Abstract

Oxidative stress and impaired antioxidant system have been implicated in the pathophysiology of diverse disease states. This research was done to investigate comparatively the possible enzymatic and non-enzymatic antioxidant properties of ethanol extracts of Cola nitida and Garcinia kola in H2O2-challenged rats. Thirty (30) Wistar albino rats were used for this study and were divided into 6 groups of 5 rats per group. Group 1 rats were normal control; group 2 rats were induced with H2O2 only (positive control). Group 3 and 4 were challenged with H2O2 and treated with 100 and 200 mg/kg b.w of ethanol extract of C. nitida, respectively. In the same vein, groups 5 and 6 rats represented H2O2-induced rats treated with 100 and 200 mg/kg b.w of ethanol extract of G. kola seed respectively. Group 2 (positive control group) rats showed a significant increase (p<0.05) in malondialdehyde (MDA) concentration compared to rats in group 1 and the treatment groups. Conversely there was a significant decrease (p<0.05) in glutathione concentration of the group when compared to rats in group 2. Group 2 showed a significant decrease (p<0.05) in vitamin C concentration compared to rats in group 1 and the treatment groups. The effects of extracts were accompanied by a significant increase (p<0.05) in the activity of endogenous antioxidant enzymes such as superoxide dismutase (SOD) when compared to the group 2 (positive control group). The two extracts exhibited a significant ferric reducing antioxidant properties (FRAP) in a concentration-dependent manner. This finding indicated that the extracts could contain antioxidant and thus have potential for scavenging free radicals, hence arresting oxidative stress. This may justify their local use in management of some hepatic dysfunction and stress related conditions. However, extracts of G. kola was seen to be more potent than that of C. nitida.

Key words: Oxidative stress, antioxidant, G. kola, C. nitida.