Hepatoprotective activity of Uvaria chamae root bark methanol extract against acetaminophen-induced liver lesions in rats

The hepatoprotective activity of Uvaria chamae P. Beav (Annonaceae) methanol root bark extracts were tested in vivo and in vitro. The plant material was defatted with n-hexane and 70% methanol, respectively. The methanol extract was recovered in a 6.13% w/w yield. An oral administration of the methanol extract (60 mg/kg) significantly reduced (p < 0.05) pentobarbitone-induced sleep in rats poisoned with acetaminophen. In this model, a protection of 92% against the cytotoxicity of acetaminophen is obtained by pretreatment with the methanol extract as compared to a protection of 89.6% when the animals were pretreated with silibinin. The n-hexane extract was without a significant hepatoprotective effect in this model. Intraperitoneal injection of the methanol extract into rats showed no significant effect on pentobarbitone-induced hypnosis. The elevation of serum glutamate oxaloacetate transaminase, glutamate pyruvate transaminase, alkaline phosphatase, and urea induced by paracetamol intoxication in rats was also significantly attenuated (p < 0.05) by the methanol extract. The methanol extract did not influence the concentration of microsomal proteins in the serum. This in vivo efficacy was substantiated by significant hepatoprotection on acetaminophen (AA)-induced hepatotoxicity in isolated rat hepatocytes. The methanol extract, at a dose of 1 mg/ml, remarkably (p < 0.05) reduced the leakage of lactate dehydrogenase in primary cultured rat hepatocytes and showed a significant effect on lipid peroxidation. The AA-induced elevation of the lipid peroxidation in rats was significantly (p < 0.05) decreased in the presence of U. chamae root bark methanol extract. A protection of 56% against the tert-butyl hydroperoxide-induced lipid peroxidation in rats was obtained by pretreatment with the methanol extract. The methanol extract also showed a significant antioxidant effect.