compounds like sesquiterpenes derivatives from β-maaliene or δ-selinene could be responsible of this antibacterial activity. Pristine cold freshwater streams showed to be interesting sources of metabolites-producing microorganisms with antibacterial activity.

Chemical composition and antibacterial activity of propolis collected by three different races of honeybees in the same region.

PubMed

Silici, Sibel; Kutluca, Semiramis

2005-05-13

The chemical analysis and antibacterial activity of three types of propolis collected three different races of Apis mellifera bee in the same apiary were investigated. Propolis samples were investigated by GC/MS, 48 compounds were identified 32 being new for propolis. The compounds identified indicated that the main plant sources of propolis were Populus alba, Populus tremuloides and Salix alba. The antimicrobial activity against Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and Candida albicans was evaluated. Ethanolic extracts of propolis samples showed high antibacterial activity against Gram-positive cocci (Staphylococcus aureus), but had a weak activity against Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa) and yeast (Candida albicans). Propolis sample collected by Apis mellifera caucasica showed a higher antibacterial activity than collected by Apis mellifera anatolica and Apis mellifera carnica.

Biosynthesis of silver nanoparticles using citrus sinensis peel extract and its antibacterial activity.

PubMed

Kaviya, S; Santhanalakshmi, J; Viswanathan, B; Muthumary, J; Srinivasan, K

2011-08-01

Biosynthesis of silver nanoparticles (AgNPs) was achieved by a novel, simple green chemistry procedure using citrus sinensis peel extract as a reducing and a capping agent. The effect of temperature on the synthesis of silver nanoparticles was carried out at room temperature (25°C) and 60°C. The successful formation of silver nanoparticles has been confirmed by UV-vis, FTIR, XRD, EDAX, FESEM and TEM analysis and their antibacterial activity against Escherichia coli, Pseudomonas aeruginosa (gram-negative), and Staphylococcus aureus (gram-positive) has been studied. The results suggest that the synthesized AgNPs act as an effective antibacterial agent. Copyright © 2011 Elsevier B.V. All rights reserved.

Evaluation of ceftobiprole activity against a variety of gram-negative pathogens, including Escherichia coli, Haemophilus influenzae (β-lactamase positive and β-lactamase negative), and Klebsiella pneumoniae, in a rabbit meningitis model.

PubMed

Stucki, A; Cottagnoud, M; Acosta, F; Egerman, U; Läuffer, J; Cottagnoud, P

2012-02-01

Ceftobiprole medocaril, a new cephalosporin, is highly active against a broad spectrum of Gram-positive and Gram-negative clinical pathogens, including methicillin-resistant Staphylococcus aureus (MRSA) and penicillin-resistant pneumococci. In this study, we tested ceftobiprole against various Gram-negative pathogens in a rabbit meningitis model and determined its penetration into the cerebrospinal fluid (CSF). In this animal model, ceftobiprole produced an antibacterial activity similar to that of cefepime against an Escherichia coli strain, a Klebsiella pneumoniae strain, and a β-lactamase-negative Haemophilus influenzae strain. Against a β-lactamase-positive H. influenzae strain, ceftobiprole was significantly superior. The penetration of ceftobiprole through inflamed meninges reached about 16% of serum levels compared to about 2% of serum levels through uninflamed meninges.

Evaluation of Ceftobiprole Activity against a Variety of Gram-Negative Pathogens, Including Escherichia coli, Haemophilus influenzae (β-Lactamase Positive and β-Lactamase Negative), and Klebsiella pneumoniae, in a Rabbit Meningitis Model

PubMed Central

Stucki, A.; Cottagnoud, M.; Acosta, F.; Egerman, U.; Läuffer, J.

2012-01-01

Ceftobiprole medocaril, a new cephalosporin, is highly active against a broad spectrum of Gram-positive and Gram-negative clinical pathogens, including methicillin-resistant Staphylococcus aureus (MRSA) and penicillin-resistant pneumococci. In this study, we tested ceftobiprole against various Gram-negative pathogens in a rabbit meningitis model and determined its penetration into the cerebrospinal fluid (CSF). In this animal model, ceftobiprole produced an antibacterial activity similar to that of cefepime against an Escherichia coli strain, a Klebsiella pneumoniae strain, and a β-lactamase-negative Haemophilus influenzae strain. Against a β-lactamase-positive H. influenzae strain, ceftobiprole was significantly superior. The penetration of ceftobiprole through inflamed meninges reached about 16% of serum levels compared to about 2% of serum levels through uninflamed meninges. PMID:22064544

In vitro study of antibacterial activity of the alga Sargassum oligocystum from the Persian Gulf.

PubMed

Tajbakhsh, S; Pouyan, M; Zandi, K; Bahramian, P; Sartavi, K; Fouladvand, M; Asayesh, G; Barazesh, A

2011-03-01

With due attention to the development of drug-resistant bacteria, discovering of new antibacterial compounds is needed. Algae produce numerous bioactive substances which may have pharmacological properties such as antibacterial activity. The objective of this investigation was to in vitro study of antibacterial activity of brown alga Sargassum oligocystum collected along the Bushehr coast of Persian Gulf (south west of Iran). Hot water extract, cold water extract, and hot glycerin extract were prepared. The effect of the extracts were investigated on Staphylococcus aureus (ATCC 25923), Staphylococcus epidermidis (ATCC 14990), Pseudomonas aeruginosa (ATCC 27853), and Escherichia coli (ATCC 25922). Hot water extract exhibited antibacterial activity against Staphylococcus aureus, Staphylococcus epidermidis, and Pseudomonas aeruginosa. Cold water extract and hot glycerin extract did not show antibacterial activity on any of the four test bacteria. The minimum inhibitory concentration (MIC) of hot water extract for both Staphylococcus aureus and Staphylococcus epidermidis was 3.175 mg/ml. However, the MIC of this extract for Pseudomonas aeruginosa was 9.556 mg/ml. In this study gram-positive bacteria were more susceptible to hot water extract than gram-negative bacteria. Extract of Sargassum oligocystum could be a candidate for purification and further in vivo studies.

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

Preparation, characterization, and antibacterial activity studies of silver-loaded poly(styrene-co-acrylic acid) nanocomposites.

PubMed

Song, Cunfeng; Chang, Ying; Cheng, Ling; Xu, Yiting; Chen, Xiaoling; Zhang, Long; Zhong, Lina; Dai, Lizong

2014-03-01

A simple method for preparing a new type of stable antibacterial agent was presented. Monodisperse poly(styrene-co-acrylic acid) (PSA) nanospheres, serving as matrices, were synthesized via soap-free emulsion polymerization. Field-emission scanning electron microscopy micrographs indicated that PSA nanospheres have interesting surface microstructures and well-controlled particle size distributions. Silver-loaded poly(styrene-co-acrylic acid) (PSA/Ag-NPs) nanocomposites were prepared in situ through interfacial reduction of silver nitrate with sodium borohydride, and further characterized by transmission electron microscopy and X-ray diffraction. Their effects on antibacterial activity including inhibition zone, minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and bactericidal kinetics were evaluated. In the tests, PSA/Ag-NPs nanocomposites showed excellent antibacterial activity against both gram-positive Staphylococcus aureus and gram-negative Escherichia coli. These nanocomposites are considered to have potential application in antibacterial coatings on biomedical devices to reduce nosocomial infection rates. Copyright © 2013 Elsevier B.V. All rights reserved.

Antibacterial and antifungal activities of some Mexican medicinal plants.

PubMed

Ruiz-Bustos, E; Velazquez, C; Garibay-Escobar, A; García, Z; Plascencia-Jatomea, M; Cortez-Rocha, M O; Hernandez-Martínez, J; Robles-Zepeda, R E

2009-12-01

In Mexico about 4,000 plant species have some medicinal use. The aim of this work was to evaluate the antimicrobial activity of six Mexican medicinal plants against fungi and Gram-positive and Gram-negative bacteria. Methanolic extracts were prepared from the Mexican medicinal plants Amphypteringium adstrigens, Castella tortuosa, Coutarea latiflora, Ibervillea sonorae, Jatropha cuneata, and Selaginella lepidophylla. The antibacterial and antifungal activities of the plants were determined by the broth microdilution method and the radial growth inhibition assay, respectively. All Mexican plants tested showed antimicrobial activity. Among the six plant extracts analyzed, J. cuneata showed the highest growth-inhibitory activity against fungi, Gram-positive and Gram-negative bacteria (J. cuneata > A. adstrigens > C. latiflora > C. tortuosa > I. sonorae approximately S. lepidophylla). Shigella flexneri and Staphylococcus aureus were the most susceptible bacteria to plant extracts. Complete inhibition of S. flexneri growth was observed with J. cuneata methanolic extract at 90 microg/mL. This plant extract also showed the strongest antifungal activity against Fusarium verticillioides and Aspergillus niger. Our data suggest that the medicinal plants tested have important antimicrobial properties. This is the first report describing the antimicrobial activities of several of the Mexican medicinal plants used in this study.

Oxidized guar gum-ZnO hybrid nanostructures: synthesis, characterization and antibacterial activity

NASA Astrophysics Data System (ADS)

Singh, Vandana; Dwivedi, Lalit Mohan; Baranwal, Kirti; Asthana, Sugandha; Sundaram, Shanthy

2018-04-01

In the present study, guar gum (GG) and oxidized guar gum (OGG) have been used for modulating the antibacterial activity of ZnO. Oxidized guar gum-zinc oxide (OGG-ZnO) or guar gum-zinc oxide (GG-ZnO) nanostructures were synthesized by adding aqueous ammonia to zinc acetate solution in the presence of OGG or GG, respectively. OGG could significantly enhance the antibacterial activity of ZnO for a range of Gram-negative and Gram-positive bacterial strains and this enhancement was most pronounced for Bacillus subtilis and Salmonella typhi. At the same time, GG-ZnO nanostructures were found to be less bioactive than the pure ZnO for the same strains. TEM analysis revealed that optimum OGG-ZnO nanostructure (Z4) is of 200 nm size, oblong in shape, and has slightly clustered texture, while XRD confirmed its crystalline structure with hexagonal phase. The extra surface oxygen species (thus oxygen deficiency) has been assigned for better antibacterial behavior of OGG-ZnO. The study may be extended for other polysaccharide/derivatives to obtain ZnO nanostructures with enhanced antibacterial properties.

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

PubMed

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

2012-09-01

Schiff bases (SB(1)-SB(3)) were synthesized from the condensation of 6-formyl-7-hydroxy-5-methoxy-2-methylbenzopyran-4-one with 2-aminopyridine (SB(1)), p-phenylenediamine (SB(2)) and o-phenylenediamine (SB(3)), while Schiff bases (SB(4)-SB(6)) were synthesized by condensation of 5,7-dihydroxy-6-formyl-2-methylbenzopyran-4-one with 2-aminopyridine (SB(4)), p-phenylenediamine (SB(5)) and o-phenylenediamine (SB(6)). Schiff bases were characterized using elemental analysis, IR, UV-Vis, (1)H NMR, (13)C 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 OCH(3) on position five have higher antibacterial activity than that containing hydroxy group on the same position. Copyright © 2012 Elsevier B.V. All rights reserved.

Functionalized ZnO Nanoparticles with Gallic Acid for Antioxidant and Antibacterial Activity against Methicillin-Resistant S. aureus

PubMed Central

Lee, Joo Min; Choi, Kyong-Hoon; Min, Jeeeun; Kim, Ho-Joong; Jee, Jun-Pil; Park, Bong Joo

2017-01-01

In this study, we report a new multifunctional nanoparticle with antioxidative and antibacterial activities in vitro. ZnO@GA nanoparticles were fabricated by coordinated covalent bonding of the antioxidant gallic acid (GA) on the surface of ZnO nanoparticles. This addition imparts both antioxidant activity and high affinity for the bacterial cell membrane. Antioxidative activities at various concentrations were evaluated using a 2,2′-azino-bis(ethylbenzthiazoline-6-sulfonic acid) (ABTS) radical scavenging method. Antibacterial activities were evaluated against Gram-positive bacteria (Staphylococcus aureus: S. aureus), including several strains of methicillin-resistant S. aureus (MRSA), and Gram-negative bacteria (Escherichia coli). The functionalized ZnO@GA nanoparticles showed good antioxidative activity (69.71%), and the bactericidal activity of these nanoparticles was also increased compared to that of non-functionalized ZnO nanoparticles, with particularly effective inhibition and high selectivity for MRSA strains. The results indicate that multifunctional ZnO nanoparticles conjugated to GA molecules via a simple surface modification process displaying both antioxidant and antibacterial activity, suggesting a possibility to use it as an antibacterial agent for removing MRSA. PMID:29099064

In vitro and in vivo antibacterial activities of E1077, a novel parenteral cephalosporin with a broad antibacterial spectrum.

PubMed Central

Hata, K; Otsuki, M; Nishino, T

1992-01-01

E1077 is a new injectable cephalosporin with a broad spectrum of antibacterial activity against gram-positive and gram-negative bacteria, including staphylococci and Pseudomonas aeruginosa. The in vitro activities of E1077 against clinical isolates of methicillin-susceptible Staphylococcus aureus (MIC of E1077 for 90% of the strains tested [MIC90], 0.78 microgram/ml) and methicillin-resistant S. aureus (MIC90, 50 micrograms/ml) were similar to those of cefpirome and flomoxef. Against Enterococcus faecalis (MIC90, 6.25 micrograms/ml), E1077 was the most active of the drugs tested and four times more active than cefpirome. The MIC90S of E1077 for streptococci, Haemophilus influenzae, and Neisseria gonorrhoeae ranged from 0.05 to 0.78 microgram/ml; E1077 was similar in activity to cefpirome. E1077 inhibited 90% of most species of the family Enterobacteriaceae at concentrations of less than or equal to 1.56 micrograms/ml, with the exception of Serratia marcescens and Proteus vulgaris (12.5 micrograms/ml). The activity of E1077 against P. aeruginosa (MIC90, 6.25 micrograms/ml) was comparable to that of ceftazidime. In vivo activity was evaluated with systemic infections in mice. E1077 showed a protective effect against systemic infections by gram-positive or gram-negative bacteria, as reflected by its in vitro activity. The protective effects of E1077 were higher than those of cefpirome against S. aureus and P. aeruginosa infections and similar to those of cefpirome against other bacterial infections. Morphological studies using differential interference and phase-contrast microscopy showed that low concentrations of E1077 caused swelling of S. aureus and spheroplast and bulge formation in P. aeruginosa. In general, the antibacterial profile of E1077 is similar to that of cefpirome. Images PMID:1416879

Design, synthesis and biological evaluation of C(4) substituted monobactams as antibacterial agents against multidrug-resistant Gram-negative bacteria.

PubMed

Kou, Qunhuan; Wang, Ting; Zou, Feng; Zhang, Shuhua; Chen, Qian; Yang, Yushe

2018-05-10

A series of novel pyridone conjugated monobactams with various substituents at the (4) position were synthesized and evaluated for their antibacterial activities against a panel of multidrug-resistant (MDR) Gram-negative bacteria in vitro. Compounds 46d, 54 and 75e displayed good to moderate activities against P. aeruginosa, among which the activity of 75e against P. aeruginosa was comparable to that of BAL30072 under iron limitation condition. Compounds 35, 46d, 54, 56a, 56c and 56d exhibited good to excellent antibacterial activities against E. coli and K. pneumoniae, which were comparable or superior to that of BAL30072. In vitro liver microsomal stability was further evaluated and the results manifested that Compounds 35, 46d and 54 were metabolically stable in human liver microsomes. Copyright © 2018 Elsevier Masson SAS. All rights reserved.

Synthesis of 4-hydroxy-3-methylchalcone from Reimer-Tiemann reaction product and its antibacterial activity test

NASA Astrophysics Data System (ADS)

Hapsari, M.; Windarti, T.; Purbowatiningrum; Ngadiwiyana; Ismiyarto

2018-04-01

A 4-hydroxy-3-methylchalcone has been synthesized from 4-hydroxy-3-methylbenzaldehyde as the Reimer-Tiemann reaction product. This research consists of three steps involve synthesize of 4-hydroxy-3-methylbenzaldehyde from ortho-cresol, synthesize of chalcone derivatives from 4-hydroxy-3-methylbenzaldehyde and 4-hydroxy-3-methoxybenzaldehyde or vanillin for the comparison, the last is antibacterial activity test of both chalcone derivatives against Escherichia coli (negative gram) and Staphylococcus aureus (positive gram) bacteria using disc diffusion method. Results of Reimer-Tiemann reaction is 4-hydroxy-3-methylbenzaldehyde compound in an orange colour solid form which has 43% yields and melting point 110-114°C. A 4-hydroxy-3-methylbenzaldehyde then reacted with acetophenone in a base condition and form 4-hydroxy-3-methylchalcone compound in a yellow colour solid form which has 40% yields and melting point 83-86°C. The antibacterial activity of the 4-hydroxy-3-methylchalcone against gram-positive bacteria Staphylococcus aureus is better than the 4-hydroxy-3-methoxychalcone.

Thiol-Capped Gold Nanoparticles Swell-Encapsulated into Polyurethane as Powerful Antibacterial Surfaces Under Dark and Light Conditions

PubMed Central

Macdonald, Thomas J.; Wu, Ke; Sehmi, Sandeep K.; Noimark, Sacha; Peveler, William J.; du Toit, Hendrik; Voelcker, Nicolas H.; Allan, Elaine; MacRobert, Alexander J.; Gavriilidis, Asterios; Parkin, Ivan P.

2016-01-01

A simple procedure to develop antibacterial surfaces using thiol-capped gold nanoparticles (AuNPs) is shown, which effectively kill bacteria under dark and light conditions. The effect of AuNP size and concentration on photo-activated antibacterial surfaces is reported and we show significant size effects, as well as bactericidal activity with crystal violet (CV) coated polyurethane. These materials have been proven to be powerful antibacterial surfaces against both Gram-positive and Gram-negative bacteria. AuNPs of 2, 3 or 5 nm diameter were swell-encapsulated into PU before a coating of CV was applied (known as PU-AuNPs-CV). The antibacterial activity of PU-AuNPs-CV samples was tested against Staphylococcus aureus and Escherichia coli as representative Gram-positive and Gram-negative bacteria under dark and light conditions. All light conditions in this study simulated a typical white-light hospital environment. This work demonstrates that the antibacterial activity of PU-AuNPs-CV samples and the synergistic enhancement of photoactivity of triarylmethane type dyes is highly dependent on nanoparticle size and concentration. The most powerful PU-AuNPs-CV antibacterial surfaces were achieved using 1.0 mg mL−1 swell encapsulation concentrations of 2 nm AuNPs. After two hours, Gram-positive and Gram-negative bacteria were reduced to below the detection limit (>4 log) under dark and light conditions. PMID:27982122

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 μg/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

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 μg/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 μg/ml and 15.88 μg/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

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 μg/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

In vitro activity of daptomycin against clinical isolates of Gram-positive bacteria.

PubMed

Piper, Kerryl E; Steckelberg, James M; Patel, Robin

2005-08-01

We determined the activity of daptomycin, a recently FDA-approved antimicrobial agent, against clinical isolates of Gram-positive bacteria, including viridans group streptococci (16 Streptococcus mitis species group, 12 S. mutans species group, 9 S. anginosus species group, 8 S. sanguinis species group, 5 S. salivarius species group) from patients with infective endocarditis, 32 methicillin-resistant Staphylococcus aureus, 32 high-level penicillin-resistant Streptococcus pneumoniae, 38 vancomycin-resistant enterococci (including 1 linezolid-resistant isolate), and the following unusual Gram-positive bacteria: 3 Listeria monocytogenes, 4 Erysipelothrix rhusiopathiae, 9 Corynebacterium species, 10 Abiotrophia/Granulicatella species, 2 Rothia (Stomatococcus) mucilaginosus, and 4 Gemella morbillorum. Daptomycin minimum inhibitory concentration (MIC)(90) values for the viridans group streptococci, methicillin-resistant S. aureus, penicillin-resistant S. pneumoniae, and Enterococcus species were 0.5, 0.5, < or =0.125, and 4 microg/ml, respectively. The daptomycin MIC range for the unusual Gram-positive bacteria was < or =0.125-2 microg/ml. We conclude that daptomycin has in vitro activity against viridans group streptococci associated with endocarditis as well as against several types of unusual Gram-positive bacteria that can cause endocarditis.

Antibacterial properties of propolis (bee glue).

PubMed Central

Grange, J M; Davey, R W

1990-01-01

Propolis (bee glue) was found to have antibacterial activity against a range of commonly encountered cocci and Gram-positive rods, including the human tubercle bacillus, but only limited activity against Gram-negative bacilli. These findings confirm previous reports of antimicrobial properties of this material, possibly attributable to its high flavonoid content. PMID:2182860

Antioxidant and antibacterial activities of selected varieties of thai mango seed extract.

PubMed

Khammuang, Saranyu; Sarnthima, Rakrudee

2011-01-01

This study reports the antioxidant and antibacterial activities of four fresh mango seed extracts from Thai varieties. Total phenol contents determined by the Folin-ciocalteu method revealed the highest values to be in MKE, Chok-a-nan variety (399.8 mgGAE/g extract) and MSE of Nam-dok-mai variety (377.2 mgGAE/g extract). Both extracts showed potent ABTS˙+ radical and DPPH˙ radical scavenging activities with the lower half inhibition concentration (IC50) values than those of the reference compounds; vitamin C, trolox and BHA, respectively. Their antioxidant property of MSE and MKE is strongly correlated with the total phenol contents (r=0.98 and 0.98, respectively). When combined the MSE and MKE of the Fah-lun variety showed the strongest antioxidant activity. All mango seed extracts showed interesting antibacterial activity against both gram positive and gram negative bacteria as determined by disc diffusion method. The most sensitive pathogenic strain inhibited by all extracts (especially Kaew variety) was Pseudomonas aeruginosa ATCC 27853. This work suggests potential applications for practical uses of mango seed extracts from Thai varieties, as sources of antioxidant and antibacterial agents.

Evaluation of cytotoxicity, immune compatibility and antibacterial activity of biogenic silver nanoparticles.

PubMed

Składanowski, M; Golinska, P; Rudnicka, K; Dahm, H; Rai, M

2016-12-01

The study was focused on assessment of antibacterial activity, cytotoxicity and immune compatibility of biogenic silver nanoparticles (AgNPs) synthesized from Streptomyces sp. NH28 strain. Nanoparticles were biosynthesized and characterized by UV-Vis spectroscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, nanoparticle tracking analysis system and zeta potential. Antibacterial activity was tested against Gram-positive and Gram-negative bacteria; minimal inhibitory concentration was recorded. Cytotoxicity was estimated using L929 mouse fibroblasts via 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide test. Biocompatibility of AgNPs was performed using THP1-XBlue™ cells. Biogenic AgNPs presented high antibacterial activity against all tested bacteria. Minimum inhibitory concentration of AgNPs against bacterial cells was found to be in range of 1.25-10 μg/mL. Silver nanoparticles did not show any harmful interaction to mouse fibroblast cell line, and no activation of nuclear factor kappa-light-chain-enhancer of activated B (NF-κB) cells was observed at concentration below 10 µg/mL. The half-maximal inhibitory concentration (IC 50 ) value was established at 64.5 μg/mL. Biological synthesis of silver can be used as an effective system for formation of metal nanoparticles. Biosynthesized AgNPs can be used as an antibacterial agent, which can be safe for eukaryotic cells.

Fighting infections due to multidrug-resistant Gram-positive pathogens.

PubMed

Cornaglia, G

2009-03-01

Growing bacterial resistance in Gram-positive pathogens means that what were once effective and inexpensive treatments for infections caused by these bacteria are now being seriously questioned, including penicillin and macrolides for use against pneumococcal infections and-in hospitals-oxacillin for use against staphylococcal infections. As a whole, multidrug-resistant (MDR) Gram-positive pathogens are rapidly becoming an urgent and sometimes unmanageable clinical problem. Nevertheless, and despite decades of research into the effects of antibiotics, the actual risk posed to human health by antibiotic resistance has been poorly defined; the lack of reliable data concerning the outcomes resulting from antimicrobial resistance stems, in part, from problems with study designs and the methods used in resistence determination. Surprisingly little is known, too, about the actual effectiveness of the many types of intervention aimed at controlling antibiotic resistance. New antibiotics active against MDR Gram-positive pathogens have been recently introduced into clinical practice, and the antibiotic pipeline contains additional compounds at an advanced stage of development, including new glycopeptides, new anti-methicillin-resistant Staphylococcus aureus (MRSA) beta-lactams, and new diaminopyrimidines. Many novel antimicrobial agents are likely to be niche products, endowed with narrow antibacterial spectra and/or targeted at specific clinical problems. Therefore, an important educational goal will be to change the current, long-lasting attitudes of both physicians and customers towards broad-spectrum and multipurpose compounds. Scientific societies, such as the European Society of Clinical Microbiology and Infectious Diseases (ESCMID), must play a leading role in this process.

Study of the antibacterial and antifungal activities of synthetic benzyl bromides, ketones, and corresponding chalcone derivatives.

PubMed

Shakhatreh, Muhamad Ali K; Al-Smadi, Mousa L; Khabour, Omar F; Shuaibu, Fatima A; Hussein, Emad I; Alzoubi, Karem H

2016-01-01

Several applications of chalcones and their derivatives encouraged researchers to increase their synthesis as an alternative for the treatment of pathogenic bacterial and fungal infections. In the present study, chalcone derivatives were synthesized through cross aldol condensation reaction between 4-( N , N -dimethylamino)benzaldehyde and multiarm aromatic ketones. The multiarm aromatic ketones were synthesized through nucleophilic substitution reaction between 4-hydroxy acetophenone and benzyl bromides. The benzyl bromides, multiarm aromatic ketones, and corresponding chalcone derivatives were evaluated for their activities against eleven clinical pathogenic Gram-positive, Gram-negative bacteria, and three pathogenic fungi by the disk diffusion method. The minimum inhibitory concentration was determined by the microbroth dilution technique. The results of the present study demonstrated that benzyl bromide derivatives have strong antibacterial and antifungal properties as compared to synthetic chalcone derivatives and ketones. Benzyl bromides (1a and 1c) showed high ester activity against Gram-positive bacteria and fungi but moderate activity against Gram-negative bacteria. Therefore, these compounds may be considered as good antibacterial and antifungal drug discovery. However, substituted ketones (2a-b) as well as chalcone derivatives (3a-c) showed no activity against all the tested strains except for ketone (2c), which showed moderate activity against Candida albicans .

Study of the antibacterial and antifungal activities of synthetic benzyl bromides, ketones, and corresponding chalcone derivatives

PubMed Central

Shakhatreh, Muhamad Ali K; Al-Smadi, Mousa L; Khabour, Omar F; Shuaibu, Fatima A; Hussein, Emad I; Alzoubi, Karem H

2016-01-01

Several applications of chalcones and their derivatives encouraged researchers to increase their synthesis as an alternative for the treatment of pathogenic bacterial and fungal infections. In the present study, chalcone derivatives were synthesized through cross aldol condensation reaction between 4-(N,N-dimethylamino)benzaldehyde and multiarm aromatic ketones. The multiarm aromatic ketones were synthesized through nucleophilic substitution reaction between 4-hydroxy acetophenone and benzyl bromides. The benzyl bromides, multiarm aromatic ketones, and corresponding chalcone derivatives were evaluated for their activities against eleven clinical pathogenic Gram-positive, Gram-negative bacteria, and three pathogenic fungi by the disk diffusion method. The minimum inhibitory concentration was determined by the microbroth dilution technique. The results of the present study demonstrated that benzyl bromide derivatives have strong antibacterial and antifungal properties as compared to synthetic chalcone derivatives and ketones. Benzyl bromides (1a and 1c) showed high ester activity against Gram-positive bacteria and fungi but moderate activity against Gram-negative bacteria. Therefore, these compounds may be considered as good antibacterial and antifungal drug discovery. However, substituted ketones (2a–b) as well as chalcone derivatives (3a–c) showed no activity against all the tested strains except for ketone (2c), which showed moderate activity against Candida albicans. PMID:27877017

In vitro antibacterial activity and beta-lactamase stability of CP-70,429 a new penem antibiotic.

PubMed

Minamimura, M; Taniyama, Y; Inoue, E; Mitsuhashi, S

1993-07-01

In in vitro susceptibility tests, the new penem CP-70,429 showed potent antibacterial activity against gram-positive and gram-negative bacteria except Pseudomonas aeruginosa and Xanthomonas maltophilia. CP-70,429 was stable to various types of beta-lactamases except for the enzyme from X. maltophilia and was 16- to 128-fold more active than the other compounds against beta-lactamase-producing strains of Enterobacter cloacae and Citrobacter freundii.

In vitro antibacterial activity and beta-lactamase stability of CP-70,429 a new penem antibiotic.

PubMed Central

Minamimura, M; Taniyama, Y; Inoue, E; Mitsuhashi, S

1993-01-01

In in vitro susceptibility tests, the new penem CP-70,429 showed potent antibacterial activity against gram-positive and gram-negative bacteria except Pseudomonas aeruginosa and Xanthomonas maltophilia. CP-70,429 was stable to various types of beta-lactamases except for the enzyme from X. maltophilia and was 16- to 128-fold more active than the other compounds against beta-lactamase-producing strains of Enterobacter cloacae and Citrobacter freundii. PMID:8363389

Negatively charged silver nanoparticles with potent antibacterial activity and reduced toxicity for pharmaceutical preparations.

PubMed

Salvioni, Lucia; Galbiati, Elisabetta; Collico, Veronica; Alessio, Giulia; Avvakumova, Svetlana; Corsi, Fabio; Tortora, Paolo; Prosperi, Davide; Colombo, Miriam

2017-01-01

The discovery of new solutions with antibacterial activity as efficient and safe alternatives to common preservatives (such as parabens) and to combat emerging infections and drug-resistant bacterial pathogens is highly expected in cosmetics and pharmaceutics. Colloidal silver nanoparticles (NPs) are attracting interest as novel effective antimicrobial agents for the prevention of several infectious diseases. Water-soluble, negatively charged silver nanoparticles (AgNPs) were synthesized by reduction with citric and tannic acid and characterized by transmission electron microscopy, dynamic light scattering, zeta potential, differential centrifuge sedimentation, and ultraviolet-visible spectroscopy. AgNPs were tested with model Gram-negative and Gram-positive bacteria in comparison to two different kinds of commercially available AgNPs. In this work, AgNPs with higher antibacterial activity compared to the commercially available colloidal silver solutions were prepared and investigated. Bacteria were plated and the antibacterial activity was tested at the same concentration of silver ions in all samples. The AgNPs did not show any significant reduction in the antibacterial activity for an acceptable time period. In addition, AgNPs were transferred to organic phase and retained their antibacterial efficacy in both aqueous and nonaqueous media and exhibited no toxicity in eukaryotic cells. We developed AgNPs with a 20 nm diameter and negative zeta potential with powerful antibacterial activity and low toxicity compared to currently available colloidal silver, suitable for cosmetic preservatives and pharmaceutical preparations administrable to humans and/or animals as needed.

Negatively charged silver nanoparticles with potent antibacterial activity and reduced toxicity for pharmaceutical preparations

PubMed Central

Salvioni, Lucia; Galbiati, Elisabetta; Collico, Veronica; Alessio, Giulia; Avvakumova, Svetlana; Corsi, Fabio; Tortora, Paolo; Prosperi, Davide; Colombo, Miriam

2017-01-01

Background The discovery of new solutions with antibacterial activity as efficient and safe alternatives to common preservatives (such as parabens) and to combat emerging infections and drug-resistant bacterial pathogens is highly expected in cosmetics and pharmaceutics. Colloidal silver nanoparticles (NPs) are attracting interest as novel effective antimicrobial agents for the prevention of several infectious diseases. Methods Water-soluble, negatively charged silver nanoparticles (AgNPs) were synthesized by reduction with citric and tannic acid and characterized by transmission electron microscopy, dynamic light scattering, zeta potential, differential centrifuge sedimentation, and ultraviolet–visible spectroscopy. AgNPs were tested with model Gram-negative and Gram-positive bacteria in comparison to two different kinds of commercially available AgNPs. Results In this work, AgNPs with higher antibacterial activity compared to the commercially available colloidal silver solutions were prepared and investigated. Bacteria were plated and the antibacterial activity was tested at the same concentration of silver ions in all samples. The AgNPs did not show any significant reduction in the antibacterial activity for an acceptable time period. In addition, AgNPs were transferred to organic phase and retained their antibacterial efficacy in both aqueous and nonaqueous media and exhibited no toxicity in eukaryotic cells. Conclusion We developed AgNPs with a 20 nm diameter and negative zeta potential with powerful antibacterial activity and low toxicity compared to currently available colloidal silver, suitable for cosmetic preservatives and pharmaceutical preparations administrable to humans and/or animals as needed. PMID:28408822

Apitherapeutics and phage-loaded nanofibers as wound dressings with enhanced wound healing and antibacterial activity.

PubMed

Sarhan, Wessam A; Azzazy, Hassan Me

2017-09-01

Develop green wound dressings which exhibit enhanced wound-healing ability and potent antibacterial effects. Honey, polyvinyl alcohol, chitosan nanofibers were electrospun and loaded with bee venom, propolis and/or bacteriophage against the multidrug-resistant Pseudomonas aeruginosa and examined for their antibacterial, wound-healing ability and cytotoxicity. Among different formulations of nanofibers, honey, polyvinyl alcohol, chitosan-bee venom/bacteriophage exhibited the most potent antibacterial activity against all tested bacterial strains (Gram-positive and -negative strains) and achieved nearly complete killing of multidrug-resistant P. aeruginosa. In vivo testing revealed enhanced wound-healing results and cytotoxicity testing proved improved biocompatibility. The developed biocompatible nanofibers represent competitive wound-healing dressings with potent antibacterial and wound-healing activity.

Eco-friendly decoration of graphene oxide with biogenic silver nanoparticles: antibacterial and antibiofilm activity

NASA Astrophysics Data System (ADS)

de Faria, Andreia Fonseca; de Moraes, Ana Carolina Mazarin; Marcato, Priscyla Daniely; Martinez, Diego Stéfani Teodoro; Durán, Nelson; Filho, Antônio Gomes Souza; Brandelli, Adriano; Alves, Oswaldo Luiz

2014-02-01

This work reports on preparation, characterization, and antibacterial activity of graphene oxide (GO) decorated with biogenic silver nanoparticles (Bio-AgNPs) produced by the fungus Fusarium oxysporum. This nanocomposite (Bio-GOAg) was prepared by an ex situ process through the physical mixture of a GO dispersion with the previously prepared Bio-AgNPs. The adsorption of the Bio-AgNPs onto the GO sheets was confirmed by transmission electron microscopy. The average size of the Bio-AgNPs anchored onto the GO surface was found to be 3.5 nm. The antibacterial activity of the Bio-GOAg nanocomposite against Gram-positive and Gram-negative microorganisms was investigated and a very promising result was found for the Gram-negative strains. In addition, the Bio-GOAg nanocomposite displayed a very strong biocidal activity against the Salmonella typhimurium strain at a concentration of 2.0 μg/mL. The antibiofilm activity toward S. typhimurium adhered on stainless steel surfaces was also investigated. The results showed 100 % inhibition of the adhered cells after exposure to the Bio-GOAg nanocomposite for 1 h.

Synthesis of new 2-substituted pyrido[2,3-d]pyrimidin-4(1H)-ones and their antibacterial activity.

PubMed

Lakshmi Narayana, B; Ram Rao, A Raghu; Shanthan Rao, P

2009-03-01

2-Substituted-5,7-dimethyl pyrido[2,3-d]pyrimidin-4(1H)-ones (8) were synthesized by oxidation of 2-substituted-5,7-dimethyl dihydropyrido[2,3-d]pyrimidin-4(1H)-ones (7) which were in turn prepared from 2-amino-4,6-dimethyl nicotinamide (5) and substituted aryl aldehydes (6). 2-Amino-4,6-dimethyl nicotinamide (5) was prepared from ethyl cyanoacetate (1) via malonamamidine hydrochloride (3). The compounds were characterized by IR, NMR, MS and elemental analyses. Compounds 7 and 8 were screened for antibacterial activity against gram positive and gram negative bacteria. Dehydrogenated compounds (8) showed less antibacterial activity than the compounds 7. Among all the test compounds screened for antibacterial activity 7c (1.25 microg/ml) showed greater activity. All the synthesized compounds were found inactive when screened for antifungal activity at the concentration of 200 microg/ml.

In vitro antibacterial activity of poly (amidoamine)-G7 dendrimer.

PubMed

Gholami, Mitra; Mohammadi, Rashin; Arzanlou, Mohsen; Akbari Dourbash, Fakhraddin; Kouhsari, Ebrahim; Majidi, Gharib; Mohseni, Seyed Mohsen; Nazari, Shahram

2017-06-05

Nano-scale dendrimers are synthetic macromolecules that frequently used in medical and health field. Traditional anibiotics are induce bacterial resistence so there is an urgent need for novel antibacterial drug invention. In the present study seventh generation poly (amidoamine) (PAMAM-G7) dendrimer was synthesized and its antibacterial activities were evaluated against representative Gram- negative and Gram-positive bacteria. PAMAM-G7 was synthesized with divergent growth method. The structural and surface of PAMAM-G7 were investigated by transmission electron microscopy, scanning electron microscope and fourier transform infrared. Pseudomonas. aeruginosa (n = 15), E. coli (n = 15), Acinetobacter baumanni (n = 15), Shigella dysenteriae (n = 15), Klebsiella pneumoniae (n = 10), Proteus mirabilis (n = 15), Staphylococcus aureus (n = 15) and Bacillus subtilis (n = 10) have been used for antibacterial activity assay. Additionally, representative standard strains for each bacterium were included. Minimum Inhibitory Concentration (MIC) was determined using microdilution method. Subsequently, Minimum Bactericidal Concentration (MBC) was determined by sub-culturing each of the no growth wells onto Mueller Hinton agar medium. The cytotoxicity of PAMAM-G7 dendrimer were evaluated in HCT116 and NIH 3 T3 cells by MTT assay. The average size of each particle was approximately 20 nm. PAMAM-G7 was potentially to inhibit both Gram positive and gram negative growth. The MIC50 and MIC90 values were determined to be 2-4 μg/ml and 4-8 μg/ml, respectively. The MBC50 and MBC90 values were found to be 64-256 μg/ml and 128-256 μg/ml, respectively. The cytotoxity effect of dendrimer on HCT116 and NIH 3 T3 cells is dependent upon exposure time to and concentration of dendrimers. The most reduction (44.63 and 43%) in cell viability for HCT116 and NIH 3 T3 cells was observed at the highest concentration, 0.85 μM after 72 h treatmentm, respectively. This study

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

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

PubMed

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.

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

PubMed

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

2015-01-01

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. 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. In disc diffusion method, all the natural products (400 μg/disc) showed moderate to potent activity against all the tested bacteria. The ethanol extract of bark (EEB) and ethanol fraction of bark (EFB) (400 μg/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 μg/ml while the LC50 of vincristine sulphate was 0.52 μg/ml. The results suggest that all the natural products possess potent antibacterial and moderate cytotoxic.

