Antioxidant and anti-proliferative activity of Rhizoma Smilacis Chinae extracts and main constituents

Rhizoma Smilacis Chinae (RSC) is a widely used herbal material in functional food and folk medicine. In this study, methanol extract (ME), water extract (WE), polysaccharide fraction and ethyl acetate fraction (EF) of RSC were prepared and the constituents were analysed by HPLC. Different antioxidant tests were employed to evaluate the antioxidant activities of RSC extracts and its main constituents, astilbin and chlorogenic acid. The results showed that RSC extracts possessed comparable antioxidant activity to butylated hydroxyanisole in a dose-dependent manner. The radical-scavenging capacity of ME and EF was even stronger than astilbin and chlorogenic acid. The EF and ME of RSC also showed stronger anti-proliferative activity on HepG2 cells than astilbin and chlorogenic acid, with IC50 values of 47 and 32 μg/mL for 24 h treatment, respectively. Flow cytometric analysis revealed that RSC extracts induced cell cycle arrest at G2/M phase and a late apoptosis of the cells.