ABSTRACT

The effects of methanol leaf extracts of Telfairia occidentalis. and Amaranthus hybridus on aspartame-induced oxidative stress in wistar Albino rats was investigated. Rats were randomly selected and divided into 5 groups (5 rats per group) and acclimatized for two weeks. Group 1 was the normal group. Group II (negative control) was given aspartame (40 mg/kg b.w) for 40 days. Groups III and IV were also given aspartame but treated with 200 mg/kg b.w methanol leaf extracts of Amaranthus hybridus  and Telfairia  occidentalis respectively. Group V was also given aspartame but subjected to co-administration of 100 mg/kg b.w each of both methanol leaf extracts of Amaranthus hybridus and Telfairia occidentalis in the ratio of 1:1 for 40 days. All the rats were fed with commercial rat chow and water ad libitum throughout the experimental period. They were then sacrificed after an overnight fast and blood collected for determination of various parameters. The results revealed a significant increase (p<0.05) in malondialdehyde (MDA) concentration in Group II (negative control) compared to the normal and treated groups III and IV but Group V recorded a significant decrease (p<0.05) in the MDA concentration compared to the other treated groups and the normal. The activities of the antioxidant enzymes superoxide dismutase and catalase were significantly decreased (p<0.05) in Group II (negative control) compared to the normal and the treated groups though catalase activity was significantly lower (p< 0.05) in the normal compared to the other treated groups. Total cholesterol concentration was significantly increased (p<0.05) in Group IV compared to other test groups and the normal while there was a significant decrease (p<0.05) in Group V compared to the normal. LDL-cholesterol concentration in Group II (negative control) recorded a significantly high increase (p<0.05) compared to all the other groups and the normal. There were no significant changes in triacylglycerols (TAGs), HDL-cholesterol and VLDL (p>0.05) in all the groups compared to the normal. Liver enzymes activity showed no significant change in AST (p>0.05) while ALT was significantly decreased (p<0.05) in all the groups compared to the normal. ALP was significantly decreased (p<0.05) in all the treated groups and the negative control compared to the normal. Total bilirubin concentration was significantly increased (p<0.05) in group V compared to the normal and the other test groups. Direct bilirubin was significantly decreased (p<0.05) in Group II and in Group III compared to the normal and the other treated groups. Total protein and globulins were significantly increased (p<0.05) in all the treated groups compared to the normal and the negative control. Albumin concentration showed no significant change (p>0.05) in all the groups compared to the normal. Serum creatinine and urea concentrations recorded no significant change (p>0.05) in all the treated groups and in the negative control group compared to the normal. These results suggest that aspartame has oxidative properties as evidenced by the significantly increased MDA concentration and decreased activities of the antioxidant enzymes in Group II (negative control) compared to the normal and the treated groups while Amaranthus hybridus and Telfairia occidentalis may have antioxidant capacities that can ameliorate oxidative stress.