Plant Extract-Mediated Synthesis of Silver Nanoparticles and Their Anticancer Potentials

Five plant extracts ( Ardisia argentea, Aegiceras corniculatum, Polycarpaea corymbosa, Maesa perlaria , and Schima wallichii ) were utilized as reducing agents in the synthesis of silver nanoparticles (AgNPs) through a green route. As the reducing power and total content of phenolic compounds in the extract increased, the absorbance of the surface plasmon resonance of the resulting AgNPs also increased. The characteristic surface plasmon resonance was clearly observed at 400∼500 nm. The AgNPs were spherical, as shown by field emission transmission electron microscopy images, with an average size between 10.4±0.3 nm and 22.2±0.8 nm. The cytotoxicity in A549 (lung cancer) and HeLa (cervical cancer) cells increased in a dose-dependent manner. Specifically, at the highest dose, the AgNPs synthesized with the A. corniculatum extract exhibited the highest cytotoxicity and induced high levels of reactive oxygen species (ROS). Interestingly, it was observed that smaller AgNPs tended to generate higher levels of ROS. Cell death was clearly observed in the treatment with the AgNPs. A G2/M phase arrest occurred in cell cycle analysis, which induced cell death. The results obtained herein support the potential of natural product-mediated synthesis of AgNPs as a promising anticancer nanomedicine.