PHYTO-ASSISTED SYNTHESIS OF ZINC OXIDE NANOPARTICLES USING LEAF EXTRACTS OF A MEDICINAL MANGROVE PLANT BRUGUIERA GYMNORHIZA L. FOR ANTIMICROBIAL AND ANTIOXIDANT ACTIVITY ASSESSMENT

Abstract

The present study involves green synthesis of ZnO nanoparticles (NPs) using aqueous leaf extract of Bruguieragymnorrhizaas green reducing agent. The ZnO NPs were characterized by X- ray diffraction (XRD), UV–visible studies and scanning electron microscopy (SEM). The NPs were evaluated for antimicrobial and antioxidant activities. The NPs were found to have a hexagonal wurtzite structure. UV-visible absorption of ZnONps showed absorption band at 320 nm which can be assigned to the intrinsic band-gap absorption of ZnO due to the electron transitions from the valence band to the conduction band. SEM image confirms the formation of nanoparticles and the average crystallite sizes were found to be 38-97 nm. Excellent bactericidal activity was shown by the NPs on Bacillus subtilis, Staphylococcus aureus, Salmonella typhi and Escherichia coli. The anti-oxidant activity was studied by % DPPH (1, 1-Diphenyl-2-picrylhydrazyl) inhibition in the concentration range of 5 μg/ml to 150 μg/mL and IC50 value was found to be 66.37, 73.93 and 92.35 μg/ mL for ascorbic acid, ZnO NPs and aqueous plant leaf extract. Hence the synthesized NPs were found to having potent anti-oxidant activity. Synthesis of multifunctional ZnO NPs using naturally occurring plant products has been advocated as a possible environment friendly alternative to chemical methods.