Ritika Chauhan

A Biological Approach to the Synthesis of Silver Nanoparticles with Streptomyces sp JAR1 and its Antimicrobial Activity

The biological approach to synthesize metal nanoparticles is an important aspect of current nanotechnology research. Silver nanoparticles have been well-known for their inhibitory and antimicrobial effects. The ever-increasing antibiotic resistance in pathogenic and opportunistic microorganisms is a major threat to the health care industry. In the present investigation, silver nanoparticles have been successfully biosynthesized by Streptomyces sp JAR1. Biosynthesized silver nanoparticles were characterized by means of several analytical techniques including a UV-Visible spectrophotometer, Fourier transform infrared spectroscopy, X-ray diffraction pattern analysis, and atomic force microscopy. An evaluation of the antimicrobial activity of silver nanoparticles (AgNPs) was carried out against clinically important pathogenic microorganisms. The metal nanoparticles were also evaluated for their combined effects with antibiotics against the clinical pathogens. The antibacterial activities of the antibiotics increased in the presence of the biologically synthesized AgNPs against the clinically important pathogens. The highest enhancing effect was observed for erythromycin against the test pathogens.

Biosynthesis of silver and zinc oxide nanoparticles using Pichia fermentans JA2 and their antimicrobial property

The development of eco-friendly alternative to chemical synthesis of metal nanoparticles is of great challenge among researchers. The present study aimed to investigate the biological synthesis, characterization, antimicrobial study and synergistic effect of silver and zinc oxide nanoparticles against clinical pathogens using Pichia fermentans JA2. The extracellular biosynthesis of silver and zinc oxide nanoparticles was investigated using Pichia fermentans JA2 isolated from spoiled fruit pulp bought in Vellore local market. The crystalline and stable metallic nanoparticles were characterized evolving several analytical techniques including UV–visible spectrophotometer, X-ray diffraction pattern analysis and FE-scanning electron microscope with EDX-analysis. The biosynthesized metallic nanoparticles were tested for their antimicrobial property against medically important Gram positive, Gram negative and fungal pathogenic microorganisms. Furthermore, the biosynthesized nanoparticles were also evaluated for their increased antimicrobial activities with various commercially available antibiotics against clinical pathogens. The biosynthesized silver nanoparticles inhibited most of the Gram negative clinical pathogens, whereas zinc oxide nanoparticles were able to inhibit only Pseudomonas aeruginosa. The combined effect of standard antibiotic disc and biosynthesized metallic nanoparticles enhanced the inhibitory effect against clinical pathogens. The biological synthesis of silver and zinc oxide nanoparticles is a novel and cost-effective approach over harmful chemical synthesis techniques. The metallic nanoparticles synthesized using Pichia fermentans JA2 possess potent inhibitory effect that offers valuable contribution to pharmaceutical associations.

Phytochemical and Cytotoxicity Analysis of Seeds and Leaves of Adenanthera pavonina

Adenanthera pavonina is an important traditional plant with various medicinal properties which cures major human ailments. The present study was carried out to explore the antimicrobial as well as anticancer effect of seed and leaves extract of red wood plant. The seed and leaves methanolic extract exhibited efficacious antimicrobial and anticancer activity against various pathogens whereas acetone seed extract did not show any biological activity. The methanol extract has anticancer effect being effective against bone cancer cell line when compared with acetone extract. A. pavonia is known to produce anti-inflammatory drugs whereas this traditional plant is used for anticancer drugs as well which will be greater benefit to mankind.

Bioactivity and Molecular Docking of Secondary Metabolites produced by Streptomyces xanthochromogenes JAR5

The present investigation was aimed to explore in vitro and in silico antimicrobial potential of secondary metabolites produced by terrestrial actinomycetes, S. xanthochromogenes JAR5 isolated from deep forest of Kodaikanal, Tamil Nadu, India and was confirmed by 16S rRNA gene sequencing analysis. The bioactive metabolites produced by the strain JAR5 were obtained from the optimized culture medium through solvent extraction method. The crude extract obtained was purified using silica gel column chromatography and partially purified active elute was characterized using UV, FTIR and GC-MS spectroscopic analysis. The partially purified bioactive metabolites produced by strain JAR5 showed 23.333±0.471 diameter zone of inhibition and minimum inhibitory concentration of 80 μg/ml against Enterococcus sp. In silico molecular docking studies revealed binding into crystal structure of topoisomerase II using Autodock vina 4.2 program. The molecular docking of biological active compounds is in good agreement with in vitro antimicrobial screening where the bioactive metabolites showed effective inhibitory effect against Enterococcus sp.

Antimicrobial and Antioxidant Potential of Penicillium decumbens Strain AJA1 Against Various Pathogens

The fungal strain AJA1 was isolated from leaf litter sample and identified as Penicillium decumbens through 18S rRNA gene sequencing. The antimicrobial potential of Penicillium decumbens strain AJA1 was investigated against medically important pathogenic microorganisms. The mycelium obtained in the presence of four different nitrogen sources sodium nitrate, potassium nitrate, casein, and soybean meal was extracted with methanol and the extracts obtained were determined for antimicrobial and antioxidant properties. The Gram positive bacteria (Staphylococcus aureus, Bacillius subtilis) were effectively inhibited by obtained methanol extract, while Gram negative bacteria (Escherichia coli, Pseudomonas aeruginosa, Salmonella sp., Shigella sp., Proteus mirabilis, Kelbsiella sp., Enterococcus sp., and Alcaligens sp.) were resistant to the extracts. The antioxidant activity was evaluated by hydroxyl free radicals and 2, 2-diphenyl-1-(2, 4, 6-trinitrophenyl) hydrazyl (DPPH). The determination of antimicrobial activity against test organisms indicated that the concentration of active components was directly influenced on the antimicrobial activity of the extracts obtained.