Catalytic, antioxidant and anticancer activities of gold nanoparticles synthesized by kaempferol glucoside from Lotus leguminosae

The aim of this study was to evaluate gold nanoparticles (AuNPs) for their anticancer activity against MCF-7 cancer cells, antioxidant activities and catalysis of the reduction of p-nitrophenol (p-NP). AuNPs were synthesized using kaempferol 3-O-β-D-apiofuranosyl-7-O-α-L-rhamnopyranoside (KG) from the plant Lotus leguminosae. The structure was determined using nuclear magnetic resonance (NMR) and electrospray (ES)-HRMS. The isolated compound was involved in the synthesis and stabilization of AuNPs. A number of parameters such as the pH and the mass ratio (HAuCl4/KG) have been optimized to produce very stable colloids of an almost spherical shaped AuNPs with an average diameter of about 37 nm. UV–Vis spectrophotometry, infrared (IR) spectroscopy, transmission electron microscopy (TEM), and thermogravimetric analysis (TGA) studies were employed to characterize the produced nanoparticles. In vitro anticancer studies were performed to assess the chemotherapeutic potential of formulating NPs against a human breast carcinoma cell line (MCF-7). It was observed that the synthesized AuNPs have mild to low cytotoxicity in MCF-7 cells at higher concentrations. The microscopic observations showed no significant changes in the morphology of control cells or the treated cells. AuNPs also displayed strong DPPH radical scavenging compared to the flavonoid extract, with an IC50 of 30.56 μg/mL. In addition, the biosynthesized AuNPs showed a highly improved catalytic activity for the reduction of p-nitrophenol (p-NP) to p-aminophenol (p-AP), indicative of its potential application in the chemical industry.