Antibacterial activities of the methanol extracts of Albizia adianthifolia, Alchornea laxiflora, Laportea ovalifolia and three other Cameroonian plants against multi-drug resistant Gram-negative bacteria.

PubMed

Tchinda, Cedric F; Voukeng, Igor K; Beng, Veronique P; Kuete, Victor

2017-05-01

In the last 10 years, resistance in Gram-negative bacteria has been increasing. The present study was designed to evaluate the in vitro antibacterial activities of the methanol extracts of six Cameroonian medicinal plants Albizia adianthifolia , Alchornea laxiflora , Boerhavia diffusa , Combretum hispidum , Laportea ovalifolia and Scoparia dulcis against a panel of 15 multidrug resistant Gram-negative bacterial strains. The broth microdilution was used to determine the minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of the extracts. The preliminary phytochemical screening of the extracts was conducted according to the reference qualitative phytochemical methods. Results showed that all extracts contained compounds belonging to the classes of polyphenols and triterpenes, other classes of chemicals being selectively distributed. The best antibacterial activities were recorded with bark and root extracts of A. adianthifolia as well as with L. ovalifolia extract, with MIC values ranging from 64 to 1024 μg/mL on 93.3% of the fifteen tested bacteria. The lowest MIC value of 64 μg/mL was recorded with A. laxiflora bark extract against Enterobacter aerogenes EA289. Finally, the results of this study provide evidence of the antibacterial activity of the tested plants and suggest their possible use in the control of multidrug resistant phenotypes.

Zinc oxide nanoparticle-coated films: fabrication, characterization, and antibacterial properties

NASA Astrophysics Data System (ADS)

Jiang, Yunhong; O'Neill, Alex J.; Ding, Yulong

2015-04-01

In this article, novel antibacterial PVC-based films coated with ZnO nanoparticles (NPs) were fabricated, characterized, and studied for their antibacterial properties. It was shown that the ZnO NPs were coated on the surface of the PVC films uniformly and that the coating process did not affect the size and shape of the NPs on the surface of PVC films. Films coated with concentrations of either 0.2 or 0.075 g/L of ZnO NPs exhibited antibacterial activity against both Gram-positive ( Staphylococcus aureus) and Gram-negative ( Escherichia coli) bacteria, but exhibited no antifungal activity against Aspergillus flavus and Penicillium citrinum. Smaller particles (100 nm) exhibited more potent antibacterial activity than larger particles (1000 nm). All ZnO-coated films maintained antibacterial activity after 30 days in water.

Evaluation of in-vitro antibacterial activity and anti-inflammatory activity for different extracts of Rauvolfia tetraphylla L. root bark

PubMed Central

Ganga Rao, B.; Umamaheswara Rao, P.; Sambasiva Rao, E.; Mallikarjuna Rao, T.; Praneeth. D, V. S.

2012-01-01

Objective To assess the in-vitro antibacterial activity and anti-inflammatory activity of orally administered different extracts (Hydro-alcoholic, methanolic, ethyl acetate and hexane) of Rauvolfia tetraphylla (R. tetraphylla) root bark in Carrageenan induced acute inflammation in rats. Methods In-vitro antibacterial activity was evaluated for extracts against four Gram positive and four Gram negative bacteria by using cylinder plate assay. Hydro-alcoholic extract (70% v/v ethanol) at 200, 400 and 800 mg/kg doses and methanolic, ethyl acetate and hexane extracts at doses 100, 200 and 400 mg/kg were tested for anti-inflammatory activity in Carrageenan induced rat paw oedema model and paw thickness was measured every one hour up to 6 hrs. Results All extracts of R. tetraphylla root bark showed good zone of inhibition against tested bacterial strains. In Carrageenan induced inflammation model, hydro-alcoholic and methanolic extract of R. tetraphylla root bark at three different doses produced significant (P<0.001) reduction when compared to vehicle treated control group and hexane, ethyl acetate extracts. Conclusions In the present study extracts of R. tetraphylla root bark shows good in-vitro antibacterial activity and in-vivo anti-inflammatory activity in rats. PMID:23569853

Evaluation of in-vitro antibacterial activity and anti-inflammatory activity for different extracts of Rauvolfia tetraphylla L. root bark.

PubMed

Ganga Rao, B; Umamaheswara Rao, P; Sambasiva Rao, E; Mallikarjuna Rao, T; Praneeth D, V S

2012-10-01

To assess the in-vitro antibacterial activity and anti-inflammatory activity of orally administered different extracts (Hydro-alcoholic, methanolic, ethyl acetate and hexane) of Rauvolfia tetraphylla (R. tetraphylla) root bark in Carrageenan induced acute inflammation in rats. In-vitro antibacterial activity was evaluated for extracts against four Gram positive and four Gram negative bacteria by using cylinder plate assay. Hydro-alcoholic extract (70% v/v ethanol) at 200, 400 and 800 mg/kg doses and methanolic, ethyl acetate and hexane extracts at doses 100, 200 and 400 mg/kg were tested for anti-inflammatory activity in Carrageenan induced rat paw oedema model and paw thickness was measured every one hour up to 6 hrs. All extracts of R. tetraphylla root bark showed good zone of inhibition against tested bacterial strains. In Carrageenan induced inflammation model, hydro-alcoholic and methanolic extract of R. tetraphylla root bark at three different doses produced significant (P<0.001) reduction when compared to vehicle treated control group and hexane, ethyl acetate extracts. In the present study extracts of R. tetraphylla root bark shows good in-vitro antibacterial activity and in-vivo anti-inflammatory activity in rats.

Surface enhanced Raman scattering, antibacterial and antifungal active triangular gold nanoparticles

NASA Astrophysics Data System (ADS)

Smitha, S. L.; Gopchandran, K. G.

2013-02-01

Shape controlled syntheses of gold nanoparticles have attracted a great deal of attention as their optical, electronic, magnetic and biological properties are strongly dependent on the size and shape of the particles. Here is a report on the surface enhanced Raman scattering (SERS) activity of Cinnamomum zeylanicum leaf broth reduced gold nanoparticles consisting of triangular and spherical like particles, using 2-aminothiophenol (2-ATP) and crystal violet (CV) as probe molecules. Nanoparticles prepared with a minimum leaf broth concentration, having a greater number of triangular like particles exhibit a SERS activity of the order of 107. The synthesized nanoparticles exhibit efficient antibacterial activity against the tested gram negative bacterium Escherichia coli and gram positive bacterium Staphylococcus aureus. Investigations on the antifungal activity of the synthesized nanoparticles against Aspergillus niger and Fusarium oxysporum positive is also discussed.

Antibacterial activity of some selected medicinal plants of Pakistan

PubMed Central

2011-01-01

Background Screening of the ethnobotenical plants is a pre-requisite to evaluate their therapeutic potential and it can lead to the isolation of new bioactive compounds. Methods The crude extracts and fractions of six medicinal important plants (Arisaema flavum, Debregeasia salicifolia, Carissa opaca, Pistacia integerrima, Aesculus indica, and Toona ciliata) were tested against three Gram positive and two Gram negative ATCC bacterial species using the agar well diffusion method. Results The crude extract of P. integerrima and A. indica were active against all tested bacterial strains (12-23 mm zone of inhibition). Other four plant's crude extracts (Arisaema flavum, Debregeasia salicifolia, Carissa opaca, and Toona ciliata) were active against different bacterial strains. The crude extracts showed varying level of bactericidal activity. The aqueous fractions of A. indica and P. integerrima crude extract showed maximum activity (19.66 and 16 mm, respectively) against B. subtilis, while the chloroform fractions of T. ciliata and D. salicifolia presented good antibacterial activities (13-17 mm zone of inhibition) against all the bacterial cultures tested. Conclusion The methanol fraction of Pistacia integerrima, chloroform fractions of Debregeasia salicifolia &Toona ciliata and aqueous fraction of Aesculus indica are suitable candidates for the development of novel antibacterial compounds. PMID:21718504

Antioxidative, antibrowning and antibacterial activities of sixteen floral honeys.

PubMed

Chang, Xin; Wang, Jiehua; Yang, Shaohui; Chen, Shan; Song, Yingjin

2011-09-01

Commonly consumed honeys from sixteen different single floral sources were analyzed for their in vitro antioxidant capacities by several methods including DPPH, ABTS, FRAP, SASR and MDA assays. The total polyphenol contents varied among the tested honeys and were highly correlated to their antioxidant capacity values. The antioxidant capacity of Chinese milk vetch flower honeys was significantly higher than those of other flower honeys. All honeys tested were active in inhibiting the browning of apple homogenate and linden honey displayed the highest inhibition rate as 85%. When the antimicrobial activity of the investigated honeys was screened using Gram-positive bacteria (Staphylococcus aureus) and Gram-negative bacteria (Escherichia coli), clover honey exhibited the strongest antibacterial activity as 2.2 mg mL(-1) kanamycin equivalent inhibition. This journal is © The Royal Society of Chemistry 2011

Antibacterial activity of some bryophytes used traditionally for the treatment of burn infections.

PubMed

Singh, Meenakshi; Singh, Shweta; Nath, Virendra; Sahu, Vinay; Rawat, Ajay Kumar Singh

2011-05-01

Plagiochasma appendiculatum L. & L. (Aytoniaceae), Conocephalum conicum (L.) Necker (Conocephalaceae), Bryum argenteum Hedw. (Bryaceae), and Mnium marginatum (With.) P. Beauv. (Mniaceae) are bryophytes (liverworts and mosses) used by traditional healers for the treatment of burn, cuts, wounds, and skin disorders. This study evaluated the antibacterial activity of four bryophytes against some common bacteria responsible for burn infections. Different fractions of bryophytes were screened using the disc diffusion (qualitative) and broth microdilution (quantitative) methods, according to the guidelines of the National Committee for Clinical and Laboratory Standards. Chloroform fractions of liverworts were more active against Gram negative strains while butanol fractions of mosses had significant activity against Gram positive bacteria. Staphylococcus aureus was the most sensitive strain of those tested with the butanol fraction of M. marginatum (moss), with the strongest inhibition zone of 102.92% and minimum inhibitory concentration of 30 μg mL(-1). Our findings support the use of the bryophytes in traditional medicine for burn infections because of their significant antibacterial activity.

Gramicidin A Mutants with Antibiotic Activity against Both Gram-Positive and Gram-Negative Bacteria.

PubMed

Zerfas, Breanna L; Joo, Yechaan; Gao, Jianmin

2016-03-17

Antimicrobial peptides (AMPs) have shown potential as alternatives to traditional antibiotics for fighting infections caused by antibiotic-resistant bacteria. One promising example of this is gramicidin A (gA). In its wild-type sequence, gA is active by permeating the plasma membrane of Gram-positive bacteria. However, gA is toxic to human red blood cells at similar concentrations to those required for it to exert its antimicrobial effects. Installing cationic side chains into gA has been shown to lower its hemolytic activity while maintaining the antimicrobial potency. In this study, we present the synthesis and the antibiotic activity of a new series of gA mutants that display cationic side chains. Specifically, by synthesizing alkylated lysine derivatives through reductive amination, we were able to create a broad selection of structures with varied activities towards Staphylococcus aureus and methicillin-resistant S. aureus (MRSA). Importantly, some of the new mutants were observed to have an unprecedented activity towards important Gram-negative pathogens, including Escherichia coli, Klebsiella pneumoniae and Psuedomonas aeruginosa. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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. Copyright © 2013 Elsevier Ltd. All rights reserved.

An unusual class of anthracyclines potentiate Gram-positive antibiotics in intrinsically resistant Gram-negative bacteria

PubMed Central

Cox, Georgina; Koteva, Kalinka; Wright, Gerard D.

2014-01-01

Objectives An orthogonal approach taken towards novel antibacterial drug discovery involves the identification of small molecules that potentiate or enhance the activity of existing antibacterial agents. This study aimed to identify natural-product rifampicin adjuvants in the intrinsically resistant organism Escherichia coli. Methods E. coli BW25113 was screened against 1120 actinomycete fermentation extracts in the presence of subinhibitory (2 mg/L) concentrations of rifampicin. The active molecule exhibiting the greatest rifampicin potentiation was isolated using activity-guided methods and identified using mass and NMR spectroscopy. Susceptibility testing and biochemical assays were used to determine the mechanism of antibiotic potentiation. Results The anthracycline Antibiotic 301A1 was isolated from the fermentation broth of a strain of Streptomyces (WAC450); the molecule was shown to be highly synergistic with rifampicin (fractional inhibitory concentration index = 0.156) and moderately synergistic with linezolid (FIC index = 0.25) in both E. coli and Acinetobacter baumannii. Activity was associated with inhibition of efflux and the synergistic phenotype was lost when tested against E. coli harbouring mutations within the rpoB gene. Structure–activity relationship studies revealed that other anthracyclines do not synergize with rifampicin and removal of the sugar moiety of Antibiotic 301A1 abolishes activity. Conclusions Screening only a subsection of our natural product library identified a small-molecule antibiotic adjuvant capable of sensitizing Gram-negative bacteria to antibiotics to which they are ordinarily intrinsically resistant. This result demonstrates the great potential of this approach in expanding antibiotic effectiveness in the face of the growing challenge of resistance in Gram-negatives. PMID:24627312

A Novel Surface Structure Consisting of Contact-active Antibacterial Upper-layer and Antifouling Sub-layer Derived from Gemini Quaternary Ammonium Salt Polyurethanes.

PubMed

He, Wei; Zhang, Yi; Li, Jiehua; Gao, Yunlong; Luo, Feng; Tan, Hong; Wang, Kunjie; Fu, Qiang

2016-08-26

Contact-active antibacterial surfaces play a vital role in preventing bacterial contamination of artificial surfaces. In the past, numerous researches have been focused on antibacterial surfaces comprising of antifouling upper-layer and antibacterial sub-layer. In this work, we demonstrate a reversed surface structure which integrate antibacterial upper-layer and antifouling sub-layer. These surfaces are prepared by simply casting gemini quaternary ammonium salt waterborne polyurethanes (GWPU) and their blends. Due to the high interfacial energy of gemini quaternary ammonium salt (GQAS), chain segments containing GQAS can accumulate at polymer/air interface to form an antibacterial upper-layer spontaneously during the film formation. Meanwhile, the soft segments composed of polyethylene glycol (PEG) formed the antifouling sub-layer. Our findings indicate that the combination of antibacterial upper-layer and antifouling sub-layer endow these surfaces strong, long-lasting antifouling and contact-active antibacterial properties, with a more than 99.99% killing efficiency against both gram-positive and gram-negative bacteria attached to them.

A Novel Surface Structure Consisting of Contact-active Antibacterial Upper-layer and Antifouling Sub-layer Derived from Gemini Quaternary Ammonium Salt Polyurethanes

PubMed Central

He, Wei; Zhang, Yi; Li, Jiehua; Gao, Yunlong; Luo, Feng; Tan, Hong; Wang, Kunjie; Fu, Qiang

2016-01-01

Contact-active antibacterial surfaces play a vital role in preventing bacterial contamination of artificial surfaces. In the past, numerous researches have been focused on antibacterial surfaces comprising of antifouling upper-layer and antibacterial sub-layer. In this work, we demonstrate a reversed surface structure which integrate antibacterial upper-layer and antifouling sub-layer. These surfaces are prepared by simply casting gemini quaternary ammonium salt waterborne polyurethanes (GWPU) and their blends. Due to the high interfacial energy of gemini quaternary ammonium salt (GQAS), chain segments containing GQAS can accumulate at polymer/air interface to form an antibacterial upper-layer spontaneously during the film formation. Meanwhile, the soft segments composed of polyethylene glycol (PEG) formed the antifouling sub-layer. Our findings indicate that the combination of antibacterial upper-layer and antifouling sub-layer endow these surfaces strong, long-lasting antifouling and contact-active antibacterial properties, with a more than 99.99% killing efficiency against both gram-positive and gram-negative bacteria attached to them. PMID:27561546

Synthesis and antibacterial evaluation of novel cationic chalcone derivatives possessing broad spectrum antibacterial activity.

PubMed

Chu, Wen-Chao; Bai, Peng-Yan; Yang, Zhao-Qing; Cui, De-Yun; Hua, Yong-Gang; Yang, Yi; Yang, Qian-Qian; Zhang, En; Qin, Shangshang

2018-01-01

There is an urgent need to identify new antibiotics with novel mechanisms that combat antibiotic resistant bacteria. Herein, a series of chalcone derivatives that mimic the essential properties of cationic antimicrobial peptides were designed and synthesized. Antibacterial activities against drug-sensitive bacteria, including Staphylococcus aureus, Enterococcus faecalis, Escherichia coli and Salmonella enterica, as well as clinical multiple drug resistant isolates of methicillin-resistant S. aureus (MRSA), KPC-2-producing and NDM-1-producing Carbapenem-resistant Enterobacteriaceae were evaluated. Representative compounds 5a (MIC: 1 μg/mL against S. aureus, 0.5 μg/mL against MRSA) and 5g (MIC: 0.5 μg/mL against S. aureus, 0.25 μg/mL against MRSA) showed good bactericidal activity against both Gram-positive and Gram-negative bacteria, including the drug-resistant species MRSA, KPC and NDM. These membrane-active antibacterial compounds were demonstrated to reduce the viable cell counts in bacterial biofilms effectively and do not induce the development of resistance in bacteria. Additionally, these representative molecules exhibited negligible toxicity toward mammalian cells at a suitable concentration. The combined results indicate that this series of cationic chalcone derivatives have potential therapeutic effects against bacterial infections. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

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

Secretory phospholipase A2 in dromedary tears: a host defense against staphylococci and other gram-positive bacteria.

PubMed

Ben Bacha, Abir; Abid, Islem

2013-03-01

The best known physiologic function of secreted phospholipase A2 (sPLA2) group IIA (sPLA2-IIA) is defense against bacterial infection through hydrolytic degradation of bacterial membrane phospholipids. In fact, sPLA2-IIA effectively kills Gram-positive bacteria and to a lesser extent Gram-negative bacteria and is considered a major component of the eye's innate immune defense system. The antibacterial properties of sPLA2 have been demonstrated in rabbit and human tears. In this report, we have analyzed the bactericidal activity of dromedary tears and the subsequently purified sPLA2 on several Gram-positive bacteria. Our results showed that the sPLA2 displays a potent bactericidal activity against all the tested bacteria particularly against the Staphylococcus strains when tested in the ionic environment of tears. There is a synergic action of the sPLA2 with lysozyme when added to the bacteria culture prior to sPLA2. Interestingly, lysozyme purified from dromedary tears showed a significant bactericidal activity against Listeria monocytogene and Staphylococcus epidermidis, whereas the one purified from human tears displayed no activity against these two strains. We have also demonstrated that Ca(2+) is crucial for the activity of dromedary tear sPLA2 and to a less extent Mg(2+) ions. Given the presence of sPLA2 in tears and intestinal secretions, this enzyme may play a substantial role in innate mucosal and systemic bactericidal defenses against Gram-positive bacteria.

Antibacterial Activity of AI-Hemocidin 2, a Novel N-Terminal Peptide of Hemoglobin Purified from Arca inflata.

PubMed

Li, Chunlei; Zhu, Jianhua; Wang, Yanqing; Chen, Yuyan; Song, Liyan; Zheng, Weiming; Li, Jingjing; Yu, Rongmin

2017-06-29

The continued emergence of antibiotic resistant bacteria in recent years is of great concern. The search for new classes of antibacterial agents has expanded to non-traditional sources such as shellfish. An antibacterial subunit of hemoglobin (Hb-I) was purified from the mantle of Arca inflata by phosphate extraction and ion exchange chromatography. A novel antibacterial peptide, AI-hemocidin 2, derived from Hb-I, was discovered using bioinformatics analysis. It displayed antibacterial activity across a broad spectrum of microorganisms, including several Gram-positive and Gram-negative bacteria, with minimal inhibitory concentration (MIC) values ranging from 37.5 to 300 μg/mL, and it exhibited minimal hemolytic or cytotoxic activities. The antibacterial activity of AI-hemocidin 2 was thermostable (25-100 °C) and pH resistant (pH 3-10). The cellular integrity was determined by flow cytometry. AI-hemocidin 2 was capable of permeating the cellular membrane. Changes in the cell morphology were observed with a scanning electron microscope. Circular dichroism spectra suggested that AI-hemocidin 2 formed an α-helix structure in the membrane mimetic environment. The results indicated that the anti-bacterial mechanism for AI-hemocidin 2 occurred through disrupting the cell membrane. AI-hemocidin 2 might be a potential candidate for tackling antibiotic resistant bacteria.

Antibacterial Activity of AI-Hemocidin 2, a Novel N-Terminal Peptide of Hemoglobin Purified from Arca inflata

PubMed Central

Li, Chunlei; Zhu, Jianhua; Wang, Yanqing; Chen, Yuyan; Song, Liyan; Zheng, Weiming; Li, Jingjing; Yu, Rongmin

2017-01-01

The continued emergence of antibiotic resistant bacteria in recent years is of great concern. The search for new classes of antibacterial agents has expanded to non-traditional sources such as shellfish. An antibacterial subunit of hemoglobin (Hb-I) was purified from the mantle of Arca inflata by phosphate extraction and ion exchange chromatography. A novel antibacterial peptide, AI-hemocidin 2, derived from Hb-I, was discovered using bioinformatics analysis. It displayed antibacterial activity across a broad spectrum of microorganisms, including several Gram-positive and Gram-negative bacteria, with minimal inhibitory concentration (MIC) values ranging from 37.5 to 300 μg/mL, and it exhibited minimal hemolytic or cytotoxic activities. The antibacterial activity of AI-hemocidin 2 was thermostable (25–100 °C) and pH resistant (pH 3–10). The cellular integrity was determined by flow cytometry. AI-hemocidin 2 was capable of permeating the cellular membrane. Changes in the cell morphology were observed with a scanning electron microscope. Circular dichroism spectra suggested that AI-hemocidin 2 formed an α-helix structure in the membrane mimetic environment. The results indicated that the anti-bacterial mechanism for AI-hemocidin 2 occurred through disrupting the cell membrane. AI-hemocidin 2 might be a potential candidate for tackling antibiotic resistant bacteria. PMID:28661457

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.

Chemical Composition, Antioxidant, DNA Damage Protective, Cytotoxic and Antibacterial Activities of Cyperus rotundus Rhizomes Essential Oil against Foodborne Pathogens

PubMed Central

Hu, Qing-Ping; Cao, Xin-Ming; Hao, Dong-Lin; Zhang, Liang-Liang

2017-01-01

Cyperus rotundus L. (Cyperaceae) is a medicinal herb traditionally used to treat various clinical conditions at home. In this study, chemical composition of Cyperus rotundus rhizomes essential oil, and in vitro antioxidant, DNA damage protective and cytotoxic activities as well as antibacterial activity against foodborne pathogens were investigated. Results showed that α-cyperone (38.46%), cyperene (12.84%) and α-selinene (11.66%) were the major components of the essential oil. The essential oil had an excellent antioxidant activity, the protective effect against DNA damage, and cytotoxic effects on the human neuroblastoma SH-SY5Y cell, as well as antibacterial activity against several foodborne pathogens. These biological activities were dose-dependent, increasing with higher dosage in a certain concentration range. The antibacterial effects of essential oil were greater against Gram-positive bacteria as compared to Gram-negative bacteria, and the antibacterial effects were significantly influenced by incubation time and concentration. These results may provide biological evidence for the practical application of the C. rotundus rhizomes essential oil in food and pharmaceutical industries. PMID:28338066

Design, synthesis and antibacterial evaluation of honokiol derivatives.

PubMed

Wu, Bo; Fu, Su-Hong; Tang, Huan; Chen, Kai; Zhang, Qiang; Peng, Ai-Hua; Ye, Hao-Yu; Cheng, Xing-Jun; Lian, Mao; Wang, Zhen-Ling; Chen, Li-Juan

2018-02-15

Staphylococcus aureus is a major and dangerous human pathogen that causes a range of clinical manifestations of varying severity, and is the most commonly isolated pathogen in the setting of skin and soft tissue infections, pneumonia, suppurative arthritis, endovascular infections, foreign-body associated infections, septicemia, osteomyelitis, and toxic shocksyndrome. Honokiol, a pharmacologically active natural compound derived from the bark of Magnolia officinalis, has antibacterial activity against Staphylococcus aureus which provides a great inspiration for the discovery of potential antibacterial agents. Herein, honokiol derivatives were designed, synthesized and evaluated for their antibacterial activity by determining the minimum inhibitory concentration (MIC) against S. aureus ATCC25923 and Escherichia coli ATCC25922 in vitro. 7c exhibited better antibacterial activity than other derivatives and honokiol. The structure-activity relationships indicated piperidine ring with amino group is helpful to improve antibacterial activity. Further more, 7c showed broad spectrum antibacterial efficiency against various bacterial strains including eleven gram-positive and seven gram-negative species. Time-kill kinetics against S. aureus ATCC25923 in vitro revealed that 7c displayed a concentration-dependent effect and more rapid bactericidal kinetics better than linezolid and vancomycin with the same concentration. Gram staining assays of S. aureus ATCC25923 suggested that 7c could destroy the cell walls of bacteria at 1×MIC and 4×MIC. Copyright © 2017. Published by Elsevier Ltd.

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.

A bioactivity guided study on the antibacterial activity of Hertia cheirifolia L. extracts.

PubMed

Majouli, Kaouther; Hamdi, Assia; Msaada, Kamel; Kenani, Abderraouf

2017-05-01

This study was carried out with the objective to investigate the antibacterial activity of Hertia cheirifolia L. extracts against Gram-positive and Gram-negative strains including Staphylococcus aureus (ATCC 6538), Bacillus subtilis (ATCC 6633), Bacillus licheniformis, Esherichia coli (ATCC 8739), Pseudomonas aeruginosa (ATCC 9027), Salmonella enterica (CIP 8039) and Salmonella typhimirium. The results of this antibacterial screening showed that the ethyl acetate (EtOAc) extracts had the best activity against the tested microorganisms. A bioassay-oriented fractionation approach for the more active extract (roots ethyl acetate extract) led to the obtaining five sub-fractions. Furthermore, these sub-fractions were also tested for antimicrobial activity and the best results were obtained for the roots EtOAc sub-fraction (C) with MICs values between 0.039 and 0.156 mg/mL. Reversed-phase high performance liquid chromatography (RP-HPLC) analysis indicated that the major phenolic components of active (EtOAc) extracts and sub-fraction (C) are fisetin hydrate (82.06%), trans cinnamic acid (63.66%), gallic acid (38.97%) and myricetin (20.92%). These results may help to improve these natural antibacterial substances that could serve as selective agents for bacterial diseases. Copyright © 2016 Elsevier Ltd. All rights reserved.

Superparamagnetic nickel colloidal nanocrystal clusters with antibacterial activity and bacteria binding ability

NASA Astrophysics Data System (ADS)

Peng, Bo; Zhang, Xinglin; Aarts, Dirk G. A. L.; Dullens, Roel P. A.

2018-06-01

Recent progress in synthetic nanotechnology and the ancient use of metals in food preservation and the antibacterial treatment of wounds have prompted the development of nanometallic materials for antimicrobial applications1-4. However, the materials designed so far do not simultaneously display antimicrobial activity and the capability of binding and capturing bacteria and spores. Here, we develop a one-step pyrolysis procedure to synthesize monodisperse superparamagnetic nickel colloidal nanocrystal clusters (SNCNCs), which show both antibacterial activity and the ability to bind Gram-positive (Bacillus subtilis) and Gram-negative (Escherichia coli) bacteria, as well as bacterial spores. The SNCNCs are formed from a rapid burst of nickel nanoparticles, which self-assemble slowly into clusters. The clusters can magnetically extract 99.99% of bacteria and spores and provide a promising approach for the removal of microbes, including hard-to-treat microorganisms. We believe that our work illustrates the exciting opportunities that nanotechnology offers for alternative antimicrobial strategies and other applications in microbiology.

[In vitro and in vivo antibacterial activities of sulopenem, a new penem antibiotic].

PubMed

Komoto, A; Otsuki, M; Nishino, T

1996-04-01

The in vitro and in vivo antibacterial activities of sulopenem, a new penem, were evaluated in comparison with imipenem (IPM), meropenem (MEPM), ceftazidime (CAZ) and flomoxef (FMOX). Sulopenem had broad and potent antibacterial spectra against Gram-positive and Gram-negative bacteria, including Enterococcus faecalis, Proteus vulgaris, Morganella morganii, Enterobacter spp. and Citrobacter freundii. Sulopenem showed concentration-dependent bactericidal activities against Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae and Acinetobacter calcoaceticus. Morphological observation using phase-contrast microscope revealed that sulopenem induced spherical cell formation with E. coli and K. pneumoniae at lower concentrations and bacteriolysis at higher concentrations. Therapeutic efficacies of sulopenem against systemic infections in mice were almost equal to those of imipenem against Streptococcus pneumoniae. While its therapeutic efficacies were superior to those of meropenem, ceftazidime and flomoxef against S. aureus and S. pneumoniae, they were inferior to those of imipenem/cilastatin against S. aureus, K. pneumoniae and A. calcoaceticus.

Antibacterial and glucosyltransferase enzyme inhibitory activity of helmyntostachyszelanica

NASA Astrophysics Data System (ADS)

Kuspradini, H.; Putri, AS; Mitsunaga, T.

2018-04-01

Helminthostachyszeylanica is a terrestrial, herbaceous, fern-like plant of southeastern Asia and Australia, commonly known as tunjuk-langit. This kind of plant have a medicinal properties such as treatment of malaria, dysentery and can be eaten with betel in the treatment of whooping cough. To evaluate the scientific basis for the use of the plant, the antimicrobial activities of extracts of the stem and leaves were evaluated. The bacteria used in this study is Streptococcus sobrinus, a species of gram-positive, that may be associated with human dental caries. The dried powdered plant parts were extracted using methanol and 50% aqueous extract and screened for their antibacterial effects of Streptococcus sobrinus using the 96 well-plate microdilution broth method. The inhibitory activities of its related enzyme were also determined. The plant extracts showed variable antibacterial and Glucosyltransferase enzyme inhibitory activity while some extracts could not cause any inhibition. It was shown that 50% ethanolics of Helminthostachyzeylanica stem have a potency as anti dental caries agents.

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 μg/mL (0.25->1 mmol/L). Gram-positive bacteria were inhibited at concentrations between 60 and 120 μg/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 μg/mL. Adherence/biofilm formations were decreased to 15 μg/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.

Linezolid: a pharmacoeconomic review of its use in serious Gram-positive infections.

PubMed

Plosker, Greg L; Figgitt, David P

2005-01-01

Linezolid (Zyvox), the first available oxazolidinone antibacterial agent, has good activity against Gram-positive pathogens, including multidrug-resistant organisms such as methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus faecium. Randomised multicentre trials in patients with various types of serious Gram-positive infections showed that clinical cure rates with linezolid were similar to those with vancomycin or teicoplanin. In some subgroup analyses, which must be interpreted with a degree of caution, clinical advantages were noted for linezolid (e.g. versus vancomycin in confirmed MRSA nosocomial pneumonia and MRSA-complicated skin and soft tissue infections). Although generally well tolerated, gastrointestinal adverse effects are relatively common with linezolid and it has been associated with thrombocytopenia and myelosuppression. The oral bioavailability of linezolid is approximately 100%, thus allowing sequential intravenous-to-oral administration without changing the drug or dosage regimen. Healthcare resource use data from various countries indicate that this practical advantage translates into at least a trend towards reduced length of hospital stay compared with vancomycin, which may offset its several-fold higher acquisition cost. Modelled analyses from the US, despite some limitations, indicate that, compared with vancomycin, linezolid is associated with lower total hospitalisation costs for the treatment of patients with cellulitis and has a favourable incremental cost-effectiveness ratio of approximately US30,000 dollars per QALY gained (2001 value) for patients with ventilator-associated pneumonia. Broadly similar results have also been reported in modelled analyses from other countries. In conclusion, for patients with serious Gram-positive infections, including those caused by suspected or proven multidrug-resistant pathogens such as MRSA, linezolid is an effective and generally well tolerated therapeutic

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.

Influence of human ascitic fluid on the in vitro antibacterial activity of moxifloxacin.

PubMed

Miglioli, P A; Cappellari, G; Cavallaro, A; Cardaioli, C; Sossai, P; Fille, M; Allerberger, F

2005-08-01

We investigated the in vitro influence of HAF on the antibacterial activity of moxifloxacin against Escherichia coli ATCC 10798, Escherichia coli K-12, Proteus rettgeri (Sanelli), Staphylococcus aureus ATCC 25923, Staphylococcus aureus NCTC 1808 and Staphylococcus epidermidis ATCC 12228. Human ascitic fluid was obtained from 6 cirrhotic patients by paracentesis. The interaction effect was evaluated by the checkerboard technique. Our results indicate the ability of human ascitic fluid to reduce minimum inhibitory concentrations of moxifloxacin against Gram-negative bacteria, but not against Gram-positives.

A novel insect defensin mediates the inducible antibacterial activity in larvae of the dragonfly Aeschna cyanea (Paleoptera, Odonata).

PubMed

Bulet, P; Cociancich, S; Reuland, M; Sauber, F; Bischoff, R; Hegy, G; Van Dorsselaer, A; Hetru, C; Hoffmann, J A

1992-11-01

The injection of low doses of bacteria into the aquatic larvae of dragonflies (Aeschna cyanea, Odonata, Paleoptera) induces the appearance in their hemolymph of a potent antibacterial activity. We have isolated a 38-residue peptide from this hemolymph which is strongly active against Gram-positive bacteria and also shows activity against one of the Gram-negative bacteria which was tested. The peptide is a novel member of the insect defensin family of inducible antibacterial peptides, which had so far only been reported from the higher insect orders believed to have evolved 100 million years after the Paleoptera. Aeschna defensin is more potent than defensin from the dipteran Phormia, from which its structure differs in several interesting aspects, which are discussed in the paper.

Trimethyl chitosan-capped silver nanoparticles with positive surface charge: Their catalytic activity and antibacterial spectrum including multidrug-resistant strains of Acinetobacter baumannii.

PubMed

Chang, T Y; Chen, C C; Cheng, K M; Chin, C Y; Chen, Y H; Chen, X A; Sun, J R; Young, J J; Chiueh, T S

2017-07-01

We report a facile route for the green synthesis of trimethyl chitosan nitrate-capped silver nanoparticles (TMCN-AgNPs) with positive surface charge. In this synthesis, silver nitrate, glucose, and trimethyl chitosan nitrate (TMCN) were used as silver precursor, reducing agent, and stabilizer, respectively. The reaction was carried out in a stirred basic aqueous medium at room temperature without the use of energy-consuming or expensive equipment. We investigated the effects of the concentrations of NaOH, glucose, and TMCN on the particle size, zeta potential, and formation yield. The AgNPs were characterized by UV-vis spectroscopy, photon correlation spectroscopy, laser Doppler anemometry, transmission electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The catalytic activity of the TMCN-AgNPs was studied by the reduction of 4-nitrophenol using NaBH 4 as a reducing agent. We evaluated the antibacterial effects of the TMCN-AgNPs on Acinetobacter baumannii, Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus using the broth microdilution method. The results showed that both gram-positive and gram-negative bacteria were killed by the TMCN-AgNPs at very low concentration (<6.13μg/mL). Moreover, the TMCN-AgNPs also showed high antibacterial activity against clinically isolated multidrug-resistant A. baumannii strains, and the minimum inhibitory concentration (MIC) was ≤12.25μg/mL. Copyright © 2017 Elsevier B.V. All rights reserved.

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 (~\

Antibacterial and Cytotoxic Activity of Compounds Isolated from Flourensia oolepis.

PubMed

Joray, Mariana Belén; Trucco, Lucas Daniel; González, María Laura; Napal, Georgina Natalia Díaz; Palacios, Sara María; Bocco, José Luis; Carpinella, María Cecilia

2015-01-01

The antibacterial and cytotoxic effects of metabolites isolated from an antibacterial extract of Flourensia oolepis were evaluated. Bioguided fractionation led to five flavonoids, identified as 2',4'-dihydroxychalcone (1), isoliquiritigenin (2), pinocembrin (3), 7-hydroxyflavanone (4), and 7,4'-dihydroxy-3'-methoxyflavanone (5). Compound 1 showed the highest antibacterial effect, with minimum inhibitory concentration (MIC) values ranging from 31 to 62 and 62 to 250 μg/mL, against Gram-positive and Gram-negative bacteria, respectively. On further assays, the cytotoxic effect of compounds 1-5 was determined by MTT assay on acute lymphoblastic leukemia (ALL) and chronic myeloid leukemia (CML) cell lines including their multidrug resistant (MDR) phenotypes. Compound 1 induced a remarkable cytotoxic activity toward ALL cells (IC50 = 6.6-9.9 μM) and a lower effect against CML cells (IC50 = 27.5-30.0 μM). Flow cytometry was used to analyze cell cycle distribution and cell death by PI-labeled cells and by Annexin V/PI staining, respectively. Upon treatment, 1 induced cell cycle arrest in the G2/M phase accompanied by a strong induction of apoptosis. These results describe for the first time the antibacterial metabolites of F. oolepis extract, with 1 being the most effective. This chalcone also emerges as a selective cytotoxic agent against sensitive and resistant leukemic cells, highlighting its potential as a lead compound.

Synthesis and Antibacterial Activity of Quaternary Ammonium 4-Deoxypyridoxine Derivatives

PubMed Central

Shtyrlin, Nikita V.; Sapozhnikov, Sergey V.; Galiullina, Albina S.; Kayumov, Airat R.; Bondar, Oksana V.; Mirchink, Elena P.; Isakova, Elena B.; Firsov, Alexander A.; Balakin, Konstantin V.

