We report on rapid one-step green synthesis of gold and silver nanoparticles using fruit extract of Averrhoa bilimbi Linn. UV-Vis absorption spectroscopy was used to monitor the quantitative formation of gold and silver nanoparticles. The characteristics of the obtained gold and silver nanoparticles were studied using UV-Vis absorption spectroscopy (UV/Vis), Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), and Energy-dispersive spectroscopy (EDX). UV/Vis spectrum showed Surface Plasmon Resonance (SPR) for both gold and silver nanoparticles at 540 and 420 nm. The EDX spectrum of the solution containing gold and silver nanoparticles confirmed the presence of elemental gold and silver signals. The average diameter of the prepared nanoparticles in solution was about 50-150 nm. Synthesized particles were either hexagonal or rhomboidal in shape. This synthesis approach of gold and silver nanoparticles is cost effective and can be widely used in biological systems. The effect of fruit extract and metal ion concentration was also studied.

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A simple and reproducible biosynthetic method was employed to synthesize iron and silver nanoparticles which resulted in monodispersed nanoparticles of high concentration. The iron oxide nanoparticles has been widely favored because of low cytotoxicity, biodegradable and reactive surface that can be modified with biocompatible coatings. Silver nanoparticles have been a potent antibacterial, antifungal, anti-viral and antiinflammatory agent. The reaction process was simple, eco-friendly, inexpensive and easy to handle. Green and chemical methods were employed to synthesize iron and silver nanoparticles. A microbial route to synthesize iron and silver nanoparticles by the fungal strain Fusarium oxysporum sp. and Actinomycetes sp. was done simultaneously. Production of nanoparticles using fungi has some advantages over other organisms as it is easy to handle and require simple raw materials. The obtained iron and silver nanoparticles were characterized by UV-vis spectroscopy, Fourier transform infrared spectroscopy (FTIR) and the morphology of prepared nanoparticles was confirmed by Transmission electron microscopy (TEM). TEM images of Iron nanoparticles synthesized by Fusarium oxysporum sp. showed 20-40 nm sized particles. These particles exhibited maximum antibacterial activity against Bacillus, E. coli and Staphylococcus sps. TEM images of biosynthesized silver nanoparticles were of smaller size (10-20 nm). The microbially synthesized silver nanoparticles using Actinomycetes were found to be highly toxic against different human pathogens due to the smaller size and due to the presence of antibiotic components available on them. The mechanism of antimicrobial property of nanoparticle lies with the fact that the extremely small size means a large surface area relative to the volume, which effectively covers the microorganisms and reduce oxygen supply for respiration. It was found that silver nanoparticles synthesized by the microbial route have a greater antibacterial activity.Keywords: Iron nanoparticles, silver nanoparticles, Phyllanthus emblica, Fusarium oxysporum sp., Actinomycetes sp., microbial synthesis Citation: A. Sunitha, et al. EEvaluation of antimicrobial activity of biosynthesized iron and silver Nanoparticles using the fungi Fusarium oxysporum and Actinomycetes sp. on human pathogens.

The present study emphasizes to reveal the antivenom activity of Aristolochia bracteolata Lam., Tylophora indica (Burm.f.) Merrill, and Leucas aspera S. which were evaluated against venoms of Daboia russelli russelli (Russell's viper) and Naja naja (Indian cobra). The aqueous extracts of leaves and roots of the above-mentioned plants and their polyherbal (1 : 1 : 1) formulation at a dose of 200 mg/kg showed protection against envenomed mice with LD50 doses of 0.44 mg/kg and 0.28 mg/kg against Russell's viper and cobra venom, respectively. In in vitro antioxidant activities sample extracts showed free radical scavenging effects in dose dependent manner. Computational drug design and docking studies were carried out to predict the neutralizing principles of type I phospholipase A2 (PLA2) from Indian common krait venom. This confirmed that aristolochic acid and leucasin can neutralize type I PLA2 enzyme. Results suggest that these plants could serve as a source of natural antioxidants and common antidote for snake bite. However, further studies are needed to identify the lead molecule responsible for antidote activity.

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