Evaluation of superoxide scavenging activities of hamamelis extract and hamamelitannin

Hamamelitannin, which is a component of bark extract of hamamelis (Hamamelis virginior L.), was found to be a potent scavenger of superoxide anion radicals. Superoxide anion scavenging activity of the compound was evaluated by ESR-spin trap method using DMPO (5,5'-dimethyl-1-pyrroline-N-oxide) as a spin trapping agent. The IC50 value (the concentration producing 50% inhibition of superoxide anion radicals) of hamamelitannin was found to be 1.38 +/- 0.06 microM much lower than that of ascorbic acid (23.31 +/- 2.23 microM). Supporting the superoxide scavenging activity of hamamelitannin, the compound showed both suppressive ability against depolymelization of hyaluronic acid and protective ability against cytotoxicity induced by superoxide anion radicals. Hamamelitannin increased the survival rate of fibroblast to 85.5 +/- 3.3%, compared with that of control (27.2 +/- 4.3%).