2016-01-01

A series of novel quaternary ammonium 4-deoxypyridoxine derivatives was synthesized. Two compounds demonstrated excellent activity against a panel of Gram-positive methicillin-resistant S. aureus strains with MICs in the range of 0.5–2 μg/mL, exceeding the activity of miramistin. At the same time, both compounds were inactive against the Gram-negative E. coli and P. aeruginosa strains. Cytotoxicity studies on human skin fibroblasts and embryonic kidney cells demonstrated that the active compounds possessed similar toxicity with benzalkonium chloride but were slightly more toxic than miramistin. SOS-chromotest in S. typhimurium showed the lack of DNA-damage activity of both compounds; meanwhile, one compound showed some mutagenic potential in the Ames test. The obtained results make the described chemotype a promising starting point for the development of new antibacterial therapies. PMID:27800491

In Vitro and In Vivo Antibacterial Activities of OPC-20011, a Novel Parenteral Broad-Spectrum 2-Oxaisocephem Antibiotic

PubMed Central

Matsumoto, Makoto; Tamaoka, Hisashi; Ishikawa, Hiroshi; Kikuchi, Mikio

1998-01-01

OPC-20011, a new parenteral 2-oxaisocephem antibiotic, has an oxygen atom at the 2- position of the cephalosporin frame. OPC-20011 had the best antibacterial activities against gram-positive bacteria, including methicillin-resistant Staphylococcus aureus (MRSA), Enterococcus faecalis, and penicillin-resistant Streptococcus pneumoniae: MICs at which 90% of the isolates were inhibited were 6.25, 6.25, and 0.05 μg/ml, respectively. Its activity is due to a high affinity of the penicillin-binding protein 2′ in MRSA, an affinity which was approximately 1,050 times as high as that for flomoxef. Against gram-negative bacteria, OPC-20011 also showed antibacterial activities similar to those of ceftazidime. The in vivo activities of OPC-20011 were comparable to or greater than those of reference compounds in murine models of systemic infection caused by gram-positive and -negative pathogens. OPC-20011 was up to 10 times as effective as vancomycin against MRSA infections in mice. This better in vivo efficacy is probably due to the bactericidal activity of OPC-20011, while vancomycin showed bacteriostatic activity against MRSA. OPC-20011 produced a significant decrease of viable counts in lung tissue at a dose of 2.5 mg/kg of body weight, an efficacy similar to that of ampicillin at a dose of 10 to 20 mg/kg on an experimental murine model of respiratory tract infection caused by non-ampicillin-susceptible S. pneumoniae T-0005. The better therapeutic efficacy of OPC-20011 was considered to be due to its potent antibacterial activity and low affinity for serum proteins of experimental animals (29% in mice and 6.4% in rats). PMID:9797230

Synthesis of nanosheets of lead using leaf extracts of Momordica charantia and studies its antibacterial activity

NASA Astrophysics Data System (ADS)

Ramteke, A. A.; Kurade, S. S.

2018-05-01

In the present paper, we have carried out a green synthesis of lead nano materials (PbNMs) using extract of Momordica charantia. We have characterized nano materials by using scanning electron microscopy, x-ray diffraction and UV-visible spectroscopy. It is found that PbNMs show antibacterial activity against pathogenic bacteria of gram positive (S. aureus,) and gram negative strains (E. coli, P. aeruginosa) using well diffusion technique and gives reasonably interesting results.

Indolo[3,2-c]cinnolines with antiproliferative, antifungal, and antibacterial activity.

PubMed

Barraja, P; Diana, P; Lauria, A; Passannanti, A; Almerico, A M; Minnei, C; Longu, S; Congiu, D; Musiu, C; La Colla, P

1999-08-01

A series of indolo[3,2-c]cinnoline derivatives was prepared and tested to evaluate their biological activity. Most of them inhibited the proliferation of leukemia, lymphoma and solid tumor-derived cell lines at micromolar concentrations, whereas none of the compounds were active against HIV-1. With the exception of 7g, all title compounds showed antibacterial activity against gram-positive bacteria, being up to 200 times more potent than the reference drug streptomycin. Some of the indolo[3,2-c]cinnolines were also endowed with good antifungal activity, particularly against Criptococcus neoformans.

Chemical composition and antibacterial activity of essential oils from Thymus spinulosus Ten. (Lamiaceae).

PubMed

De Feo, Vincenzo; Bruno, Maurizio; Tahiri, Bochra; Napolitano, Francesco; Senatore, Felice

2003-06-18

The chemical composition of essential oils from aerial parts of Thymus spinulosus Ten. (Lamiaceae) is reported. Four oils from plants growing in different environmental conditions were characterized by GC and GC-MS methods; the oils seem to indicate a new chemotype in the genus Thymus. Influences of soil and altitude characteristics on the essential oil composition are discussed. The oils showed antibacterial activity against Gram-positive (Staphylococcus aureus, Streptococcus faecalis, Bacillus subtilis, and Bacillus cereus) and Gram-negative (Proteus mirabilis, Escherichia coli, Salmonella typhimuium Ty2, and Pseudomonas aeruginosa) bacteria.

Antioxidant Potential and Antibacterial Efficiency of Caffeic Acid-Functionalized ZnO Nanoparticles

PubMed Central

Choi, Kyong-Hoon; Nam, Ki Chang; Lee, Sang-Yoon; Cho, Guangsup; Jung, Jin-Seung; Kim, Ho-Joong; Park, Bong Joo

2017-01-01

We report a novel zinc oxide (ZnO) nanoparticle with antioxidant properties, prepared by immobilizing the antioxidant 3-(3,4-dihydroxyphenyl)-2-propenoic acid (caffeic acid, CA) on the surfaces of micro-dielectric barrier discharge (DBD) plasma-treated ZnO nanoparticles. The microstructure and physical properties of ZnO@CA nanoparticles were characterized by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), infrared spectroscopy, and steady state spectroscopic methods. The antioxidant activity of ZnO@CA nanoparticles was evaluated using an ABTS (3-ethyl-benzothiazoline-6-sulfonic acid) radical cation decolorization assay. ZnO@CA nanoparticles exhibited robust antioxidant activity. Moreover, ZnO@CA nanoparticles showed strong antibacterial activity against Gram-positive bacteria (Staphylococcus aureus) including resistant bacteria such as methicillin-resistant S. aureus and against Gram-negative bacteria (Escherichia coli). Although Gram-negative bacteria appeared to be more resistant to ZnO@CA nanoparticles than Gram-positive bacteria, the antibacterial activity of ZnO@CA nanoparticles was dependent on particle concentration. The antioxidant and antibacterial activity of ZnO@CA may be useful for various biomedical and nanoindustrial applications. PMID:28621707

Antioxidant and antibacterial activity of six edible wild plants (Sonchus spp.) in China.

PubMed

Xia, Dao-Zong; Yu, Xin-Fen; Zhu, Zhuo-Ying; Zou, Zhuang-Dan

2011-12-01

The total phenolic and flavonoid, antioxidant and antibacterial activities of six Sonchus wild vegetables (Sonchus oleraceus L., Sonchus arvensis L., Sonchus asper (L.) Hill., Sonchus uliginosus M.B., Sonchus brachyotus DC. and Sonchus lingianus Shih) in China were investigated. The results revealed that S. arvensis extract and S. oleraceus extract contained the highest amount of phenolic and flavonoid, respectively. Among the methanol extracts of six Sonchus species, S. arvensis extract exhibited the highest radical (DPPH and ABTS+ scavenging power and lipid peroxidation inhibitory power. It also exhibited the highest reducing power at 500 µg mL⁻¹ by A (700) = 0.80. The results of antibacterial test indicated that the S. oleraceus extract showed higher activity than the other five Sonchus wild vegetables extracts, both in Gram-negative bacteria (Escherichia coli, Salmonella enterica and Vibrio parahaemolyticus) and in a Gram-positive bacterium (Staphylococcus aureus). These results indicate that Sonchus wild food plants might be applicable in natural medicine and healthy food.

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.

Antibacterial activities of the methanol extracts of ten Cameroonian vegetables against Gram-negative multidrug-resistant bacteria

PubMed Central

2013-01-01

Background Many edible plants are used in Cameroon since ancient time to control microbial infections. This study was designed at evaluating the antibacterial activities of the methanol extracts of ten Cameroonian vegetables against a panel of twenty nine Gram negative bacteria including multi-drug resistant (MDR) strains. Methods The broth microdilution method was used to determine the Minimal Inhibitory Concentrations (MIC) and the Minimal Bactericidal Concentrations (MBC) of the studied extracts. When chloramphenicol was used as a reference antibiotic, the MICs were also determined in the presence of Phenylalanine-Arginine β-Naphtylamide (PAβN), an efflux pumps inhibitor (EPI). The phytochemical screening of the extracts was performed using standard methods. Results All tested extracts exhibited antibacterial activities, with the MIC values varying from 128 to 1024 mg/L. The studied extracts showed large spectra of action, those from L. sativa, S. edule, C. pepo and S. nigrum being active on all the 29 bacterial strains tested meanwhile those from Amaranthus hybridus, Vernonia hymenolepsis, Lactuca.carpensis and Manihot esculenta were active on 96.55% of the strains used. The plant extracts were assessed for the presence of large classes of secondary metabolites: alkaloids, anthocyanins, anthraquinones, flavonoids, phenols, saponins, steroids, tannins and triterpenes. Each studied plant extract was found to contain compounds belonging to at least two of the above mentioned classes. Conclusion These results confirm the traditional claims and provide promising baseline information for the potential use of the tested vegetables in the fight against bacterial infections involving MDR phenotypes. PMID:23368430

Chemical synthesis and characterization of chitosan/silver nanocomposites films and their potential antibacterial activity.

PubMed

Shah, Aamna; Hussain, Izhar; Murtaza, Ghulam

2018-05-12

This study provides the optimum preparation parameters for functional chitosan silver nanocomposite (CSN) films with promising antibacterial efficacy though prepared with very low silver nitrate (AgNO 3 ) concentration. Chitosan nano‑silver composites were fabricated by In-situ chemical method utilizing the reducing ability of sodium borohydride (NaBH 4 ) and afterward casted into films. Utilization of response surface methodology, NCSS, and SigmaPlot for the optimization of CSN and their predicted antibacterial efficacy assessment of the selected bacterial strains (standard and clinical) was the essential part of the study. The cumulative silver ions released from the CSN films was examined by AAS and was found pH dependent. The developed nanocomposite films exhibited strong antibacterial activity against ATCC strains of Gram-positive Staphylococcus aureus, Gram-negative bacteria (Pseudomonas aeruginosa) and clinically isolated strains of MRSA. The antibacterial activity CSN films were compared with three commercially available dressings (Aquacel Ag®, Bactigras®, and Kaltostat®) and Quench cream. Statistical analysis of the results indicated that the developed CSN films were equally or even more effective than commercial products. Thus the fabricated CSN films may act as a potential candidate to overcome the emerging antibiotic resistance particularly in hospital-acquired skin infections caused by MRSA. Copyright © 2018. Published by Elsevier B.V.

Phenolic composition, antioxidant capacity and antibacterial activity of selected Irish Brassica vegetables.

PubMed

Jaiswal, Amit Kumar; Rajauria, Gaurav; Abu-Ghannam, Nissreen; Gupta, Shilpi

2011-09-01

Vegetables belonging to the Brassicaceae family are rich in polyphenols, flavonoids and glucosinolates, and their hydrolysis products, which may have antibacterial, antioxidant and anticancer properties. In the present study, phenolic composition, antibacterial activity and antioxidant capacity of selected Brassica vegetables, including York cabbage, Brussels sprouts, broccoli and white cabbage were evaluated after extraction with aqueous methanol. Results obtained showed that York cabbage extract had the highest total phenolic content, which was 33.5, followed by 23.6, 20.4 and 18.4 mg GAE/g of dried weight (dw) of the extracts for broccoli, Brussels sprouts and white cabbage, respectively. All the vegetable extracts had high flavonoid contents in the order of 21.7, 17.5, 15.4 and 8.75 mg QE/g of extract (dw) for York cabbage, broccoli, Brussels sprouts and white cabbage, respectively. HPLC-DAD analysis showed that different vegetables contain a mixture of distinct groups of phenolic compounds. All the extracts studied showed a rapid and concentration dependent antioxidant capacity in diverse antioxidant systems. The antibacterial activity was determined against Gram-positive and Gram-negative bacteria. York cabbage extract exhibited significantly higher antibacterial activity against Listeria monocytogenes (100%) and Salmonella abony (94.3%), being the most susceptible at a concentration of 2.8%, whereas broccoli, Brussels sprouts and white cabbage had moderate to weak activity against all the test organisms. Good correlation (r2 0.97) was found between total phenolic content obtained by spectrophotometric analysis and the sum of the individual polyphenols monitored by HPLC-DAD.

Synthesis and Antibacterial Evaluation of Novel 3-Substituted Ocotillol-Type Derivatives as Leads.

PubMed

Bi, Yi; Liu, Xian-Xuan; Zhang, Heng-Yuan; Yang, Xiao; Liu, Ze-Yun; Lu, Jing; Lewis, Peter John; Wang, Chong-Zhi; Xu, Jin-Yi; Meng, Qing-Guo; Ma, Cong; Yuan, Chun-Su

2017-04-07

Due to the rapidly growing bacterial antibiotic-resistance and the scarcity of novel agents in development, bacterial infection is still a global problem. Therefore, new types of antibacterial agents, which are effective both alone and in combination with traditional antibiotics, are urgently needed. In this paper, a series of antibacterial ocotillol-type C-24 epimers modified from natural 20( S )-protopanaxadiol were synthesized and evaluated for their antibacterial activity. According to the screening results of Gram-positive bacteria ( B. subtilis 168 and MRSA USA300) and Gram-negative bacteria ( P. aer PAO1 and A. baum ATCC19606) in vitro, the derivatives exhibited good antibacterial activity, particularly against Gram-positive bacteria with an minimum inhibitory concentrations (MIC) value of 2-16 µg/mL. The subsequent synergistic antibacterial assay showed that derivatives 5c and 6c enhanced the susceptibility of B. subtilis 168 and MRSA USA300 to chloramphenicol (CHL) and kanamycin (KAN) (FICI < 0.5). Our data showed that ocotillol-type derivatives with long-chain amino acid substituents at C-3 were good leads against antibiotic-resistant pathogens MRSA USA300, which could improve the ability of KAN and CHL to exhibit antibacterial activity at much lower concentrations with reduced toxicity.

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

PubMed

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

2015-07-01

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

An unusual class of anthracyclines potentiate Gram-positive antibiotics in intrinsically resistant Gram-negative bacteria.

PubMed

Cox, Georgina; Koteva, Kalinka; Wright, Gerard D

2014-07-01

An orthogonal approach taken towards novel antibacterial drug discovery involves the identification of small molecules that potentiate or enhance the activity of existing antibacterial agents. This study aimed to identify natural-product rifampicin adjuvants in the intrinsically resistant organism Escherichia coli. E. coli BW25113 was screened against 1120 actinomycete fermentation extracts in the presence of subinhibitory (2 mg/L) concentrations of rifampicin. The active molecule exhibiting the greatest rifampicin potentiation was isolated using activity-guided methods and identified using mass and NMR spectroscopy. Susceptibility testing and biochemical assays were used to determine the mechanism of antibiotic potentiation. The anthracycline Antibiotic 301A(1) was isolated from the fermentation broth of a strain of Streptomyces (WAC450); the molecule was shown to be highly synergistic with rifampicin (fractional inhibitory concentration index = 0.156) and moderately synergistic with linezolid (FIC index = 0.25) in both E. coli and Acinetobacter baumannii. Activity was associated with inhibition of efflux and the synergistic phenotype was lost when tested against E. coli harbouring mutations within the rpoB gene. Structure-activity relationship studies revealed that other anthracyclines do not synergize with rifampicin and removal of the sugar moiety of Antibiotic 301A(1) abolishes activity. Screening only a subsection of our natural product library identified a small-molecule antibiotic adjuvant capable of sensitizing Gram-negative bacteria to antibiotics to which they are ordinarily intrinsically resistant. This result demonstrates the great potential of this approach in expanding antibiotic effectiveness in the face of the growing challenge of resistance in Gram-negatives. © The Author 2014. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

The investigation of antibacterial activity of selected native plants from North of Iran.

PubMed

Koohsari, H; Ghaemi, E A; Sadegh Sheshpoli, M; Jahedi, M; Zahiri, M

2015-01-01

Plant derived products have been used for medicinal purposes during centuries. Bacterial resistance to currently used antibiotics has become a concern to public health. The development of bacterial super resistant strains has resulted in the currently used antibiotic agents failing to end many bacterial infections. For this reason, the search is ongoing for new antimicrobial agents, both by the design and by the synthesis of new agents, or through the search of natural sources for yet undiscovered antimicrobial agents. Herbal medications in particular have seen a revival of interest due to a perception that there is a lower incidence of adverse reactions to plant preparations compared to synthetic pharmaceuticals. Coupled with the reduced costs of plant preparations, this makes the search for natural therapeutics an attractive option. This research was carried out to assess the antibacterial activity aqueous and ethanolic extracts of six Azadshahr township Native plants in north of Iran against six species of pathogen bacteria by using three methods of Disk diffusion, Well method and MBC. The results of this research indicated that the effect of ethanol extracts were more than aqueous extract and among six plants, Lippia citriodora and Plantago major ethanol extract had the most antibacterial activity in any of the three methods. Gram-positive bacteria were more sensitive than gram-negative bacteria. Staphylococcus epidermidis and Staphylococcus aureus were the most susceptible Gram-positive bacteria.

Antibacterial activity of lactose-binding lectins from Bufo arenarum skin.

PubMed

Sánchez Riera, Alicia; Daud, Adriana; Gallo, Adriana; Genta, Susana; Aybar, Manuel; Sánchez, Sara

2003-04-01

Amphibians respond to microbial infection through cellular and humoral defense mechanisms such as antimicrobial protein secretion. Most humoral defense proteins are synthetized in the skin. In this study we isolated two beta-galactoside-binding lectins with molecular weights of 50 and 56 KDa from the skin of Bufo arenarum. These lectins have significant hemagglutination activity against trypsinized rabbit erythrocytes, which was inhibited by galactose-containing saccharides. They are water-soluble and independent of the presence of calcium. The antimicrobial analysis for each lectin was performed. At mumolar concentration lectins show strong bacteriostatic activity against Gram negative bacteria (Escherichia coli K12 4100 and wild strains of Escherichia coli and Proteus morganii) and Gram positive bacteria (Enterococcus faecalis). The antibacterial activity of these lectins may provide an effective defense against invading microbes in the amphibian Bufo arenarum.

The oxadiazole antibacterials.

PubMed

Janardhanan, Jeshina; Chang, Mayland; Mobashery, Shahriar

2016-10-01

The oxadiazoles are a class of antibacterials discovered by in silico docking and scoring of compounds against the X-ray structure of a penicillin-binding protein. These antibacterials exhibit activity against Gram-positive bacteria, including against methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus (VRE). They show in vivo efficacy in murine models of peritonitis/sepsis and neutropenic thigh MRSA infection. They are bactericidal and orally bioavailable. The oxadiazoles show promise in treatment of MRSA infection. Copyright © 2016 Elsevier Ltd. All rights reserved.

Identification of novel macrolides with antibacterial, anti-inflammatory and type I and III IFN-augmenting activity in airway epithelium.

PubMed

Porter, James D; Watson, Jennifer; Roberts, Lee R; Gill, Simren K; Groves, Helen; Dhariwal, Jaideep; Almond, Mark H; Wong, Ernie; Walton, Ross P; Jones, Lyn H; Tregoning, John; Kilty, Iain; Johnston, Sebastian L; Edwards, Michael R

2016-10-01

Exacerbations of asthma and COPD are triggered by rhinoviruses. Uncontrolled inflammatory pathways, pathogenic bacterial burden and impaired antiviral immunity are thought to be important factors in disease severity and duration. Macrolides including azithromycin are often used to treat the above diseases, but exhibit variable levels of efficacy. Inhaled corticosteroids are also readily used in treatment, but may lack specificity. Ideally, new treatment alternatives should suppress unwanted inflammation, but spare beneficial antiviral immunity. In the present study, we screened 225 novel macrolides and tested them for enhanced antiviral activity against rhinovirus, as well as anti-inflammatory activity and activity against Gram-positive and Gram-negative bacteria. Primary bronchial epithelial cells were grown from 10 asthmatic individuals and the effects of macrolides on rhinovirus replication were also examined. Another 30 structurally similar macrolides were also examined. The oleandomycin derivative Mac5, compared with azithromycin, showed superior induction (up to 5-fold, EC50 = 5-11 μM) of rhinovirus-induced type I IFNβ, type III IFNλ1 and type III IFNλ2/3 mRNA and the IFN-stimulated genes viperin and MxA, yet had no effect on IL-6 and IL-8 mRNA. Mac5 also suppressed rhinovirus replication at 48 h, proving antiviral activity. Mac5 showed antibacterial activity against Gram-positive Streptococcus pneumoniae; however, it did not have any antibacterial properties compared with azithromycin when used against Gram-negative Escherichia coli (as a model organism) and also the respiratory pathogens Pseudomonas aeruginosa and non-typeable Haemophilus influenzae. Further non-toxic Mac5 derivatives were identified with various anti-inflammatory, antiviral and antibacterial activities. The data support the idea that macrolides have antiviral properties through a mechanism that is yet to be ascertained. We also provide evidence that macrolides can be developed with

Novel antibacterial polypeptide produced by Lactobacillus paracasei strain NRRL B-50314

USDA-ARS?s Scientific Manuscript database

This study reports the production and characterization of a novel antibacterial polypeptide, designated as laparaxin, which is secreted by Lactobacillus paracasei NRRL B-50314. The crude laparaxin has antibacterial activity against a range of Gram-positive bacteria including the following: lactic a...

Gepotidacin (GSK2140944) In Vitro Activity against Gram-Positive and Gram-Negative Bacteria

PubMed Central

Farrell, D. J.; Rhomberg, P. R.; Scangarella-Oman, N. E.; Sader, H. S.

2017-01-01

ABSTRACT Gepotidacin is a first-in-class, novel triazaacenaphthylene antibiotic that inhibits bacterial DNA replication and has in vitro activity against susceptible and drug-resistant pathogens. Reference in vitro methods were used to investigate the MICs and minimum bactericidal concentrations (MBCs) of gepotidacin and comparator agents for Staphylococcus aureus, Streptococcus pneumoniae, and Escherichia coli. Gepotidacin in vitro activity was also evaluated by using time-kill kinetics and broth microdilution checkerboard methods for synergy testing and for postantibiotic and subinhibitory effects. The MIC90 of gepotidacin for 50 S. aureus (including methicillin-resistant S. aureus [MRSA]) and 50 S. pneumoniae (including penicillin-nonsusceptible) isolates was 0.5 μg/ml, and for E. coli (n = 25 isolates), it was 4 μg/ml. Gepotidacin was bactericidal against S. aureus, S. pneumoniae, and E. coli, with MBC/MIC ratios of ≤4 against 98, 98, and 88% of the isolates tested, respectively. Time-kill curves indicated that the bactericidal activity of gepotidacin was observed at 4× or 10× MIC at 24 h for all of the isolates. S. aureus regrowth was observed in the presence of gepotidacin, and the resulting gepotidacin MICs were 2- to 128-fold higher than the baseline gepotidacin MICs. Checkerboard analysis of gepotidacin combined with other antimicrobials demonstrated no occurrences of antagonism with agents from multiple antimicrobial classes. The most common interaction when testing gepotidacin was indifference (fractional inhibitory concentration index of >0.5 to ≤4; 82.7% for Gram-positive isolates and 82.6% for Gram-negative isolates). The postantibiotic effect (PAE) of gepotidacin was short when it was tested against S. aureus (≤0.6 h against MRSA and MSSA), and the PAE–sub-MIC effect (SME) was extended (>8 h; three isolates at 0.5× MIC). The PAE of levofloxacin was modest (0.0 to 2.4 h), and the PAE-SME observed varied from 1.2 to >9 h at 0.5× MIC

The position of prenylation of isoflavonoids and stilbenoids from legumes (Fabaceae) modulates the antimicrobial activity against Gram positive pathogens.

PubMed

Araya-Cloutier, Carla; den Besten, Heidy M W; Aisyah, Siti; Gruppen, Harry; Vincken, Jean-Paul

2017-07-01

The legume plant family (Fabaceae) is a potential source of antimicrobial phytochemicals. Molecular diversity in phytochemicals of legume extracts was enhanced by germination and fungal elicitation of seven legume species, as established by RP-UHPLC-UV-MS. The relationship between phytochemical composition, including different types of skeletons and substitutions, and antibacterial properties of extracts was investigated. Extracts rich in prenylated isoflavonoids and stilbenoids showed potent antibacterial activity against Listeria monocytogenes and methicillin-resistant Staphylococcus aureus at concentrations between 0.05 and 0.1% (w/v). Prenylated phenolic compounds were significantly (p<0.01) correlated with the antibacterial properties of the extracts. Furthermore, the position of the prenyl group within the phenolic skeleton also influenced the antibacterial activity. Overall, prenylated phenolics from legume seedlings can serve multiple purposes, e.g. as phytoestrogens they can provide health benefits and as natural antimicrobials they offer preservation of foods. Copyright © 2017 Elsevier Ltd. All rights reserved.

[Estimation of activity of pharmakopeal disinfectants and antiseptics against Gram-negative and Gram-positive bacteria isolated from clinical specimens, drugs and environment].

PubMed

Grzybowska, Wanda; Młynarczyk, Grazyna; Młynarczyk, Andrzej; Bocian, Ewa; Luczak, Mirosław; Tyski, Stefan

2007-01-01

The MIC of nine different disinfectants and antiseptics were determined for the Gram-negative and Gram-positive bacteria. Strains originated from clinical specimens, drugs and environment. A sensitivity was determined against chlorhexidinum digluconate (Gram-negative: 0,625-80 mg/L, Gram-positive: 0,3-10 mg/L), benzalconium chloride (Gram-negative: 2,5-1280 mg/L, Gram-positive: 1,25-20 mg/L), salicilic acid (Gram-negative and Gram-positive: 400-1600 mg/L), benzoic acid (Gram-negative: 800-1600 mg/L, Gram-positive: 400-1 600 mg/L), boric acid (Gram-negative: 800-12 800 mg/L, Gram-positive: 1 600-6400 mg/L), chloramine B (Gram-negative: 1600-6400 mg/L, Gram-positive:800- 6400 mg/L), jodine (Gram-negative: 200-1600 mg/L, Gram-positive: 200-1600 mg/L), etacridine lactate (Gram-negative: 40 do > 20480 mg/L, Gram-positive: 40-1280 mg/L) and resorcine (Gram-negative: 1600-6400 mg/L, Gram-positive: 800-6400 mg/L). Diversified values of MIC for different strains were obtained, especially in the case of benzalconium chloride, etacridine lactate, chlorhexidinum digluconate, boric acid and iodine. Strains isolated from environment were usually more susceptible to examined compounds than clinical strains. The biggest diversification of sensitivity was observed among strains originated from drugs where besides sensitive appeared strains characterizing by very high MIC values of some substances, eg. boric acid.

Axinellamines as Broad-Spectrum Antibacterial Agents: Scalable Synthesis and Biology

PubMed Central

2015-01-01

Antibiotic-resistant bacteria present an ongoing challenge to both chemists and biologists as they seek novel compounds and modes of action to out-maneuver continually evolving resistance pathways, especially against Gram-negative strains. The dimeric pyrrole–imidazole alkaloids represent a unique marine natural product class with diverse primary biological activity and chemical architecture. This full account traces the strategy used to develop a second-generation route to key spirocycle 9, culminating in a practical synthesis of the axinellamines and enabling their discovery as broad-spectrum antibacterial agents, with promising activity against both Gram-positive and Gram-negative bacteria. While their detailed mode of antibacterial action remains unclear, the axinellamines appear to cause secondary membrane destabilization and impart an aberrant cellular morphology consistent with the inhibition of normal septum formation. This study serves as a rare example of a natural product initially reported to be devoid of biological activity surfacing as an active antibacterial agent with an intriguing mode of action. PMID:25328977

Synthesis and antibacterial activities of new 1 beta-methylcarbapenems having a 1,3-diazabicyclo[3.3.0]octan-2,4-dione moiety.

PubMed

Nam, K H; Oh, C H; Ham, Y W; Lee, K S; Cho, J H

1997-08-01

The synthesis of a new series of 1 beta-methylcarbapenems having a 1,3-diazabicyclo[3.3.0]octane-2,4-dione moiety is described. Their in vitro antibacterial activities against both Gram-positive and Gram-negative bateria are determined and the effect of substituent on the bicyclic ring as well as stereoisomerism was investigated.

Antibacterial and Cytotoxic Activity of Compounds Isolated from Flourensia oolepis

PubMed Central

Joray, Mariana Belén; Trucco, Lucas Daniel; González, María Laura; Napal, Georgina Natalia Díaz; Palacios, Sara María; Bocco, José Luis; Carpinella, María Cecilia

2015-01-01

The antibacterial and cytotoxic effects of metabolites isolated from an antibacterial extract of Flourensia oolepis were evaluated. Bioguided fractionation led to five flavonoids, identified as 2′,4′-dihydroxychalcone (1), isoliquiritigenin (2), pinocembrin (3), 7-hydroxyflavanone (4), and 7,4′-dihydroxy-3′-methoxyflavanone (5). Compound 1 showed the highest antibacterial effect, with minimum inhibitory concentration (MIC) values ranging from 31 to 62 and 62 to 250 μg/mL, against Gram-positive and Gram-negative bacteria, respectively. On further assays, the cytotoxic effect of compounds 1–5 was determined by MTT assay on acute lymphoblastic leukemia (ALL) and chronic myeloid leukemia (CML) cell lines including their multidrug resistant (MDR) phenotypes. Compound 1 induced a remarkable cytotoxic activity toward ALL cells (IC50 = 6.6–9.9 μM) and a lower effect against CML cells (IC50 = 27.5–30.0 μM). Flow cytometry was used to analyze cell cycle distribution and cell death by PI-labeled cells and by Annexin V/PI staining, respectively. Upon treatment, 1 induced cell cycle arrest in the G2/M phase accompanied by a strong induction of apoptosis. These results describe for the first time the antibacterial metabolites of F. oolepis extract, with 1 being the most effective. This chalcone also emerges as a selective cytotoxic agent against sensitive and resistant leukemic cells, highlighting its potential as a lead compound. PMID:26819623

Fabrication of Fe3O4@CuO core-shell from MOF based materials and its antibacterial activity

NASA Astrophysics Data System (ADS)

Rajabi, S. K.; Sohrabnezhad, Sh.; Ghafourian, S.

2016-12-01

Magnetic Fe3O4@CuO nanocomposite with a core/shell structure was successfully synthesized via direct calcinations of magnetic Fe3O4@HKUST-1 in air atmosphere. The morphology, structure, magnetic and porous properties of the as-synthesized nano composites were characterized by using scanning electron microscope (SEM), transmission electron microscopy (TEM), powder X-ray diffraction (PXRD), and vibration sample magnetometer (VSM). The results showed that the nanocomposite material included a Fe3O4 core and a CuO shell. The Fe3O4@CuO core-shell can be separated easily from the medium by a small magnet. The antibacterial activity of Fe3O4-CuO core-shell was investigated against gram-positive and gram-negative bacteria. A new mechanism was proposed for inactivation of bacteria over the prepared sample. It was demonstrated that the core-shell exhibit recyclable antibacterial activity, acting as an ideal long-acting antibacterial agent.

Simultaneous Fluorescent Gram Staining and Activity Assessment of Activated Sludge Bacteria

PubMed Central

Forster, Scott; Snape, Jason R.; Lappin-Scott, Hilary M.; Porter, Jonathan

2002-01-01

Wastewater treatment is one of the most important commercial biotechnological processes, and yet the component bacterial populations and their associated metabolic activities are poorly understood. The novel fluorescent dye hexidium iodide allows assessment of Gram status by differential absorption through bacterial cell walls. Differentiation between gram-positive and gram-negative wastewater bacteria was achieved after flow cytometric analysis. This study shows that the relative proportions of gram-positive and gram-negative bacterial cells identified by traditional microscopy and hexidium iodide staining were not significantly different. Dual staining of cells for Gram status and activity proved effective in analyzing mixtures of cultured bacteria and wastewater populations. Levels of highly active organisms at two wastewater treatment plants, both gram positive and gram negative, ranged from 1.5% in activated sludge flocs to 16% in the activated sludge fluid. Gram-positive organisms comprised <5% of the total bacterial numbers but accounted for 19 and 55% of the highly active organisms within flocs at the two plants. Assessment of Gram status and activity within activated sludge samples over a 4-day period showed significant differences over time. This method provides a rapid, quantitative measure of Gram status linked with in situ activity within wastewater systems. PMID:12324319

Simultaneous fluorescent gram staining and activity assessment of activated sludge bacteria.

PubMed

Forster, Scott; Snape, Jason R; Lappin-Scott, Hilary M; Porter, Jonathan

2002-10-01

Wastewater treatment is one of the most important commercial biotechnological processes, and yet the component bacterial populations and their associated metabolic activities are poorly understood. The novel fluorescent dye hexidium iodide allows assessment of Gram status by differential absorption through bacterial cell walls. Differentiation between gram-positive and gram-negative wastewater bacteria was achieved after flow cytometric analysis. This study shows that the relative proportions of gram-positive and gram-negative bacterial cells identified by traditional microscopy and hexidium iodide staining were not significantly different. Dual staining of cells for Gram status and activity proved effective in analyzing mixtures of cultured bacteria and wastewater populations. Levels of highly active organisms at two wastewater treatment plants, both gram positive and gram negative, ranged from 1.5% in activated sludge flocs to 16% in the activated sludge fluid. Gram-positive organisms comprised <5% of the total bacterial numbers but accounted for 19 and 55% of the highly active organisms within flocs at the two plants. Assessment of Gram status and activity within activated sludge samples over a 4-day period showed significant differences over time. This method provides a rapid, quantitative measure of Gram status linked with in situ activity within wastewater systems.

Antibacterial activity of Zuccagnia punctata Cav. ethanolic extracts.

PubMed

Zampini, Iris C; Vattuone, Marta A; Isla, Maria I

2005-12-01

The present study was conducted to investigate antibacterial activity of Zuccagnia punctata ethanolic extract against 47 strains of antibiotic-resistant Gram-negative bacteria and to identify bioactive compounds. Inhibition of bacterial growth was investigated using agar diffusion, agar macrodilution, broth microdilution and bioautographic methods. Zuccagnia punctata extract was active against all assayed bacteria (Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Enterobacter cloacae, Serratia marcescens, Morganella morganii, Acinetobacter baumannii, Pseudomonas aeruginosa, Stenotrophomonas maltophilia) with minimal inhibitory concentration (MIC) values ranging from 25 to 200 microg/mL. Minimal bactericidal concentration (MBC) values were identical or two-fold higher than the corresponding MIC values. Contact bioautography, indicated that Zuccagnia punctata extracts possess one major antibacterial component against Pseudomonas aeruginosa and at least three components against. Klebsiella pneumoniae and Escherichia coli. Activity-guided fractionation of 1he ethanol extract on a silica gel column yielded a compound (2',4'-dihydroxychalcone), which exhibited strong antibacterial activity with MIC values between 0.10 and 1.00 microg/mL for Proteus mirabilis, Enterobacter cloacae, Serratia marcescens, Morganella morganii, Acinetobacter baumannii, Pseudomonas aeruginosa, Stenotrophomonas maltophilia. These values are lower than imipenem (0.25-16 microg/mL). Zuccagnia punctata might provide promising therapeutic agents against infections with multi-resistant Gram-negative bacteria.

Synthesis, Anti-inflammatory and Antibacterial Activities of Novel Pyrazolo[4,3-g]pteridines.

PubMed

Abdel-Mohsen, Shawkat Ahmed; El-Emary, Talaat Ibrahim; El-Kashef, Hussein Salama

2016-01-01

A novel series of 6-substituted pyrazolo[3,4-g]pteridines 2-9 and pyrazolo[4,3-e][1,2,4]triazolo[1,5-c]pteridin-2(3H)-one (thione) 10 and 11 was synthesized using the starting compound 3,7-dimethyl-1-phenylpyrazolo[4',3':5,6]pyrazino[2,3-d][1,3]oxazin-5(1H)-one 2. The structure of the newly synthesized compounds was elucidated by IR, (1)H-NMR, (13)C-NMR, mass spectroscopy and elemental analyses. The anti-inflammatory activity of all the newly synthesized compounds was evaluated using the carrageenan-induced paw oedema test in rats using indomethacin as the reference drug. Compound 11 and the two derivatives 7f and 8b were the most active compounds, showing an activity comparable to indomethacin. Also, the synthesized compounds were evaluated for their antibacterial activity against Gram-positive bacteria (Staphylococcus aureus and Bacillus cereus) and Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa) using chloramphenicol as control. The pyrazolotriazolopteridin-2-thione 11, 6-hydroxyethyl- 6a, 6-(4-nitrophenyl)-7g, and 6-(phenylamino) 8b derivatives were found to be the most active compounds against the Gram-positive species. None of them showed any activity against Gram-negative species.

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.

Potent and broad-spectrum antibacterial activity of indole-based bisamidine antibiotics: synthesis and SAR of novel analogs of MBX 1066 and MBX 1090

PubMed Central

Williams, John D.; Nguyen, Son T.; Gu, Shen; Ding, Xiaoyuan; Butler, Michelle M.; Tashjian, Tommy F.; Opperman, Timothy J.; Panchal, Rekha G.; Bavari, Sina; Peet, Norton P.; Moir, Donald T.; Bowlin, Terry L.

2013-01-01

The prevalence of drug-resistant bacteria in the clinic has propelled a concerted effort to find new classes of antibiotics that will circumvent current modes of resistance. We have previously described a set of bisamidine antibiotics that contains a core composed of two indoles and a central linker. The first compounds of the series, MBX 1066 and MBX 1090, have potent antibacterial properties against a wide range of Gram-positive and Gram-negative bacteria. We have conducted a systematic exploration of the amidine functionalities, the central linker, and substituents at the indole 3-position to determine the factors involved in potent antibacterial activity. Some of the newly synthesized compounds have even more potent and broad-spectrum activity than MBX 1066 and MBX 1090. PMID:24239389

Diaminomaleonitrile-based azo receptors: Synthesis, DFT studies and their antibacterial activities

NASA Astrophysics Data System (ADS)

Khanmohammadi, Hamid; Arab, Vajihe; Rezaeian, Khatereh; Talei, Gholam Reza; Pass, Maryam; Shabani, Nafiseh

2017-02-01

New unsymmetric diaminomaleonitrile-based azo receptors (H3Ln, n = 1-3) have been synthesized via condensation reaction of 5-(4-X-phenyl)-azo-salicyladehyde (X = NO2, OMe and CH3) with 2-amino-3-(5-bromo-2-hydroxybenzylamino)maleonitrile. The solvatochromic behaviors of the molecules were probed by studying their UV-Vis spectra in five pure organic solvents of different polarities. The p-NO2 substituted receptor shows a dramatic color change from yellow to blue upon the addition of fluoride ion in CH3CN. This capability was studied by systematic TD-DFT calculations. These compounds were assayed for their in vitro antibacterial activities against Gram-positive (S. aureus, S. epidermidis and L. monocytogenes) and Gram-negative (E. coli, P. aeruginosa and K. pneumonia.) bacteria by disc diffusion method. The results indicated that the compounds show good inhibition against Gram positive bacteria namely L. monocytogenes as compared to standard drugs.

Antibacterial and cytotoxic activities of naphthoquinone pigments from Onosma visianii Clem.

