One-pot synthesis, characterisation and biological activities of gold nanoparticles prepared using aqueous seed extract of Garcinia kola

Recently, biogenic synthesis of gold nanoparticles (AuNPs) has become a focus area in cancer research owing to the eco-friendliness and cost effectiveness of the synthetic method. In this study, aqueous extract of Garcinia kola seed (AEGKs) was used for the bio-reduction of Au3+ to Au0. The synthesised AEGKs-AuNPs was characterised by ultraviolet-visible (UV-Vis) spectroscopy, dynamic light scattering (DLS), high-resolution transmission electron microscopy (HRTEM) and Fourier transform-infrared (FT-IR) spectroscopy. The in vitro antioxidant activity of the AEGKs and AEGKs-AuNPs was evaluated using 2,2-diphenyl-1-picrylhydrazyl radical scavenging ability and ferric reducing antioxidant power assays. The AEGKs-AuNPs showed an absorption maximum at 512 nm, and the HRTEM images revealed mostly, spherical-shaped AuNPs in the size range of 2-17 nm. The FT-IR spectroscopy revealed that polyphenolic compounds and proteins were predominant, and responsible for the reduction and capping of the AuNPs. The AEGKs-AuNPs showed concentration dependent antioxidant activities, while dose-dependent in vitro anti-cancer activity of the AEGKs-AuNPs was demonstrated against lungs, prostrate, human cervical and human colon cancer cells, using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide tetrazolium reduction (MTT) assay. The antioxidant and anti-cancer activities of the AEGKs-AuNPs could be attributed to the presence of phytochemicals and physicochemical properties of the AuNPs.