ATCC 6538P Research Articles

A fully validated microbiological assay to evaluate the potency of ceftriaxone sodium

Ceftriaxone (CFTX) sodium is a third-generation, broad-spectrum cephalosporin that is resistant to beta-lactamases. An alternative bioassay for the assessment of the potency of this drug in pharmaceutical formulations has not been previously reported. Thus, this paper reports the development and full validation of a 3 x 3 agar diffusion bioassay using a cylinder-plate method to quantify CFTX sodium in pharmaceutical samples. The strain Staphylococcus aureus ATCC 6538P was used as the test microorganism, and the results of the proposed bioassay displayed high linearity, precision, accuracy, specificity and robustness. All potency results were statistically analyzed using an analysis of variance (ANOVA) and were found to be linear (r=0.99999) in the range of 16-64 µg/mL, accurate (100.5%), and precise [repeatability: relative standard deviation (RSD)=1.4%; intermediate precision: between-day RSD=2.1% and between-analyst RSD=2.5%]. The specificity of the bioassay was determined by evaluating a degraded sample (50 ºC) at 0, 24 and 48 hours as compared against the results from the pharmacopeial liquid chromatography method for CFTX. The results validated the proposed microbiological assay, which allows reliable quantitation of CFTX in pharmaceutical samples. Moreover, it is a useful, simple and low-cost alternative method for monitoring the quality of this medicine.

Comparative testing of antimicrobial activity of aqueous extracts of Aloe vera and Lycium barbarium

Plants have a very important role in natural medicine because of their composition rich in vitamins, minerals, antimicrobial and immunomodulatory compounds. Since antibioresistance to some antibiotics used in current therapy in human medicine and veterinary medicine is nowadays a major problem, researches have searched for alternative methods of replacement or combination of antibiotics with different plant extracts with antimicrobial and/or immunomodulatory effect. This experiment was designed to evaluate the comparative antimicrobial effect of aqueous extracts of aloe (Aloe vera) and goji berries (Lycium barbarum) on some species of bacteria and fungi. We used for this experiment five kinds of aqueous extracts of aloe vera (two extracted from the for six months old plant, two from a 4 years old plants and a standard commercially available aqueous extract). Five types of aqueous extracts of goji fruit (1/1 goji soak, total aqueous extract, fruit centrifuged supernatant, fruits supernatant filtered through 0.2μm Millipore and watery sediment from plant mortar) were also tested. Four kinds of microorganisms including Gram-positive bacteria (Staphylococcus aureus ATCC 6538P), Gram-negative bacteria (Escherichia coli ATCC 10536, Pseudomonas aeruginosa ATCC 27853) and fungi (Candida albicans ATCC 10231) were used for determining the sensitivity. Testing was done by disc diffusion method with some changes according to the tested compounds. The interpretation of disk diffusion test revealed that Aloe vera extracts had inhibitory effect only on the strains of Staphylococcus aureus ATCC 6538P, the effect being stronger for total extract (100%) as well as for standardized extract. The growth of Escherichia coli ATCC 10536 strain, was increased instead of being inhibited. On Candida albicans ATCC 10231 strain, only standardized extract had a good inhibitory effect. Regarding the antimicrobial effect of aqueous extracts of goji fruit we found a weak inhibitory effect, however, observing a strong inhibitory effect on E. coli strain. This study demonstrated that aqueous extracts of aloe and goji have antimicrobial effect, which depends on the concentration of the extract and the type of microorganism tested. The results can represent a prospect into the use of these extracts as substitutes for antibiotics or along with antibiotics and may have practical applications in medicine, cosmetics and food industry.

