In vitro antioxidant and antiproliferative activity of the stem extracts from Graptopetalum paraguayense

This study was aimed to evaluate the antioxidant abilities of water (SGWE), 50% ethanolic (SGE50) and 95% ethanolic (SGE95) extracts from the stem of Graptopetalum paraguayense, and the extract with the highest antioxidant activity was assayed for its inhibitory effect on proliferation of human hepatoma (Hep G2) cell line. Antioxidant abilities of extracts were assessed their radical-scavenging abilities and effects on Fe/ascorbate-induced lipid peroxidation in a liposome model system. The results of this study showed that antioxidant activities were increased with the increase of the extracts concentrations, and the activities correlated with both the total phenol and anthocyanin contents. A comparison of the 50% inhibition concentration (IC(50)) values of different antioxidant reactions revealed that SGWE was the more effective at scavenging superoxide anion radical and preventing lipid peroxidation than SGE50 and SGE95 (p<0.05). The flow cytometry results indicated that SGWE lowered cell viability, and induced G1 phase arrest and apoptosis in Hep G2 cells. These results demonstrated the antioxidant and anti-hepatoma potential of stem of Graptopetalum paraguayense.