Comparative evaluation of chemically and green synthesized zinc oxide nanoparticles: their in vitro antioxidant, antimicrobial, cytotoxic and anticancer potential towards HepG2 cell line

The major goal of this study was to fabricate ZnO nanoparticles (NPs) via chemical and biological routes to evaluate and compare their physiochemical behavior (size and morphology) and biological potentials. The synthesized NPs were confirmed via various spectroscopy and imagining techniques such as XRD, FT-IR, HPLC and SEM. The characterized NPs were then assessed for various in vitro biological applications. Furthermore, apoptotic potential was investigated using HepG2 cell lines by evaluating various signature markers of apoptosis including mitochondrial membrane potential, reactive oxygen/nitrogen (ROS/RNS) production, peroxidases and pro-apoptotic caspase 3 activation. Crystalline, hexagonal structured NPs with an average crystalline size distribution of 32 nm and 23 nm was obtained. Both green-mediated zinc oxide nanoparticles (G-ZnO NPs) and chemically derived NPs (C-ZnO NPs) exhibited high antioxidant, moderate enzyme inhibition, antibacterial and cytotoxicity potential. However, G-ZnO NPs exhibited excellent DPPH (80.1% +/- 1.3%), TPC (97 +/- 1.22 mu gAAE/mg), TRP (94.5 +/- 1.48 mu gAAE/mg), lipase inhibition (82%), urease inhibition (81.3%), and alpha-amylase inhibition (18.9%) activity as compared to C-ZnO NPs. Both G-ZnO NPs and C-ZnO NPs showed good antimicrobial potential, however, effect of G-ZnO NPs was more potent than counter C-ZnO NPs. Results from apoptotic assays revealed that G-ZnO NPs showed excellent apoptotic potential in contrast to C-ZnO NPs. Overall results suggested that green route-mediated ZnO NPs exhibits excellent biological potential and could be used for future biomedical applications especially in antimicrobial and cancer therapeutics. To the best of our knowledge, this is the first ever study on Boerhavia diffusa linn-mediated biosynthesis of ZnO nanoparticles and evaluation of their biological activities.