Quercetin attenuates ethanol-derived microsomal oxidative stress: Implication of haem oxygenase-1 induction

As the main source of reactive oxygen species (ROS), hepatic microsomes are susceptible to ROS attack, especially upon CYP2E1 activation by ethanol. The objective of this study was to evaluate the hepatoprotective effect of quercetin, by inducing haem oxygenase-1 (HO-1), on ethanol-induced microsomal oxidative stress. Chronic alcohol administration to adult rats (4.0 g/kg for 90 days) resulted in microsomal redox disturbance and liver dysfunction, accompanying CYP2E1 upregulation and HO-1 downregulation of both protein expression and enzymatic activity. Quercetin (100 mg/kg) induced HO-1, which was not completely suppressed by ethanol. Moreover, quercetin pretreatment to ethanol-fed rats lowered CYP2E1 induction, partially normalised ethanol-overwhelmed microsomal antioxidative system, decreased ROS level and lipid peroxidation, and alleviated the leakage of transaminases. Given the beneficial effect of HO-1, its induction by quercetin may contribute to the protective role against CYP2E1-mediated oxidative stress on hepatic microsomes.