Rhapontigenin from Rheum undulatum Protects Against Oxidative-Stress-Induced Cell Damage Through Antioxidant Activity

Abstract

The antioxidant properties of rhapontigenin and rhaponticin isolated from Rheum undulatum were investigated. Rhapontigenin was found to scavenge intracellular reactive oxygen species (ROS), the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical, and hydrogen peroxide (H₂O₂). The radical scavenging effect of rhapontigenin was more effective than rhaponticin. Rhapontigenin protected against H₂O₂-induced membrane lipid peroxidation and cellular DNA damage, which are the main targets of oxidative stress-induced cellular damage. The radical scavenging activity of rhapontigenin protected Chinese hamster lung fibroblast (V79-4) cells exposed to H₂O₂ by inhibiting apoptosis. Rhapontigenin inhibited cell damage induced by serum starvation and was also found to increase the activity of catalase and its protein expression. Further, rhapontigenin increased phosphorylation of extracellular signal-regulated kinase (ERK) and inhibited the activity of activator protein 1 (AP-1), a redox-sensitive transcription factor. In summary, these results suggest that rhapontigenin protects V79-4 cells against oxidative damage by enhancing the cellular antioxidant activity and modulating cellular signal pathways.

This research was supported by a grant (L06010) from Korea Institute of Oriental Medicine, by the Korea Research Foundation grant funded by the Korea government (KRF-2005-211-E00041).