PubMed

Vukic, Milena D; Vukovic, Nenad L; Djelic, Gorica T; Popovic, Suzana Lj; Zaric, Milan M; Baskic, Dejan D; Krstic, Gordana B; Tesevic, Vele V; Kacaniova, Miroslava M

2017-01-01

In this study, the antibacterial and cytotoxic activities of isolated compounds from the roots of Onosma visianii were investigated. By using different chromatographic techniques and appropriate spectroscopic methods, the seven naphthoquinones were described: deoxyshikonin ( 1 ), isobutyrylshikonin ( 2 ), α-methylbutyrylshikonin ( 3 ), acetylshikonin ( 4 ), β-hydroxyisovalerylshikonin ( 5 ), 5,8- O -dimethyl isobutyrylshikonin ( 6 ) and 5,8- O -dimethyl deoxyshikonin ( 7 ). Among the tested compounds, 3 and 4 exhibited the highest antibacterial activities toward all tested bacterial species (MIC 50 and MIC 90 for gram positive bacteria: 6.40 μg/mL-12.79 μg/mL and 6.82 μg/mL-13.60 μg/mL, respectively; for gram negative bacteria: 4.27 μg/mL-8.53 μg/mL and 4.77 μg/mL-9.54 μg/mL, respectively). Also, naphthoquinones 3 and 4 exhibited strong cytotoxic activity against MDA-MB-231 cells (IC 50 values 86.0 μg/mL and 80.2 μg/mL, respectively), while compounds 1 , 3 , 4 and 5 significantly decreased viability of HCT116 cells (IC 50 values of 97.8 μg/mL, 15.2 μg/mL, 24.6 μg/mL and 30.9 μg/mL, respectively). Our results indicated that all tested naphthoquinone pigments are potential candidates for clinical uses as antibacterial and cytotoxic agents.

Antibacterial and cytotoxic activities of naphthoquinone pigments from Onosma visianii Clem

PubMed Central

Vukic, Milena D.; Vukovic, Nenad L.; Djelic, Gorica T.; Popovic, Suzana Lj.; Zaric, Milan M.; Baskic, Dejan D.; Krstic, Gordana B.; Tesevic, Vele V.; Kacaniova, Miroslava M.

2017-01-01

In this study, the antibacterial and cytotoxic activities of isolated compounds from the roots of Onosma visianii were investigated. By using different chromatographic techniques and appropriate spectroscopic methods, the seven naphthoquinones were described: deoxyshikonin (1), isobutyrylshikonin (2), α-methylbutyrylshikonin (3), acetylshikonin (4), β-hydroxyisovalerylshikonin (5), 5,8-O-dimethyl isobutyrylshikonin (6) and 5,8-O-dimethyl deoxyshikonin (7). Among the tested compounds, 3 and 4 exhibited the highest antibacterial activities toward all tested bacterial species (MIC50 and MIC90 for gram positive bacteria: 6.40 μg/mL-12.79 μg/mL and 6.82 μg/mL-13.60 μg/mL, respectively; for gram negative bacteria: 4.27 μg/mL-8.53 μg/mL and 4.77 μg/mL-9.54 μg/mL, respectively). Also, naphthoquinones 3 and 4 exhibited strong cytotoxic activity against MDA-MB-231 cells (IC50 values 86.0 μg/mL and 80.2 μg/mL, respectively), while compounds 1, 3, 4 and 5 significantly decreased viability of HCT116 cells (IC50 values of 97.8 μg/mL, 15.2 μg/mL, 24.6 μg/mL and 30.9 μg/mL, respectively). Our results indicated that all tested naphthoquinone pigments are potential candidates for clinical uses as antibacterial and cytotoxic agents. PMID:28435429

Effect of zinc oxide amounts on the properties and antibacterial activities of zeolite/zinc oxide nanocomposite.

PubMed

Alswat, Abdullah A; Ahmad, Mansor Bin; Saleh, Tawfik A; Hussein, Mohd Zobir Bin; Ibrahim, Nor Azowa

2016-11-01

Nanocomposites of zinc oxide loaded on a zeolite (Zeolite/ZnO NCs) were prepared using co-precipitation method. The ratio effect of ZnO wt.% to the Zeolite on the antibacterial activities was investigated. Various techniques were used for the nanocomposite characterization, including UV-vis, FTIR, XRD, EDX, FESEM and TEM. XRD patterns showed that ZnO peak intensity increased while the intensities of Zeolite peaks decreased. TEM images indicated a good distribution of ZnO-NPs onto the Zeolite framework and the cubic structure of the zeolite was maintained. The average particle size of ZnO-nanoparticles loaded on the surface of the Zeolite was in the range of 1-10nm. Moreover, Zeolite/ZnO NCs showed noticeable antibacterial activities against the tested bacteria; Gram- positive and Gram- negative bacteria, under normal light. The efficiency of the antibacterial increased with increasing the wt.% from 3 to 8 of ZnO NPs, and it reached 87% against Escherichia coli E266. Copyright © 2016 Elsevier B.V. All rights reserved.

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. Copyright © 2013 Elsevier B.V. All rights reserved.

A study of the antibacterial activity of L-phenylalanine and L-tyrosine esters in relation to their CMCs and their interactions with 1,2-dipalmitoyl-sn-glycero-3-phosphocholine, DPPC as model membrane.

PubMed

Joondan, Nausheen; Jhaumeer-Laulloo, Sabina; Caumul, Prakashanand

2014-01-01

Cationic amino acid-based surfactants are known to interact with the lipid bilayer of cell membranes resulting in depolarization, lysis and cell death through a disruption of the membrane topology. A range of cationic surfactant analogues derived from L-Phenylalanine (C1-C20) and L-Tyrosine (C8-C14) esters have been synthesized and screened for their antibacterial activity. The esters were more active against gram positive than gram negative bacteria. The activity increased with increasing chain length, exhibiting a cut-off effect at C12 for gram positive and C8/C10 for gram negative bacteria. The cut-off effect for gram negative bacteria was observed at a lower alkyl chain length. The CMC was correlated with the MIC, inferring that micellar activity contribute to the cut-off effect in antibacterial activity. The interaction of the cationic surfactants with the phospholipid vesicles (1,2-dipalmitoyl-sn-glycero-3-phosphocholine, DPPC) in the presence of 1-anilino-8-naphthalene sulfonate (ANS) and 1,6-diphenyl-1,3,5-hexatriene (DPH) as fluorescence probes showed that an increase in ionic interaction causes an increase in antibacterial activity. Increase in hydrophobic interaction increases the antibacterial activity only to a certain chain length, attributing to the cut-off effect. Therefore, both electrostatic and hydrophobic interactions, involving the polar and nonpolar moieties are of paramount importance for the bactericidal properties. Copyright © 2014 Elsevier GmbH. All rights reserved.

Plasmin digest of κ-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 κ-casein and the fractions (named κC1, κC2, κC3, κC4, and κC5) 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 κC3 peptide being the most active. The plasmin digest of bovine κ-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 κ-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 κ-casein has a high antibacterial potential and can be considered as a natural antibacterial agent in the food chain.

Preparation, characterization, and antibacterial activity of silver nanoparticle-decorated graphene oxide nanocomposite.

PubMed

Shao, Wei; Liu, Xiufeng; Min, Huihua; Dong, Guanghui; Feng, Qingyuan; Zuo, Songlin

2015-04-01

In this work, we report a facile and green approach to prepare a uniform silver nanoparticles (AgNPs) decorated graphene oxide (GO) nanocomposite (GO-Ag). The nanocomposite was fully characterized by transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectra, ultraviolet-visible (UV-vis) absorption spectra, and X-ray photoelectron spectroscopy (XPS), which demonstrated that AgNPs with a diameter of approximately 22 nm were uniformly and compactly deposited on GO. To investigate the silver ion release behaviors, HEPES buffers with different pH (5.5, 7, and 8.5) were selected and the mechanism of release actions was discussed in detail. The cytotoxicity of GO-Ag nanocomposite was also studied using HEK 293 cells. GO-Ag nanocomposite displayed good cytocompatibility. Furthermore, the antibacterial properties of GO-Ag nanocomposite were studied using Gram-negative E. coli ATCC 25922 and Gram-positive S. aureus ATCC 6538 by both the plate count method and disk diffusion method. The nanocomposite showed excellent antibacterial activity. These results demonstrated that GO-Ag nanocomposite, as a kind of antibacterial material, had a great promise for application in a wide range of biomedical applications.

Antibacterial activity of trimetal (CuZnFe) oxide nanoparticles.

PubMed

Alzahrani, Khalid E; Niazy, Abdurahman A; Alswieleh, Abdullah M; Wahab, Rizwan; El-Toni, Ahmed M; Alghamdi, Hamdan S

2018-01-01

The increasing resistance of pathogenic bacteria to antibiotics is a challenging worldwide health problem that has led to the search for new and more efficient antibacterial agents. Nanotechnology has proven to be an effective tool for the fight against bacteria. In this paper, we present the synthesis and traits of trimetal (CuZnFe) oxide nanoparticles (NPs) using X-ray diffraction, high-resolution transmission electron microscopy, and energy dispersive x-ray spectroscopy. We evaluated the antibacterial activity of these NPs against gram-negative Escherichia coli and gram-positive Enterococcus faecalis and then compared it to that of their pure single-metal oxide components CuO and ZnO. Our study showed that the antibacterial activity of the trimetal oxide NPs was greater against E . coli than against E . faecalis . Overall, the antimicrobial effect of trimetal NPs is between those of pure ZnO and CuO nanoparticles, which may mean that their cytotoxicity is also between that of pure ZnO and CuO NPs, making them potential antibiotics. However, the cytotoxicity of trimetal NPs to mammalian cells needs to be verified. The combination of three metal oxide NPs (ZnO, CuO, and Fe 2 O 3 ) in one multimetal (CuZnFe) oxide NPs will enhance the therapeutic strategy against a wide range of microbial infections. Bacteria are unlikely to develop resistance against this new NP because bacteria must go through a series of mutations to become resistant to the trimetal oxide NP. Therefore, this NP can combat existing and emerging bacterial infections.

Synthesis, micellisation and interaction of novel quaternary ammonium compounds derived from l-Phenylalanine with 1,2-dipalmitoyl-sn-glycero-3-phosphocholine as model membrane in relation to their antibacterial activity, and their selectivity over human red blood cells.

PubMed

Joondan, Nausheen; Caumul, Prakashanand; Akerman, Matthew; Jhaumeer-Laulloo, Sabina

2015-02-01

A series of quaternary ammonium compounds (QUATS) derived from l-Phenylalanine have been synthesized and their antibacterial efficiencies were determined against various strains of Gram-positive and Gram-negative bacteria. The antibacterial activity increased with increasing chain length, exhibiting a cut-off effect at C14 for Gram-positive and C12 for Gram-negative bacteria. The l-Phenylalanine QUATS displayed enhanced antibacterial properties with a higher cut-off point compared to their corresponding l-Phenylalanine ester hydrochlorides. The CMC was correlated with the MIC, inferring that micellar activity contributes to the cut-off effect in antibacterial activity. The hemolytic activities (HC50) of the QUATS against human red blood cells were also determined to illustrate the selectivity of these QUATS for bacterial over mammalian cells. In general, the MIC was lower than the HC50, and assessment of the micellar contribution to the antibacterial and hemolytic evaluation in TBS as a common medium confirmed that these QUATS can act as antibacterial, yet non-toxic molecules at their monomer concentrations. The interaction of the QUATS with the phospholipid vesicles (1,2-dipalmitoyl-sn-glycero-3-phosphocholine, DPPC) in the presence of 1-anilino-8-naphthalene sulfonate (ANS) and 1,6-diphenyl-1,3,5-hexatriene (DPH) as fluorescence probes showed that the presence of the quaternary ammonium moiety causes an increase in hydrophobic interactions, thus causing an increase in antibacterial activity. Copyright © 2015 Elsevier Inc. All rights reserved.

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.

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. Copyright © 2015 Elsevier Inc. All rights reserved.

Diversity and antibacterial activities of fungi derived from the Gorgonian Echinogorgia rebekka from the South China Sea.

PubMed

Wang, Ya-Nan; Shao, Chang-Lun; Zheng, Cai-Juan; Chen, Yi-Yan; Wang, Chang-Yun

2011-01-01

The diversity of symbiotic fungi associated with the gorgonian coral Echinogorgia rebekka from the Weizhou coral reef in the South China Sea was investigated. Combined with morphologic traits, ITS-rDNA sequences revealed 18 fungal strains from this gorgonian. All of the 18 fungi belonged to the phylum Ascomycota and were distributed among seven genera in five orders: Eurotiales (Aspergillus and Penicillium), Pleosporales (Alternaria), Capnodiales (Cladosporium), Trichosphaeriales (Nigrospora) and Hypocreales (Hypocrea and Nectria). Antibacterial activities of these fungal strains were investigated with five pathogenic bacteria. All of the 18 fungal strains displayed different levels of antibacterial activities, most of which exhibited moderate to high antibacterial activities to the Gram-positive pathogens Staphylococcus aureus and Micrococcus tetragenus, and showed relatively low bioactivities to other three pathogenic bacteria. Several fungal strains in the genera Penicillium and Cladosporium with strong antibacterial activities provide potential for further research on isolation of bioactive secondary metabolites.

Antibacterial activity of crude extracts of prasaprohyai formula and its components against pathogenic bacteria.

PubMed

Sattaponpan, Chisanucha; Kondo, Sumalee

2011-12-01

Prasaprohyai formula is a Thai Traditional Medicine which has been used for reducing feverish in child. Fever is a symptom resulting from various infections and diseases. The major cause of fever is bacterial and viral infections. The Prasaprohyai formula and its components potentially have biological activities including antipyretic and antimicrobial activities. It is in a hope to develop the formula and its components for an alternative medicine of infectious diseases. To study antibacterial activity of Prasaprohyai formula and its components against pathogenic bacteria. Prasaprohyai formula and its components were extracted by different methods, A: maceration with 95% ethanol followed by evaporation (ET), B: ET followed by freeze drying (EF) and C: water distillation (VO). All extracts were tested against clinical isolates from Thammasat University Hospital, Staphylococcus aureus ATCC 25923 and Escherichia coli ATCC 25922. Disk diffusion and broth dilution methods were performed. Crude extracts of ET had higher yield of extraction than other methods. The results showed that the crude extract from different methods of Syzygium aromaticum (Linn) Merr & Perry (Flower) was effective against all bacterial strains with the inhibition zone ranging from 9 to 19 mm. The VO extract of Prasaprohyai formula showed antibacterial activity against most of the pathogenic bacteria in the present study. The activity against Streptococcus pyogenes was found in the VO extract of some components. The ET extracts of Lepidium sativum Linn, Myristica fragrans Houtt (seed) and Myristica fragrans Houtt (aril) had no antibacterial activity against all microorganism. However the EF extracts of this formula and some components were able to mostly inhibit Gram positive bacteria. The results indicated that Prasaprohyai formula and its components were able to inhibit the growth of both Gram positive and Gram negative bacteria including multiresistant strains. The volatile oil extracts seemed

Novel Polymyxin Derivatives Carrying Only Three Positive Charges Are Effective Antibacterial Agents ▿

PubMed Central

Vaara, Martti; Fox, John; Loidl, Günther; Siikanen, Osmo; Apajalahti, Juha; Hansen, Frank; Frimodt-Møller, Niels; Nagai, Junya; Takano, Mikihisa; Vaara, Timo

2008-01-01

The lack of novel antibiotics against gram-negative bacteria has reinstated polymyxins as the drugs of last resort to treat serious infections caused by extremely multiresistant gram-negative organisms. However, polymyxins are nephrotoxic, and this feature may complicate therapy or even require its discontinuation. Like that of aminoglycosides, the nephrotoxicity of polymyxins might be related to the highly cationic nature of the molecule. Colistin and polymyxin B carry five positive charges. Here we show that novel polymyxin derivatives carrying only three positive charges are effective antibacterial agents. NAB739 has a cyclic peptide portion identical to that of polymyxin B, but in the linear portion of the peptide, it carries the threonyl-d-serinyl residue (no cationic charges) instead of the diaminobutyryl-threonyl-diaminobutyryl residue (two cationic charges). The MICs of NAB739 for 17 strains of Escherichia coli were identical, or very close, to those of polymyxin B. Furthermore, NAB739 was effective against other polymyxin-susceptible strains of Enterobacteriaceae and against Acinetobacter baumannii. At subinhibitory concentrations, it dramatically sensitized A. baumannii to low concentrations of antibiotics such as rifampin, clarithromycin, vancomycin, fusidic acid, and meropenem. NAB739 methanesulfonate was a prodrug analogous to colistin methanesulfonate. NAB740 was the most active derivative against Pseudomonas aeruginosa. NAB7061 (linear portion of the peptide, threonyl-aminobutyryl) lacked direct antibacterial activity but sensitized the targets to hydrophobic antibiotics by factors up to 2,000. The affinities of the NAB compounds for isolated rat kidney brush border membrane were significantly lower than that of polymyxin B. PMID:18591267

Extraction of chitosan from shrimp shells waste and application in antibacterial finishing of bamboo rayon.

PubMed

Teli, M D; Sheikh, Javed

2012-06-01

Chitosan can be best utilized as safe antibacterial agent for textiles but there is always a limitation of its durability. The chitin containing shellfish waste is available in huge quantities, but very low quantities are utilized for extraction of high value products like chitosan. In the current work chitosan was extracted from shrimp shells and then used as antibacterial exhaust finishing agent for grafted bamboo rayon. Chitosan bound bamboo rayon was then evaluated for antibacterial activity against both gram positive and gram negative bacteria. The product showed antibacterial activity against both types of bacterias which was durable till 30 washes. Copyright © 2012 Elsevier B.V. All rights reserved.

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

Synthesis and structure-activity relationship of amidine derivatives of 3,4-ethylenedioxythiophene as novel antibacterial agents.

PubMed

Stolić, Ivana; Čipčić Paljetak, Hana; Perić, Mihaela; Matijašić, Mario; Stepanić, Višnja; Verbanac, Donatella; Bajić, Miroslav

2015-01-27

Current antibacterial chemotherapeutics are facing an alarming increase in bacterial resistance pressuring the search for novel agents that would expand the available therapeutic arsenal against resistant bacterial pathogens. In line with these efforts, a series of 9 amidine derivatives of 3,4-ethylenedioxythiophene were synthesized and, together with 18 previously synthesized analogs, evaluated for their relative DNA binding affinity, in vitro antibacterial activities and preliminary in vitro safety profile. Encouraging antibacterial activity of several subclasses of tested amidine derivatives against Gram-positive (including resistant MRSA, MRSE, VRE strains) and Gram-negative bacterial strains was observed. The bis-phenyl derivatives were the most antibacterially active, while compound 19 from bis-benzimidazole class exhibited the widest spectrum of activity (with MIC of 4, 2, 0.5 and ≤0.25 μg/ml against laboratory strains of Staphyloccocus aureus, Streptococcus pneumoniae, Streptococcus pyogenes, Moraxella catarrhalis, respectively and 4-32 μg/ml against clinical isolates of sensitive and resistant S. aureus, Staphylococcus epidermidis and Enterococcus faecium) and also demonstrated the strongest DNA binding affinity (ΔTm of 15.4 °C). Asymmetrically designed compounds and carboxamide-amidines were, in general, less active. Molecular docking indicated that the shape of the 3,4-ethylenedioxythiophene derivatives and their ability to form multiple electrostatic and hydrogen bonds with DNA, corresponds to the binding modes of other minor-groove binders. Herein reported results encourage further investigation of this class of compounds as novel antibacterial DNA binding agents. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

In vitro activities of dalbavancin and nine comparator agents against anaerobic gram-positive species and corynebacteria.

PubMed

Goldstein, Ellie J C; Citron, Diane M; Merriam, C Vreni; Warren, Yumi; Tyrrell, Kerin; Fernandez, Helen T

2003-06-01

Dalbavancin is a novel semisynthetic glycopeptide with enhanced activity against gram-positive species. Its comparative in vitro activities and those of nine comparator agents, including daptomycin, vancomycin, linezolid, and quinupristin-dalfopristin, against 290 recent gram-positive clinical isolates strains, as determined by the NCCLS agar dilution method, were studied. The MICs of dalbavancin at which 90% of various isolates tested were inhibited were as follows: Actinomyces spp., 0.5 microg/ml; Clostridium clostridioforme, 8 microg/ml; C. difficile, 0.25 microg/ml; C. innocuum, 0.25 microg/ml; C. perfringens, 0.125 microg/ml; C. ramosum, 1 microg/ml; Eubacterium spp., 1 microg/ml; Lactobacillus spp., >32 microg/ml, Propionibacterium spp., 0.5 microg/ml; and Peptostreptococcus spp., 0.25 microg/ml. Dalbavancin was 1 to 3 dilutions more active than vancomycin against most strains. Dalbavancin exhibited excellent activity against gram-positive strains tested and warrants clinical evaluation.

Expanding the Use of a Fluorogenic Method to Determine Activity and Mode of Action of Bacillus thuringiensis Bacteriocins Against Gram-Positive and Gram-Negative Bacteria

PubMed Central

de la Fuente-Salcido, Norma M.; Barboza-Corona, J. Eleazar; Espino Monzón, A. N.; Pacheco Cano, R. D.; Balagurusamy, N.; Bideshi, Dennis K.; Salcedo-Hernández, Rubén

2012-01-01

Previously we described a rapid fluorogenic method to measure the activity of five bacteriocins produced by Mexican strains of Bacillus thuringiensis against B. cereus 183. Here we standardize this method to efficiently determine the activity of bacteriocins against both Gram-positive and Gram-negative bacteria. It was determined that the crucial parameter required to obtain reproducible results was the number of cells used in the assay, that is, ~4 × 108 cell/mL and ~7 × 108 cell/mL, respectively, for target Gram-positive and Gram-negative bacteria. Comparative analyses of the fluorogenic and traditional well-diffusion assays showed correlation coefficients of 0.88 to 0.99 and 0.83 to 0.99, respectively, for Gram-positive and Gram-negative bacteria. The fluorogenic method demonstrated that the five bacteriocins of B. thuringiensis have bacteriolytic and bacteriostatic activities against all microorganisms tested, including clinically significant bacteria such as Listeria monocytogenes, Proteus vulgaris, and Shigella flexneri reported previously to be resistant to the antimicrobials as determined using the well-diffusion protocol. These results demonstrate that the fluorogenic assay is a more sensitive, reliable, and rapid method when compared with the well-diffusion method and can easily be adapted in screening protocols for bacteriocin production by other microorganisms. PMID:22919330

Assessment of the antioxidant and antibacterial activities of different olive processing wastewaters

PubMed Central

Tan, Shiau Pin; El-Abbassi, Abdelilah; Kiai, Hajar; Hafidi, Abdellatif; O’Donovan, Orla; McLoughlin, Peter

2017-01-01

Olive processing wastewaters (OPW), namely olive mill wastewater (OMW) and table-olive wastewaters (TOW) were evaluated for their antibacterial activity against five Gram-positive and two Gram-negative bacteria using the standard disc diffusion and thin layer chromatography (TLC)-bioautography assays. Disc diffusion screening and bioautography of OMW were compared to the phenolic extracts of table-olive brines. Positive activity against S. aureus was demonstrated. The optimization of chromatographic separation revealed that hexane/acetone in the ratio of 4:6 was the most effective for phenolic compounds separation. A HPLC-MS analysis was performed showing that only two compounds, hydroxytyrosol and tyrosol, were the predominant phenolic compounds in all OPW. The phenolic extract of OMW generated by a semi-modern process showed the highest free radical-scavenging activity (DPPH assay) compared to the other phenolic extracts. It is apparent from the present study that OPW are a rich source of antioxidants suitable for use in food, cosmetic or pharmaceutical applications. PMID:28873097

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. Copyright © 2015 Elsevier B.V. All rights reserved.

Using Chemoinformatics, Bioinformatics, and Bioassay to Predict and Explain the Antibacterial Activity of Nonantibiotic Food and Drug Administration Drugs.

PubMed

Kahlous, Nour Aldin; Bawarish, Muhammad Al Mohdi; Sarhan, Muhammad Arabi; Küpper, Manfred; Hasaba, Ali; Rajab, Mazen

2017-04-01

Discovering of new and effective antibiotics is a major issue facing scientists today. Luckily, the development of computer science offers new methods to overcome this issue. In this study, a set of computer software was used to predict the antibacterial activity of nonantibiotic Food and Drug Administration (FDA)-approved drugs, and to explain their action by possible binding to well-known bacterial protein targets, along with testing their antibacterial activity against Gram-positive and Gram-negative bacteria. A three-dimensional virtual screening method that relies on chemical and shape similarity was applied using rapid overlay of chemical structures (ROCS) software to select candidate compounds from the FDA-approved drugs database that share similarity with 17 known antibiotics. Then, to check their antibacterial activity, disk diffusion test was applied on Staphylococcus aureus and Escherichia coli. Finally, a protein docking method was applied using HYBRID software to predict the binding of the active candidate to the target receptor of its similar antibiotic. Of the 1,991 drugs that were screened, 34 had been selected and among them 10 drugs showed antibacterial activity, whereby drotaverine and metoclopramide activities were without precedent reports. Furthermore, the docking process predicted that diclofenac, drotaverine, (S)-flurbiprofen, (S)-ibuprofen, and indomethacin could bind to the protein target of their similar antibiotics. Nevertheless, their antibacterial activities are weak compared with those of their similar antibiotics, which can be potentiated further by performing chemical modifications on their structure.

Assessment of phytochemical content, polyphenolic composition, antioxidant and antibacterial activities of Leguminosae medicinal plants in Peninsular Malaysia.

PubMed

Chew, Yik Ling; Chan, Elaine Wan Ling; Tan, Pei Ling; Lim, Yau Yan; Stanslas, Johnson; Goh, Joo Kheng

2011-02-10

Many medicinal plants from Leguminosae family can be found easily in Malaysia. These plants have been used as traditional medicines by local ethnic groups, where they are prepared as decoction, pastes for wound infections, and some have been eaten as salad. This paper focused on the assessment of antioxidant potential, antibacterial activity and classes of phytochemicals of nine plants from the Leguminosae family. Acacia auriculiformis, Bauhinia kockiana, Bauhinia purpurea, Caesalpinia pulcherrima, Calliandra tergemina, Cassia surattensis, Leucaena leucocephala, Peltophorum pterocarpum, and Samanea saman were extracted with aqueous methanol and dichloromethane:methanol mixture to test for antioxidant and antibacterial activities. The Folin-Ciocalteu assay was conducted to quantify the total phenolic content and 2, 2-diphenyl-1-picrylhydrazyl (DPPH) assay was used to determine the free radical quenching capacity. Antibacterial activity was assessed using disc diffusion (Kirby-Bauer) assay. Screening for major classes of phytochemical was done using standard chemical tests. B. kockiana flowers and C. pulcherrima leaves contained high total phenolic content (TPC) and strong DPPH radical scavenging ability with TPC of 8280 ± 498 mg GAE/100 g, IC(50) of 27.0 ± 5.0 μg/mL and TPC of 5030 ± 602 mg GAE/100 g, IC(50) of 50.0 ± 5.0 μg/mL respectively. Positive correlation was observed between TPC and free radical scavenging ability. Most extracts showed antibacterial activity against Gram positive bacteria at 1 mg, while none showed activity against Gram negative bacteria at the same dose. All extracts (except Samanea saman flower) showed antibacterial activity against two strains of methicillin resistant Staphylococcus aureus (MRSA) with MID values ranging between 100 μg/disc and 500 μg/disc. The potential source of antioxidant and antibacterial agents, especially for MRSA infection treatments were found in B. kockiana, C. pulcherrima, C. tergemina and P. pterocarpum

Assessment of phytochemical content, polyphenolic composition, antioxidant and antibacterial activities of Leguminosae medicinal plants in Peninsular Malaysia

PubMed Central

2011-01-01

Background Many medicinal plants from Leguminosae family can be found easily in Malaysia. These plants have been used as traditional medicines by local ethnic groups, where they are prepared as decoction, pastes for wound infections, and some have been eaten as salad. This paper focused on the assessment of antioxidant potential, antibacterial activity and classes of phytochemicals of nine plants from the Leguminosae family. Methods Acacia auriculiformis, Bauhinia kockiana, Bauhinia purpurea, Caesalpinia pulcherrima, Calliandra tergemina, Cassia surattensis, Leucaena leucocephala, Peltophorum pterocarpum, and Samanea saman were extracted with aqueous methanol and dichloromethane:methanol mixture to test for antioxidant and antibacterial activities. The Folin-Ciocalteu assay was conducted to quantify the total phenolic content and 2, 2-diphenyl-1-picrylhydrazyl (DPPH) assay was used to determine the free radical quenching capacity. Antibacterial activity was assessed using disc diffusion (Kirby-Bauer) assay. Screening for major classes of phytochemical was done using standard chemical tests. Results B. kockiana flowers and C. pulcherrima leaves contained high total phenolic content (TPC) and strong DPPH radical scavenging ability with TPC of 8280 ± 498 mg GAE/100 g, IC50 of 27.0 ± 5.0 μg/mL and TPC of 5030 ± 602 mg GAE/100 g, IC50 of 50.0 ± 5.0 μg/mL respectively. Positive correlation was observed between TPC and free radical scavenging ability. Most extracts showed antibacterial activity against Gram positive bacteria at 1 mg, while none showed activity against Gram negative bacteria at the same dose. All extracts (except Samanea saman flower) showed antibacterial activity against two strains of methicillin resistant Staphylococcus aureus (MRSA) with MID values ranging between 100 μg/disc and 500 μg/disc. Conclusion The potential source of antioxidant and antibacterial agents, especially for MRSA infection treatments were found in B. kockiana, C

Design, Synthesis and Qualitative Structure Activity Relationship Evaluations of Quinoline-Based Bisarylimidazoles as Antibacterial Motifs.

PubMed

Al-Qawasmeh, Raed A; Huthail, Basil B; Sinnokrot, Mutasem O; Semreen, Mohammad H; Odeh, Raed A; Abu-Zarga, Musa H; Tarazi, Hamadeh; Yousef, Imad A; Al-Tel, Taleb H

2016-01-01

The emergence of drug-resistant bacteria in clinical practice has propelled a concerted effort to find new classes of antibiotics that will circumvent current modes of resistance. We previously described a set of imidazopyridine antibacterial leads that contain a core composed of benzimidazole and a central phthalic acid linker. These compounds showed potent antibacterial properties against a wide range of Gram-positive and Gram-negative bacteria. In this respect, we conducted a systematic exploration of new disubstituted imidazole functionalities on quinoline 4-position as the central linker, to determine the factors that direct the potent antibacterial activity. We found that some of the newly synthesized compounds possessed more potent activity compared to currently available medications. The newly synthesized compounds were screened against several clinical isolates and Staphylococcus aureus, including the methicillinresistant (MRSA) and the methicillin-sensitive (MSAA). The goal of this work is to undertake rigorous testing of new hybrid scaffolds of quinoline flanked by diaryl imidazoles and their structure-activity against a range of bacterial strains. Described herein is the account of the modification of the central linker region, the imidazole functionality, and substituents at the 4-position of the quinoline, and their effect on the antibacterial potency of the resulting derivatives. Our efforts here have been driven by previous reports on the applications of Pfitzinger cyclization protocol. This complexity-generating reaction transforms a relatively simple substrate, into a more complex products with the potential for diversification via functionalization of the resultant acid. We identified compounds that possess potent and broad-spectrum antibacterial activities against clinical isolates and drug resistant strains. Structure-Activity relationships of these compounds were further explored to determine the crucial structural features needed to enhance

Novel antibacterial polypeptide laparaxin produced by Lactobacillus paracasei strain NRRL B-50314 via fermentation

USDA-ARS?s Scientific Manuscript database

This study reports the production and characterization of a novel antibacterial polypeptide, designated laparaxin, which is secreted by Lactobacillus paracasei NRRL B-50314. Crude laparaxin has antibacterial activity against a wide variety of Gram-positive bacteria, including: lactic acid bacteria ...

Preliminary investigations on the antibacterial activity of zinc oxide nanostructures

NASA Astrophysics Data System (ADS)

Ramani, Meghana; Ponnusamy, S.; Muthamizhchelvan, C.

2013-04-01

In this study, we present a systematic investigation on the evolution of nanorods of diameter 35-40 nm and 1-2 μm length from nanoparticles of diameter 30-35 nm by varying the concentration of 2,6-lutidine which acts as a shape-directing agent in the synthesis process. This variation in morphology was studied using transmission electron microscopy. The surface capping agent was subsequently removed by heating during the synthesis process and confirmed using Fourier Transform Infra-red spectroscopy. Sufficient quantity of surface defects in the form of oxygen vacancies was observed from the photoluminescence analysis of the synthesized nanostructures. The concentration of defects decreased as the shape transits from nanoparticles to nanorods. The synthesized samples were preliminarily studied for their antibacterial activity against four model (gram-positive and gram-negative) pathogens by disk diffusion method and growth curve analysis. The calculated generation time indicates higher activity for nanoparticles than nanorods. However, the difference in the activity against different pathogens and their dependence on the concentration of defects indicate oxidative stress in addition to mechanical membrane damage as the major toxicity mechanism. Overall, the experimental findings are preliminary evidence supporting the possibility of developing zinc oxide nanostructures as antibacterial agents against a wide range of microorganisms to control and prevent the spreading of bacterial infections.

A comparison of antibacterial and antibiofilm efficacy of phenothiazinium dyes between Gram positive and Gram negative bacterial biofilm.

PubMed

Misba, Lama; Zaidi, Sahar; Khan, Asad U

2017-06-01

Antimicrobial photodynamic therapy (APDT) is a process that generates reactive oxygen species (ROS) in presence of photosensitizer, visible light and oxygen which destroys the bacterial cells. We investigated the photoinactivation efficiency of phenothiazinium dyes and the effect of ROS generation on Gram positive and Gram negative bacterial cell as well as on biofilm. Enterococcus faecalis and Klebsiella pneumonia were incubated with all the three phenothiazinium dyes and exposed to 630nm of light. After PDT, colony forming unit (CFU) were performed to estimate the cell survival fraction. Intracellular reactive oxygen species (ROS) was detected by DCFH-DA. Crystal violet (CV) assay and extracellular polysaccharides (EPS) reduction assay were performed to analyze antibiofilm effect. Confocal laser electron microscope (CLSM) scanning electron microscope (SEM) was performed to assess the disruption of biofilm. 8log 10 reduction in bacterial count was observed in Enterococcus faecalis while 3log 10 in Klebsiella pneumoniae. CV and EPS reduction assay revealed that photodynamic inhibition was more pronounced in Enterococcus faecalis. In addition to this CLSM and SEM study showed an increase in cell permeability of propidium iodide and leakage of cellular constituents in treated preformed biofilm which reflects the antibiofilm action of photodynamic therapy. We conclude that Gram-positive bacteria (Enterococcus faecalis) are more susceptible to APDT due to increased level of ROS generation inside the cell, higher photosensitizer binding efficiency and DNA degradation. Phenothiazinium dyes are proved to be highly efficient against both planktonic and biofilm state of cells. Copyright © 2017 Elsevier B.V. All rights reserved.

Gram positive and Gram negative bacteria differ in their sensitivity to cold plasma

NASA Astrophysics Data System (ADS)

Mai-Prochnow, Anne; Clauson, Maryse; Hong, Jungmi; Murphy, Anthony B.

2016-12-01

Cold atmospheric-pressure plasma (CAP) is a relatively new method being investigated for antimicrobial activity. However, the exact mode of action is still being explored. Here we report that CAP efficacy is directly correlated to bacterial cell wall thickness in several species. Biofilms of Gram positive Bacillus subtilis, possessing a 55.4 nm cell wall, showed the highest resistance to CAP, with less than one log10 reduction after 10 min treatment. In contrast, biofilms of Gram negative Pseudomonas aeruginosa, possessing only a 2.4 nm cell wall, were almost completely eradicated using the same treatment conditions. Planktonic cultures of Gram negative Pseudomonas libanensis also had a higher log10 reduction than Gram positive Staphylococcus epidermidis. Mixed species biofilms of P. aeruginosa and S. epidermidis showed a similar trend of Gram positive bacteria being more resistant to CAP treatment. However, when grown in co-culture, Gram negative P. aeruginosa was more resistant to CAP overall than as a mono-species biofilm. Emission spectra indicated OH and O, capable of structural cell wall bond breakage, were present in the plasma. This study indicates that cell wall thickness correlates with CAP inactivation times of bacteria, but cell membranes and biofilm matrix are also likely to play a role.

Chemical composition and antibacterial activity of the essential oil of Retrohpyllum rospigliosii fruits from Colombia.

PubMed

Quijano-Celis, Clara E; Gaviria, Mauricio; Consuelo, Vanegas-López; Ontiveros, Ina; Echeverri, Leonardo; Morales, Gustavo; Pino, Jorge A

2010-07-01

The essential oil from fruits of Retrophyllum rospigliosii (Pilger) C.N. Page grown in Colombia was analyzed by GC and GC/MS. Ninety-one compounds were identified, of which the most prominent were limonene (37.7%) and alpha-pinene (16.3%). The in vitro antibacterial activity of the essential oil was studied against seven bacterial strains using the disc diffusion method. The strongest activity of the oil was against the Gram-positive bacterium Bacillus cereus.

Characterization of Antibacterial Activities of Eastern Subterranean Termite, Reticulitermes flavipes, against Human Pathogens

PubMed Central

Zeng, Yuan; Hu, Xing Ping

2016-01-01

The emergence and dissemination of multidrug resistant bacterial pathogens necessitate research to find new antimicrobials against these organisms. We investigated antimicrobial production by eastern subterranean termites, Reticulitermes flavipes, against a panel of bacteria including three multidrug resistant (MDR) and four non-MDR human pathogens. We determined that the crude extract of naïve termites had a broad-spectrum activity against the non-MDR bacteria but it was ineffective against the three MDR pathogens Pseudomonas aeruginosa, methicillin-resistant Staphylococcus aureus (MRSA), and Acinetobacter baumannii. Heat or trypsin treatment resulted in a complete loss of activity suggesting that antibacterial activity was proteinaceous in nature. The antimicrobial activity changed dramatically when the termites were fed with either heat-killed P. aeruginosa or MRSA. Heat-killed P. aeruginosa induced activity against P. aeruginosa and MRSA while maintaining or slightly increasing activity against non-MDR bacteria. Heat-killed MRSA induced activity specifically against MRSA, altered the activity against two other Gram-positive bacteria, and inhibited activity against three Gram-negative bacteria. Neither the naïve termites nor the termites challenged with heat-killed pathogens produced antibacterial activity against A. baumannii. Further investigation demonstrated that hemolymph, not the hindgut, was the primary source of antibiotic activity. This suggests that the termite produces these antibacterial activities and not the hindgut microbiota. Two-dimensional gel electrophoretic analyses of 493 hemolymph protein spots indicated that a total of 38 and 65 proteins were differentially expressed at least 2.5-fold upon being fed with P. aeruginosa and MRSA, respectively. Our results provide the first evidence of constitutive and inducible activities produced by R. flavipes against human bacterial pathogens. PMID:27611223

Selective antibacterial effects of mixed ZnMgO nanoparticles

NASA Astrophysics Data System (ADS)

Vidic, Jasmina; Stankic, Slavica; Haque, Francia; Ciric, Danica; Le Goffic, Ronan; Vidy, Aurore; Jupille, Jacques; Delmas, Bernard

2013-05-01

Antibiotic resistance has impelled the research for new agents that can inhibit bacterial growth without showing cytotoxic effects on humans and other species. We describe the synthesis and physicochemical characterization of nanostructured ZnMgO whose antibacterial activity was compared to its pure nano-ZnO and nano-MgO counterparts. Among the three oxides, ZnO nanocrystals—with the length of tetrapod legs about 100 nm and the diameter about 10 nm—were found to be the most effective antibacterial agents since both Gram-positive ( B. subtilis) and Gram-negative ( E. coli) bacteria were completely eradicated at concentration of 1 mg/mL. MgO nanocubes (the mean cube size 50 nm) only partially inhibited bacterial growth, whereas ZnMgO nanoparticles (sizes corresponding to pure particles) revealed high specific antibacterial activity to Gram-positive bacteria at this concentration. Transmission electron microscopy analysis showed that B. subtilis cells were damaged after contact with nano-ZnMgO, causing cell contents to leak out. Our preliminary toxicological study pointed out that nano-ZnO is toxic when applied to human HeLa cells, while nano-MgO and the mixed oxide did not induce any cell damage. Overall, our results suggested that nanostructured ZnMgO, may reconcile efficient antibacterial efficiency while being a safe new therapeutic for bacterial infections.

