Antioxidant, antimicrobial and cytotoxic activities of silver and gold nanoparticles synthesized using Plumbago zeylanica bark

Utilization of bioresources for the synthesis of metal nanoparticles is the latest field in green chemistry. The present work reports the utilization of the aqueous bark extract of Plumbago zeylanica for the biosynthesis of Ag and Au NPs. The Ag and Au NPs thus obtained were characterized by UV–Vis, FT-IR, TEM, XRD, and EDAX analysis. The water-soluble components of the extract were responsible for the reduction of Ag? and Au3? ions. FT-IR spectra revealed that the –OH and[C=O groups present in the biomolecules were responsible for reduction and stabilization of nanoparticles. TEM images showed the existence of spherical Ag and Au NPs with average size of 28.47 and 16.89 nm, respectively, which was further substantiated by XRD analysis. The presence of elemental Ag and Au along with C and O from the attached biomolecules was proved by EDAX analysis. The antimicrobial, antioxidant, and in vitro cytotoxic activities of the synthesized nanoparticles were studied by disc diffusion, DPPH, and MTT assay methods, respectively. The free radical inhibition was found to be 78.17 and 87.34 % for Ag and Au nanoparticles, respectively. The Ag and Au NPs showed 61.56 and 65.61 % toxicity against DLA cell line, respectively. The DNA binding ability of Ag and Au NPs were investigated using CT-DNA. The hyperchromism shift inferred the groove binding of nanoparticles with CT-DNA