Antibacterial and antioxidant properties of biosynthesized zinc oxide nanoparticles from Ceropegia candelabrum L. - An endemic species.

Zinc oxide nanoparticles (ZnO-NPs) were synthesized for the first time from any of the species of Ceropegia. Presently, ZnO-NPs were synthesized from the leaf extract of Ceropegia candelabrum with zinc nitrate using a simple hydrothermal process. The synthesized ZnO-NPs showed an absorption peak at 320nm which is one of the characteristic features of ZnO-NPs. The FT-IR characterization revealed a spectrum band at 551.93cm-1 corresponding to the functional group metal oxide. SEM images showed agglomeration of nanoparticles with a hexagonal shape. XRD results are in corroboration with SEM images as the synthesized particles were of hexagonal wurtzite shape and the size of the particles was in the range of 12-35nm calculated using Scherrer's formula. The elemental analysis using EDS confirmed high zinc content of 70.48% stating that the process of biosynthesis of nanoparticles was carried out in accordance. The biosynthesized ZnO-NPs offered significant antibacterial potential against S. aureus, B. subtilis, E. coli and S. typhi. The antioxidant results revealed significant (p≤0.05) RSA from 0% to 55.43% (IC50=95.09μgmL-1). The results affirm that biosynthesized ZnO-NPs can be used as an alternative to present-day chemical compounds.