Comparative evaluation of the protective effect of leaf extracts of Vernonia amygdalina (bitter leaf) and Ocimum canum (curry) on acetaminophen induced acute liver toxicity

The quest for alternate medicine in preventing and combating hepatotoxicity led to the screening of aqueous and ethanol extracts of dried leaves of Vernonia amygdalina Delile (bitter leaf) and Ocimum canum Linn (curry leaf) for phytochemicals and in vitro antioxidant properties. Some rats were pretreated with the extracts and later administered with 2g/kg of body weight single dose of acetaminophen and the hepatoprotective effect of the extracts was determined by assessing the liver function, antioxidant enzyme activities and histological status of their livers, using standard biochemical methods.The extracts were rich in bioactive compounds and showed concentration-dependent variation in in vitro free radical (DPPH) scavenging activity. A 400mg/kg of body weight per day pretreatment (for seven days) with the extracts gave hepatoprotection to the rats. This was evidenced in the reduction of the activities of alanine aminotransferase (ALT) by 43% in aqueous extract of O. canum to 92% in V. amygdalina and marked increase of the serum albumin concentration. Aqueous leaf extract of V. amygdalina caused the highest increase in GPx activity while ethanol leaf extract of O. canum gave the highest (350%) increase in superoxide dismutase (SOD) activity, compared to the negative control. Also the lobular architecture of the hepatocytes was preserved. V. amygdalina and O. canum have important role in medicine as they contain substances that scavenge free radicals, stimulate activities of antioxidant enzymes and preserve the liver architecture in occasion of acetaminophen-induced liver toxicity. Key words: Vernonia amygdalina, Ocimum canum, hepatoprotection, oxidative stress, free radical-scavenging, hepatocytes.