Abstract

Many human diseases are caused due to oxidative stress involving excessive production of free radicals that can be ameliorated by the antioxidant activities of plant extracts. Present study was designed to characterize the chemical composition of Oxalis corniculata methanol extract (OCME) and its various fractions; O. corniculata n-hexane (OCHE), O. corniculataethyl acetate (OCEE), O. corniculata chloroform (OCCE) and O. corniculata aqueous (OCAE); and to determine the antioxidant potential by different in vitro assays. OCME was also evaluated for its antioxidant capacity against hepatotoxicity induced with carbon tetrachloride (CCl₄: 1 ml/kg b.w., 20% in olive oil, seven doses) in rat. The results showed the presence of flavonoids, alkaloids, terpenoids, saponins, cardiac glycosides, phlobatannins and steroids in OCME while tannins were absent. Total amount of phenolic and flavonoids was affected by the solvents and the sequence of solvents for phenolic contents was OCME > OCAE > OCCE > OCEE > OCHE while for flavonoids was OCME > OCCE > OCAE > OCEE > OCHE. Free radicals were scavenged by the extract/fraction in a dose response curve in all models. Biochemical parameters of serum; aspartate transaminase (AST), alanine transaminase (ALT), alkaline phosphatase (ALP), lactate dehydrogenase (LDH), gamma-glutamyl transpeptidase (γ-GT), total bilirubin, cholesterol and triglycerides were significantly increased while total protein and albumin were decreased by CCl₄. Treatment of CCl₄ significantly decreased the liver contents of reduced glutathione (GSH) and activities of antioxidant enzymes; catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), glutathione-S-transferase (GST), glutathione reductase (GSR) and quinone reductase (QR) whereas elevated the thiobarbituric acid reactive substances (TBARS) contents, and hepatic lesions. All the parameters were brought back to control levels by the supplement of OCME. The results of the present study suggest the antioxidant potential of OCME and its fractions as evidenced by scavenging of free radicals and hepatoprotective capacity.

Key words: Oxalis corniculata, carbon tetrachloride (CCl₄), 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonate) (ABTS), diphenylpicrylhydrazyl (DPPH), hepatoprotective, lipid peroxidation.