MODULATION OF ANTIOXIDANT AND LIVER FUNCTIONS OF RAT LIVER HOMOGENATE INTOXICATED WITH MERCURY BY WILD COLOCYNTH(Adenopus breviflorus BENTH) SEED

Abstract

Liver is one of the main organs targeted by inorganic mercury compounds, such as mercuric chloride (HgCl2). Multiple mechanisms have been proposed to explain the biological toxicity of HgCl2 as pro-oxidant by investigating the biochemical fate of various mercury forms. Plants generally contain antioxidants which are capable of counteracting the effects caused by prooxidants in the living systems. Adenopus breviflorus Benth is a medicinal plant with anti inflammatory, analgesic and anti-ulcerogenic activities. This study evaluated the in vitro antioxidant properties of crude and defatted seed extracts of Adenopus breviflorus and the modulating effect of the extracts in rat liver homogenate assaulted with mercury. Crude and defatted seed extracts of Adenopus breviflorus were prepared, phytochemically screened and evaluated for antioxidant activity using the reducing potential, DPPH, ABTS and hydroxyl radical scavenging assays as well as tests for lipid peroxidation inhibitory and metal chelating activities. Additionally, reduced glutathione and TBARS levels; activities of SOD, CAT and GPx as well as activities of ALT, AST and ALP were evaluated in rat liver homogenate intoxicated with 100µg/ml HgCl2 with or without seed extracts of Adenopus breviflorus. Phytochemical analysis of the seed extracts of Adenopus breviflorus revealed the presence of flavonoids, tannins, saponins, cardiac glycosides and alkaloids. In addition, crude extract of Adenopus breviflorus tested positive for terpenoids and steroids. However, both extracts tested negative for phlobatannins and anthraquinones. The crude exhibited greater antioxidative activity than the defatted extract as revealed by the in vitro antioxidant assays. Mercury intoxication in the liver homogenate resulted in statistically significant (P< 0.05) decreases in the level of GSH and activities of GPx, SOD, CAT, AST, ALP, and ALT and an increase in TBARS compared with the control. However, both extracts ameliorated these deleterious effects in a concentration dependent manner (100-1000 µg/ml) with the crude extract exhibiting greater effectiveness than the defatted which could be as a result of phytoconstituents that are lost in the process of defatting. These findings suggest that the rich phytochemical constituent of the seed of Adenopus breviflorus and its good antioxidant activity may be responsible for its popular and wide traditional use and therefore could be adopted in ameliorating mercury toxicity.