Large Scale Screening of Ethnomedicinal Plants for Identification of Potential Antibacterial Compounds.

PubMed

Panda, Sujogya Kumar; Mohanta, Yugal Kishore; Padhi, Laxmipriya; Park, Young-Hwan; Mohanta, Tapan Kumar; Bae, Hanhong

2016-03-14

The global burden of bacterial infections is very high and has been exacerbated by increasing resistance to multiple antibiotics. Antibiotic resistance leads to failed treatment of infections, which can ultimately lead to death. To overcome antibiotic resistance, it is necessary to identify new antibacterial agents. In this study, a total of 662 plant extracts (diverse parts) from 222 plant species (82 families, 177 genera) were screened for antibacterial activity using the agar cup plate method. The aqueous and methanolic extracts were prepared from diverse plant parts and screened against eight bacterial (two Gram-positive and six Gram-negative) species, most of which are involved in common infections with multiple antibiotic resistance. The methanolic extracts of several plants were shown to have zones of inhibition ≥ 12 mm against both Gram-positive and Gram-negative bacteria. The minimum inhibitory concentration was calculated only with methanolic extracts of selected plants, those showed zone of inhibition ≥ 12 mm against both Gram-positive and Gram-negative bacteria. Several extracts had minimum inhibitory concentration ≤ 1 mg/mL. Specifically Adhatoda vasica, Ageratum conyzoides, Alangium salvifolium, Alpinia galanga, Andrographis paniculata, Anogeissus latifolia, Annona squamosa, A. reticulate, Azadirachta indica, Buchanania lanzan, Cassia fistula, Celastrus paniculatus, Centella asiatica, Clausena excavate, Cleome viscosa, Cleistanthus collinus, Clerodendrum indicum, Croton roxburghii, Diospyros melanoxylon, Eleutherine bulbosa, Erycibe paniculata, Eryngium foetidum, Garcinia cowa, Helicteres isora, Hemidesmus indicus, Holarrhena antidysenterica, Lannea coromandelica, Millettia extensa, Mimusops elengi, Nyctanthes arbor-tristis, Oroxylum indicum, Paederia foetida, Pterospermum acerifolium, Punica granatum, Semecarpus anacardium, Spondias pinnata, Terminalia alata and Vitex negundo were shown to have significant antimicrobial activity. The species

Antioxidant activity via DPPH, gram-positive and gram-negative antimicrobial potential in edible mushrooms.

PubMed

Ahmad, Nisar; Mahmood, Fazal; Khalil, Shahid Akbar; Zamir, Roshan; Fazal, Hina; Abbasi, Bilal Haider

2014-10-01

Edible mushrooms (EMs) are nutritionally rich source of proteins and essential amino acids. In the present study, the antioxidant activity via 1,1-diphenyl-2-picrylhydrazyl (DPPH) and antimicrobial potential in EMs (Pleurotus ostreatus, Morchella esculenta, P. ostreatus (Black), P. ostreatus (Yellow) and Pleurotus sajor-caju) were investigated. The DPPH radical scavenging activity revealed that the significantly higher activity (66.47%) was observed in Morchella esculenta at a maximum concentration. Similarly, the dose-dependent concentrations (200, 400, 600, 800 and 1000 µg) were also used for other four EMs. Pleurotus ostreatus exhibited 36.13% activity, P. ostreatus (Black (B)) exhibited 30.64%, P. ostreatus (Yellow (Y)) exhibited 40.75% and Pleurotus sajor-caju exhibited 47.39% activity at higher concentrations. Furthermore, the antimicrobial potential were investigated for its toxicity against gram-negative bacterial strains (Escherichia coli, Pseudomonas aeroginosa, Salmonella typhi, Klebsiella pneumonia, Erwinia carotovora and Agrobacterium tumifaciens), gram-positive bacterial strains (Bacillus subtilis, Bacillus atrophaeus and Staphylococcus aureus) and a fungal strain (Candida albicans) in comparison with standard antibiotics. Antimicrobial screening revealed that the ethanol extract of P. ostreatus was active against all microorganism tested except E. coli. Maximum zone of inhibition (13 mm) was observed against fungus and A. tumifaciens. P. sajor-caju showed best activities (12.5 mm) against B. subtilis, B. atrophaeus and K. pneumonia. P. ostreatus (Y) showed best activities against P. aeroginosa (21.83 mm), B. atrophaeus (20 mm) and C. albicans (21 mm). P. ostreatus (B) exhibited best activities against C. albicans (16 mm) and slightly lower activities against all other microbes except S. typhi. M. esculenta possess maximum activities in terms of inhibition zone against all microorganisms tested except S. typhi. © The Author(s) 2012.

In vitro activity of monoclonal and recombinant yeast killer toxin-like antibodies against antibiotic-resistant gram-positive cocci.

PubMed Central

Conti, S.; Magliani, W.; Arseni, S.; Dieci, E.; Frazzi, R.; Salati, A.; Varaldo, P. E.; Polonelli, L.

2000-01-01

BACKGROUND: Monoclonal (mAbKT) and recombinant single-chain (scFvKT) anti-idiotypic antibodies were produced to represent the internal image of a yeast killer toxin (KT) characterized by a wide spectrum of antimicrobial activity, including gram-positive cocci. Pathogenic eukaryotic and prokaryotic microorganisms, such as Candida albicans, Pneumocystis carinii, and a multidrug-resistant strain of Mycobacterium tuberculosis, presenting specific, although yet undefined, KT-cell wall receptors (KTR), have proven to be killed in vitro by mAbKT and scFvKT. mAbKT and scFvKT exert a therapeutic effect in vivo in experimental models of candidiasis and pneumocystosis by mimicking the functional activity of protective antibodies naturally produced in humans against KTR of infecting microorganisms. The swelling tide of concern over increasing bacterial resistance to antibiotic drugs gives the impetus to develop new therapeutic compounds against microbial threat. Thus, the in vitro bactericidal activity of mAbKT and scFvKT against gram-positive, drug-resistant cocci of major epidemiological interest was investigated. MATERIALS AND METHODS: mAbKT and scFvKT generated by hybridoma and DNA recombinant technology from the spleen lymphocytes of mice immunized with a KT-neutralizing monoclonal antibody (mAb KT4) were used in a conventional colony forming unit (CFU) assay to determine, from a qualitative point of view, their bactericidal activity against Staphylococcus aureus, S. haemolyticus, Enterococcus faecalis, E. faecium, and Streptococcus pneumoniae strains. These bacterial strains are characterized by different patterns of resistance to antibiotics, including methicillin, vancomycin, and penicillin. RESULTS: According to the experimental conditions adopted, no bacterial isolate proved to be resistant to the activity of mAbKT and scFvKT. CONCLUSIONS: scFvKT exerted a microbicidal activity against multidrug resistant bacteria, which may represent the basis for the drug modeling

Three New Abietane-Type Diterpenoids from Plectranthus africanus and Their Antibacterial Activities.

PubMed

Nzogong, Raïssa T; Nganou, Blaise K; Tedonkeu, Alex T; Awouafack, Maurice D; Tene, Mathieu; Ito, Takuya; Tane, Pierre; Morita, Hiroyuki

2018-01-01

Three new abietane-type diterpenoids, plectranthroyleanones A - C (1:  - 3: ), together with five known compounds (4:  - 8: ) were isolated from the methanol extract of the whole plant of Plectranthus africanus using column chromatography techniques. The structures of the new compounds were elucidated using a combination of 1D and 2D NMR and HRESIMS analyses. Compound 1: exhibited weak activities with minimal inhibitory concentration values of 75 µg/mL against gram-positive bacteria, Bacillus subtilis and Staphylococcus aureus , and 150 µg/mL against two gram-negative bacteria, Pseudomonas aeruginosa and Klebsiella pneumoniae , respectively, while 2: and 3: had moderate antibacterial activity against K. pneumoniae with a minimal inhibitory concentration value of 37.5 µg/mL. Georg Thieme Verlag KG Stuttgart · New York.

Antibacterial Activity of Free Fatty Acids from Hydrolyzed Virgin Coconut Oil Using Lipase from Candida rugosa.

PubMed

Nguyen, Van Thi Ai; Le, Truong Dang; Phan, Hoa Ngoc; Tran, Lam Bich

2017-01-01

Free fatty acids (FFAs) were obtained from hydrolyzed virgin coconut oil (VCO) by Candida rugosa lipase (CRL). Four factors' influence on hydrolysis degree (HD) was examined. The best hydrolysis conditions in order to get the highest HD value were determined at VCO to buffer ratio 1 : 5 (w/w), CRL concentration 1.5% (w/w oil), pH 7, and temperature 40°C. After 16 hours' reaction, the HD value achieved 79.64%. FFAs and residual hydrolyzed virgin coconut oil (HVCO) were isolated from the hydrolysis products. They were tested for their antibacterial activity against Gram-negative and Gram-positive bacteria, which can be found in contaminated food and cause food poisoning. FFAs showed their inhibition against Bacillus subtilis (ATCC 11774), Escherichia coli (ATCC 25922), Salmonella enteritidis (ATCC 13076), and Staphylococcus aureus (ATCC 25923) at minimum inhibitory concentration (MIC) of 50%, 60%, 20%, and 40%, respectively. However, VCO and HVCO did not show their antibacterial activity against these tested bacteria.

Synthesis of SiC/Ag/Cellulose Nanocomposite and Its Antibacterial Activity by Reactive Oxygen Species Generation

PubMed Central

Borkowski, Andrzej; Cłapa, Tomasz; Szala, Mateusz; Gąsiński, Arkadiusz; Selwet, Marek

2016-01-01

We describe the synthesis of nanocomposites, based on nanofibers of silicon carbide, silver nanoparticles, and cellulose. Silver nanoparticle synthesis was achieved with chemical reduction using hydrazine by adding two different surfactants to obtain a nanocomposite with silver nanoparticles of different diameters. Determination of antibacterial activity was based on respiration tests. Enzymatic analysis indicates oxidative stress, and viability testing was conducted using an epifluorescence microscope. Strong bactericidal activity of nanocomposites was found against bacteria Escherichia coli and Bacillus cereus, which were used in the study as typical Gram-negative and Gram-positive bacteria, respectively. It is assumed that reactive oxygen species generation was responsible for the observed antibacterial effect of the investigated materials. Due to the properties of silicon carbide nanofiber, the obtained nanocomposite may have potential use in technology related to water and air purification. Cellulose addition prevented silver nanoparticle release and probably enhanced bacterial adsorption onto aggregates of the nanocomposite material. PMID:28335299

Antibacterial Activity of Free Fatty Acids from Hydrolyzed Virgin Coconut Oil Using Lipase from Candida rugosa

PubMed Central

Phan, Hoa Ngoc; Tran, Lam Bich

2017-01-01

Free fatty acids (FFAs) were obtained from hydrolyzed virgin coconut oil (VCO) by Candida rugosa lipase (CRL). Four factors' influence on hydrolysis degree (HD) was examined. The best hydrolysis conditions in order to get the highest HD value were determined at VCO to buffer ratio 1 : 5 (w/w), CRL concentration 1.5% (w/w oil), pH 7, and temperature 40°C. After 16 hours' reaction, the HD value achieved 79.64%. FFAs and residual hydrolyzed virgin coconut oil (HVCO) were isolated from the hydrolysis products. They were tested for their antibacterial activity against Gram-negative and Gram-positive bacteria, which can be found in contaminated food and cause food poisoning. FFAs showed their inhibition against Bacillus subtilis (ATCC 11774), Escherichia coli (ATCC 25922), Salmonella enteritidis (ATCC 13076), and Staphylococcus aureus (ATCC 25923) at minimum inhibitory concentration (MIC) of 50%, 60%, 20%, and 40%, respectively. However, VCO and HVCO did not show their antibacterial activity against these tested bacteria. PMID:29259829

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 μg/mL, 7.3 μg/mL, 3 μg/mL and 12 μg/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 μg/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

Gas chromatography - Mass spectrometry analysis and antibacterial activity of Cinnamomum burmanii essential oil to Staphylococcus aureus and Escherichia coli by gaseous contact

NASA Astrophysics Data System (ADS)

Chairunnisa, Tamhid, Hady Anshory; Nugraha, Arde Toga

2017-03-01

Infectious diseases and antibiotic resistance becomes a problem that must be resolved. Plant based products are among the alternative agents examined in order to replace conventional antibiotics. Cinnamaldehyde is one of the compound in cinnamon oil that has antibacterial activity. But the other compounds in cinnamon oil has also the potential antibacterial activity. The purpose of this study to conduct GC-MS analysis of cinnamon oil and its antibacterial activity to Staphylococcus aureus and Escherichia coli by gaseous contact. Cinnamomum burmannii was distilled by water-steam distillation to obtain essential oil. Identification of compounds was analyzed by GC-MS. Antibacterial activity was observed by gaseous contact method in airtight boxes. The GC-MS analyzed showed that there are four major compounds of cinnamon oil, trans-cinnamaldehyde (56,10%), 1,8-cineole (16,53%), α-pinene (3,44%) and α -terpineol (3,05%). The Minimum Inhibitory Dose (MID) of cinnamon oil to E. coli and S. aureus was 12.5 µL/L and 6.26 µL/L respectively. Gas compounds of cinnamon oil has more effective to gram-positive bacteria than gram-negative bacteria.

Novel Self-assembled Organic Nanoprobe for Molecular Imaging and Treatment of Gram-positive Bacterial Infection.

PubMed

Gao, Tang; Zeng, Hongliang; Xu, Huan; Gao, Feng; Li, Wei; Zhang, Shengwang; Liu, Yi; Luo, Guifang; Li, Mingdan; Jiang, Dejian; Chen, Zhigao; Wu, Yong; Wang, Wei; Zeng, Wenbin

2018-01-01

Background: Increasing bacterial infections as well as a rise in bacterial resistance call for the development of novel and safe antimicrobial agents without inducing bacterial resistance. Nanoparticles (NPs) present some advantages in treating bacterial infections and provide an alternative strategy to discover new antibiotics. Here, we report the development of novel self-assembled fluorescent organic nanoparticles ( FONs ) with excellent antibacterial efficacy and good biocompatibility. Methods: Self-assembly of 1-(12-(pyridin-1-ium-1-yl)dodecyl)-4-(1,4,5-triphenyl-1H-imidazol-2-yl)pyridin-1-ium (TPIP) in aqueous solution was investigated using dynamic light scattering (DLS) and transmission electron microscopy (TEM). The bacteria were imaged under a laser scanning confocal microscope. We evaluated the antibacterial efficacy of TPIP-FONs in vitro using sugar plate test. The antimicrobial mechanism was explored by SEM. The biocompatibility of the nanoparticles was examined using cytotoxicity test, hemolysis assay, and histological staining. We further tested the antibacterial efficacy of TPIP-FONs in vivo using the S. aureus -infected rats. Results: In aqueous solution, TPIP could self-assemble into nanoparticles ( TPIP-FONs ) with characteristic aggregation-induced emission (AIE). TPIP-FONs could simultaneously image gram-positive bacteria without the washing process. In vitro antimicrobial activity suggested that TPIP-FONs had excellent antibacterial activity against S. aureus (MIC = 2.0 µg mL -1 ). Furthermore, TPIP-FONs exhibited intrinsic biocompatibility with mammalian cells, in particular, red blood cells. In vivo studies further demonstrated that TPIP-FONs had excellent antibacterial efficacy and significantly reduced bacterial load in the infectious sites. Conclusion: The integrated design of bacterial imaging and antibacterial functions in the self-assembled small molecules provides a promising strategy for the development of novel antimicrobial

Antibacterial activity of some African medicinal plants used traditionally against infectious diseases.

PubMed

Madureira, Ana M; Ramalhete, Cátia; Mulhovo, Silva; Duarte, Aida; Ferreira, Maria-José U

2012-04-01

Plants are known to play a crucial role in African traditional medicine for the treatment of infection diseases. To investigate the claimed antimicrobial properties of plants traditionally used in African countries, providing scientific validation for their use. Eighty-three polar and non-polar extracts from 22 medicinal plants were screened for their antibacterial activity against Gram-positive (Staphylococcus aureus and Enterococcus faecalis) and Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae) and Mycobacterium smegmatis using the broth microdilution method. In vitro antibacterial activity against one or more tested bacteria was shown by 83% of the extracts. The highest activity was obtained with the methanol extracts of the aerial parts of Acacia karroo Hayne (Fabaceae) and Anacardium occidentale L. (Anacardiaceae) and the roots of Bridelia cathartica G. Bertol (Euphorbiaceae), against S. aureus (minimum inhibitory concentration (MIC) = 7.5 µg/mL). The same MIC values were exhibited against E. faecalis by the methanol extract of A. occidentale, the dichloromethane and methanol extracts of B. cathartica and the ethyl acetate extract of Momordica balsamina l. (Curcubitaceae) leaves. Gram-negative bacteria were less sensitive; the growth of P. aeruginosa was significantly inhibited (MIC = 31 µg/mL) by the n-hexane and methanol extracts of Gomphocarpus fruticosus (l.) Ait. (Asclepiadaceae) fruits and by the dichloromethane extract of Trichilia emetica Vahl (Meliaceae) seeds. Most of the active extracts were rich in fenols/flavonoids. This study supports the use of most of the studied plants in traditional medicine, for the treatment of infectious diseases. Some of them are worthy of further investigation.

Antibacterial and antifungal activities of the polyphenolic fractions isolated from the seed coat of Abrus precatorius and Caesalpinia crista.

PubMed

Mobin, Lubna; Saeed, Syed Asad; Ali, Rashida; Saeed, Syed Ghufran; Ahmed, Rahil

2017-09-26

Crude seed coat extracts from Abrus precatorius and Caesalpinia crista were purified into four different fractions namely phenolic acids, flavonols, flavanols and anthocyanin which were then examined for their polyphenol contents and antimicrobial potentials. The fractions derived from seed coat of A. precatorius were found more potent with high phenolic and flavonoid contents as compared to C. crista fractions. The significant antibacterial activity was observed against all strain tested by the fractions of both samples apart from anthocyanin fraction. It was interesting to note that the phenolic acid fractions of both samples was found more active against gram-negative bacteria, while gram-positive bacteria were found to be more sensitive towards flavonol fractions. The phenolic acid and flavonol fractions being potent antibacterial were selected to demonstrate the antifungal capacity of two samples. Among them, phenolic acid fraction of both samples was found active towards all the fungal strain.

In vitro antibacterial and antitumor activities of some medicinal plant extracts, growing in Turkey.

PubMed

Yildirim, Arzu Birinci; Karakas, Fatma Pehlivan; Turker, Arzu Ucar

2013-08-01

To investigate antibacterial and antitumor activities of 51 different extracts prepared with 3 types of solvents (water, ethanol and methanol) of 16 different plant species (Ajuga reptans (A. reptans) L., Phlomis pungens (P. pungens) Willd., Marrubium astracanicum (M. astracanicum) Jacq., Nepeta nuda (N. nuda) L., Stachys annua (S. annua) L., Genista lydia (G. lydia) Boiss., Nuphar lutea (N. lutea) L., Nymphaea alba (N. alba) L., Vinca minor (V. minor) L., Stellaria media (S. media) L., Capsella bursa-pastoris (C. bursa-pastoris) L., Galium spurium (G. spurium) L., Onosma heterophyllum (O. heterophyllum) Griseb., Reseda luteola (R. luteola) L., Viburnum lantana (V. lantana) L. and Mercurialis annua (M. annua) L.) grown in Turkey was conducted. Antibacterial activity was evaluated with 10 bacteria including Streptococcus pyogenes (S. pyogenes), Staphylococcus aureus (S. aureus), Staphylococcus epidermidis (S. epidermidis), Escheria coli (E. coli), Pseudomonas aeruginosa (P. aeruginosa), Salmonella typhimurium (S. typhimurium), Serratia marcescens (S. marcescens), Proteus vulgaris (P. vulgaris), Enterobacter cloacae (E. cloacea), and Klebsiella pneumoniae (K. pneumoniae) by using disc diffusion method. Antitumor activity was evaluated with Agrobacterium tumefaciens (A. tumefaciens)-induced potato disc tumor assay. Best antibacterial activity was obtained with ethanolic extract of P. pungens against S. pyogenes. Ethanolic and methanolic extract of N. alba and ethanolic extract of G. lydia also showed strong antibacterial activities. Results indicated that alcoholic extracts especially ethanolic extracts exhibited strong antibacterial activity against both gram-positive and gram-negative bacteria. Best antitumor activity was obtained with methanolic extracts of N. alba and V. lantana (100% tumor inhibition). Ethanolic extract of N. alba, alcoholic extracts of N. lutea, A. reptans and V. minor flowers, methanolic extracts of G. lydia and O. heterophyllum and ethanolic

Understanding the properties of chitosan aryl substituted thioureas in their role and potential as antibacterial agents

NASA Astrophysics Data System (ADS)

Khairul, Wan M.; Daud, Adibah Izzati; Ismail, Noraznawati

2018-02-01

In this study, the effort was to design and synthesize a series of thiourea-chitosan derivatives featuring five aryl substituted members namely N-chitosan-N'-(4-nitrobenzoyl) thiourea (1), N-chitosan-N'-(4-chlorobenzoyl) thiourea (2), N-chitosan-N'-(4-methylbenzoyl) thiourea (3), N-chitosan-N'-(2-iodobenzoyl) thiourea (4), and N-chitosan-N'-(2-methylbenzoyl) thiourea (5) via SN2 reaction pathway having different donating and withdrawing groups. Their molecular structures were then characterised by FT-IR, UV-Vis, and thermogravimetric analysis (TGA). The antimicrobial activities of these derivatives against four species bacteria Bacillus cereus, Staphylococcus aureus, Salmonella typhi, and Escherichia coli of both Gram-positive and Gram-negative type bacteria at minimum concentration 6mg/ml were carried out to investigate their potential as antibacterial agents. Compound 1 exhibited specific activity as it can only inhibit Gram-positive bacteria while other compounds 2-5 showed broad range spectrum activity as they were able to inhibit both Gram-positive and Gram-negative bacteria. Therefore, 1-5 showed good antibacterial activity and have high potential to be further developed as active materials in pharmaceutical interests.

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

Preparation and antibacterial properties of O-carboxymethyl chitosan/lincomycin hydrogels.

PubMed

He, Guanghua; Chen, Xiang; Yin, Yihua; Cai, Weiquan; Ke, Wanwan; Kong, Yahui; Zheng, Hua

2016-01-01

In this study, O-carboxymethyl chitosan (O-CMCS) was synthesized from chitosan and monochloroacetic acid. Then O-CMCS hydrogel was prepared by 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS) in which the lincomycin was packaged. The Fourier transform infrared spectrum and scanning electron microscopy were adopted to characterize the structure and morphology of the product. The influences of dosage of EDC/NHS and concentration of O-CMCS on the swelling properties of the hydrogels were investigated. The hydrogels performed good swelling capacities and obvious pH-sensitive properties. The antibacterial activities of the hydrogels were tested against Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus). Compared with pure O-CMCS hydrogels, the antibacterial activities of O-CMCS/lincomycin hydrogels were significantly improved with the increase in the concentration of lincomycin against E. coli and S. aureus. With the increase in dosage of crosslinking agent or concentration of O-CMCS, the antibacterial activities both decreased gradually against the two bacteria. O-CMCS/lincomycin hydrogel was expected to be used for antibacterial material in view of its significant antibacterial activities.

Synthesis and antibacterial activity of Schiff bases and amines derived from alkyl 2-(2-formyl-4-nitrophenoxy)alkanoates.

PubMed

Goszczyńska, Agata; Kwiecień, Halina; Fijałkowski, Karol

A series of novel Schiff bases and secondary amines were obtained in good yields, as a result of the reductive amination of alkyl 2-(2-formyl-4-nitrophenoxy)alkanoates with both aniline and 4-methoxyaniline under established mild reaction conditions. Sodium triacetoxyborohydride as well as hydrogen in the presence of palladium on carbon were used as efficient reducing agents of the Schiff bases, in both direct and stepwise reductive amination processes. The Schiff bases, amines, and amine hydrochlorides were designed as potential antibacterial agents, and structure-activity relationship could be established following in vitro assays against Gram-positive and Gram-negative bacteria. The minimal inhibitory concentration and zone of inhibition were also determined. In these tests, some of Schiff bases and secondary amine hydrochlorides showed moderate-to-good activity against Gram-positive bacteria, including S. aureus , M. luteus , and S. mutans .

Enhanced antibacterial activity of amino acids-functionalized multi walled carbon nanotubes by a simple method.

PubMed

Zardini, Hadi Zare; Amiri, Ahmad; Shanbedi, Mehdi; Maghrebi, Morteza; Baniadam, Majid

2012-04-01

Multi-walled carbon nanotubes (MWCNTs) were first functionalized by arginine and lysine under microwave radiation. Surface functionalization was confirmed by Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, and transmission electron microscopy (TEM). After the MWCNTs were functionalized by arginine and lysine, the antibacterial activity of all treated samples was increased significantly against all bacteria that were tested. Based on the observed minimum inhibitory concentration and radial diffusion assay, the sequence of antibacterial activity was MWCNTs-arginine>MWCNTs-lysine>pristine MWCNTs. The functionalized MWCNTs were especially effective against gram-negative bacteria (e.g., Escherichia coli and Salmonella typhimurium). Interestingly, the MWCNT samples were effective against the resistant strain Staphylococcos aureus. The enhanced antibacterial activity was attributed to electrostatic adsorption of bacteria membrane due to positive charges of the functional groups on MWCNTs surface. Since MWCNTs have lower cytotoxicity than single-walled carbon nanotubes, their functionalization with cationic amino acids could be a beneficial approach in the disinfection industry. Copyright © 2011 Elsevier B.V. All rights reserved.

Efficient photodynamic therapy against gram-positive and gram-negative bacteria using THPTS, a cationic photosensitizer excited by infrared wavelength.

PubMed

Schastak, Stanislaw; Ziganshyna, Svitlana; Gitter, Burkhard; Wiedemann, Peter; Claudepierre, Thomas

2010-07-20

The worldwide rise in the rates of antibiotic resistance of bacteria underlines the need for alternative antibacterial agents. A promising approach to kill antibiotic-resistant bacteria uses light in combination with a photosensitizer to induce a phototoxic reaction. Concentrations of 1, 10 and 100microM of tetrahydroporphyrin-tetratosylat (THPTS) and different incubation times (30, 90 and 180min) were used to measure photodynamic efficiency against two Gram-positive strains of S.aureus (MSSA and MRSA), and two Gram-negative strains of E.coli and P.aeruginosa. We found that phototoxicity of the drug is independent of the antibiotic resistance pattern when incubated in PBS for the investigated strains. Also, an incubation with 100microM THPTS followed by illumination, yielded a 6lg (> or =99.999%) decrease in the viable numbers of all bacteria strains tested, indicating that the THPTS drug has a high degree of photodynamic inactivation. We then modulated incubation time, photosensitizer concentration and monitored the effect of serum on the THPTS activity. In doing so, we established the conditions to obtain the strongest bactericidal effect. Our results suggest that this new and highly pure synthetic compound should improve the efficiency of photodynamic therapy against multiresistant bacteria and has a significant potential for clinical applications in the treatment of nosocomial infections.

The antibacterial activity of extracts of nine plant species with good activity against Escherichia coli against five other bacteria and cytotoxicity of extracts.

PubMed

Elisha, Ishaku Leo; Botha, Francien S; McGaw, Lyndy Joy; Eloff, Jacobus Nicolaas

2017-02-28

The development of antibiotic resistant bacteria stems from a number of factors, including inappropriate use of antibiotics in human and animal health and their prolonged use as growth promoters at sub-clinical doses in poultry and livestock production. We were interested in investigating plants that could be useful in protecting humans or animals against diarrhoea. We decided to work on extracts of nine plant species with good activity against Escherichia coli based on earlier work in the Phytomedicine Programme. Leaves of nine medicinal plant species with high antibacterial activity against Escherichia coli were extracted with acetone and their minimal inhibitory concentration (MIC) values determined using a microplate serial dilution technique against Gram-positive (Staphylococcus aureus, Enterococcus faecalis and Bacillus cereus) and Gram-negative (Escherichia coli, Salmonella Typhimurium and Pseudomonas aeruginosa) bacteria. Bioautography was used to determine the number of bioactive compounds in each extract. In vitro safety of the extracts was determined using the 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide reduction assay on Vero cells. The extracts were active against all the pathogens with average MICs ranging from 0.02 to 0.52 mg/ml. As expected E. coli was relatively sensitive, while E. faecalis and S. Typhimurium were more resistant to the extracts (average MICs of 0.28 mg/ml and 0.22 mg/ml respectively). Cremaspora triflora and Maesa lanceolata leaf extracts had higher activity than the other extracts against Gram-positive and Gram-negative pathogens with mean MICs of 0.07 mg/ml and 0.09 mg/ml respectively. Extracts of Maesa lanceolata and Hypericum roeperianum had the highest total antibacterial activity (TAA) at 1417 and 963 ml/g respectively. All extracts with the exception of that of Maesa lanceolata, Elaeodendron croceum and Calpurnia aurea had relatively low cytotoxicity with LC 50  > 20 μg/ml. Cremaspora triflora had

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.

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

2015-03-05

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. Copyright © 2014 Elsevier B.V. All rights reserved.

Multifunction Sr, Co and F co-doped microporous coating on titanium of antibacterial, angiogenic and osteogenic activities

PubMed Central

Zhou, Jianhong; Zhao, Lingzhou

2016-01-01

Advanced multifunction titanium (Ti) based bone implant with antibacterial, angiogenic and osteogenic activities is stringently needed in clinic, which may be accomplished via incorporation of proper inorganic bioactive elements. In this work, microporous TiO2/calcium-phosphate coating on Ti doped with strontium, cobalt and fluorine (SCF-TiCP) was developed, which had a hierarchical micro/nano-structure with a microporous structure evenly covered with nano-grains. SCF-TiCP greatly inhibited the colonization and growth of both gram-positive and gram-negative bacteria. No cytotoxicity appeared for SCF-TiCP. Furthermore, SCF-TiCP stimulated the expression of key angiogenic factors in rat bone marrow stem cells (MSCs) and dramatically enhanced MSC osteogenic differentiation. The in vivo animal test displayed that SCF-TiCP induced more new bone and tighter implant/bone bonding. In conclusion, multifunction SCF-TiCP of antibacterial, angiogenic and osteogenic activities is a promising orthopedic and dental Ti implant coating for improved clinical performance. PMID:27353337

Procalcitonin levels in gram-positive, gram-negative, and fungal bloodstream infections.

PubMed

Leli, Christian; 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.

2-(3′-Indolyl)-N-arylthiazole-4-carboxamides: Synthesis and evaluation of antibacterial and anticancer activities

PubMed Central

Tantak, Mukund P.; Wang, Jing; Singh, Rajnish Prakash; Kumar, Anil; Shah, Kavita; Kumar, Dalip

2015-01-01

A new series of 2-(3′-indolyl)-N-arylthiazole-4-carboxamides 17a-p has been designed and synthesized. Initial reaction of readily available thioamides 15 with bromopyruvic acid under refluxing conditions produced different thiazole carboxylic acids 16 which upon coupling with arylamines by using EDCI.HCl and HOBt afforded diverse arylthiazole-4-carboxamides 17a-p in 78-87% yields. Antibacterial activity evaluation against Gram-positive and Gram-negative bacterial strains led to compounds 17i-k and 17o as potent and selectively (Gram-negative) antibacterial agents. The cytotoxicity of thiazole carboxamides 17a-p was also evaluated on a panel of human cancer cell lines. Among the tested derivatives, compounds 17i (IC50 = 8.64 μM; HEK293T) and 17l (IC50 = 3.41 μM; HeLa) were identified as the most potent analogues of the series. Preliminary mechanism of action studies of thiazole carboxamide 17i suggested that its cytotoxicity against HeLa cells involves the induction of cell death by apoptosis. PMID:26298501

Identification of key genes in Gram-positive and Gram-negative sepsis using stochastic perturbation

PubMed Central

Li, Zhenliang; Zhang, Ying; Liu, Yaling; Liu, Yanchun; Li, Youyi

2017-01-01

Sepsis is an inflammatory response to pathogens (such as Gram-positive and Gram-negative bacteria), which has high morbidity and mortality in critically ill patients. The present study aimed to identify the key genes in Gram-positive and Gram-negative sepsis. GSE6535 was downloaded from Gene Expression Omnibus, containing 17 control samples, 18 Gram-positive samples and 25 Gram-negative samples. Subsequently, the limma package in R was used to screen the differentially expressed genes (DEGs). Hierarchical clustering was conducted for the specific DEGs in Gram-negative and Gram-negative samples using cluster software and the TreeView software. To analyze the correlation of samples at the gene level, a similarity network was constructed using Cytoscape software. Functional and pathway enrichment analyses were conducted for the DEGs using DAVID. Finally, stochastic perturbation was used to determine the significantly differential functions between Gram-positive and Gram-negative samples. A total of 340 and 485 DEGs were obtained in Gram-positive and Gram-negative samples, respectively. Hierarchical clustering revealed that there were significant differences between control and sepsis samples. In Gram-positive and Gram-negative samples, myeloid cell leukemia sequence 1 was associated with apoptosis and programmed cell death. Additionally, NADH:ubiquinone oxidoreductase subunit S4 was associated with mitochondrial respiratory chain complex I assembly. Stochastic perturbation analysis revealed that NADH:ubiquinone oxidoreductase subunit B2 (NDUFB2), NDUFB8 and ubiquinol-cytochrome c reductase hinge protein (UQCRH) were associated with cellular respiration in Gram-negative samples, whereas large tumor suppressor kinase 2 (LATS2) was associated with G1/S transition of the mitotic cell cycle in Gram-positive samples. NDUFB2, NDUFB8 and UQCRH may be biomarkers for Gram-negative sepsis, whereas LATS2 may be a biomarker for Gram-positive sepsis. These findings may promote the

Antibacterial activity of Pd(II) complexes with salicylaldehyde-amino acids Schiff bases ligands.

PubMed

Rîmbu, Cristina; Danac, Ramona; Pui, Aurel

2014-01-01

Palladium(II) complexes with Schiff bases ligands derived from salicylaldehyde and amino acids (Ala, Gly, Met, Ser, Val) have been synthesized and characterized by Fourier transform (FT)-IR, UV-Vis and (1)H-NMR spectroscopy. The electrospray mass spectrometry (ES-MS) spectrometry confirms the formation of palladium(II) complexes in 1/2 (M/L) molar ratio. All the Pd(II) complexes 1, [Pd(SalAla)2]Cl2; 2, [Pd(SalGly)2]Cl2; 3, [Pd(SalMet)2]Cl2; 4, [Pd(SalSer)2]Cl2; 5, [Pd(SalVal)2]Cl2; have shown antibacterial activity against Gram-positive bacteria Staphylococcus aureus and Gram-negative bacteria Escherichia coli.

Gram-negative, but not Gram-positive, bacteria elicit strong PGE2 production in human monocytes.

PubMed

Hessle, Christina C; Andersson, Bengt; Wold, Agnes E

2003-12-01

Gram-positive and Gram-negative bacteria induce different cytokine patterns in human mononuclear cells. We have seen that Gram-positives preferentially induce IL-12 and TNF-alpha, whereas Gram-negatives induce more IL-10, IL-6, and IL-8. In this study, we compared the capacity of these two groups of bacteria to induce PGE2. Monocytes stimulated with Gram-negative bacterial species induced much more PGE2 than did Gram-positive bacteria (5600 +/- 330 vs. 1700 +/- 670 pg/mL, p < 0.001). Blocking of COX-2 by NS398 abolished PGE2 production, but did not alter the cytokine patterns induced by Gram-positive and Gram-negative bacteria. We suggest that Gram-positive and Gram-negative bacteria may stimulate different innate effector functions; Gram-positive bacteria promoting cell-mediated effector functions whereas Gram-negative bacteria inducing mediators inhibiting the same.

Antibacterial and antioxidant activity of Juniperus thurifera L. leaf extracts growing in East of Algeria

PubMed Central

Manel, Merradi; Nouzha, Heleili; Rim, Mekari; Imane, Mekkaoui; Sana, Aouachria; Yasmine, Oucheriah; Ammar, Ayachi

2018-01-01

Aim: This work aimed to evaluate the biological activity of the leaf extracts of Juniperus thurifera L., which is an Algerian endemic tree that belongs to the family of Cupressaceae. Materials and Methods: The plant leaves were extracted in solvents of increasing polarity to obtain different extracts such as methanol, petroleum ether, chloroform, ethyl acetate, and aqueous extracts (MeE, PEE, ChlE, EtAE, and AqE). The antioxidant activity of four extracts (MeE, ChlE, EtAE, and AqE) was assessed by trapping test of 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical. The evaluation of antibacterial activity of MeE, ChlE, EtAE, and PEE was done using the disk diffusion method on solid agar. Results: The three extracts of EtAE, AqE, and MeE showed high antiradical activity toward the DPPH radical (IC50=29.348 µg/mL, 37.538 µg/mL, and 52.573 µg/mL, respectively), while the lowest radical scavenging activity was expressed by the ChlE (IC50=70.096 µg/mL). These extracts were active only toward the Gram-positive bacteria (Staphylococcus aureus ATCC and methicillin-resistant S. aureus) at different concentrations, and the highest activity was obtained with the ChlE with an inhibition diameter of 14 mm at the concentration of 1 g/mL. No inhibition was detected for all of these extracts against the Gram-negative tested strains (Escherichia coli ATCC, Pseudomonas aeruginosa ATCC, and Enterobacter cloacae (extended spectrum β-lactamase). Conclusion: From this study, on the one hand, it was concluded that J. thurifera L. leaves extracts exhibited a very intense antioxidant potential toward the DPPH radical, and on the other hand, the antibacterial activity showed an action spectrum exclusively toward the Gram-positive bacteria. PMID:29657432

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

Gallesia integrifolia (Spreng.) Harms: In vitro and in vivo antibacterial activities and mode of action.

