Effects of yam peel extract against carbon tetrachloride-induced hepatotoxicity in rats

The phenolic acid and flavonoid profiles in yam peel extract were determined by HPLC. Quercetin, hesperidin, and apigenin were predominant components in yam peel extract. Male Wistar rats were orally treated with yam peel extract (100.02, 266.72, and 433.42 mg/kg) or silymarin (200 mg/kg) daily, with administration of CCl4 (1 mL/kg, 20% CCl4 in olive oil) twice a week. Yam peel extract for 8 weeks significantly reduced the impact of CCl4 toxicity on the serum markers of liver damage, aspartate aminotransferase (AST), alanine aminotransferase (ALT), and alkaline phosphatase (ALP). The overall potential of the antioxidant system was significantly enhanced by the yam peel extract supplements as the plasma and hepatic thiobarbituric acid reactive substances (TBARS) levels were lowered, whereas the hepatic superoxide dismutase (SOD) and catalase (CAT) activities and glutathione peroxidase (GSH-Px) protein level were elevated. Yam peel extract decreased the level of nitric oxide (NO) production, tumor necrosis factor-alpha (TNF-α), and nuclear factor-kappa B (NF-κB) in CCl4. These results point out that yam peel extract can inhibit lipid peroxidation, enhance the activities of antioxidant enzymes, and decrease the TNF-α/NF-κB level, nitric oxide production, and inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) expressions. Therefore, it was speculated that yam peel extract protects rats from liver damage through its anti-inflammation capacity.