Hepatoprotective and free radical scavenging activities of phenolic petrosins and flavonoids isolated from Equisetum arvense

Hepatoprotective activity-guided fractionation of the MeOH extract of Equisetunt arvense L. (Equisetaceae) resulted in the isolation of two phenolic petrosins, onitin (1) and onitin-9-O-glucoside (2), along with four flavonoids, apigenin (3), luteolin (4), kaempferol-3-O-glucoside (5), and quercetin-3-O-glucoside (6). Among these, compounds 1 and 4 exhibited hepatoprotective activities on tacrine-induced cylotoxicity in human liver-derived Hep G2 cells, displaying EC50 values of 85.8 +/- 9.3 muM and 20.2 +/- 1.4 muM, respectively. Silybin, used as a positive control, showed the EC50 value of 69.0 +/- 3.3 muM. Compounds I and 4 also showed superoxide scavenging effects (IC50 = 35.3 +/- 0.2 muM and 5.9 +/- 0.3 muM, respectively) and DPPH free radical scavenging effect (IC50 of 35.8 +/- 0.4 muM and 22.7 +/- 2.8 muM, respectively). These results support the use of this plant for the treatment of hepatitis in oriental traditional medicine. (C) 2004 Elsevier Ireland Ltd. All rights reserved.