PubMed

Arunachalam, Karuppusamy; Ascêncio, Sérgio Donizeti; Soares, Ilsamar Mendes; Souza Aguiar, Raimundo Wagner; da Silva, Larissa Irene; de Oliveira, Ruberlei Godinho; Balogun, Sikiru Olaitan; de Oliveira Martins, Domingos Tabajara

2016-05-26

Gallesia integrifolia (Phytolaccaceae) is commonly known as "pau-d'alho" in Brazil or "garlic plant" due to the strong scent of garlic peculiar to all parts of the plant. The bark decoction is used for the treatment of microbial infections among other diseases by different ethnic groups in Brazil, Peruvian Amazonians, Bolivia and Mosetene Indians. This study aimed to advance in the antibacterial activity and characterize the mode of action of the hydroethanolic extract of the inner stem bark of G. integrifolia (HEGi) using in vivo and in vitro experimental models. The qualitative and quantitative phytochemical analyzes of HEGi were carried out using colorimetric and HPLC technique. The cytotoxic potential of HEGi was evaluated against CHO-K1 cells by Alamar blue assay and its acute toxicity was assessed by the Hippocratic screening test using Swiss-Webster mice. The antibacterial activity was evaluated by micro- dilution method against ten strains of Gram-positive and Gram-negative bacteria. The mode of action of HEGi was investigated by outer membrane permeability, nucleotide leakage and potassium efflux assays. In vivo infection model was established by using Staphylococcus aureus infection model Wistar rats. Qualitative phytochemical analysis of HEGi revealed the presence of saponins, alkaloids, phenolic compounds and flavonoids. Phytochemical quantification of HEGi showed that higher total phenolic (80.10±0.62mg GAE/g) and flavonoid (16.10±0.03mg RE/g) contents. HPLC fingerprint analysis revealed the presence of gallic acid, rutin, and morin. In the Alamar blue assay no cytotoxic effect of HEGi in CHO-K1 cells was observed up to 200µg/mL, and no signs or symptoms of acute toxicity were observed in mice of both sexes at higher doses of up to 2000mg/kg, p.o. HEGi demonstrated bacteriostatic effect against selected Gram positive and Gram negative bacterial pathogens. Its mode of action is associated, at least partly, with changes in the permeability of

Synthesis, characterization, and antibacterial activities of ZnLaFe2O4/NiTiO3 nanocomposite

NASA Astrophysics Data System (ADS)

Sobhani-Nasab, Ali; Zahraei, Zohreh; Akbari, Maryam; Maddahfar, Mahnaz; Hosseinpour-Mashkani, S. Mostafa

2017-07-01

In this research, for the first time, ZnLaFe2O4/NiTiO3 nanocomposites have been synthesized through a polyol assistant sol-gel method. To investigate the effect of different surfactants on the morphology and particle size of ZnLaFe2O4 nanostructure, cetrimonium bromide, sodium dodecyl sulfate, polyvinylpyrrolidone, polyvinyl alcohol, and oleic acid were used as surfactant agents. Based on the SEM results, it was found that morphology and particle size of the products could be affected by these surfactants. Furthermore, study on antibacterial effect of ZnLaFe2O4/NiTiO3 nanocomposites by colony forming unit (CFU) reduction assay showed that ZnLaFe2O4/NiTiO3 nanocomposites have antibacterial activity against Gram-negative Escherchia coli (ATCC 10536) and Gram-positive Staphylococcus aureus (ATCC 29737). Antibacterial results demonstrate that nanocomposite significantly reduced the growth rate of E. coli bacteria and S. aureus after 120 min. The structure and morphology of the resulting particles were characterized by XRD, FT-IR, EDX, and SEM analysis.

Antibacterial clay against gram-negative antibiotic resistant bacteria.

PubMed

Zarate-Reyes, Luis; Lopez-Pacheco, Cynthia; Nieto-Camacho, Antonio; Palacios, Eduardo; Gómez-Vidales, Virginia; Kaufhold, Stephan; Ufer, Kristian; García Zepeda, Eduardo; Cervini-Silva, Javiera

2018-01-15

Antibiotic resistant bacteria persist throughout the world because they have evolved the ability to express various defense mechanisms to cope with antibiotics and the immune system; thus, low-cost strategies for the treatment of these bacteria are needed, such as the usage of environmental minerals. This paper reports the antimicrobial properties of a clay collected from Brunnenberg, Germany, that is composed of ferroan saponite with admixtures of quartz, feldspar and calcite as well as exposed or hidden (layered at inner regions) nano Fe(0). Based on the growth curves (log phase) of six antibiotic resistant bacteria (4 gram-negative and 2 gram-positive), we concluded that the clay acted as a bacteriostat; however, the clay was only active against the gram-negative bacteria (except for resilient Klebsiella pneumonia). The bacteriostatic mode of action was evidenced by the initial lack of Colony Forming Units on agar plates with growth registered afterward, certainly after 24h, and can be explained because interactions between membrane lipopolysaccharides and the siloxane surfaces of the clay. Labile or bioavailable Fe in the clay (extracted by EDTA or DFO-B) induced the quantitative production of HO as well as oxidative stress, which, nevertheless, did not account for by its bacteriostatic activity. Copyright © 2017 Elsevier B.V. All rights reserved.

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 μM to 50 μM based on a linear decrease of fluorescence intensity as well as a detection limit of 0.2 μM 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 μM to 50 μM based on a linear decrease of fluorescence intensity as well as a detection limit of 0.2 μM 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

Chemotyping of diverse Eucalyptus species grown in Egypt and antioxidant and antibacterial activities of its respective essential oils.

PubMed

Salem, Mohamed Z M; Ashmawy, Nader A; Elansary, Hosam O; El-Settawy, Ahmed A

2015-01-01

The chemical composition of the essential oil from the leaves of Eucalyptus camaldulensis, Eucalyptus camaldulensis var. obtusa and Eucalyptus gomphocephala grown in northern Egypt was analysed by using GC-FID and GC-MS techniques. The antibacterial (agar disc diffusion and minimum inhibitory concentration methods) and antioxidant activities (2,2'-diphenypicrylhydrazyl) were examined. The main oils constituents were 1,8-cineole (21.75%), β-pinene (20.51%) and methyleugenol (6.10%) in E. camaldulensis; spathulenol (37.46%), p-cymene (17.20%) and crypton (8.88%) in E. gomphocephala; spathulenol (18.37%), p-cymene (19.38%) and crypton (16.91%) in E. camaldulensis var. obtusa. The essential oils from the leaves of Eucalyptus spp. exhibited considerable antibacterial activity against Gram-positive and Gram-negative bacteria. The values of total antioxidant activity were 70 ± 3.13%, 50 ± 3.34% and 84 ± 4.64% for E. camaldulensis, E. camaldulensis var. obtusa and E. gomphocephala, respectively. The highest antioxidant activity value of 84 ± 4.64% could be attributed to the high amount of spathulenol (37.46%).

Comparison of the polyphenolic profile and antibacterial activity of the leaves, fruits and flowers of Rhododendron ambiguum and Rhododendron cinnabarinum.

PubMed

Shrestha, Abhinandan; Rezk, Ahmed; Said, Inamullah Hakeem; von Glasenapp, Victoria; Smith, Rachelle; Ullrich, Matthias S; Schepker, Hartwig; Kuhnert, Nikolai

2017-07-20

Rhododendron species have been traditionally used in countries like China, Nepal, Russia and North America for treating human diseases. These species are known to be a good source of polyphenolic plant secondary plant metabolites. They are known to have beneficial health properties for humans and have been used to treat diseases like asthma, skin diseases. In this contribution we investigate the phenolic profile and antibacterial activity of extracts from several plant organs including for the first time from leaves of different development stages. In this study, the polyphenolic profile of fruits, flowers and leaves of different ages of Rhododendron ambiguum and Rhododendron cinnabarinum were studied by using HPLC-MS and compounds identified based on high resolution masses and identity of tandem mass spectra, UV/VIS spectra and retention times if compared to standards. Fifty-nine different polyphenols including isomers were identified in these species by their fragmentation pattern and high resolution data. Also, the antibacterial activity of these parts (leaves, fruits and flowers) against gram-positive bacteria was studied. The leaves and fruits contained more polyphenols than the flowers. With the exception of flowers, the fruits and leaves of both species were also determined to have a significant antibacterial effect against four gram-positive bacteria.

Isolation of the Entomopathogenic Fungal Strain Cod-MK1201 from a Cicada Nymph and Assessment of Its Antibacterial Activities.

PubMed

Sangdee, Kusavadee; Nakbanpote, Woranan; Sangdee, Aphidech

2015-01-01

The entomopathogenic fungus Cod-MK1201 was isolated from a dead cicada nymph. Three regions of ribosomal nuclear DNA, the internal transcribed spacers of nuclear ribosomal DNA repeats (ITS), the partial small subunit of rDNA (nrSSU) , and the partial large subunit of rDNA (nrLSU), and two protein-coding regions, the elongation factor 1α (EF-1α), and the largest subunit of the RNA polymerase II (rpb1) gene, were sequenced and used for fungal identification. The phylogenetic analysis of the ITS and the combined data set of the five genes indicated that the fungal isolate Cod-MK1201 is a new strain of Cordyceps sp. that is closely related to Cordyceps nipponica and C. kanzashiana. Crude extracts of mycelium-cultured Cod-MK1201 were obtained using distilled water and 50% (v/v) ethanol, and the antibacterial activity of each was determined. Both extracts had activity against Gram-positive and Gram-negative bacteria, but the ethanol extract was the more potent of the two. The antibacterial activity of the protein fractions of these extracts was also determined. The protein fraction from the ethanol extract was more antibacterial than the protein fraction from the aqueous extract. Three antibacterial constituents including adenosine, the total phenolic content (TPC), and the total flavonoid content (TFC) was also determined. The results showed that the adenosine content, the TPC, and the TFC of the ethanol extract were more active than those of the aqueous extract. Moreover, synergism was detected between these antibacterial constituents. In conclusion, the entomopathogenic fungal isolate Cod-MK1201 represents a natural source of antibacterial agents.

Amino acid conjugated antimicrobial drugs: Synthesis, lipophilicity- activity relationship, antibacterial and urease inhibition activity.

PubMed

Ullah, Atta; Iftikhar, Fatima; Arfan, Muhammad; Batool Kazmi, Syeda Tayyaba; Anjum, Muhammad Naveed; Haq, Ihsan-Ul; Ayaz, Muhammad; Farooq, Sadia; Rashid, Umer

2018-02-10

Present work describes the in vitro antibacterial evaluation of some new amino acid conjugated antimicrobial drugs. Structural modification was attempted on the three existing antimicrobial pharmaceuticals namely trimethoprim, metronidazole, isoniazid. Twenty one compounds from seven series of conjugates of these drugs were synthesized by coupling with some selected Boc-protected amino acids. The effect of structural features and lipophilicity on the antibacterial activity was investigated. The synthesized compounds were evaluated against five standard American type culture collection (ATCC) i.e. Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Pseudomonas aeruginosa and Salmonella typhi strains of bacteria. Our results identified a close relationship between the lipophilicity and the activity. Triazine skeleton proved beneficial for the increase in hydrophobicity and potency. Compounds with greater hydrophobicity have shown excellent activities against Gram-negative strains of bacteria than Gram-positive. 4-amino unsubstituted trimethoprim-triazine derivative 7b have shown superior activity with MIC = 3.4 μM (2 μg/mL) for S. aureus and 1.1 μM (0.66 μg/mL) for E. coli. The synthesized compounds were also evaluated for their urease inhibition study. Microbial urease from Bacillus pasteurii was chosen for this study. Triazine derivative 7a showed excellent inhibition with IC 50  = 6.23 ± 0.09 μM. Docking studies on the crystal structure of B. pasteurii urease (PDB ID 4UBP) were carried out. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Andrographolide: antibacterial activity against common bacteria of human health concern and possible mechanism of action.

PubMed

Banerjee, Malabika; Parai, Debaprasad; Chattopadhyay, Subrata; Mukherjee, Samir Kumar

2017-05-01

Increasing bacterial resistance to common drugs is a major public health concern for the treatment of infectious diseases. Certain naturally occurring compounds of plant sources have long been reported to possess potential antimicrobial activity. This study was aimed to investigate the antibacterial activity and possible mechanism of action of andrographolide (Andro), a diterpenoid lactone from a traditional medicinal herb Andrographis paniculata. Extent of antibacterial action was assessed by minimal bactericidal concentration method. Radiolabeled N-acetyl glucosamine, leucine, thymidine, and uridine were used to determine the effect of Andro on the biosyntheses of cell wall, protein, DNA, and RNA, respectively. In addition, anti-biofilm potential of this compound was also tested. Andro showed potential antibacterial activity against most of the tested Gram-positive bacteria. Among those, Staphylococcus aureus was found to be most sensitive with a minimal inhibitory concentration value of 100 μg/mL. It was found to be bacteriostatic. Specific inhibition of intracellular DNA biosynthesis was observed in a dose-dependent manner in S. aureus. Andro mediated inhibition of biofilm formation by S. aureus was also found. Considering its antimicrobial potency, Andro might be accounted as a promising lead for new antibacterial drug development.

Enhanced Antibacterial Activity of Ent-Labdane Derivatives of Salvic Acid (7α-Hydroxy-8(17)-ent-Labden-15-Oic Acid): Effect of Lipophilicity and the Hydrogen Bonding Role in Bacterial Membrane Interaction.

PubMed

Echeverría, Javier; Urzúa, Alejandro; Sanhueza, Loreto; Wilkens, Marcela

2017-06-23

In the present study, the antibacterial activity of several ent -labdane derivatives of salvic acid (7α-hydroxy-8(17)- ent -labden-15-oic acid) was evaluated in vitro against the Gram-negative bacterium Escherichia coli and the Gram-positive bacteria Staphylococcus aureus and Bacillus cereus . For all of the compounds, the antibacterial activity was expressed as the minimum inhibitory concentration (MIC) in liquid media and minimum inhibitory amount (MIA) in solid media. Structure activity relationships (SAR) were employed to correlate the effect of the calculated lipophilicity parameters (logP ow ) on the inhibitory activity. Employing a phospholipidic bilayer (POPG) as a bacterial membrane model, ent -labdane-membrane interactions were simulated utilizing docking studies. The results indicate that (i) the presence of a carboxylic acid in the C-15 position, which acted as a hydrogen-bond donor (HBD), was essential for the antibacterial activity of the ent -labdanes; (ii) an increase in the length of the acylated chain at the C-7 position improved the antibacterial activity until an optimum length of five carbon atoms was reached; (iii) an increase in the length of the acylated chain by more than five carbon atoms resulted in a dramatic decrease in activity, which completely disappeared in acyl chains of more than nine carbon atoms; and (iv) the structural factors described above, including one HBD at C-15 and a hexanoyloxi moiety at C-7, had a good fit to a specific lipophilic range and antibacterial activity. The lipophilicity parameter has a predictive characteristic feature on the antibacterial activity of this class of compounds, to be considered in the design of new biologically active molecules.

Phosphonopeptides as Antibacterial Agents: Alaphosphin and Related Phosphonopeptides

PubMed Central

Allen, John G.; Atherton, Frank R.; Hall, Michael J.; Hassall, Cedric H.; Holmes, Simon W.; Lambert, Robert W.; Nisbet, Louis J.; Ringrose, Peter S.

1979-01-01

Alaphosphin, l-alanyl-l-1-aminoethylphosphonic acid, was selected from a range of phosphonopeptides for evaluation in humans on the basis of its antibacterial activity, pharmacokinetics, and stability to intestinal and kidney peptidases. In vitro, the antibacterial action was antagonized by small peptides, resulting in low activity on peptone media. On an antagonist-free medium alaphosphin was bactericidal and rapidly lysed most susceptible gram-negative bacteria, but it was largely bacteriostatic and essentially nonlytic against gram-positive organisms. Its spectrum included most strains normally isolated from urinary tract infections, but potency was greatly reduced by very high inoculum levels and by alkaline pH. Although strains of Proteus and Pseudomonas were less susceptible to alaphosphin than were other common gram-negative bacteria, like other species they formed spheroplasts when exposed under appropriate conditions. Alaphosphin was equally effective against penicillin-susceptible and -resistant strains and showed no cross-resistance with known antibiotics. Good synergy and increased bactericidal activity were demonstrated with combinations of alaphosphin and d-cycloserine or β-lactam antibiotics. Images PMID:43113

Discovery of 2-aminothiazolyl berberine derivatives as effectively antibacterial agents toward clinically drug-resistant Gram-negative Acinetobacter baumanii.

PubMed

Gao, Wei-Wei; Gopala, Lavanya; Bheemanaboina, Rammohan R Yadav; Zhang, Guo-Biao; Li, Shuo; Zhou, Cheng-He

2018-02-25

Aminothiazolyl berberine derivatives as potentially antimicrobial agents were designed and synthesized in an effort to overcome drug resistance. The antimicrobial assay revealed that some target compounds exhibited significantly inhibitory efficiencies toward bacteria and fungi including drug-resistant pathogens, and the aminothiazole and Schiff base moieties were helpful structural fragments for aqueous solubility and antibacterial activity. Especially, aminothiazolyl 9-hexyl berberine 9c and 2,4-dichlorobenzyl derivative 18a exhibited good activities (MIC = 2 nmol/mL) against clinically drug-resistant Gram-negative Acinetobacter baumanii with low cytotoxicity to hepatocyte LO2 cells, rapidly bactericidal effects and quite slow development of bacterial resistance toward A. baumanii. Molecular modeling indicated that compounds 9c and 18a could bind with GLY-102, ARG-136 and/or ALA-100 residues of DNA gyrase through hydrogen bonds. It was found that compounds 9c and 18a were able to disturb the drug-resistant A. baumanii membrane effectively, and molecule 9c could not only intercalate but also cleave bacterial DNA isolated from resistant A. baumanii, which might be the preliminary antibacterial action mechanism of inhibiting the growth of A. baumanii strain. In particular, the combination use of compound 9c with norfloxacin could enhance the antibacterial activity, broaden antibacterial spectrum and overcome the drug resistance. Copyright © 2018 Elsevier Masson SAS. All rights reserved.

Effects of antibacterial mineral leachates on the cellular ultrastructure, morphology, and membrane integrity of Escherichia coli and methicillin-resistant Staphylococcus aureus

PubMed Central

2010-01-01

Background We have previously identified two mineral mixtures, CB07 and BY07, and their respective aqueous leachates that exhibit in vitro antibacterial activity against a broad spectrum of pathogens. The present study assesses cellular ultrastructure and membrane integrity of methicillin-resistant Staphylococcus aureus (MRSA) and Escherichia coli after exposure to CB07 and BY07 aqueous leachates. Methods We used scanning and transmission electron microscopy to evaluate E. coli and MRSA ultrastructure and morphology following exposure to antibacterial leachates. Additionally, we employed Baclight LIVE/DEAD staining and flow cytometry to investigate the cellular membrane as a possible target for antibacterial activity. Results Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) imaging of E. coli and MRSA revealed intact cells following exposure to antibacterial mineral leachates. TEM images of MRSA showed disruption of the cytoplasmic contents, distorted cell shape, irregular membranes, and distorted septa of dividing cells. TEM images of E. coli exposed to leachates exhibited different patterns of cytoplasmic condensation with respect to the controls and no apparent change in cell envelope structure. Although bactericidal activity of the leachates occurs more rapidly in E. coli than in MRSA, LIVE/DEAD staining demonstrated that the membrane of E. coli remains intact, while the MRSA membrane is permeabilized following exposure to the leachates. Conclusions These data suggest that the leachate antibacterial mechanism of action differs for Gram-positive and Gram-negative organisms. Upon antibacterial mineral leachate exposure, structural integrity is retained, however, compromised membrane integrity accounts for bactericidal activity in Gram-positive, but not in Gram-negative cells. PMID:20846374

Fabrication of Fe{sub 3}O{sub 4}@CuO core-shell from MOF based materials and its antibacterial activity

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

Rajabi, S.K.; Sohrabnezhad, Sh., E-mail: sohrabnezhad@guilan.ac.ir; Ghafourian, S.

Magnetic Fe{sub 3}O{sub 4}@CuO nanocomposite with a core/shell structure was successfully synthesized via direct calcinations of magnetic Fe{sub 3}O{sub 4}@HKUST-1 in air atmosphere. The morphology, structure, magnetic and porous properties of the as-synthesized nano composites were characterized by using scanning electron microscope (SEM), transmission electron microscopy (TEM), powder X-ray diffraction (PXRD), and vibration sample magnetometer (VSM). The results showed that the nanocomposite material included a Fe{sub 3}O{sub 4} core and a CuO shell. The Fe{sub 3}O{sub 4}@CuO core-shell can be separated easily from the medium by a small magnet. The antibacterial activity of Fe{sub 3}O{sub 4}-CuO core-shell was investigated againstmore » gram-positive and gram-negative bacteria. A new mechanism was proposed for inactivation of bacteria over the prepared sample. It was demonstrated that the core-shell exhibit recyclable antibacterial activity, acting as an ideal long-acting antibacterial agent. - Graphical abstract: Fe{sub 3}O{sub 4}@CuO core-shell release of copper ions. These Cu{sup 2+} ions were responsible for the exhibited antibacterial activity. - Highlights: • The Fe{sub 3}O{sub 4}@CuO core-shell was prepared by MOF method. • This is the first study of antibacterial activity of core-shell consist of CuO and Fe{sub 3}O{sub 4}. • The core-shell can be reused effectively. • Core-shell was separated from the reaction solution by external magnetic field.« less

Functional Iron Oxide-Silver Hetero-Nanocomposites: Controlled Synthesis and Antibacterial Activity

NASA Astrophysics Data System (ADS)

Trang, Vu Thi; Tam, Le Thi; Van Quy, Nguyen; Huy, Tran Quang; Thuy, Nguyen Thanh; Tri, Doan Quang; Cuong, Nguyen Duy; Tuan, Pham Anh; Van Tuan, Hoang; Le, Anh-Tuan; Phan, Vu Ngoc

2017-06-01

Iron oxide-silver nanocomposites are of great interest for their antibacterial and antifungal activities. We report a two-step synthesis of functional magnetic hetero-nanocomposites of iron oxide nanoparticles and silver nanoparticles (Fe3O4-Ag). Iron oxide nanoparticles were prepared first by a co-precipitation method followed by the deposition of silver nanoparticles via a hydrothermal route. The prepared Fe3O4-Ag hetero-nanocomposites were characterized by x-ray diffraction, transmission electron microscopy, high resolution transmission electron microscopy and vibrating sample magnetometry. Their antibacterial activities were investigated by using paper-disc diffusion and direct-drop diffusion methods. The results indicate that the Fe3O4-Ag hetero-nanocomposites exhibit excellent antibacterial activities against two Gram-negative bacterial strains ( Salmonella enteritidis and Klebsiella pneumoniae).

Antibacterial properties of the skin mucus of the freshwater fishes, Rita rita and Channa punctatus.

PubMed

Kumari, U; Nigam, A K; Mitial, S; Mitial, A K

2011-07-01

The skin mucus of Rita rita and Channa punctatus was investigated to explore the possibilities of its antibacterial properties. Skin mucus was extracted in acidic solvents (0.1% trifluoroacetic acid and 3% acetic acid) and in triple distilled water (aqueous medium). The antibacterial activity of the mucus extracts was analyzed, using disc diffusion method, against five strains of bacteria--the Gram-positive Staphylococcus aureus and Micrococcus luteus; and the Gram negative Escherichia coli, Pseudomonas aeruginosa and Salmonella typhi. In both Rita rita and Channa punctatus, the skin mucus extracted in acidic solvents as well as in aqueous medium show antibacterial activity against Staphylococcus aureus and Micrococcus luteus. Nevertheless, the activity is higher in acidic solvents than that in aqueous medium. The acidic mucus extracts of Rita rita, show antibacterial activity against Salmonella typhi as well. The results suggest that fish skin mucus have bactericidal properties and thus play important role in the protection of fish against the invasion of pathogens. Fish skin mucus could thus be regarded as a potential source of novel antibacterial components.

RNases and Helicases in Gram-Positive Bacteria.

PubMed

Durand, Sylvain; Condon, Ciaran

2018-04-01

RNases are key enzymes involved in RNA maturation and degradation. Although they play a crucial role in all domains of life, bacteria, archaea, and eukaryotes have evolved with their own sets of RNases and proteins modulating their activities. In bacteria, these enzymes allow modulation of gene expression to adapt to rapidly changing environments. Today, >20 RNases have been identified in both Escherichia coli and Bacillus subtilis , the paradigms of the Gram-negative and Gram-positive bacteria, respectively. However, only a handful of these enzymes are common to these two organisms and some of them are essential to only one. Moreover, although sets of RNases can be very similar in closely related bacteria such as the Firmicutes Staphylococcus aureus and B. subtilis , the relative importance of individual enzymes in posttranscriptional regulation in these organisms varies. In this review, we detail the role of the main RNases involved in RNA maturation and degradation in Gram-positive bacteria, with an emphasis on the roles of RNase J1, RNase III, and RNase Y. We also discuss how other proteins such as helicases can modulate the RNA-degradation activities of these enzymes.

Sulfaguanidine cocrystals: Synthesis, structural characterization and their antibacterial and hemolytic analysis.

PubMed

Abidi, Syed Sibte Asghar; Azim, Yasser; Khan, Shahper Nazeer; Khan, Asad U

2018-02-05

Sulfaguanidine (SG), belongs to the class of sulfonamide drug used as an effective antibiotic. In the present work, using crystal engineering approach two novel cocrystals of SG were synthesized (SG-TBA and SG-PT) with thiobarbutaric acid (TBA) and 1,10-phenanthroline (PT), characterized by solid state techniques viz., powder X-ray diffraction (PXRD), fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC) and the crystal structures were determined by single crystal X-ray diffraction studies. A comparative antibacterial activity and hemolytic potential was done on SG drug, coformers and their cocrystals. The tested cocrystals formulations showed almost two fold higher antibacterial activity against the tested strains of bacteria Gram-positive bacteria (S. mutans and E. faecalis) and Gram-negative bacteria (E. coli, K. pneumonia and E. clocae) over SG alone and their coformers. Cocrystal SG-TBA showed better antibacterial activity and reduced hemolysis, thereby, reduced cytotoxicity than SG-PT. Copyright © 2017 Elsevier B.V. All rights reserved.

Antibacterial Potential of Northeastern Portugal Wild Plant Extracts and Respective Phenolic Compounds

PubMed Central

Ferreira, Isabel C. F. R.; Barros, Lillian; Carvalho, Ana Maria; Soares, Graça; Henriques, Mariana

2014-01-01

The present work aims to assess the antibacterial potential of phenolic extracts, recovered from plants obtained on the North East of Portugal, and of their phenolic compounds (ellagic, caffeic, and gallic acids, quercetin, kaempferol, and rutin), against bacteria commonly found on skin infections. The disk diffusion and the susceptibility assays were used to identify the most active extracts and phenolic compounds. The effect of selected phenolic compounds on animal cells was assessed by determination of cellular metabolic activity. Gallic acid had a higher activity, against gram-positive (S. epidermidis and S. aureus) and gram-negative bacteria (K. pneumoniae) at lower concentrations, than the other compounds. The caffeic acid, also, showed good antibacterial activity against the 3 bacteria used. The gallic acid was effective against the 3 bacteria without causing harm to the animal cells. Gallic and caffeic acid showed a promising applicability as antibacterial agents for the treatment of infected wounds. PMID:24804249

Transformation of gram positive bacteria by sonoporation

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

Yang, Yunfeng; Li, Yongchao

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.

Controlled release and long-term antibacterial activity of reduced graphene oxide/quaternary ammonium salt nanocomposites prepared by non-covalent modification.

PubMed

Ye, Xiaoli; Feng, Jin; Zhang, Jingxian; Yang, Xiujiang; Liao, Xiaoyan; Shi, Qingshan; Tan, Shaozao

2017-01-01

In order to control the long-term antibacterial property of quaternary ammonium salts, dodecyl dimethyl benzyl ammonium chloride (rGO-1227) and rGO-bromohexadecyl pyridine (rGO-CPB) were self-assembled on surfaces of reduced graphene oxide (rGO) via π-π interactions. The obtained rGO-1227 and rGO-CPB nanocompounds were characterized by X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM).The antibacterial activities were evaluated on Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus. Both rGO-CPB and rGO-1227 reduced the cytotoxicity of the pure antimicrobial agents and presented strong antimicrobial properties. Especially, CPB could be loaded efficiently on the surface of rGO via π-π conjugate effect, which resulted in a nanocomposite presenting a long-term antibacterial capability due to the more important quantity of free π electrons compared to that of 1227. When comparing the advantages of both prepared nanocomposites, rGO-CPB displayed a better specific-targeting capability and a longer-term antibacterial property. Copyright © 2016 Elsevier B.V. All rights reserved.

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

PubMed

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 AgNO(3). 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.

Mimics of pramanicin derived from pyroglutamic acid and their antibacterial activity.

PubMed

Tan, Song Wei Benjamin; Chai, Christina L L; Moloney, Mark G

2017-02-22

Mono and dihydroxypyrrolidinones are readily available by direct oxygenation of a pyroglutamate-derived bicyclic lactam with high diastereoselectivity, and these may be manipulated further in protected or unprotected form by Grignard addition to a pendant Weinreb amide to give acylhydroxypyrrolidinones, which are analogues of the natural product, pramanicin. Preliminary bioassay against S. aureus and E. coli indicated that some compounds exhibit selective Gram-negative antibacterial activity, and may offer promise for the development of novel systems suitable for antibacterial drug development.

Prospects for new antibacterials: can we do better?

PubMed

Georgopapadakou, Nafsika H

2014-02-01

Bacterial resistance to antibacterial drugs has been increasing relentlessly over the past two decades. This includes common residents of the human body: Staphylococcus aureus (methicillin resistant or MRSA) Enteroccus faecalis and E. faecium (vancomycin resistant or VRE): Enterobacteriaceae (multiresistant, carbapenems included or CRE). It also includes environmental, opportunistic, but intrinsically multiresistant species: Pseudomonas aeruginosa and Acinetobacter baumannii. Financial considerations have curtailed R&D activity in the antibacterial field in all, but a couple of large pharmaceutical companies and small biotech companies have largely been unable to fill the drug discovery gap. Antibacterials currently under development have targeted, almost exclusively, Gram-positive bacteria; hence, greater effort must be directed against Gram-negative bacteria, particularly enterobacteria. There also has to be more transparency and care in clinical development. To get ahead of the problem of resistance, we must look for first-in-class antibacterials and new targets. The need to innovate is best addressed through partnerships between drug-makers and public institutions. Such partnerships would provide a long-term view and stability to projects, but also balance the interests of corporate and public stakeholders.

[Post-marketing surveillance of antibacterial activities of cefozopran against various clinical isolates--II. Gram-negative bacteria].

PubMed

Igari, Jun; Oguri, Toyoko; Hiramatsu, Nobuyoshi; Akiyama, Kazumitsu; Koyama, Tsuneo

2002-02-01

As a post-marketing surveillance, the in vitro antibacterial activities of cefozopran (CZOP), an agent of cephems, against various clinical isolates were yearly evaluated and compared with those of other cephems, oxacephems, penicillins, monobactams, and carbapenems. Changes in CZOP susceptibility for the bacteria were also evaluated with the bacterial resistance ratio calculated with the breakpoint MIC. Twenty-five species (3,362 strains) of Gram-negative bacteria were isolated from the clinical materials annually collected from 1996 to 2000, and consisted of Moraxella (Branhamella) catarrhalis (n = 136), Haemophilus influenzae (n = 289), Escherichia coli (n = 276), Klebsiella pneumoniae (n = 192), Klebsiella oxytoca (n = 157), Enterobacter cloacae (n = 189), Enterobacter aerogenes (n = 93), Serratia marcescens (n = 172), Serratia liquefaciens (n = 24), Citrobacter freundii (n = 177), Citrobacter koseri (n = 70), Proteus mirabilis (n = 113), Proteus vulgaris (n = 89), Morganella morganii (n = 116), Providencia spp. (n = 41), Pseudomonas aeruginosa (n = 290), Pseudomonas fluorescens (n = 56), Pseudomonas putida (n = 63), Acinetobacter baumannii (n = 146), Acinetobacter lwoffii (n = 34), Burkholderia cepacia (n = 101), Stenotrophomonas maltophilia (n = 169), Bacteroides fragilis group (n = 196), and Prevotella/Porphyromonas (n = 173). An antibacterial activity of CZOP against E. coli, K. pneumoniae, K. oxytoca, and S. marcescens was potent and consistent with or more preferable than the study results obtained until the new drug application approval. MIC90 of CZOP against M.(B.) catarrhalis, C. koseri, and P. aeruginosa was not considerably changed and consistent with the study results obtained until the new drug application approval. MIC90 of CZOP against E. cloacae, E. aerogenes, and P. mirabilis increased year by year. The increase in MIC90 of CZOP against E. aerogenes and P. mirabilis, however, was not considered to be an obvious decline in susceptibility. In

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. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis and pharmacological evaluation of pyrazolo[4,3-c]cinnoline derivatives as potential anti-inflammatory and antibacterial agents.

PubMed

Tonk, Rajiv Kumar; Bawa, Sandhya; Chawla, Gita; Deora, Girdhar Singh; Kumar, Suresh; Rathore, Vandana; Mulakayala, Naveen; Rajaram, Azad; Kalle, Arunasree M; Afzal, Obaid

2012-11-01

A series of pyrazolo[4,3-c]cinnoline derivatives was synthesized, characterized and evaluated for anti-inflammatory and antibacterial activity. Test compounds that exhibited good anti-inflammatory activity were further screened for their ulcerogenic and lipid peroxidation activity. Compounds 4d and 4l showed promising anti-inflammatory activity with reduced ulcerogenic and lipid peroxidation activity when compared to naproxen. Docking results of these two compounds with COX-2 (PDB ID: 1CX2) also exhibited a strong binding profile. Among the test derivatives, compound 4i displayed significant antibacterial property against gram-negative (Escherichia coli and Pseudomonas aeruginosa) and gram-positive (Staphylococcus aureus) bacteria. However, compound 4b emerged as the best dual anti-inflammatory-antibacterial agent in the present study. Copyright © 2012 Elsevier Masson SAS. All rights reserved.

Visible light photocatalytic antibacterial activity of Ni-doped and N-doped TiO2 on Staphylococcus aureus and Escherichia coli bacteria.

PubMed

Ananpattarachai, Jirapat; Boonto, Yuphada; Kajitvichyanukul, Puangrat

2016-03-01

The Ni-doped and N-doped TiO2 nanoparticles were investigated for their antibacterial activities on Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) bacteria. Their morphological features and characteristics such as particle size, surface area, and visible light absorbing capacity were compared and discussed. Scanning electron microscopy, X-ray diffraction, and UV-visible spectrophotometry were used to characterize both materials. The inactivation of E. coli (as an example of Gram-negative bacteria) and S. aureus (as an example of Gram-positive bacteria) with Ni-doped and N-doped TiO2 was investigated in the absence and presence of visible light. Antibacterial activity tests were conducted using undoped, Ni-doped, and N-doped TiO2. The N-doped TiO2 nanoparticles show higher antibacterial activity than Ni-doped TiO2. The band gap narrowing of N-doped TiO2 can induce more visible light absorption and leads to the superb antibacterial properties of this material. The complete inactivation time for E. coli at an initial cell concentration of 2.7 × 10(4) CFU/mL was 420 min which is longer than the 360 min required for S. aureus inactivation. The rate of inactivation of S. aureus using the doped TiO2 nanoparticles in the presence of visible light is greater than that of E. coli. The median lethal dose (LD50) values of S. aureus and E. coli by antibacterial activity under an 18-W visible light intensity were 80 and 350 mg/ml for N-doped TiO2, respectively.

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

PubMed

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

2015-01-05

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. Copyright © 2014 Elsevier B.V. All rights reserved.

Design, synthesis and biological evaluation of novel aryldiketo acids with enhanced antibacterial activity against multidrug resistant bacterial strains.

PubMed

Cvijetić, Ilija N; Verbić, Tatjana Ž; Ernesto de Resende, Pedro; Stapleton, Paul; Gibbons, Simon; Juranić, Ivan O; Drakulić, Branko J; Zloh, Mire

2018-01-01

Antimicrobial resistance (AMR) is a major health problem worldwide, because of ability of bacteria, fungi and viruses to evade known therapeutic agents used in treatment of infections. Aryldiketo acids (ADK) have shown antimicrobial activity against several resistant strains including Gram-positive Staphylococcus aureus bacteria. Our previous studies revealed that ADK analogues having bulky alkyl group in ortho position on a phenyl ring have up to ten times better activity than norfloxacin against the same strains. Rational modifications of analogues by introduction of hydrophobic substituents on the aromatic ring has led to more than tenfold increase in antibacterial activity against multidrug resistant Gram positive strains. To elucidate a potential mechanism of action for this potentially novel class of antimicrobials, several bacterial enzymes were identified as putative targets according to literature data and pharmacophoric similarity searches for potent ADK analogues. Among the seven bacterial targets chosen, the strongest favorable binding interactions were observed between most active analogue and S. aureus dehydrosqualene synthase and DNA gyrase. Furthermore, the docking results in combination with literature data suggest that these novel molecules could also target several other bacterial enzymes, including prenyl-transferases and methionine aminopeptidase. These results and our statistically significant 3D QSAR model could be used to guide the further design of more potent derivatives as well as in virtual screening for novel antibacterial agents. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Will new antimicrobials overcome resistance among Gram-negatives?

PubMed

Bassetti, Matteo; Ginocchio, Francesca; Mikulska, Małgorzata; Taramasso, Lucia; Giacobbe, Daniele Roberto

2011-10-01

The spread of resistance among Gram-positive and Gram-negative bacteria represents a growing challenge for the development of new antimicrobials. The pace of antibiotic drug development has slowed during the last decade and, especially for Gram-negatives, clinicians are facing a dramatic shortage in the availability of therapeutic options to face the emergency of the resistance problem throughout the world. In this alarming scenario, although there is a shortage of compounds reaching the market in the near future, antibiotic discovery remains one of the keys to successfully stem and maybe overcome the tide of resistance. Analogs of already known compounds and new agents belonging to completely new classes of antimicrobials are in early stages of development. Novel and promising anti-Gram-negative antimicrobials belong both to old (cephalosporins, carbapenems, β-lactamase inhibitors, monobactams, aminoglycosides, polymyxin analogues and tetracycline) and completely new antibacterial classes (boron-containing antibacterial protein synthesis inhibitors, bis-indoles, outer membrane synthesis inhibitors, antibiotics targeting novel sites of the 50S ribosomal subunit and antimicrobial peptides). However, all of these compounds are still far from being introduced into clinical practice. Therefore, infection control policies and optimization in the use of already existing molecules are still the most effective approaches to reduce the spread of resistance and preserve the activity of antimicrobials.

