In vitro anti-oxidant and cytotoxic activities of gold nanoparticles synthesized from an aqueous extract of the Xylopia aethiopica fruit

Abstract The development of gold nanoparticles (AuNPs) using a green approach has drawn considerable interest in the field of nanomedicine. Its wide application in clinical diagnosis, imaging and therapeutics portrays its importance for human existence. In this study, we reported on the biogenic synthesis of AuNPs using the aqueous extract of the Xylopia aethiopica fruit (AEXAf), which acts as both a reducing and stabilizing agent. The characterization of AEXAf-AuNPs was performed using ultraviolet-visible spectroscopy, dynamic light scattering and zeta potential measurements, high-resolution transmission electron microscopy and Fourier transform-infrared spectroscopy. The i n vitro anti-oxidant activities of the AEXAf-AuNPs and AEXAf were evaluated using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing anti-oxidant power. The in vitro cytotoxic activities of the AEXAf-AuNPs and AEXAf against breast and colorectal cancer cells were evaluated using 3,-(4,5 dimethylthiazol)-2,5 diphenyl tetrazolium bromide (MTT) viability and annexin V/PI assays. The AEXAf-AuNPs exhibited surface plasmon absorption maximum at 522 nm and were stable for 4 weeks. The average size of the AEXAf-AuNPs was 10.61 ± 3.33 nm on the high-resolution transmission electron microscopy images. The in vitro anti-oxidant activities of the AEXAf-AuNPs and AEXAf were concentration dependent. The AEXAf-AuNPs were cytotoxic to the cancer cells and non-toxic to the non-cancerous human fibroblast cells (KMST-6) (up to 200 μ g ml −1 ). From these results, the AEXAf-AuNPs showed good anti-oxidant and anti-cancer activities, and can be suggested as a possible therapeutic agent for breast and colorectal cancer.