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

Hepatoprotective activity-guided fractionation of the MeOH extract of Equisetum 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 cytotoxicity in human liver-derived Hep G2 cells, displaying EC 50 values of 85.8 ± 9.3 μM and 20.2 ± 1.4 μM, respectively. Silybin, used as a positive control, showed the EC 50 value of 69.0 ± 3.3 μM. Compounds 1 and 4 also showed superoxide scavenging effects (IC 50 = 35.3 ± 0.2 μM and 5.9 ± 0.3 μM, respectively) and DPPH free radical scavenging effect (IC 50 of 35.8 ± 0.4 μM and 22.7 ± 2.8 μM, respectively). These results support the use of this plant for the treatment of hepatitis in oriental traditional medicine.