Physiochemical properties and novel biological applications of Callistemon viminalis-mediated α-Cr2O3 nanoparticles

We report an eco-friendly synthesis of alpha-Cr2O3 nanoparticles (NPs) using Callistemon viminalis (Bottle Brush) flower extracts as an efficient reducing and capping agent. NPs of sizes 15 nm and 17 nm were synthesized by annealing them at 400 degrees C and 500 degrees C, respectively, which were characterized by X-ray diffraction, UV-Vis, Fourier transform-infrared, high-resolution-transmission electron microscopy/scanning electron microscopy, SAED, energy-dispersive X-ray spectroscopy and SQUID. Microplate-based assay was used for examining antibacterial potential against 12 pathogenic bacterial strains, and their minimum inhibitory concentrations were calculated. MTT cytotoxic assay was accomplished on Leishmania tropica amastigotes and promastigotes, which revealed IC50 values of 44 mu g/ml and 10.56 mu g/ml, respectively. An IC50 value of 46.32 mu g/ml was obtained for HepG2 cancer cells. Enzyme inhibition studies indicated good acetylcholinesterase, moderate butyrylcholinesterase and low alpha-glucosidase inhibition. Hemolytic assay indicated hemocompatibility at low concentration. In addition, good DPPH radical scavenging and moderate reducing power and total antioxidant potential was revealed by alpha-Cr2O3 NPs.