A Comparative Study of Linezolid Stability samples by Validated Spectrophotometric and Turbidimetic-Microbial Assay Methods

Linezolid is one of the first commercially available and most widely used oxazolidinone antibiotics. This study describes the development of a microbiological assay, applying the turbidimetric method for the determination of linezolid, as well as the evaluation of the ability of the method in determining the stability of linezolid against acidic, basic, neutral, thermal and photolytic degradants using Staphylococcus aureus ATCC 6538P as the test micro-organism. The results obtained with the microbial method were compared with the results obtained from the spectrophotometric method, developed and validated using ferric citrate and 1, 10-phenanthroline reagents to give an orange coloured chromogen, measured at 510 nm. The MIC value for standard linezolid was found to be 2.7 μg/ml. It was observed that linezolid is unstable in acid and alkali. The potency of linezolid is critically reduced under these stress conditions, whereas under neutral, thermal and photolytic stress conditions the potency of linezolid was reduced to a smaller extent.

Exploitation of Haloferax alexandrinus for Biogenic Synthesis of Silver Nanoparticles Antagonistic to Human and Lower Mammalian Pathogens

In the present study we report the use of cells of a Haloarchaeon for the green synthesis of silver nanoparticles. Biosynthesis of AgNPs occurred within 30 s on exposure of cells of Haloferax alexandrinus to silver nitrate in direct sunlight. Maximum AgNPs production was achieved within 4 min of exposure of silver nitrate (0.05 %) to cells (5 mg/ml), at pH 7, at ambient day temperature (26–34 °C). The AgNPs had characteristic surface plasmon resonance at 420 nm in UV–Vis spectra. Spherical and irregular crystals ranging from 2 to 60 nm in size with an average size of 18 nm were observed in TEM analysis. The FTIR spectral analysis indicated involvement of N–H, –OH, C=O, C–O functional groups present in cells of Haloferax alexandrinus MTCC 3265. The biogenic AgNPs exhibited broad spectrum antimicrobial activity against human and mammalian pathogens, in the order of Pseudomonas aeruginosa ATCC 9027 > Bordetella bronchiseptica ATCC 4617 > Bacillus subtilis ATCC 6633 > Staphylococcus aureus ATCC 6538P > Staphylococcus epidermidis ATCC 12228 > Escherichia coli ATCC 8739 > Salmonella typhimurium ATCC 14028.

Antimicrobial activity of quinoxaline 1,4-dioxide with 2- and 3-substituted derivatives

Quinoxaline is a chemical compound that presents a structure that is similar to quinolone antibiotics. The present work reports the study of the antimicrobial activity of quinoxaline N,N-dioxide and some derivatives against bacterial and yeast strains. The compounds studied were quinoxaline-1,4-dioxide (QNX), 2-methylquinoxaline-1,4-dioxide (2MQNX), 2-methyl-3-benzoylquinoxaline-1,4-dioxide (2M3BenzoylQNX), 2-methyl-3-benzylquinoxaline-1,4-dioxide (2M3BQNX), 2-amino-3-cyanoquinoxaline-1,4-dioxide (2A3CQNX), 3-methyl-2-quinoxalinecarboxamide-1,4-dioxide (3M2QNXC), 2-hydroxyphenazine-N,N-dioxide (2HF) and 3-methyl-N-(2-methylphenyl)quinoxalinecarboxamide-1,4-dioxide (3MN(2MF)QNXC). The prokaryotic strains used were Staphylococcus aureus ATCC 6538, S. aureus ATCC 6538P, S. aureus ATCC 29213, Escherichia coli ATCC 25922, E. coli S3R9, E. coli S3R22, E. coli TEM-1 CTX-M9, E. coli TEM-1, E. coli AmpC Mox-2, E. coli CTX-M2 e E. coli CTX-M9. The Candida albicans ATCC 10231 and Saccharomyces cerevisiae PYCC 4072 were used as eukaryotic strains. For the compounds that presented activity using the disk diffusion method, the minimum inhibitory concentration (MIC) was determined. The alterations of cellular viability were evaluated in a time-course assay. Death curves for bacteria and growth curves for S. cerevisiae PYCC 4072 were also accessed. The results obtained suggest potential new drugs for antimicrobial activity chemotherapy since the MIC's determined present low values and cellular viability tests show the complete elimination of the bacterial strain. Also, the cellular viability tests for the eukaryotic model, S. cerevisiae, indicate low toxicity for the compounds tested.

