Hepatoprotective action of an oleanolic acid-enriched extract of Ligustrumlucidum fruits is mediated through an enhancement on hepatic glutathione regeneration capacity in mice

The fruits of Ligustrum lucidum Ait. (FLL) were fractionated into petroleum ether (FLL-Pe), chloroform (FLL-Ch), butanol (IFLL-Bu) and aqueous (FLL-Aq ) fractions, of which FLL-Ch and FLL-Bu were found to be enriched with olea nolic acid (OLA). The in vivo antioxidant activities of various FLL fractio ns and OLA were assessed by examining the effect on carbon tetrachloride (C Cl4)-induced hepatotoxicity in mice. Pretreatment of animals with various F LL fractions could protect against CCl4-induced hepatotoxicity to a varying degree, with OLA-enriched FLL-Bu and FLL-Ch being more potent. However, a mortality rate of 60% was observed in the FLL-Ch pretreated and CCl4-intoxi cated mice. OLA pretreatment also produced a dose-dependent protection agai nst CCl4 hepatotoxicity. The hepatoprotection afforded by FLL-Bu or OLA pre treatment was associated with an enhancement of hepatic glutathione regener ation capacity (GRC). In contrast, the inability of FLL-Aq pretreatment to enhance hepatic GRC resulted in a failure to prevent CCl4-induced hepatic i njury. The results suggest that the hepatoprotective action afforded by OLA -enriched FLL-Bu or OLA pretreatment may be mainly mediated by the enhancem ent of hepatic GRC, particularly under conditions of CCl4-induced oxidative stress. Copyright (C) 2001 John Wiley & Sons, Ltd.