Antibacterial activity study of Attacus atlas cocoon against Staphylococcus aureus and Escherichia coli with diffusion and dilution method

NASA Astrophysics Data System (ADS)

Aminah; Nugraheni, E. R.; Yugatama, A.

2018-03-01

The aim of this study was to evaluate the antibacterial activity from Attacus atlas cocoon extract against Gram-negative bacteria (Escherichia coli) and Gram-positive bacteria (Staphylococcus aureus) with 3 diffferent solvents polar, semi-polar and non polar which was ethanol, ethyl acetate and chloroform, also to determine the Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) of the extract. Cocoon was extracted with maceration method using 3 solvents with ratio of sample and solvent 1:10. Antibacterial activity of the Extracts obtained was evaluated with Agar disk diffusion method. The best result was then continued to determine the MIC and MBC of the extract using broth macro-dilution method. The results show that each of the extracts have antibacterial activity with broad spectrum against two different type of bacteria at concentration of 1 g/mL with different clear zone between these extracts. Clear zone from the biggest to the smallest against Escherichia coli was ethyl acetate (10.5 mm), chloroform (9 mm) and ethanol (8 mm). While against Staphylococcus aureus, was obtained by chloroform (12.5 mm), ethyl acetate (10.5 mm) and ethanol (7 mm). The MIC value of extracts can not be determine. The smallest MBC value against both bacteria was obtained by ethyl acetate with concentration of 3.125% b/v as a bactericidal.

Synthesis and structure-activity relationship studies of novel [6,6,5] tricyclic oxazolidinone derivatives as potential antibacterial agents.

PubMed

Xue, Tao; Ding, Shi; Guo, Bin; Chu, Wenjing; Wang, Hui; Yang, Yushe

2015-01-01

In our previous Letter, we reported the discovery of a novel benzoxazinyl-oxazolidinone antibacterial candidate 2. In order to identify a potential backup compound, extensive modifications on the B/C ring and C3 side chain were undertaken. A series of novel [6,6,5] tricyclic analogues were synthesized and their in vitro antibacterial activities were tested against a panel of susceptible and resistant Gram-positive pathogens. Among of them, benzothiazinyl-oxazolidinones with acetamide or thioamide as C3 side chains exhibited moderate to good antibacterial activity, such as compounds 54, 58, 59 and 63. In vitro liver microsomal stability was further evaluated and the results manifested that compounds 54 and 58 were both metabolically stable in rat and human liver microsomes. Additionally, insights gained from this investigation should provide directions for the further research of new oxazolidinone antibiotics. Copyright © 2015 Elsevier Ltd. All rights reserved.

Diagnosing periprosthetic infection: false-positive intraoperative Gram stains.

PubMed

Oethinger, Margret; Warner, Debra K; Schindler, Susan A; Kobayashi, Hideo; Bauer, Thomas W

2011-04-01

Intraoperative Gram stains have a reported low sensitivity but high specificity when used to help diagnose periprosthetic infections. In early 2008, we recognized an unexpectedly high frequency of apparent false-positive Gram stains from revision arthroplasties. The purpose of this report is to describe the cause of these false-positive test results. We calculated the sensitivity and specificity of all intraoperative Gram stains submitted from revision arthroplasty cases during a 3-month interval using microbiologic cultures of the same samples as the gold standard. Methods of specimen harvesting, handling, transport, distribution, specimen processing including tissue grinding/macerating, Gram staining, and interpretation were studied. After a test modification, results of specimens were prospectively collected for a second 3-month interval, and the sensitivity and specificity of intraoperative Gram stains were calculated. The retrospective review of 269 Gram stains submitted from revision arthroplasties indicated historic sensitivity and specificity values of 23% and 92%, respectively. Systematic analysis of all steps of the procedure identified Gram-stained but nonviable bacteria in commercial broth reagents used as diluents for maceration of periprosthetic membranes before Gram staining and culture. Polymerase chain reaction and sequencing showed mixed bacterial DNA. Evaluation of 390 specimens after initiating standardized Millipore filtering of diluent fluid revealed a reduced number of positive Gram stains, yielding 9% sensitivity and 99% specificity. Clusters of false-positive Gram stains have been reported in other clinical conditions. They are apparently rare related to diagnosing periprosthetic infections but have severe consequences if used to guide treatment. Even occasional false-positive Gram stains should prompt review of laboratory methods. Our observations implicate dead bacteria in microbiologic reagents as potential sources of false-positive Gram

Comparison of chemical composition and antibacterial activity of Nigella sativa seed essential oils obtained by different extraction methods.

PubMed

Kokoska, L; Havlik, J; Valterova, I; Sovova, H; Sajfrtova, M; Jankovska, I

2008-12-01

Nigella sativa L. seed essential oils obtained by hydrodistillation (HD), dry steam distillation (SD), steam distillation of crude oils obtained by solvent extraction (SE-SD), and supercritical fluid extraction (SFE-SD) were tested for their antibacterial activities, using the broth microdilution method and subsequently analyzed by gas chromatography and gas chromatography-mass spectrometry. The results showed that the essential oils tested differed markedly in their chemical compositions and antimicrobial activities. The oils obtained by HD and SD were dominated by p-cymene, whereas the major constituent identified in both volatile fractions obtained by SD of extracted oils was thymoquinone (ranging between 0.36 and 0.38 g/ml, whereas in oils obtained by HD and SD, it constituted only 0.03 and 0.05 g/ml, respectively). Both oils distilled directly from seeds showed lower antimicrobial activity (MICs > or = 256 and 32 microg/ml for HD and SD, respectively) than those obtained by SE-SD and SFE-SD (MICs > or = 4 microg/ml). All oil samples were significantly more active against gram-positive than against gram-negative bacteria. Thymoquinone exhibited potent growth-inhibiting activity against gram-positive bacteria, with MICs ranging from 8 to 64 microg/ml.

Evaluation of antileishmanial, antibacterial and brine shrimp cytotoxic potential of crude methanolic extract of Herb Ocimum basilicum (Lamiacea).

PubMed

Khan, Imran; Ahmad, Kafeel; Khalil, Ali Talha; Khan, Jangrez; Khan, Yusra Ali; Saqib, Muhammad Shahab; Umar, Muhamad Naveed; Ahmad, Hilal

2015-06-01

To collect and screen for ethnopharmacological properties (antileishmanial, antibacterial and brine lethality assays) of medicinal plan Ocimum basilicum from Peshawar region (34.008 latitude and 71.57 altitudes). In the present study a general antileishmanial activity against Leishmania tropica strair was carried out. The antibacterial potential of the plant was performed against 06 gram positiv and 06 gram negative bacteria. Brine shrimp cyto- toxicity assay at different concentrations were investigated. The anti-promastigotes profile of the plant showed good antileishmanial activity exhibited LC50 value 21.67 µg/mL. The result for gram positive antibacterial activity revealed that the O. basilicum leaves extract possesses significant inhibitory activity at highest two concentrations ranging from 20.66 ± 0.31 to 31.86 ± 0.80 for Clostridium perfringens type C and Bacillus subtitilis, respectively, as compared to the gentamycin (27.36 ± 0.55 and 21.80 ± 0.72, respectively). For gram negative bacteria good activity was observed. A highest zone of inhibition was recorded for Pseudomonas aeroginosa (28.83 ± 0.28) at the highest concentration (10 mg/ mL). The LC50 value obtained for brine shrimp lethality assay was 91.56 µg/mL. The herb basil possesses effective cidal activities which make this plant a good candidate for the isolation of antiprotozoal and antibacterial compounds which may lead to the development of novel drug.

Antioxidative and antibacterial activities of aqueous ethanol extracts of berries, leaves, and branches of berry plants.

PubMed

Tian, Ye; Puganen, Anna; Alakomi, Hanna-Leena; Uusitupa, Aleksi; Saarela, Maria; Yang, Baoru

2018-04-01

Phenolic compounds were extracted with food grade solvent of acidified aqueous ethanol from leaves, berries, berry press cakes, and branches of Finnish berry plants and analyzed with HPLC-DAD, UPLC-DAD-ESI-MS and NMR. In addition, press cakes from two berry species and branches from one species were also extracted and analyzed with the same methods. The antioxidant activities of the extracts were evaluated using Folin-Ciocalteau, oxygen radical absorbance capacity (ORAC), DPPH free radical scavenging, and total radical trapping antioxidant parameter (TRAP) assays. The antibacterial activities were investigated against various Gram-negative and Gram-positive foodborne pathogens. The leaf extracts showed higher antioxidative activities (3-20 fold in ORAC assay, 10-20 fold in TRAP) than the berry extracts, in association with the higher contents of phenolic compounds in the leaf extracts; Strongest anti-bacterial effects was observed in the leaf extracts of lingonberry (Vaccinium vitis-idaea), sea buckthorn (Hippophaë rhamnoides ssp. rhamnoides) and saskatoon (Amelanchier alnifolia) on Staphylococcus aureus, Listeria monocytogenes, and Bacillus cereus. However, the antibacterial efficacy varied with bacterial species and strains. The Folin-Ciocalteu, ORAC, and TRAP values was strongly correlated with the total content of flavonoids with less association shown with the content of total phenolics and flavonol glycosides. The results suggest a major contribution of pranthocyanidins and flavan-3-ols to the antioxidative activities of the extracts. The growth inhibition on Staphylococcus aureus and Bacillus cereus was clearly associated with the content of total phenolics and ellagitannins. Copyright © 2017 Elsevier Ltd. All rights reserved.

Selective Imaging of Gram-Negative and Gram-Positive Microbiotas in the Mouse Gut.

PubMed

Wang, Wei; Zhu, Yuntao; Chen, Xing

2017-08-01

The diverse gut microbial communities are crucial for host health. How the interactions between microbial communities and between host and microbes influence the host, however, is not well understood. To facilitate gut microbiota research, selective imaging of specific groups of microbiotas in the gut is of great utility but remains technically challenging. Here we present a chemical approach that enables selective imaging of Gram-negative and Gram-positive microbiotas in the mouse gut by exploiting their distinctive cell wall components. Cell-selective labeling is achieved by the combined use of metabolic labeling of Gram-negative bacterial lipopolysaccharides with a clickable azidosugar and direct labeling of Gram-positive bacteria with a vancomycin-derivatized fluorescent probe. We demonstrated this strategy by two-color fluorescence imaging of Gram-negative and Gram-positive gut microbiotas in the mouse intestines. This chemical method should be broadly applicable to different gut microbiota research fields and other bacterial communities studied in microbiology.

Synthesis, anti-MRSA, and anti-VRE activity of hemin conjugates with amino acids and branched peptides.

PubMed

Okorochenkov, Sergei A; Zheltukhina, Galina A; Mirchink, Elena P; Isakova, Elena B; Feofanov, Alexey V; Nebolsin, Vladimir E

2013-10-01

The increasing prevalence of antibiotic-resistant bacterial strains has necessitated the synthesis of novel antibacterial agents. It was previously shown that naturally occurring metalloporphyrin hemin possesses dark antibacterial activity against Gram-positive bacteria. To improve hemin antibacterial activity, we synthesized a number of hemin conjugates with amino acids and branched peptides. Arginine-containing hemin conjugates demonstrated high antibacterial activity against Gram-positive bacteria including methicillin- and vancomycin-resistant strains in vitro. Most of the synthesized conjugates showed low toxicity against human erythrocytes and leukocytes. © 2013 John Wiley & Sons A/S.

Effect of drying on the bioactive compounds, antioxidant, antibacterial and antityrosinase activities of pomegranate peel.

PubMed

Mphahlele, Rebogile R; Fawole, Olaniyi A; Makunga, Nokwanda P; Opara, Umezuruike L

2016-05-26

The use of pomegranate peel is highly associated with its rich phenolic concentration. Series of drying methods are recommended since bioactive compounds are highly sensitive to thermal degradation. The study was conducted to evaluate the effects of drying on the bioactive compounds, antioxidant as well as antibacterial and antityrosinase activities of pomegranate peel. Dried pomegranate peels with the initial moisture content of 70.30 % wet basis were prepared by freeze and oven drying at 40, 50 and 60 °C. Difference in CIE-LAB, chroma (C*) and hue angle (h°) were determined using colorimeter. Individual polyphenol retention was determined using LC-MS and LC-MS(E) while total phenolics concentration (TPC), total flavonoid concentration (TFC), total tannins concentration (TTC) and vitamin C concentration were measured using colorimetric methods. The antioxidant activity was measured by radical scavenging activity (RSA) and ferric reducing antioxidant power (FRAP). Furthermore, the antibacterial activity of methanolic peel extracts were tested on Gram negative (Escherichia coli and Klebsiella pneumonia) and Gram positive bacteria (Staphylococcus aureus and Bacillus subtilis) using the in vitro microdilution assays. Tyrosinase enzyme inhibition was investigated against monophenolase (tyrosine) and diphenolase (DOPA), with arbutin as positive controls. Oven drying at 60 °C resulted in high punicalin concentration (888.04 ± 141.03 mg CE/kg dried matter) along with poor red coloration (high hue angle). Freeze dried peel contained higher catechin concentration (674.51 mg/kg drying matter) + catechin and -epicatechin (70.56 mg/kg drying matter) compared to oven dried peel. Furthermore, freeze dried peel had the highest total phenolic, tannin and flavonoid concentrations compared to oven dried peel over the temperature range studied. High concentration of vitamin C (31.19 μg AAE/g dried matter) was observed in the oven dried (40 °C) pomegranate peel

Antibacterial activity of amino- and amido- terminated poly (amidoamine)-G6 dendrimer on isolated bacteria from clinical specimens and standard strains.

PubMed

Rastegar, Ayoob; Nazari, Shahram; Allahabadi, Ahmad; Falanji, Farahnaz; Akbari Dourbash, Fakhreddin Akbari Dourbash; Rezai, Zahra; Alizadeh Matboo, Soudabeh; Hekmat-Shoar, Reza; Mohseni, Seyed Mohsen; Majidi, Gharib

2017-01-01

Background: Nanoscale poly (amidoamine) dendrimers have been investigated for their biological demands, but their antibacterial activity has not been widely discovered. Thus, the sixth generation of poly (amidoamine) dendrimer (PAMAM-G6) was synthesized and its antibacterial activities were evaluated on Gram-negative bacteria; P. aeruginosa, E. coli, A. baumannii, S. typhimurium, S. dysenteriae, K. pneumoniae, P. mirabilis , and Gram-positive bacteria, and S.aureus and B. subtilis , which were isolated from different clinical specimens and standard strains of these bacteria. Methods: In this study, 980 specimens including urine (47%), blood (27%), sputum (13%), wounds (8%), and burns (5%) were collected from clinical specimens of 16 hospitals and clinics in city of Sabzevar, Iran. Then, the target bacteria were isolated and identified using standard methods. Minimum inhibitory concentration and minimum bactericidal concentrations against Gram-positive and Gram-negative bacteria were determined according to guidelines described by clinical and laboratory standards institute (CLSI). Standard discs were prepared using 0.025, 0.25, 2.5, and 25 μg/mL concentrations of PAMAM-G6 on Mueller-Hinton agar plates to determinate the zone of inhibition. The cytotoxicity of PAMAM-G6 dendrimer was evaluated in HCT116 cells by MTT assay. Results: The most important isolated bacteria were E. coli (23.65%), S. aureus (24.7%), P. aeruginosa (10.49%), B. subtilis (7.7%), S. typhimurium (8.87%), A. baumannii (7.02%), K. pneumoniae (7.1%), P. mirabilis (6.46%), and S. dysenteriae (3.6%). Moreover, it was found that poly (amidoamine)-G6 exhibited more antibacterial efficacy on standard strains than isolated bacteria from clinical samples (p<0.05). The cytotoxicity of PAMAM-G6 to the cells showed that cytotoxicity depended on the concentration level and exposure time. Conclusion: The PAMAM-G6 dendrimer showed a positive impact on the removal of dominant bacterial isolated from clinical

Antibacterial activity of amino- and amido- terminated poly (amidoamine)-G6 dendrimer on isolated bacteria from clinical specimens and standard strains

PubMed Central

Rastegar, Ayoob; Nazari, Shahram; Allahabadi, Ahmad; Falanji, Farahnaz; Akbari Dourbash, Fakhreddin Akbari Dourbash; Rezai, Zahra; Alizadeh Matboo, Soudabeh; Hekmat-Shoar, Reza; Mohseni, Seyed Mohsen; Majidi, Gharib

2017-01-01

Background: Nanoscale poly (amidoamine) dendrimers have been investigated for their biological demands, but their antibacterial activity has not been widely discovered. Thus, the sixth generation of poly (amidoamine) dendrimer (PAMAM-G6) was synthesized and its antibacterial activities were evaluated on Gram-negative bacteria; P. aeruginosa, E. coli, A. baumannii, S. typhimurium, S. dysenteriae, K. pneumoniae, P. mirabilis, and Gram-positive bacteria, and S.aureus and B. subtilis, which were isolated from different clinical specimens and standard strains of these bacteria. Methods: In this study, 980 specimens including urine (47%), blood (27%), sputum (13%), wounds (8%), and burns (5%) were collected from clinical specimens of 16 hospitals and clinics in city of Sabzevar, Iran. Then, the target bacteria were isolated and identified using standard methods. Minimum inhibitory concentration and minimum bactericidal concentrations against Gram-positive and Gram-negative bacteria were determined according to guidelines described by clinical and laboratory standards institute (CLSI). Standard discs were prepared using 0.025, 0.25, 2.5, and 25 μg/mL concentrations of PAMAM-G6 on Mueller-Hinton agar plates to determinate the zone of inhibition. The cytotoxicity of PAMAM-G6 dendrimer was evaluated in HCT116 cells by MTT assay. Results: The most important isolated bacteria were E. coli (23.65%), S. aureus (24.7%), P. aeruginosa (10.49%), B. subtilis (7.7%), S. typhimurium (8.87%), A. baumannii (7.02%), K. pneumoniae (7.1%), P. mirabilis (6.46%), and S. dysenteriae (3.6%). Moreover, it was found that poly (amidoamine)–G6 exhibited more antibacterial efficacy on standard strains than isolated bacteria from clinical samples (p<0.05). The cytotoxicity of PAMAM-G6 to the cells showed that cytotoxicity depended on the concentration level and exposure time. Conclusion: The PAMAM-G6 dendrimer showed a positive impact on the removal of dominant bacterial isolated from clinical

Evaluation of antibacterial activity, phytochemical constituents, and cytotoxicity effects of Thai household ancient remedies.

PubMed

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

2014-12-01

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. 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. With the exception of Dhart-Ban-Chob extract, significant minimum inhibitory concentrations (MICs) of <16 to 32 μg/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 μg/mL against all methicillin-resistant Staphylococcus aureus isolates. 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.

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 μg/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 μg/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

Besifloxacin, a novel fluoroquinolone, has broad-spectrum in vitro activity against aerobic and anaerobic bacteria.

PubMed

Haas, Wolfgang; Pillar, Chris M; Zurenko, Gary E; Lee, Jacqueline C; Brunner, Lynne S; Morris, Timothy W

2009-08-01

The antibacterial spectrum of besifloxacin, a novel fluoroquinolone recently approved for treatment of ocular infections, was studied using 2,690 clinical isolates representing 40 species. Overall, besifloxacin was the most potent agent tested against gram-positive pathogens and anaerobes and was generally equivalent to comparator fluoroquinolones in activity against most gram-negative pathogens. Besifloxacin demonstrated potent, broad-spectrum activity, which was particularly notable against gram-positive and gram-negative isolates that were resistant to other fluoroquinolones and classes of antibacterial agents.

Study on the antibacterial mechanism of copper ion- and neodymium ion-modified α-zirconium phosphate with better antibacterial activity and lower cytotoxicity.

PubMed

Cai, Xiang; Zhang, Bin; Liang, Yuanyuan; Zhang, Jinglin; Yan, Yinghui; Chen, Xiaoyin; Wu, Zhimin; Liu, Hongxi; Wen, Shuiping; Tan, Shaozao; Wu, Ting

2015-08-01

To improve the antibacterial activity of Cu(2+), a series of Cu(2+) and/or Nd(3+)-modified layered α-zirconium phosphate (ZrP) was prepared and characterized, and the antibacterial activities of the prepared Cu(2+) and/or Nd(3+)-modified ZrP on Gram-negative Escherichia coli were investigated. The results showed that the basal spacing of ZrP was not obviously affected by the incorporation of Cu(2+), but the basal spacing of the modified ZrP changed into an amorphous state with increasing additions of Nd(3+). An antibacterial mechanism showed that Cu(2+) and Nd(3+) could enter into E. coli cells, leading to changes in ion concentrations and leakage of DNA, RNA and protein. The Cu(2+)- and Nd(3+)-modified ZrP, combining the advantages of Cu(2+) and Nd(3+), displayed excellent additive antibacterial activity and lower cytotoxicity, suggesting the great potential application as an antibacterial powder for microbial control. Crown Copyright © 2015. Published by Elsevier B.V. All rights reserved.

Antibacterial activity and the histopathological study of crude extracts and isolated tecomine from Tecoma stans Bignoniaceae in Iraq

PubMed Central

Al-Azzawi, Amad M.; Al-Khateeb, Ekbal; Al-Sameraei, Kulood; Al-Juboori, Alyaa G

2012-01-01

Background: Tecoma stans (Bignoniaceae) is a central and south American tree used for the control of diabetes, also known as Yellow Elder, it was collected from the gardens of Al-Jadria in Iraq. Materials and Methods: One of the main reported alkaloidal constituents, tecomine, was isolated and confirmed by spectral analysis. The bacteriological assay for different plant leaves extracts; aqueous, ethanolic, and isolated tecomine were conducted to evaluate the antibacterial effect against gram-negative and gram-positive bacteria. Results: Whole alcoholic and aqueous extract exhibited the antibacterial activity and isolated tecomine. Histopathological evaluation was demonstrated on the liver, spleen, and pancreas of the BALB/c mice given the whole alcoholic and aqueous extract that showed no significant changes in the organ texture. Conclusion: Biochemical analysis of the serum obtained showed decrease in the glucose level in the mice treated with plant extract at the most two higher concentrations used with no change in the cholesterol and triglyceride level. PMID:22224060

Evaluation of antibacterial, antioxidant and nootropic activities of Tiliacora racemosa Colebr. leaves: In vitro and in vivo approach.

PubMed

T, Vivek Kumar; M, Vishalakshi; M, Gangaraju; Das, Parijat; Roy, Pratiti; Banerjee, Anindita; Dutta Gupta, Sayan

2017-02-01

The antibacterial and antioxidant potential of Tiliacora racemosa leaf extracts in various solvents (methanolic, hexane, chloroform and ethyl acetate) was determined. Additionally, the presence of bisbenzylisoquinoline alkaloids in the plant prompted us to evaluate the nootropic activity of the methanolic extract in mice. Further, we seek to verify the nootropic effect by examining the anticholinesterase inhibition potential of the methanolic extract. The leaf extracts in various solvents were evaluated for their antibacterial and antioxidant activity by agar diffusion technique and α, α-diphenyl-β-picrylhydrazyl (DPPH) free radical scavenging method, respectively. The ex vivo acetylcholine esterase inhibitory activity of the methanolic extract was carried out by Ellman's method in male Wistar rats. The nootropic capacity of the methanolic extract was examined in Swiss albino mice by utilizing the diazepam induced acute amnesic model. The chloroform/n-hexane and ethyl acetate fraction showed promising antioxidant and antibacterial (Gram positive and Gram negative bacteria) property, respectively. The methanolic extract was able to diminish the amnesic effect induced by diazepam (1mg/kg i.p.) in mice. The extract also showed significant acetyl cholinesterase inhibition in rats. The findings prove that the memory enhancing capability is due to increased acetyl choline level at the nerve endings. The strong antioxidant nature and potential nootropic activity shown by the extract suggests its future usage in the treatment of neurodegenerative disorders such as dementia and Alzheimer. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Native and heterologous production of bacteriocins from gram-positive microorganisms.

PubMed

Muñoz, Mabel; Jaramillo, Diana; Melendez, Adelina Del Pilar; J Alméciga-Diaz, Carlos; Sánchez, Oscar F

2011-12-01

In nature, microorganisms can present several mechanisms for setting intercommunication and defense. One of these mechanisms is related to the production of bacteriocins, which are peptides with antimicrobial activity. Bacteriocins can be found in Gram-positive and Gram-negative bacteria. Nevertheless, bacteriocins produced by Gram-positive bacteria are of particular interest due to the industrial use of several strains that belong to this group, especially lactic acid bacteria (LAB), which have the status of generally recognized as safe (GRAS) microorganisms. In this work, we will review recent tendencies in the field of invention and state of art related to bacteriocin production by Gram-positive microorganism. Hundred-eight patents related to Gram-positive bacteriocin producers have been disclosed since 1965, from which 57% are related bacteriocins derived from Lactococcus, Lactobacillus, Streptococcus, and Pediococcus strains. Surprisingly, patents regarding heterologous bacteriocins production were mainly presented just in the last decade. Although the major application of bacteriocins is concerned to food industry to control spoilage and foodborne bacteria, during the last years bacteriocin applications have been displacing to the diagnosis and treatment of cancer, and plant disease resistance and growth promotion.

The Causes of Post-Operative Meningitis: The Comparison Of Gram-Negative and Gram-Positive Pathogens.

PubMed

Kurtaran, Behice; Kuscu, Ferit; Ulu, Aslihan; Inal, Ayse Seza; Komur, Suheyla; Kibar, Filiz; Cetinalp, Nuri Eralp; Ozsoy, Kerem Mazhar; Arslan, Yusuf Kemal; Aksu, Hasan Salih; Tasova, Yesim

2017-06-20

In this study, we aim to determine the microbiological etiology in critically ill neurosurgical patients with nosocomial meningitis (NM) and show the impact of Gram-negative rods and differences of patient's characteristics, clinical and prognostic measures between Gram-negative and Gram-positive meningitis. In this prospective, one center study we reviewed all adult patients hospitalized during a 12-year period and identified pathogens isolated from post-neurosurgical cases of NM. Demographic, clinical, and treatment characteristics were noted from the medical records. Of the 134 bacterial NM patients, 78 were male and 56 were female, with a mean age of 46±15.9 and median age of 50 (18-80) years. 141 strains isolated; 82 (58.2%) were Gram negative, 59 (41.8%) were Gram positive. Most common isolated microorganism was Acinetobacter baumannii (%34.8). In comparison of mortality data shows that the patients who have meningitis with Gram-negative pathogens have higher mortality than with Gram positives (p=0.034). The duration between surgery and meningitis was shorter in Gram negative meningitis cases compared to others (p=0.045) but the duration between the diagnosis and death was shorter in Gram-positive meningitis cases compared to Gram negatives (p= 0.017). CSF protein and lactate level were higher and glucose level was lower in cases of NM with Gram negatives (p value were respectively, 0.022, 0.039 and 0.049). As conclusions; in NM, Gram-negative pathogens were seen more frequently; A.baumanni was the predominant pathogen; and NM caused by Gram negatives had worse clinical and laboratory characteristic and prognostic outcome than Gram positives.

Egg extract of apple snail for eco-friendly synthesis of silver nanoparticles and their antibacterial activity.

PubMed

Janthima, Ratima; Khamhaengpol, Arunrat; Siri, Sineenat

2018-03-01

Green synthesis of silver nanoparticles (AgNPs) provides the alternative method with cost effectiveness and the eco-friendly process by using natural biomolecules as reducing and stabilizing agents. Alternative to the most studies of plant extracts, this work demonstrated a use of egg extract of apple snail (Pomacea canaliculata) for an eco-friendly production of AgNPs. The extract contained at least six proteins with the molecular weight in a range of 24-65 kDa that exhibited the reducing activity. The dispersive AgNPs were produced in the reaction containing only the extract and silver nitrate, as determined by the characteristic surface plasmon resonance peak of silver at 412 nm. The synthesized AgNPs were spherical with the average diameter of 9.0 ± 5.9 nm. The X-ray diffraction pattern and selected area electron diffraction (SAED) analyses confirmed the face-cubic centre (fcc) unit cell structure of AgNPs. The synthesized AgNPs exhibited the antibacterial activity against both Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli. Results of this work clearly showed the potential use of the egg extract of apple snail for a green synthesis of small size AgNPs exhibiting the antibacterial activity.

Highly dynamic biodegradable micelles capable of lysing Gram-positive and Gram-negative bacterial membrane.

PubMed

Qiao, Yuan; Yang, Chuan; Coady, Daniel J; Ong, Zhan Yuin; Hedrick, James L; Yang, Yi-Yan

2012-02-01

The development of biodegradable antimicrobial polymers adds to the toolbox of attractive antimicrobial agents against antibiotic-resistant microbes. To this end, the potential of polycarbonate polymers as such materials were explored. A series of random polycarbonate polymers consisting of monomers MTC-OEt and MTC-CH(2)CH(3)Cl were designed and synthesized using metal-free organocatalytic ring-opening polymerization. Random polycarbonate polymers self-assembled in solution but appeared highly dynamic; such behaviors are desirable as ready disassembly of polymers at the microbial membrane facilitates membrane disruption. Their activities against clinically relevant Gram-positive (Staphylococcus aureus) and Gram-negative bacteria (E.coli and Pseudomonas aeruginosa) revealed that the hydrophobic-hydrophilic composition balance in polymers are important to render antimicrobial potency. Scanning electron microscopy (SEM) studies indicated microbial cell surface damage after treatment with polymers, and confocal microscopy studies also showed entry of FITC-dextran dye in Escherichia coli as a result of membrane disruption. On the other hand, the polymers exhibited minimal toxicity against red blood cells in hemolysis tests. Therefore, these random polycarbonate polymers are promising antimicrobial agents against both Gram-positive and Gram-negative bacteria for various biomedical applications. Copyright © 2011 Elsevier Ltd. All rights reserved.

[The history of the development and changes of quinolone antibacterial agents].

PubMed

Takahashi, Hisashi; Hayakawa, Isao; Akimoto, Takeshi

2003-01-01

The quinolones, especially the new quinolones (the 6-fluoroquinolones), are the synthetic antibacterial agents to rival the Beta-lactam and the macrolide antibacterials for impact in clinical usage in the antibacterial therapeutic field. They have a broad antibacterial spectrum of activity against Gram-positive, Gram-negative and mycobacterial pathogens as well as anaerobes. Further, they show good-to-moderate oral absorption and tissue penetration with favorable pharmacokinetics in humans resulting in high clinical efficacy in the treatment of many kinds of infections. They also exhibit excellent safety profiles as well as those of oral Beta-lactam antibiotics. The bacterial effects of quinolones inhibit the function of bacterial DNA gyrase and topoisomerase IV. The history of the development of the quinolones originated from nalidixic acid (NA), developed in 1962. In addition, the breakthrough in the drug design for the scaffold and the basic side chains have allowed improvements to be made to the first new quinolone, norfloxacin (NFLX), patented in 1978. Although currently more than 10,000 compounds have been already synthesized in the world, only two percent of them were developed and tested in clinical studies. Furthermore, out of all these compounds, only twenty have been successfully launched into the market. In this paper, the history of the development and changes of the quinolones are described from the first quinolone, NA, via, the first new quinolone (6-fluorinated quinolone) NFLX, to the latest extended-spectrum quinolone antibacterial agents against multi-drug resistant bacterial infections. NA has only modest activity against Gram-negative bacteria and low oral absorption, therefore a suitable candidate for treatment of systemic infections (UTIs) is required. Since the original discovery of NA, a series of quinolones, which are referred to as the old quinolones, have been developed leading to the first new quinolone, NFLX, with moderate improvements

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

PubMed

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

2007-12-01

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.

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

Antibacterial and leishmanicidal activities of temporin-SHd, a 17-residue long membrane-damaging peptide.

PubMed

Abbassi, Feten; Raja, Zahid; Oury, Bruno; Gazanion, Elodie; Piesse, Christophe; Sereno, Denis; Nicolas, Pierre; Foulon, Thierry; Ladram, Ali

2013-02-01

Temporins are a family of short antimicrobial peptides (8-17 residues) that mostly show potent activity against Gram-positive bacteria. Herein, we demonstrate that temporin-SHd, a 17-residue peptide with a net charge of +2 (FLPAALAGIGGILGKLF(amide)), expressed a broad spectrum of antimicrobial activity. This peptide displayed potent antibacterial activities against Gram-negative and Gram-positive bacteria, including multi-drug resistant Staphylococcus aureus strains, as well as antiparasitic activity against promastigote and the intracellular stage (amastigote) of Leishmania infantum, at concentration not toxic for the macrophages. Temporin-SHd that is structured in a non-amphipathic α-helix in anionic membrane-mimetic environments, strongly and selectively perturbs anionic bilayer membranes by interacting with the polar head groups and acyl region of the phospholipids, with formation of regions of two coexisting phases: one phase rich in peptide and the other lipid-rich. The disruption of lipid packing within the bilayer may lead to the formation of transient pores and membrane permeation/disruption once a threshold peptide accumulation is reached. To our knowledge, Temporin-SHd represents the first known 17-residue long temporin expressing such broad spectrum of antimicrobial activity including members of the trypanosomatidae family. Additionally, since only a few shorter members (13 residues) of the temporin family are known to display antileishmanial activity (temporins-TA, -TB and -SHa), SHd is an interesting tool to analyze the antiparasitic mechanism of action of temporins. Copyright © 2012 Elsevier Masson SAS. All rights reserved.

Shape-dependent bactericidal activity of copper oxide nanoparticle mediated by DNA and membrane damage

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

Laha, Dipranjan; Pramanik, Arindam; Laskar, Aparna

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. Sphericalmore » 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.« less

The in vitro activity of flomoxef compared to four other cephalosporins and imipenem.

PubMed

Shah, P M; Knothe, H

1991-01-01

The antibacterial activity of the oxacephalosporin flomoxef was evaluated in comparison to cefpirome, cefuzoname, cefotaxime, ceftazidime, and imipenem against fresh clinical isolates. Flomoxef is an antibiotic with strong antibacterial activity against staphylococci including methicillin-resistant strains and streptococci with the exception of Enterococcus faecalis and Enterococcus faecium. It is very active against gram-negative cocci and rods including gram-positive and gram-negative anaerobes. Against Pseudomonas sp. flomoxef has no activity.

Forthcoming therapeutic perspectives for infections due to multidrug-resistant Gram-positive pathogens.

PubMed

Cornaglia, G; Rossolini, G M

2009-03-01

Multidrug resistance in Gram-positive pathogens emerged as a major therapeutic challenge over two decades ago. The worldwide spread of methicillin-resistant Staphylococcus aureus (MRSA), glycopeptide-resistant enterococci and other resistant Gram-positive pathogens had a major impact on antibiotic policies, and prompted the discovery and development of new antibiotics to combat difficult-to-treat infections caused by such pathogens. Several new antibiotics active against multidrug-resistant Gram-positive pathogens have recently been introduced into clinical practice, and the antibiotic pipeline contains additional anti-Gram-positive drugs at an advanced stage of development, including new glycopeptides (dalbavancin, oritavancin, and telavancin), new anti-MRSA beta-lactams (ceftobiprole), and new diaminopyrimidines (iclaprim). This article provides a brief overview of these upcoming agents, partially based on the material presented at the ESCMID Conference entitled 'Fighting infections due to multidrug-resistant Gram-positives' (Venice, Italy, 29-31 May 2008) and on the most recent literature.

In vitro activity of tigecycline and comparator agents against a global collection of Gram-negative and Gram-positive organisms: tigecycline Evaluation and Surveillance Trial 2004 to 2007.

PubMed

Garrison, Mark W; Mutters, Reinier; Dowzicky, Michael J

2009-11-01

The Tigecycline Evaluation and Surveillance Trial began in 2004 to monitor the in vitro activity of tigecycline and comparator agents against a global collection of Gram-negative and Gram-positive pathogens. Against Gram negatives (n = 63 699), tigecycline MIC(90)'s ranged from 0.25 to 2 mg/L for Escherichia coli, Haemophilus influenzae, Acinetobacter baumannii, Klebsiella oxytoca, Enterobacter cloacae, Klebsiella pneumoniae, and Serratia marcescens (but was > or =32 for Pseudomonas aeruginosa). Against Gram-positive organisms (n = 32 218), tigecycline MIC(90)'s were between 0.06 and 0.25 mg/L for Streptococcus pneumoniae, Enterococcus faecium, Streptococcus agalactiae, Staphylococcus aureus, and Enterococcus faecalis. The in vitro activity of tigecycline was maintained against resistant phenotypes, including multidrug-resistant A. baumannii (9.2% of isolates), extended-spectrum beta-lactamase-producing E. coli (7.0%) and K. pneumoniae (14.0%), beta-lactamase-producing H. influenzae (22.2%), methicillin-resistant S. aureus (44.5%), vancomycin-resistant E. faecium (45.9%) and E. faecalis (2.8%), and penicillin-resistant S. pneumoniae (13.8%). Tigecycline represents a welcome addition to the armamentarium against difficult to treat organisms.

Microbicidal effects of plain soap vs triclocarban-based antibacterial soap.

PubMed

Kim, S A; Rhee, M S

2016-11-01

The aim of this study was to determine the bactericidal effects of plain and antibacterial soap. The bactericidal effects of plain and antibacterial soap containing 0.3% triclocarban were examined against 10 Gram-positive and 10 Gram-negative bacterial strains after exposure at 22°C and 40°C for 20 s. Gram-negative bacteria were more susceptible to both soaps than Gram-positive bacteria. However, with one exception (Enterococcus faecalis ATCC 19433 at 40°C), there was no significant difference between the effects of medicated and non-medicated soap at either temperature. Triclocarban in soap does not lead to a meaningful reduction in bacterial levels during use. Copyright © 2016 The Healthcare Infection Society. Published by Elsevier Ltd. All rights reserved.

Preparation, characterization, and antibacterial activity of γ-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 γ-irradiation of aqueous solutions containing AgNO3 and gelatin as a silver source and stabilizer, respectively. The absorbed dose of γ-irradiation influences the particle diameter of the Ag-NPs, as evidenced from surface plasmon resonance (SPR) and transmission electron microscopy (TEM) images. When the γ-irradiation dose was increased (from 2 to 50 kGy), the mean particle size was decreased continuously as a result of γ-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 γ-irradiation-mediated method is a promising simple route for synthesizing highly stable Ag-NPs in aqueous solutions with good antibacterial properties for different applications.

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% (IC₅₀=141.89 μg/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% (IC₅₀=53.70 μg/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. Copyright © 2015. Published by Elsevier Ltd.

Chemical composition and antibacterial activity of Cordia verbenacea extracts obtained by different methods.