Antibacterial Activity of Methanolic Extracts, Decoction and Isolated Triterpene Products from Different Parts of Birch, Betula pendula, Roth

Five methanolic extracts obtained from different parts of birch, Betula pendula, Roth. (external and internal bark, flowers, leaves and buds), were evaluated for their antibacterial activity in this study. Triterpene compounds, betulin, betulinic acid, oleanolic acid and lupeol, were isolated from the external parts of birch bark using the method of dry column chromatography (DCC) as well as preparative thin layer chromatography (TLC). These compounds were also investigated for their antibacterial activity. Taking into account that decoction is the most commonly used pharmaceutical form of herbal drug, decoctions made from external bark, leaf, flower and bud were investigated for their antibacterial activity. Antibacterial screening, against selected Gram-positive bacteria, Bacillus subtilis ATCC 6633, Staphylococcus aureus ATCC 6538P and Gram-negative bacteria, Escherichia coli ATCC 8739 and Pseudomonas aeruginosa ATCC 9027 was carried out. The methods of diffusion and dilution were used for this investigation according to European Pharmacopoea, 1996. The most prominent antibacterial activity showed oleanolic acid against bacterial species Staphylococcus aureus, expressed as minimal inhibitory concentration (MIC): 1.25% and Bacillus subtilis MIC: 0.625%. Escherichia coli showed resistance on all investigated samples.

CHARACTERIZATION AND ANTIMICROBIAL ACTIVITY OF STREPTOMYCES STRAINS FROM THAI MANGROVE SOILS

Four actinomycete isolates, SAM2-1, SMP3-1, and J8-1 and J17-2 were isolated from mangrove soils collected in Samut Prakarn and Samut Songkram provinces, the inner gulf of Thailand. These isolates were identified as Streptomyces based on their phenotypic and chemotaxonomic characteristics. They contained L–diaminopimelic acid in cell wall. Their major menaquinone components were MK-9 (H6) and MK-9 (H8). On the screening of antimicrobial activity, they could inhibit Staphylococcus aureus ATCC 6538P and Bacillus subtilis ATCC 6633 but showed weak inhibitory activity against Kocuria rhizophila ATCC 9341, Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853 and no activity against Candida albicans ATCC 10231. Only isolate J8-1 showed strong inhibitory activity against Bacillus subtilis ATCC 6633. The isolates SAM2-1, SMP3-1, J8-1 and J17-2 were closely related to S. sundarbansensis DSM 42019T (98.4%), S. diastaticus subsp. ardesiacus JCM 5815T (97.1%), S. iranensis JCM 17327T (96.4%) and S. seoulensis NBRC 16668T (95.3%), respectively based on 16S rRNA gene analyses.

In-Vivo and In-Vitro Biocompatibility Evaluations of Silver Nanoparticles with Antimicrobial Activity

In this study, the biocompatibility and antimicrobial activity of silver nanoparticles (Ag NPs) were evaluated in vitro and in vivo. The cytotoxicity of Ag NPs (average diameter: 2-5 nm) against CHO-K1 cells was determined via WST-8 assay, and their genotoxicity was examined via Salmonella typhimurium reverse mutation assay (Ames test). The acute toxicity and intracutaneous reactivity of Ag NPs were evaluated using animal models of mice and rabbits, respectively. The antibacterial effects of Ag NPs on the Gram (-) bacterial strains of Escherichia coli ATCC 8739 and Pseudomonas aeruginosa ATCC 9027 and on the Gram (+) bacterial strains of Staphylococcus aureus ATCC 6538p and Bacillus subtilius ATCC 6633 were determined by measuring the minimum inhibitory concentrations. The Ag NPs were highly cytotoxic to the L-929 cells at over 2 ppm but were non-cytotoxic at lower than 1 ppm. Moreover, the Ag NPs at 1 ppm or lower did not show genotoxicity, acute toxicity and intracutaneous reactivity. It was also found that the Ag NPs exerted effective antimicrobial activities on both the Gram (-) and (+) bacterial strains within the range from 0.06 to 0.98 ppm for 50% MIC.

