Rhapontigenin from Rheum undulatum protects against oxidative-stress-induced cell damage through antioxidant activity - Zhang, R; Kang, K A; Piao, M J; Lee, K H; Jang, H S; Park, M J; Kim, B J; Kim, J S; Kim, Y S; Ryu, S Y; Hyun, J W (J Toxicol Environ Health A, 2007)