PubMed

Michielin, Eliane M Z; Salvador, Ana A; Riehl, Carlos A S; Smânia, Artur; Smânia, Elza F A; Ferreira, Sandra R S

2009-12-01

The present study describes the chemical composition and the antibacterial activity of extracts from Cordia verbenacea DC (Borraginaceae), a traditional medicinal plant that grows widely along the southeastern coast of Brazil. The extracts were obtained using different extraction techniques: high-pressure operations and low-pressure methods. The high-pressure technique was applied to obtain C. verbenacea extracts using pure CO(2) and CO(2) with co-solvent at pressures up to 30MPa and temperatures of 30, 40 and 50 degrees C. Organic solvents such as n-hexane, ethyl acetate, ethanol, acetone and dichloromethane were used to obtain extracts by low-pressure processes. The antibacterial activity of the extracts was also subjected to screening against four strains of bacteria using the agar dilution method. The extraction yields were up to 5.0% w/w and up to 8.6% w/w for supercritical fluid extraction with pure CO(2) and with ethyl acetate as co-solvent, respectively, while the low-pressure extraction indicates yields up to 24.0% w/w in the soxhlet extraction using water and aqueous mixture with 50% ethanol as solvents. The inhibitory activity of the extracts in gram-positive bacteria was significantly higher than in gram-negative. The quantification and the identification of the extracts recovered were accomplished using GC/MS analysis. The most important components identified in the extract were artemetin, beta-sitosterol, alpha-humulene and beta-caryophyllene, among others.

Synthesis and characterization of bactericidal oligopeptides designed on the basis of an insect anti-bacterial peptide.

PubMed Central

Saido-Sakanaka, H; Ishibashi, J; Sagisaka, A; Momotani, E; Yamakawa, M

1999-01-01

Defensin from a beetle, Allomyrina dichotoma, is known to have anti-bacterial activity against Gram-positive bacteria. This peptide, which comprises 43 amino acid residues, was effective against methicillin-resistant Staphylococcus aureus. We identified the active site of beetle defensin by measuring anti-bacterial activity against S. aureus of 64 overlapping 12-mer peptides with either a free carboxylate or a free amide group at their C-termini. An LCAAHCLAIGRR-NH2 (19L-30R-NH2) fragment showed the greatest activity of the synthetic oligopeptides. The 19L-30R-NH2 fragment was effective against both Gram-positive and Gram-negative bacteria. CD spectra showed that the 19L-30R-NH2 fragment formed an alpha-helical structure in the lipidic environment. The anti-bacterial effect of the 19L-30R-NH2 fragment was due to its interaction with bacterial membranes, judging from the leakage of liposome-entrapped glucose. Its anti-bacterial activity was increased when certain amino acid residues were replaced. Truncated peptides having had some amino acids removed from the N-terminus of the 19L-30R-NH2 fragment (8-10-mer peptides) still had strong anti-bacterial activity. Deleting some amino acids from the C-terminal region of the fragment dramatically reduced activity, indicating that the C-terminal region of the 19L-30R-NH2 fragment, i.e. RR-NH2, is important for exerting anti-bacterial activity. The AHCLAIGRR-NH2 (22A-30R-NH2) fragment and its analogues exhibited about 3-fold and 9-12-fold higher activity against S. aureus than did the 19L-30R-NH2 fragment, and these analogues were effective against methicillin-resistant S. aureus and Pseudomonas aeruginosa isolated from patients. These oligopeptides showed no haemolytic activity and did not inhibit the growth of murine fibroblast cells. PMID:9931294

Novel substituted (pyridin-3-yl)phenyloxazolidinones: antibacterial agents with reduced activity against monoamine oxidase A and increased solubility.

PubMed

Reck, Folkert; Zhou, Fei; Eyermann, Charles J; Kern, Gunther; Carcanague, Dan; Ioannidis, Georgine; Illingworth, Ruth; Poon, Grace; Gravestock, Michael B

2007-10-04

Oxazolidinones represent a new and promising class of antibacterial agents. Current research in this area is mainly concentrated on improving the safety profile and the antibacterial spectrum. Oxazolidinones bearing a (pyridin-3-yl)phenyl moiety (e.g., 3) generally show improved antibacterial activity compared to linezolid but suffer from potent monoamine oxidase A (MAO-A) inhibition and low solubility. We now disclose the finding that new analogues of 3 with acyclic substituents on the pyridyl moiety exhibit excellent activity against Gram-positive pathogens, including linezolid-resistant Streptococcus pneumoniae. Generally, more bulky substituents yielded significantly reduced MAO-A inhibition relative to the unsubstituted compound 3. The MAO-A SAR can be rationalized on the basis of docking studies using a MAO-A/MAO-B homology model. Solubility was enhanced with incorporation of polar groups. One optimized analogue, compound 13, showed low clearance in the rat and efficacy against S. pneumoniae in a mouse pneumonia model.

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.

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

Comparative in-vitro activities of quinupristin-dalfopristin against Gram-positive bloodstream isolates.

PubMed

Schouten, M A; Hoogkamp-Korstanje, J A

1997-08-01

The in-vitro activity of quinupristin-dalfopristin was compared with those of vancomycin, teicoplanin, erythromycin, clarithromycin, rifampicin, imipenem, meropenem, ciprofloxacin and sparfloxacin against 414 bloodstream isolates of Gram-positive cocci. Quinupristin-dalfopristin inhibited strains of Streptococcus pyogenes and Streptococcus agalactiae at 0.12 mg/L, methicillin- and/or erythromycin-resistant Staphylococcus aureus and Staphylococcus epidermidis at 0.5 mg/L, Staphylococcus haemolyticus, Enterococcus faecium, Streptococcus pneumoniae, Streptococcus mitis, Streptococcus bovis, Streptococcus sanguis and Streptococcus anginosus at 1 mg/L and Enterococcus faecalis at 8 mg/L.

Efficacy of direct Gram stain in differentiating staphylococci from streptococci in blood cultures positive for gram-positive cocci.

PubMed Central

Agger, W A; Maki, D G

1978-01-01

A preponderance of clusters seen on direct Gram stain of blood cultures positive for gram-positive cocci was 98% sensitive and 100% specific for identification of staphylococcal species or of Peptococcus. A preponderance of chains, pairs, or both was 100% sensitive and 98% specific for identifying streptococci. Further presumptive identification of either staphylococci or streptococci based on microscopic morphology was unreliable. The direct Gram stain is highly reliable for differentiating staphylococci from streptococci and should be of considerable value to clinicians selecting initial antimicrobial therapy. PMID:75888

Characterization of the antibacterial activity and the chemical components of the volatile oil of the leaves of Rubus parvifolius L.

PubMed

Cai, Yongqing; Hu, Xiaogang; Huang, Mingchun; Sun, Fengjun; Yang, Bo; He, Juying; Wang, Xianfeng; Xia, Peiyuan; Chen, Jianhong

2012-06-25

Rubus parvifolius L. (Rp) is a medicinal herb that possesses antibacterial activity. In this study, we extracted the volatile oil from the leaves of Rp to assess its antibacterial activity and analyze its chemical composition. A uniform distribution design was used to optimize the extraction procedure, which yielded 0.36% (w/w) of light yellowish oil from the water extract of Rp leaves. We found that the extracted oil effectively inhibited the growth of a wide range of Gram positive and negative bacteria, including Staphylococcus aureus, Staphylococcus epidermidis, Enterococcus faecalis, Escherichia coli, Pseudomonas aeruginosa, Acinetobacter baumanii, Bacillus cloacae, and Klebsiella pneumoniae. We further analyzed the components contained in the hydro-distillated Rp volatile oil by gas chromatography-mass spectroscopy. Twenty nine compounds were identified, including 4-hydroxy-3-methoxystyrene (66%), 3,7,11,15-tetramethyl-2-hexadecen-1-ol (10%) and 4-tert-butylbenzoic acid (2%). Our results suggest that one or multiple constituents contained in Rp volatile oil may account for its antibacterial activity.

Antibacterial and antibiotic resistance modifying activity of the extracts from Allanblackia gabonensis, Combretum molle and Gladiolus quartinianus against Gram-negative bacteria including multi-drug resistant phenotypes.

PubMed

Fankam, Aimé G; Kuiate, Jules R; Kuete, Victor

2015-06-30

Bacterial resistance to antibiotics is becoming a serious problem worldwide. The discovery of new and effective antimicrobials and/or resistance modulators is necessary to tackle the spread of resistance or to reverse the multi-drug resistance. We investigated the antibacterial and antibiotic-resistance modifying activities of the methanol extracts from Allanblackia gabonensis, Gladiolus quartinianus and Combretum molle against 29 Gram-negative bacteria including multi-drug resistant (MDR) phenotypes. The broth microdilution method was used to determine the minimal inhibitory concentrations (MIC) and minimal bactericidal concentrations (MBC) of the samples meanwhile the standard phytochemical methods were used for the preliminary phytochemical screening of the plant extracts. Phytochemical analysis showed the presence of alkaloids, flavonoids, phenols and tannins in all studied extracts. Other chemical classes of secondary metabolites were selectively presents. Extracts from A. gabonensis and C. molle displayed a broad spectrum of activity with MICs varying from 16 to 1024 μg/mL against about 72.41% of the tested bacteria. The extract from the fruits of A. gabonensis had the best activity, with MIC values below 100 μg/mL on 37.9% of tested bacteria. Percentages of antibiotic-modulating effects ranging from 67 to 100% were observed against tested MDR bacteria when combining the leaves extract from C. molle (at MIC/2 and MIC/4) with chloramphenicol, kanamycin, streptomycin and tetracycline. The overall results of the present study provide information for the possible use of the studied plant, especially Allanblackia gabonensis and Combretum molle in the control of Gram-negative bacterial infections including MDR species as antibacterials as well as resistance modulators.

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. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

The Central Hinge Link Truncation of the Antimicrobial Peptide Fowlicidin-3 Enhances Its Cell Selectivity without Antibacterial Activity Loss

PubMed Central

Qu, Pei; Gao, Wei; Chen, Huixian; Li, Dan; Yang, Na; Zhu, Jian; Li, Zhongqiu

2016-01-01

Antimicrobial peptides (AMPs) have been paid considerable attention because of their broad-spectrum antimicrobial activity and a reduced possibility of the development of bacterial drug resistance. Fowlicidin-3 (Fow-3) is an identified type of chicken cathelicidin AMP that has exhibited considerable antimicrobial activity and cytotoxicity. To reduce cell toxicity and improve cell selectivity, several truncated peptides of fowlicidin-3, Fow-3(1-15), Fow-3(1-19), Fow-3(1-15-20-27), and Fow-3(20-27), were synthesized. Our results indicated that neither the N- nor C-terminal segment alone [Fow-3(1-15), Fow-3(1-19), Fow-3(20-27)] was sufficient to confer antibacterial activity. However, Fow-3(1-19) with the inclusion of the central hinge link (-AGIN-) retained substantial cell toxicity, which other analogs lost. Fow-3(1-15-20-27) displayed potent antimicrobial activity for a wide range of Gram-negative and Gram-positive bacteria and no obvious hemolytic activity or cytotoxicity. The central link region was shown to be critically important in the function of cell toxicity but was not relevant to antibacterial activity. Fow-3(1-15-20-27) maintained antibacterial activity in the presence of physiological concentrations of salts. The results from fluorescence spectroscopy, scanning electron microcopy, and transmission electron microcopy showed that Fow-3(1-15-20-27) as well as fowlicidin-3 killed bacterial cells by increasing membrane permeability and damaging the membrane envelope integrity. Fow-3(1-15-20-27) could be a promising antimicrobial agent for clinical application. PMID:26902768

Probiotic Properties of Lactobacillus fermentum Strains Isolated from Human Oral Samples and Description of their Antibacterial Activity.

PubMed

Fuochi, Virginia; Volti, Giovanni Li; Furneri, Pio M

2017-01-01

Gram positive bacteria produce peptides, defined bacteriocins which exhibit good antibacterial activity. We evaluated the ability of L. fermentum to produce bacteriocins having therefore, good probiotic features and finally, be safe towards microglial cells. Eight wild strains, identified using molecular techniques, were investigated for the evaluation of resistance to bile salts, low pH, H2O2 production, biofilm formation, antibacterial activity and safety on microglia cells (BV2). The determination of the susceptibility/resistance profile showed that the strains are sensitive to the antibiotics tested. All strains showed a good tolerability to extremely low pH as well as resisting in presence of bile salts. In addition, the strains showed excellent activity against pathogens and one of them (LAC 42) showed activity also against Pseudomonas aeruginosa and Klebsiella pneumoniae. Finally, LAC 42 and its active compound did not change microglia cell viability following 24h exposure. Our data on this antibacterial molecule suggest that it is a compound with low molecular weight and with highly hydrophilic component. These results describe the characteristics of Lactobacillus strains and provide evidences for their possible use as new potential probiotic. In addition, other studies are now warranted to exploit the antibacterial activity of the supernatant LAC 42 and for its complete chemical characterization. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Type I and Type II mechanisms of antimicrobial photodynamic therapy: an in vitro study on gram-negative and gram-positive bacteria.

PubMed

Huang, Liyi; Xuan, Yi; Koide, Yuichiro; Zhiyentayev, Timur; Tanaka, Masamitsu; Hamblin, Michael R

2012-08-01

Antimicrobial photodynamic therapy (APDT) employs a non-toxic photosensitizer (PS) and visible light, which in the presence of oxygen produce reactive oxygen species (ROS), such as singlet oxygen ((1) O(2), produced via Type II mechanism) and hydroxyl radical (HO(.), produced via Type I mechanism). This study examined the relative contributions of (1) O(2) and HO(.) to APDT killing of Gram-positive and Gram-negative bacteria. Fluorescence probes, 3'-(p-hydroxyphenyl)-fluorescein (HPF) and singlet oxygen sensor green reagent (SOSG) were used to determine HO(.) and (1) O(2) 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 (NaN(3)) is a quencher of (1) O(2). Both APDT and killing by Fenton reaction (chemical generation of HO(.)) were carried out on Gram-positive bacteria (Staphylococcus aureus and Enterococcus faecalis) and Gram-negative bacteria (Escherichia coli, Proteus mirabilis, and Pseudomonas aeruginosa). Conjugate PEI-ce6 mainly produced (1) O(2) (quenched by NaN(3)), while BB6 produced HO(.) in addition to (1) O(2) when NaN(3) potentiated probe activation. NaN(3) 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. NaN(3) 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 NaN(3) dose-dependent inhibition of APDT killing using both PEI-ce6 and BB6 against Gram-negative bacteria while NaN(3) almost failed to inhibit killing of Gram-positive bacteria. Azidyl radicals may be formed from NaN(3) and HO(.). It may be that Gram-negative bacteria are more susceptible to HO(.) while Gram-positive bacteria are more susceptible to (1) O(2). The differences in Na

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.

Antibacterial Properties of Nonwoven Wound Dressings Coated with Manuka Honey or Methylglyoxal

PubMed Central

Bulman, Sophie E. L.; Carr, Chris; Russell, Stephen J.

2017-01-01

Manuka honey (MH) is used as an antibacterial agent in bioactive wound dressings via direct impregnation onto a suitable substrate. MH provides unique antibacterial activity when compared with conventional honeys, owing partly to one of its constituents, methylglyoxal (MGO). Aiming to investigate an antibiotic-free antimicrobial strategy, we studied the antibacterial activity of both MH and MGO (at equivalent MGO concentrations) when applied as a physical coating to a nonwoven fabric wound dressing. When physically coated on to a cellulosic hydroentangled nonwoven fabric, it was found that concentrations of 0.0054 mg cm−2 of MGO in the form of MH and MGO were sufficient to achieve a 100 colony forming unit % bacteria reduction against gram-positive Staphylococcus aureus and gram-negative Klebsiella pneumoniae, based on BS EN ISO 20743:2007. A 3- to 20-fold increase in MGO concentration (0.0170–0.1 mg cm−2) was required to facilitate a good antibacterial effect (based on BS EN ISO 20645:2004) in terms of zone of inhibition and lack of growth under the sample. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) was also assessed for MGO in liquid form against three prevalent wound and healthcare-associated pathogens, i.e., Staphylococcus aureus, gram-negative Pseudomonas aeruginosa and gram-positive Enterococcus faecalis. Other than the case of MGO-containing fabrics, solutions with much higher MGO concentrations (128 mg L−1–1024 mg L−1) were required to provide either a bacteriostatic or bactericidal effect. The results presented in this study therefore demonstrate the relevance of an MGO-based coating as an environmentally friendly strategy for the design of functional dressings with antibiotic-free antimicrobial chemistries. PMID:28813014

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.

TLR4-mediated podosome loss discriminates gram-negative from gram-positive bacteria in their capacity to induce dendritic cell migration and maturation.

PubMed

van Helden, Suzanne F G; van den Dries, Koen; Oud, Machteld M; Raymakers, Reinier A P; Netea, Mihai G; van Leeuwen, Frank N; Figdor, Carl G

2010-02-01

Chronic infections are caused by microorganisms that display effective immune evasion mechanisms. Dendritic cell (DC)-dependent T cell-mediated adaptive immunity is one of the mechanisms that have evolved to prevent the occurrence of chronic bacterial infections. In turn, bacterial pathogens have developed strategies to evade immune recognition. In this study, we show that gram-negative and gram-positive bacteria differ in their ability to activate DCs and that gram-negative bacteria are far more effective inducers of DC maturation. Moreover, we observed that only gram-negative bacteria can induce loss of adhesive podosome structures in DCs, a response necessary for the induction of effective DC migration. We demonstrate that the ability of gram-negative bacteria to trigger podosome turnover and induce DC migration reflects their capacity to selectively activate TLR4. Examining mice defective in TLR4 signaling, we show that this DC maturation and migration are mainly Toll/IL-1 receptor domain-containing adaptor-inducing IFNbeta-dependent. Furthermore, we show that these processes depend on the production of PGs by these DCs, suggesting a direct link between TLR4-mediated signaling and arachidonic metabolism. These findings demonstrate that gram-positive and gram-negative bacteria profoundly differ in their capacity to activate DCs. We propose that this inability of gram-positive bacteria to induce DC maturation and migration is part of the armamentarium necessary for avoiding the induction of an effective cellular immune response and may explain the frequent involvement of these pathogens in chronic infections.

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 α-pinene (5.71%), α-terpinene (2.63%), and β-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.

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.

Synthesis and Bioactivity Evaluation of Novel 2-Salicyloylbenzofurans as Antibacterial Agents.

PubMed

Phan, Phuong-Thuy T; Nguyen, Thu-Trang T; Nguyen, Hong-Nhung T; Le, Bao-Khanh N; Vu, Thao T; Tran, Dong C; Pham, Tuan-Anh N

2017-04-25

In order to discover new antibacterial agents, series of 2-salicyloylbenzofuran derivatives were designed, synthesized and evaluated for their antibacterial activities against three Gram-(+) strains (methicillin-sensitive Staphylococcus aureus (MSSA) ATCC 29213, methicillin-resistant Staphylococcus aureus (MRSA) ATCC 43300, and Streptococcus faecalis ( S. faecalis ) ATCC 29212) and one Gram-(-) strain ( Escherichia coli (E. coli) ATCC 25922). The 2-salicyloylbenzofuran heterocycles were generated by Rap-Stoermer condensation of salicylaldehydes with phenacyl bromides and then converted to diverse O -ether derivatives by Williamson synthesis. The targeted products were screened for in vitro qualitative (zone of inhibition) and quantitative (MIC) antibacterial activities by agar well diffusion assay and agar dilution method. Amongst the compounds, those bearing carboxylic acid functional group were found to exhibit reasonable activity against Gram-(+) bacterial strains including S. faecalis , MSSA and MRSA with the most potent antibacterial agent 8h (MICs = 0.06-0.12 mM). Besides, the 2-salicyloylbenzofurans partly displayed inhibitory activity against MRSA with the best MICs = 0.14 mM ( 8f ) and 0.12 mM ( 8h ). Finally, the antibacterial results preliminarily suggested that the substituent bearing carboxylic acid group at salicyloyl-C2 and the bromine atoms on the benzofuran moiety seem to be the functionality necessary for antibacterial activities.

A comparative study of pure and copper (Cu)-doped ZnO nanorods for antibacterial and photocatalytic applications with their mechanism of action

NASA Astrophysics Data System (ADS)

Bhuyan, Tamanna; Khanuja, Manika; Sharma, R.; Patel, S.; Reddy, M. R.; Anand, S.; Varma, A.

2015-07-01

The present study reports the synthesis of pure and Cu-doped ZnO nanorods for antibacterial and photocatalytic applications. The samples were synthesized by simple, low cost mechanical-assisted thermal decomposition process. The synthesized materials were characterized by scanning electron microscopy, UV-Visible spectroscopy, and photoluminescence studies. The antibacterial activity of characterized samples was determined against Gram-positive bacteria such as Staphylococcus aureus and Streptococcus pyogenes and Gram-negative bacteria such as Escherichia coli using shake flask method with respect to time. The significant antibacterial activity was perceived from scanning electron micrographs that clearly revealed bacterial cell lysis resulting in the release of cytoplasmic content followed by cell death. The degradation of methylene blue was used as a model organic dye for photocatalytic activity. The present study demonstrates the superior photocatalytic and antibacterial activity of Cu-doped ZnO nanorods with respect to pure ZnO nanorods.

Shape-dependent antibacterial activity of silver nanoparticles on Escherichia coli and Enterococcus faecium bacterium

NASA Astrophysics Data System (ADS)

Alshareef, A.; Laird, K.; Cross, R. B. M.

2017-12-01

Silver nanoparticles (AgNPs) have been shown to exhibit strong antibacterial activity against both Gram-positive bacteria and Gram-negative bacteria including antibiotic resistant strains. This study aims to compare the bactericidal effect of different shaped AgNPs (spherical and truncated octahedral) against Escherichia coli and Enterococcus faecium. The antimicrobial activity of a range of concentrations (50, 100, 1000 μg/ml) was determined over 24 h using both optical density and viable counts. Truncated octahedral AgNPs (AgNOct) were found to be more active when compared with spherical AgNPs (AgNS). The difference in shape resulted in differences in efficacy which may be due to the higher surface area of AgNOct compared to AgNS, and differences in active facets and surface energies, with AgNPs having a bacteriostatic effect and AgNOct being bactericidal after 4 h. The results suggest that AgNPs can be used as effective growth inhibitors in different microorganisms, rendering them applicable to various medical devices and antimicrobial control systems.

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

Synthesis, construction, and evaluation of self-assembled nano-bacitracin A as an efficient antibacterial agent in vitro and in vivo.

PubMed

Hong, Wei; Gao, Xiang; Qiu, Peng; Yang, Jie; Qiao, Mingxi; Shi, Hong; Zhang, Dexian; Tian, Chunlian; Niu, Shengli; Liu, Mingchun

2017-01-01

Bacitracin A (BA) is an excellent polypeptide antibiotic that is active against gram-positive bacteria without triggering multidrug resistance. However, BA is inactive against gram-negative bacteria because of its inability to cross the outer membrane of these cells, and it has strong nephrotoxicity, thus limiting its clinical applications. Nanoantibiotics can effectively localize antibiotics to the periplasmic space of bacteria while decreasing the adverse effects of antibiotics. In this study, biodegradable hydrophobic copolymers of poly (d,l-lactide-co-glycolide) (PLGA) were attached to the N-termini of BA to design a novel class of self-assembled nano-bacitracin A (nano-BAs), and their potential as antibacterial agents was evaluated in vitro and in vivo. Nano-BAs had a core-shell structure with a mean diameter <150 nm. Impressively, nano-BAs had strong antibacterial properties against both gram-positive and gram-negative bacteria, and the distribution of antibacterial activity as a function of PLGA block length was skewed toward longer PLGA chains. No cytotoxicity against HK-2 cells or human red blood cells (hRBCs) was observed in vitro, suggesting good biocompatibility. A high local density of BA mass on the surface promoted endocytotic cellular uptake, and hydrophobic interactions between the PLGA block and lipopolysaccharide (LPS) facilitated the uptake of nano-BAs, thereby leading to greater antibacterial activities. In addition, Nano-BA 5K was found to be effective in vivo, and it served as an anti-infective agent for wound healing. Collectively, this study provides a cost-effective means of developing self-assembling nano-polypeptide antibiotic candidates with a broader antibacterial spectrum and a lower toxicity than commercially available peptide antibiotics, owing to their modification with biodegradable copolymers.

Antibacterial effects of minerals from ores indigenous to Korea.

PubMed

Park, Seul Ki; Lee, Chang Won; Lee, Mi Young

2009-01-01

We tested the antibacterial properties of a mix of minerals consisting mainly of sericite, talc, and halloysite from Korea. The preparation showed clear growth inhibition of the gram-negative bacteria Escherichia coli and Pseudomonas aeruginosa, and the gram-positive bacteria Staphylococcus aureus subsp. aureus, S. epidermidis, and Bacillus cereus, as well as the anaerobic bacterium Propionibacterium acnes. These results indicate that this preparation, made from ore minerals indigenous to Korea, could be used to develop new antibacterial reagents.

In Vitro Antibacterial Properties of Cefiderocol, a Novel Siderophore Cephalosporin, against Gram-Negative Bacteria

PubMed Central

Sato, Takafumi; Ota, Merime; Takemura, Miki; Nishikawa, Toru; Toba, Shinsuke; Kohira, Naoki; Miyagawa, Satoshi; Ishibashi, Naoki; Nakamura, Rio; Tsuji, Masakatsu; Yamano, Yoshinori

2017-01-01

ABSTRACT Cefiderocol (CFDC; S-649266), a novel parenteral siderophore cephalosporin conjugated with a catechol moiety, has a characteristic antibacterial spectrum with a potent activity against a broad range of aerobic Gram-negative bacterial species, including carbapenem-resistant strains of Enterobacteriaceae and nonfermenting bacteria such as Pseudomonas aeruginosa and Acinetobacter baumannii. Cefiderocol has affinity mainly for penicillin-binding protein 3 (PBP3) of Enterobacteriaceae and nonfermenting bacteria similar to that of ceftazidime. A deficiency of the iron transporter PiuA in P. aeruginosa or both CirA and Fiu in Escherichia coli caused 16-fold increases in cefiderocol MICs, suggesting that these iron transporters contribute to the permeation of cefiderocol across the outer membrane. The deficiency of OmpK35/36 in Klebsiella pneumoniae and the overproduction of efflux pump MexA-MexB-OprM in P. aeruginosa showed no significant impact on the activity of cefiderocol. PMID:29061741

3D-printed bioceramic scaffolds with antibacterial and osteogenic activity.

PubMed

Zhang, Yongliang; Zhai, Dong; Xu, Mengchi; Yao, Qingqiang; Zhu, Huiying; Chang, Jiang; Wu, Chengtie

2017-06-20

Bacterial infection poses a significant risk with the wide application of bone graft materials. Designing bone grafts with good antibacterial performance and excellent bone-forming activity is of particular significance for bone tissue engineering. In our study, a 3D printing method was used to prepare β-tricalcium phosphate (β-TCP) bioceramic scaffolds. Silver (Ag) nanoparticles were uniformly dispersed on graphene oxide (GO) to form a homogeneous nanocomposite (named Ag@GO) with different Ag-to-graphene oxide mass ratios, with this being synthesized via the liquid chemical reduction approach. Ag@GO nanocomposites were successfully modified on the β-TCP scaffolds by a simple soaking method to achieve bifunctional biomaterials with antibacterial and osteogenic activity. The prepared scaffolds possessed a connected network with triangle pore morphology and the surfaces of the β-TCP scaffolds were uniformly modified by the Ag@GO nanocomposite layers. The Ag content in the scaffolds was controlled by changing the coating times and concentration of the Ag@GO nanocomposites. The antibacterial activity of the scaffolds was assessed with Gram-negative bacteria (Escherichia coli, E. coli). The results demonstrated that the scaffolds with Ag@GO nanocomposites presented excellent antibacterial activity. In addition, the scaffolds coated with Ag@GO nanocomposites conspicuously accelerated the osteogenic differentiation of rabbit bone marrow stromal cells by improving their alkaline phosphatase activity and bone-related gene expression (osteopontin, runt-related transcription factor 2, osteocalcin and bone sialoprotein). This study demonstrates that bifunctional scaffolds with a combination of antibacterial and osteogenic activity can be achieved for the reconstruction of large-bone defects while preventing or treating infections.

Evaluation of Antimicrobial Activity of the Methanol Extracts from 8 Traditional Medicinal Plants

PubMed Central

Kang, Chang-Geun; Hah, Dae-Sik; Kim, Chung-Hui; Kim, Young-Hwan; Kim, Euikyung

2011-01-01

The methanol extract of 12 medicinal plants were evaluated for its antibacterial activity against Gram-positive (5 strains) and Gram-negative bacteria (10 strains) by assay for minimum inhibitory concentration (MIC) and minimum bacterial concentration (MBC) . The antibacterial activity was determined by an agar dilution method (according to the guidelines of Clinical and Laboratory Standard Institute) . All the compounds (12 extracts) of the 8 medicinal plants (leaf or root) were active against both Gram-negative and Gram-positive bacteria. Gram-negative showed a more potent action than Gram positive bacteria. The MIC concentrations were various ranged from 0.6 μg/ml to 5000 μg/ml. The lowest MIC (0.6 μg/ml) and MBC (1.22 μg/ml) values were obtained with extract on 4 and 3 of the 15 microorganisms tested, respectively. PMID:24278548

Antibacterial activity of antibacterial cutting boards in household kitchens.

PubMed

Kounosu, Masayuki; Kaneko, Seiichi

2007-12-01

We examined antibacterial cutting boards with antibacterial activity values of either "2" or "4" in compliance with the JIS Z 2801 standard, and compared their findings with those of cutting boards with no antibacterial activity. These cutting boards were used in ten different households, and we measured changes in the viable cell counts of several types of bacteria with the drop plate method. We also identified the detected bacterial flora and measured the minimum antimicrobial concentrations of several commonly used antibacterial agents against the kinds of bacteria identified to determine the expected antibacterial activity of the respective agents. Cutting boards with activity values of both "2" and "4" proved to be antibacterial in actual use, although no correlation between the viable cell counts and the antibacterial activity values was observed. In the kitchen environment, large quantities of Pseudomonas, Flavobacterium, Micrococcus, and Bacillus were detected, and it was confirmed that common antibacterial agents used in many antibacterial products are effective against these bacterial species. In addition, we measured the minimum antimicrobial concentrations of the agents against lactobacillus, a typical good bacterium, and discovered that this bacterium is less sensitive to these antibacterial agents compared to more common bacteria.

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

Development of novel antibacterial drugs to combat multiple resistant organisms.

PubMed

Bassetti, Matteo; Righi, Elda

2015-02-01

Infections due to multidrug-resistant (MDR) bacteria are increasing both in hospitals and in the community and are characterized by high mortality rates. New molecules are in development to face the need of active compounds toward resistant gram-positive and gram-negative pathogens. In particular, the Infectious Diseases Society of America (IDSA) has supported the initiative to develop ten new antibacterials within 2020. Principal targets are the so-called ESKAPE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumanii, Pseudomonas aeruginosa, and Enterobacteriaceae). To review the characteristics and the status of development of new antimicrobials including new cephalosporins, carbapenems, beta-lactamase inhibitors, aminoglycosides, quinolones, oxazolidones, glycopeptides, and tetracyclines. While numerous new compounds target resistant gram-positive pathogens and have been approved for clinical use, very few new molecules are active against MDR gram-negative pathogens, especially carbapenemase producers. New glycopeptides and oxazolidinones are highly efficient against methicillin-resistant S. aureus (MRSA), and new cephalosporins and carbapenems also display activity toward MDR gram-positive bacteria. Although new cephalosporins and carbapenems have acquired activity against MRSA, they offer few advantages against difficult-to-treat gram-negatives. Among agents that are potentially active against MDR gram-negatives are ceftozolane/tazobactam, new carbapenems, the combination of avibactam with ceftazidime, and plazomicin. Since a relevant number of promising antibiotics is currently in development, regulatory approvals over the next 5 years are crucial to face the growing threat of multidrug resistance.

The effectiveness of processed grapefruit-seed extract as an antibacterial agent: I. An in vitro agar assay.

PubMed

Reagor, Lee; Gusman, Jean; McCoy, Lana; Carino, Edith; Heggers, John P

2002-06-01

Grapefruit-seed extract (GSE) Citricidal has, in recent reports, been reported to be successful in combating a variety of common infectious agents. In our study, drops of concentrated grapefruit-seed extract were tested for antibacterial properties against a number of gram-positive and gram-negative organisms. Sixty-seven (67) distinct biotypes were tested for their susceptibilities to the GSE as well as to 5 other topical antibacterials (Silvadene, Sulfamylon, Bactroban, Nitrofurazone, and Silvadene, Nystatin). Wells were punched into Mueller-Hinton agar plates, which were then inoculated with the organism to be tested; each well was then inoculated with one of the antibacterial agents. After an overnight incubation period, the plates were checked for zones of bacterial susceptibility around the individual wells, with a measured susceptibility zone diameter of 10 mm or more considered a positive result. The GSE was consistently antibacterial against all of the biotypes tested, with susceptibility zone diameters equal to or greater than 15 mm in each case. Our preliminary data thus suggest an antibacterial characteristic to GSE that is comparable to that of proven topical antibacterials. Although the GSE appeared to have a somewhat greater inhibitory effect on gram-positive organisms than on gram-negative organisms, its comparative effectiveness against a wide range of bacterial biotypes is significant.

Essential Oil Yield Pattern and Antibacterial and Insecticidal Activities of Trachyspermum ammi and Myristica fragrans.

PubMed

Soni, Rajgovind; Sharma, Gaurav; Jasuja, Nakuleshwar Dut

2016-01-01

Two Indian spices, Trachyspermum ammi and Myristica fragrans, were studied for their essential oil (EO) yielding pattern, insecticidal activity, antibacterial activity, and composition. The essential oils (EOs) of T. ammi (1.94 ± 30 mL/100 gm) and M. fragrans (5.93 ± 90 mL/100 gm) were extracted using hydrodistillation method. In Gas Chromatography analysis, the beta-pinene, alpha-pinene, alpha-p-menth-1-en-4-ol, Limonene, and elemicin were found as major constituents of T. ammi essential oil whereas M. fragrans essential oil mostly contains Gamma-Terpinolene, p-Cymene, Thymol, and beta-pinene. The insecticidal activities of EO were demonstrated using LC50 values against Plodia interpunctella and EO of T. ammi was found comparatively more effective than EO of M. fragrans. Further, individual EO and combination of essential oil were examined for antibacterial activity against three Gram (-) bacterial strains (E. coli-MTCC 443, P. vulgaris-MTCC 1771, and K. pneumoniae-MTCC number 7028) and three Gram (+) bacterial strains (S. aureus-MTCC 3381, B. subtilis-MTCC 10619, and B. megaterium-MTCC 2412) by well agar diffusion method. The essential oil in combination (CEO) exhibited higher antibacterial activity as compared with individual essential oils.

Highly bacterial resistant silver nanoparticles: synthesis and antibacterial activities

NASA Astrophysics Data System (ADS)

Chudasama, Bhupendra; Vala, Anjana K.; Andhariya, Nidhi; Mehta, R. V.; Upadhyay, R. V.

2010-06-01

In this article, we describe a simple one-pot rapid synthesis route to produce uniform silver nanoparticles by thermal reduction of AgNO3 using oleylamine as reducing and capping agent. To enhance the dispersal ability of as-synthesized hydrophobic silver nanoparticles in water, while maintaining their unique properties, a facile phase transfer mechanism has been developed using biocompatible block co-polymer pluronic F-127. Formation of silver nanoparticles is confirmed by X-ray diffraction (XRD), transmission electron microscopy (TEM) and UV-vis spectroscopy. Hydrodynamic size and its distribution are obtained from dynamic light scattering (DLS). Hydrodynamic size and size distribution of as-synthesized and phase transferred silver nanoparticles are 8.2 ± 1.5 nm (σ = 18.3%) and 31.1 ± 4.5 nm (σ = 14.5%), respectively. Antimicrobial activities of hydrophilic silver nanoparticles is tested against two Gram positive ( Bacillus megaterium and Staphylococcus aureus), and three Gram negative ( Escherichia coli, Proteus vulgaris and Shigella sonnei) bacteria. Minimum inhibitory concentration (MIC) values obtained in the present study for the tested microorganisms are found much better than those reported for commercially available antibacterial agents.

Determination of Antibacterial and Antioxidant Potential of Some Medicinal Plants from Saurashtra Region, India

PubMed Central

Kaneria, M.; Baravalia, Y.; Vaghasiya, Y.; Chanda, S.

2009-01-01

Many plants used in Saurashtra folk medicine have been reported to exhibit high antibacterial and antioxidant activities. In the present study, some parts of five plants, Guazuma ulmifolia L., Manilkara zapota L., Melia azedarach L., Syzygium cumini L. and Wrightia tomentosa R.& S., were evaluated for their antibacterial activity, total phenol content, flavonoid content, 2,2-diphenyl-1-picrylhydrazyl free radical scavenging activity and phytochemical analysis, using successive extraction by cold percolation method with petroleum ether, ethyl acetate, methanol and water. In vitro antibacterial activity was evaluated against five bacterial strains viz. Bacillus subtilis, Staphylococcus aureus, Pseudomonas aeruginosa, Salmonella typhimurium and Enterobacter aerogenes by agar well diffusion method. Among the plants screened, W. tomentosa leaf and fruit showed the best antibacterial activity. The Gram-positive bacteria were more susceptible than Gram-negative bacteria. Methanol extract of M. zapota showed the best 2,2-diphenyl-1-picrylhydrazyl free radical scavenging activity. Highest total phenol content was shown by M. zapota and S. cumini in methanol extract, while highest flavonoid content was shown by W. tomentosa stem in petroleum ether extract and ethyl acetate extract. In all the plants, cardiac glycosides and triterpenes were more as compared to other phytoconstituents. PMID:20502546

Isolation and Identification of Active Compounds from Papaya Plants and Activities as Antimicrobial

NASA Astrophysics Data System (ADS)

Prasetya, A. T.; Mursiti, S.; Maryan, S.; Jati, N. K.

2018-04-01

Extraction and isolation of papaya seeds and leaves (Carica papaya L) has been performed using n-hexane and ethanol solvents. Further isolation of the extract obtained using ethyl acetate and diethyl ether solvents. The result of the phytochemical test of papaya extract obtained by mixture of an active compound of flavonoids, alkaloids, tannins, steroids, and saponins. Ethyl acetate isolates containing only flavonoids and diethyl ether isolates contain only alkaloids. Extracts and isolates from papaya plants had gram-positive antibacterial activity greater than the gram-negative bacteria, but both did not have antifungal activity. Papaya extracts have greater antibacterial activity than flavonoid isolates and alkaloid isolates. Strong antibacterial inhibitory sequences are extracts of papaya plants, flavonoid isolates, and alkaloid isolates.

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