In vitro effect of ozonated saline on microorganisms involved in pancreatic and peripancreatic necrosis infection in severe acute pancreatitis

The unsatisfactory results obtained in the treatment of severe acute pancreatitis or the great abdominal drama; with pancreatic and peripancreatic infected necrosis require new therapeutic methods. This paper aims to evaluate the antimicrobial effect of ozonated saline on bacterial and yeast species commonly involved in pancreatic and peripancreatic necrosis infection in severe acute pancreatitis. Tests were conducted on four bacterial species (Staphylococcus aureus ATCC 6538P, Escherichia coli ATCC 10536, Klebsiella pneumoniae and Pseudomonas aeruginosa ATCC 27853) and one Candida albicans ATCC 90028 strain. Ozonated saline and Imipenem (antibiotic) was used for all microbial strains. Two types of tests were used: the first on solid medium to determine the number of colonies (CFU/mL) and the second type of tests was the liquid medium for MIC determination. The results show that ozonated saline caused a reduction in the number of bacteria and yeast colonies even in small concentrations in plates. Minimum inhibitory concentrations obtained were very small for the strains of S. aureus ATCC 6538P (0.001563 mg/mL) and E. coli ATCC 10536 (0.003125 mg/mL) and; somewhat higher for K. pneumoniae (0.05 mg/mL), P. aeruginosa ATCC 27853 (0.1 mg/ml) and C. albicans. These results are encouraging in terms of possible use by peritoneal lavage of ozonated saline for pancreatic necrosis infection in acute pancreatitis.

Study on antibacterial alginate-stabilized copper nanoparticles by FT-IR and 2D-IR correlation spectroscopy.

BackgroundThe objective of this study was to clarify the intermolecular interaction between antibacterial copper nanoparticles (Cu NPs) and sodium alginate (NaAlg) by Fourier transform infrared spectroscopy (FT-IR) and to process the spectra applying two-dimensional infrared (2D-IR) correlation analysis. To our knowledge, the addition of NaAlg as a stabilizer of copper nanoparticles has not been previously reported. It is expected that the obtained results will provide valuable additional information on: (1) the influence of reducing agent ratio on the formation of copper nanoparticles in order to design functional nanomaterials with increased antibacterial activity, and (2) structural changes related to the incorporation of Cu NPs into the polymer matrix.MethodsCu NPs were prepared by microwave heating using ascorbic acid as reducing agent and NaAlg as stabilizing agent. The characterization of synthesized Cu NPs by ultraviolet visible spectroscopy, transmission electron microscopy (TEM), electron diffraction analysis, X-ray diffraction (XRD), and semiquantitative analysis of the weight percentage composition indicated that the average particle sizes of Cu NPs are about 3–10 nm, they are spherical in shape, and consist of zerovalent Cu and Cu2O. Also, crystallite size and relative particle size of stabilized Cu NPs were calculated by XRD using Scherrer’s formula and FT from the X-ray diffraction data. Thermogravimetric analysis, differential thermal analysis, differential scanning calorimetry (DSC), FT-IR, second-derivative spectra, and 2D-IR correlation analysis were applied to studying the stabilization mechanism of Cu NPs by NaAlg molecules. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of stabilized Cu NPs against five bacterial strains (Staphylococccus aureus ATCC 6538P, Escherichia coli ATCC 25922 and O157: H7, and Salmonella enterica serovar Typhimurium ATCC 13311 and 14028) were evaluated with macrodilution, agar dilution plate count, and well-diffusion methods.ResultsOn the basis of the semiquantitative analysis, there was a direct correlation between the reducing agent ratio and the percentage of zerovalent Cu. This was confirmed with the statistical analysis of population of Cu NPs from TEM micrographs. At lower reducing agent ratios, two phases coexist (Cu2O and zerovalent Cu) due to incomplete reduction of copper ions by the reducing agent; however, at higher reducing agent ratios, the Cu NPs consist mainly of zerovalent Cu. Crystallite size and relative particle size of stabilized Cu NPs showed considerable differences in results and tendencies in respect to TEM analysis. However, the relative particle size values obtained from FT of XRD data agreed well with the histograms from the TEM observations. From FT results, the relative particle size and reducing agent ratio of stabilized Cu NPs showed an inverse correlation. The incomplete reduction of copper ions at lower reducing agent ratios was also confirmed by DSC studies. FT-IR and 2D-IR correlation spectra analysis suggested the first event involved in the stabilization of Cu NPs is their electrostatic interaction with –C=O of carboxylate groups of NaAlg, followed by the interaction with the available O–C–O−, and finally with the –OH groups. Bacterial susceptibility to stabilized nanoparticles was found to vary depending on the bacterial strains. The lowest MIC and MBC of stabilized Cu NPs ranged between 2 mg/L and 8 mg/L for all studied strains. Disk-diffusion studies with both E. coli strains revealed greater effectiveness of the stabilized Cu NPs compared to the positive controls (cloxacillin, amoxicillin, and nitrofurantoin). S. aureus showed the highest sensitivity to stabilized Cu NPs compared to the other studied strains.ConclusionCu NPs were successfully synthesized via chemical reduction assisted with microwave heating. Average particle size, polydispersity, and phase composition of Cu NPs depended mainly on the reducing agent ratio. Likewise, thermal stability and antibacterial activity of stabilized Cu NPs were affected by their phase composition. Because of the carboxylate groups in polymer chains, the structural changes of stabilized Cu NPs are different from those of NaAlg. NaAlg acted as a size controller and stabilizing agent of Cu NPs, due to their ability to bind strongly to the metal surface. Our study on the stabilizing agent–dependent structural changes of stabilized NPs is helpful for wide application of NaAlg as an important biopolymer.

