Chemoprotective effect of Vernonia amygdalina Del. (Astereacea) against 2-acetylaminofluorene-induced hepatotoxicity in rats

Natural products possessing antioxidant properties play a very crucial role in ameliorating deleterious effects of reactive oxygen species. This study investigated the chemoprotective properties of methanolic extract of Vernonia amygdalina (MEVA) in an experimental model of hepatic oxidative damage induced by 2-acetylaminofluorene (2-AAF). Rats were divided into six groups. Groups 1 and 2 received saline and dimethyl sulfoxide, respectively, and served as controls. Group 3 received MEVA at a dose of 250 mg/kg, while groups 5 and 6 were pretreated for 14 days with MEVA at 250 mg/kg and 500 mg/kg doses before coadministration with 2-AAF at 100 mg/kg for another 7 days. 2-AAF was administered to group 4 for the last 7 days. Animals were killed 24 h after the last administration of 2-AAF. 2-AAF significantly (p < 0.05) induced marked hepatic damage as revealed by increased activities of serum enzymes such as alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, and γ-glutamyl transferase and bilirubin concentration. 2-AAF also elicited decrease in the activities of antioxidant enzymes such as superoxide dismutase, catalase, glutathione-S-transferase, and glutathione peroxidase, depletion of reduced glutathione, and increase in malondialdehyde levels. The activities of glucose-6-phosphatase and 5′-nucleotidase were also depleted. MEVA at 250 mg/kg and 500 mg/kg significantly (p < 0.05) ameliorated the oxidative damage, functional impairments, and histopathological changes associated with 2-AAF toxicity by reducing the activities of serum enzymes, upregulating the antioxidant defense enzymes and glutathione with decrease in malondialdehyde level. In this study, the revealed ameliorative and hepatoprotective effects of MEVA against 2-AAF-induced toxicity may be due to its antioxidant and free-radical scavenging activities, thus suggesting its usefulness as a possible chemoprophylactic agent.