Studies on the antioxidative activity of Graptopetalum paraguayense E.!Walther

This study was aimed to evaluate the antioxidative activities of water (GWE), 50% ethanolic (GE50), and 95% ethanolic (GE95) extracts of Graptopetalum paraguayense. The antioxidant activities, including the radical-scavenging effect, reducing power, and antioxidative effect on Fe/ascorbate-induced lipid peroxidation in a liposome model system, were studied in vitro. The results showed that GWE, GE50 and GE95 possessed antioxidant characteristics including radical scavenging, reducing power, and lipid peroxidation inhibition. It was found that the antioxidative activities of all the extracts increased with increasing 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 antioxidative reactions revealed that GE50 was more effective in scavenging alpha,alpha-diphenyl-beta-picrylhydrazyl (DPPH) radical and showed a higher reducing power than GWE and GE95. However, there were no significant differences (P > 0.05) in the lipid peroxidation-prevention effects among the extracts. (C) 2004 Elsevier Ltd. All rights reserved.