Anti-Staphylococcus Activity of Uruguayan Riverside Forest Plants

Methicillin resistant Staphylococcus aureus is a major nosocomial pathogen which causes increased morbidity and mortality worldwide. Interest in plants with antimicrobial properties has thus revived as a consequence of current problems associated with the use of antibiotics. In previous work we undertook the biological and chemical prospection of the gallery forest of the northern Uruguay River basin. Plants were selected after an exhaustive review of the available literature according at its ethnopharmacological use and submitted to antimicrobial assays and phytochemical characterization. Extracts that were positive in the qualitative diffusion tests against S. aureus were selected for a more detailed study. The objective of the present work is to study the anti MRSA activity of 37 plant extracts that have previously shown activity against S. aureus in a qualitative diffusion assay. The plant material were separately twice extracted by maceration with EtOH/H2O 70:30, acetone and CHCl3. Minimum inhibitory concentration (MIC) was determined by the microdilution technique according to Clinical and Laboratory Standards Institute using sensitive (ATCC 6538p) and resistant (ATCC 43300, ATCC 700699 and USA 100) strains. Some of the extracts showed good activity specially species of the Myrtaceae family with MICs as low s 7.8 μg/mL. These promissory results were obtained encourage further work to be done regarding the isolation and structural elucidation of the active compound(s).

The Study of the Antimicrobial Activity of Transylvanian (Romanian) Propolis

The aim of the present study was to investigate the antibacterial activity of propolis samples collected from various regions in Transylvania (Romania) against six bacterial strains: three Gram-positive bacteria (Staphylococcus aureus ATCC 6538P, Bacillus cereus ATCC 14579, Listeria monocytogenes ATCC 7644), two Gram-negative bacteria (Escherichia coli ATCC 10536, Pseudomonas aeruginosa ATCC 27853) and one yeast strain (Candida albicans ATCC 90028). Ethanolic extracts of the studied samples were prepared for the evaluation of antimicrobial activity, which was appreciated by measuring the inhibition zones diameters. The methodology used was agar diffusion technique inside Petri dishes with nine wells. Enroxil was used as control. A better sensibility of the Gram-positive bacteria (Staphylococcus aureus, Bacillus cereus, Listeria monocytogenes) was noticed; the diameter of the inhibition zones ranged between 8 mm and 17 mm. As for Gram-negative bacteria, results were different for every tested bacterial strain. Inhibition zones diameter for E. coli ranged between 7 mm and 12 mm, while for P. aeruginosa a total resistance was noticed. Inhibition zones diameters for Candida albicans showed a variation which ranged between 0 mm and 10 mm. Minimum inhibitory concentration (MIC) was evaluated for sample PS 20 due to the positive results showed against Staphylococcus aureus. According to the results obtained, it might be concluded that the tested propolis samples showed good results against Gram-positive bacteria.

Antibacterial effect of silver nanoparticles on Staphylococcus aureus

The antibacterial activity and mechanism of silver nanoparticles (Ag-NPs) on Staphylococcus aureus ATCC 6538P were investigated in this study. The experiment results showed the minimum bactericidal concentration (MBC) of Ag-NPs to S. aureus was 20 μg/ml. Moreover, when bacteria cells were exposed to 50 μg/ml Ag-NPs for 6 h, the cell DNA was condensed to a tension state and could have lost their replicating abilities. When S. aureus cells were exposed to 50 μg/ml Ag-NPs for 12 h, the cell wall was breakdown, resulting in the release of the cellular contents into the surrounding environments, and finally became collapsed. And Ag-NPs could reduce the enzymatic activity of respiratory chain dehydrogenase. Furthermore, the proteomic analysis showed that the expression abundance of some proteins was changed in the treated bacterial cell with Ag-NPs, formate acetyltransferase increased 5.3-fold in expression abundance, aerobic glycerol-3-phosphate dehydrogenase decreased 6.5-fold, ABC transporter ATP-binding protein decreased 6.2-fold, and recombinase A protein decreased 4.9-fold.

Design and synthesis of novel methylene‐bis‐fused pyrazoles as biologically active molecules

Abstract magnified image A series of novel methylene‐bis‐fused pyrazoles 12a, 12b, 12c, 12d and methylene‐bis‐2‐(4‐methylsulfonyl)‐phenyl substituted fused pyrazoles 15a, 15b, 15c, 15d have been synthesized by the reaction of methylene‐bis‐aryl‐6‐hydroxymethylene‐2‐cyclohexenones 10 with hydrazine hydrate or (4‐methylsulfonyl)‐phenyl hydrazine 13. Chemical structures of all the newly synthesized compounds were elucidated by their IR, 1H NMR, 13C NMR, and MS spectral data. The compounds 15a, 15b, 15c, 15d were evaluated for their cyclooxygenase‐2 (COX‐2) inhibitory activity, and the compound 15b showed appreciable COX‐2 inhibition and selectivity. Further, all the new compounds were screened for their antimicrobial activity against Gram‐positive, Gram‐negative bacteria, and fungi. Amongst the screened compounds, 12c, 15a, and 15b were found to be the most active against almost all the test bacteria. The compound 15b displayed notable antibacterial activity against Bacillus subtilis (ATCC 6633), Staphylococcus aureus (ATCC 6538p), Micrococcus luteus (IFC 12708), Proteus vulgaris (ATCC 3851), and Salmonella typhimurium (ATCC 14028), equal to that of ampicillin. Similarly, these compounds also showed potent antifungal activity against Candida albicans (ATCC 10231), Aspergillus fumigatus (HIC 6094), Trichophyton rubrum (IFO 9185), and Trichophyton mentagrophytes (IFO 40996). J. Heterocyclic Chem., (2010).

In vitroeffect of branch extracts ofJuniperusspecies from Turkey onStaphylococcus aureusbiofilm

Methanol and aqueous branch extracts of five Juniperus species were examined for their effects on Staphylococcus aureus ATCC 6538P and S. aureus 810 biofilm. The Turkish plant material was Juniperus communis L. var. communis, J. communis L. var. saxatilis Pall., Juniperus drupacea Labill., Juniperus oxycedrus L. ssp. oxycedrus, J. oxycedrus L. ssp. macrocarpa (Sibth. & Sm.) Ball. The Juniperus extracts were subjected to preliminary phytochemical analysis by thin-layer chromatography. The antimicrobial activity was evaluated using the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC). The effects of the extracts on biofilm formation and preformed biofilm were quantified by both biomass OD and the CFU counting method. The phytochemical screening revealed the presence of polyphenols, coumarins, lignans, steroids, alkaloids and terpenes. For both strains, the MICs of all extracts were in the range of 4.88-78.12 microg mL(-1). On S. aureus ATCC 6538P, the effects of subinhibitory concentration (0.5 MIC) of the extracts were minimal on planktonic growth and on adhering cells, whereas they were greater on biofilm formation. Differently, on S. aureus 810, they showed only a rather low efficacy on biofilm formation. The extracts at 2 MIC demonstrated a good activity on a preformed biofilm of S. aureus ATCC 6538P.

Extracellular Synthesis of Silver Nanoparticles Using Dried Leaves of Pongamia pinnata (L) Pierre

Extract of oven dried leaves of Pongamia pinnata (L) Pierre was used for the synthesis of silver nanoparticles. Stable and crystalline silver nanoparticles were formed by the treatment of aqueous solution of AgNO3 (1mM) with dried leaf extract of Pongamia pinnata (L) Pierre. UV-visible spectroscopy studies were carried out to quantify the formation of silver nanoparticles. Transmission electron microscopy, X-ray diffraction and Fourier transform infrared spectroscopy were used to characterize the silver nanoparticles. TEM image divulges that silver nanoparticles are quite polydispersed, the size ranging from 20 nm to 50 nm with an average of 38 nm. Water soluble heterocyclic compounds such as flavones were mainly responsible for the reduction and stabilization of the nanoparticles. Silver nanoparticles were effective against Escherichia coli (ATCC 8739), Staphylococcus aureus (ATCC 6538p), Pseudomonas aeruginosa (ATCC 9027) and Klebsiella pneumoniae (clinical isolate). The move towards extracellular synthesis using dried biomass appears to be cost effective, eco-friendly to the conventional methods of nanoparticles synthesis.

Synthesis of some new 3-[5-(2-oxo-2 H-3-chromenyl)-1,3-oxazol-2-yl]-1,3-thiazolan-4-ones as antimicrobials

A series of some new 2-imino-5-[( Z)-1-(4-methylphenyl)methylidene]-3-[5-(2-oxo-2 H-3-chromenyl)-1,3-oxazol-2-yl]-1,3-thiazolan-4-ones 5a– j has been synthesized and assayed for their antibacterial activity against Gram-positive bacteria viz. Bacillus subtilis (ATCC 6633), Staphylococcus aureus (ATCC 6538p) and Micrococcus luteus (IFC 12708), and Gram-negative bacteria viz. Proteus vulgaris (ATCC 3851), Salmonella typhimurium (ATCC 14028) and Escherichia coli (ATCC 25922). Among the screened compounds, 5d, 5e, 5f, 5g, and 5j exhibited potent inhibitory activity compared to standard drug, and emerged as potential molecules for further development.

Extracellular synthesis of silver nanoparticles using dried leaves of pongamia pinnata (L) pierre

Abstract Extract of oven dried leaves of Pongamia pinnata (L) Pierre was used for the synthesis of silver nanoparticles. Stable and crystalline silver nanoparticles were formed by the treatment of aqueous solution of AgNO3 (1mM) with dried leaf extract of Pongamia pinnata (L) Pierre. UV-visible spectroscopy studies were carried out to quantify the formation of silver nanoparticles. Transmission electron microscopy, X-ray diffraction and Fourier transform infrared spectroscopy were used to characterize the silver nanoparticles. TEM image divulges that silver nanoparticles are quite polydispersed, the size ranging from 20 nm to 50 nm with an average of 38 nm. Water soluble heterocyclic compounds such as flavones were mainly responsible for the reduction and stabilization of the nanoparticles. Silver nanoparticles were effective against Escherichia coli (ATCC 8739), Staphylococcus aureus (ATCC 6538p), Pseudomonas aeruginosa (ATCC 9027) and Klebsiella pneumoniae (clinical isolate). The move towards extracellular synthesis using dried biomass appears to be cost effective, eco-friendly to the conventional methods of nanoparticles synthesis.

Cellular effects induced by Inula graveolens and Santolina corsica essential oils on Staphylococcus aureus

This study was conducted to evaluate the antibacterial activity of Inula graveolens and Santolina corsica essential oils on Staphylococcus aureus and investigate their effects at the cellular level. The mode of inhibition of both essential oils against S. aureus ATCC 6538P (CIP 53.156) was assessed by determining the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC). The effects of time and treatment dose on cell viability were determined by time-kill and bacteriolysis assays. Marked structural changes were observed by transmission electron microscopy (TEM). A bactericidal mode of inhibition was established for both essential oils, which rapidly reduced the cell viability of S. aureus at their MIC (5 mg.ml(-1)). No lysis occurred after treatments with the MIC and eight times the MIC of each essential oil. Invaginations of the plasmic membrane with thickenings of the cell wall as well as an aggregation of the cytoplasmic contents were observed in S. aureus cells treated with the MIC of both essential oils. These results suggest that the cytoplasmic membrane and the cell wall are involved in the toxic action of Inula graveolens and Santolina corsica essential oils.

Synthesis, Nematicidal and Antimicrobial Activity of 3-(5-3-Methyl-5-[(3-methyl-7-5-[2-(aryl)-4-oxo-1,3-thiazolan-3-yl]-1,3,4-thiadiazol-2-ylbenzo[<i>b</i>]furan-5-yl)methyl]benzo[<i>b</i>]furan-7-yl-1,3,4-thiadiazol-2-yl)-2-(aryl)-1,3-thiazolan-4-one

A new series of 3-(5-3-methyl-5-[(3-methyl-7-5-[2-(aryl)-4-oxo-1,3-thiazolan-3-yl]-1,3,4-thiadiazol-2-ylbenzo[b]furan-5-yl)methyl]benzo[b]furan-7-yl-1,3,4-thiadiazol-2-yl)-2-(aryl)-1,3-thiazolan-4-one 5a-j has been synthesized by the reaction of N2-[(E)-1-(4-methylphenyl)methylidene]-5-(3-methyl-5-[3-methyl-7-(5-[(E)-1-(4-methylphenyl)methylidene]amino-1,3,4-thiadiazol-2-yl)benzo[b]furan-5-yl]methylbenzo[b]furan-7-yl)-1,3,4-thiadiazol-2-amine 4a-j with thioglycolic acid. Chemical structures of all the new compounds were established by their IR, 1H-NMR, 13C-NMR, MS and elemental data. The 5a-j have been assayed for their nematicidal activity against Ditylenchus myceliophagus and Caenorhabditis elegans by aqueous in vitro screening technique. The screened data reveal that, the 5e is most effective against D. myceliophagus and C. elegans with 50% lethal dose (LD(50)) of 170 and 190 ppm, respectively and is almost equal to the activity of standard levamisole. The 5h and 5j are also most active against C. elegans with LD(50) of 200 ppm and D. myceliophagus with LD(50) of 190 ppm, respectively. Further, the 5a-j were screened for their antibacterial activity against three representative, Gram-positive bacteria viz. Bacillus subtilis ATCC 6633, Staphylococcus aureus ATCC 6538p and Micrococcus luteus IFC 12708, and three Gram-negative bacteria viz. Proteus vulgaris ATCC 3851, Salmonella typhimurium ATCC 14028 and Escherichia coli ATCC 25922, and also screened for their antifungal activity against four fungal organisms viz. Candida albicans ATCC 10231, Aspergillus fumigatus HIC 6094, Trichophyton rubrum IFO 9185 and Trichophyton mentagrophytes IFO 40996. Most of these new compounds showed appreciable activity against the test bacteria and fungi, and emerged as potential molecules for further development.