Thesis Abstract

Globally, the estimated incidence of diabetes and projection for the year 2030 as given by the International Diabetes Federation (IDF) is 350 million. Kigelia africana is highly used for ethnomedicinal purposes although there is paucity of scientific information on its use. This work was therefore, aimed at evaluating the anti-diabetic and antioxidative potential of the plant. Ethanol, methanol and n- hexane extracts of the leaves of Kigelia africana were used for the study. Alloxan diabetes was induced in a total of 60 adult male albino rats weighing between 90 and 160 g. The alloxan was dissolved in cold normal saline. After 72 hr, diabetes was confirmed and the rats were divided into twelve (12) groups of five (5) rats each. Group 1 served as the normal control, group 2 was the diabetic untreated, group 3 received 2.5 mg /kg b.wt of glibenclamide, groups 4, 6 and 8 received ethanol, methanol and n-hexane leaves extract while group 5, 7 and 9 received ethanol, methanol and n-hexane fruit extract respectively of 500 mg/kg b.wt of the extracts. Groups 10-12 were administered equal combination of the leaves and fruits extracts. The rats were fed orally for 21 days after which some biochemical and oxidative parameters were statistically analysed. Phytochemical screening for different bioactive compounds was done using standard methods and indicated the presence of flavoniods, alkaloids, saponins, soluble carbohydrates, tannin, steroids, glycosides and reducing sugars. Proximate analysis revealed the presence of proteins (13.9%), carbohydrates (63.5%), fats and oil (11.4%) and crude fibre (2.2%). LD50 showed that the extracts were safe. The glucose level decreased while body weight increased in all the treated groups compared with the diabetic rats untreated. Oral administration of 500mg/kg b.w of K. africana extract significantly reduced (p<0.05), the sorbitol, glycohaemoglobin (HbA1c), total protein, and vitamin C concentrations in diabetic rats (groups 4-12) in comparison with the positive control. There were significant differences in glycohaemogolin, sobitol, total protein and vitamin C concentration in diabetic rats fed with a combination of the two parts of the plant extracts (groups 10-12) as against groups 4-9 administered single extracts. Malondiadehyde (MDA) concentration significantly decreased (p < 0.05) in all the test groups compared with the diabetic untreated rats. Low density lipoprotein, total cholesterol, and triacylgycerol levels decreased significantly (p < 0.05) in the treated groups in comparison with the positive control animals (group 3). However, administration of 500 mg/kg b.w of K. africana increased significantly (p<0.05) the high density lipoprotein (HDL) across the test groups as against the diabetic untreated group. Significant decreased (p<0.05) in the lipid profiles (except HDL) was recorded in groups 10, 11 and 12 treated with a combination of two parts (leaf and fruit) of K. africana in comparison with groups 4-9 orally fed with a single plant extract. Furthermore, the data recorded significantly increased (p < 0.05) antioxidant enzymes (SOD, CAT GPX) activities in diabetic treated groups (both combination and single) with reference to the positive control group. Similarly, significant increase (p > 0.05) of SOD and CAT activities and SOD percentage inhibition was observed in group 3 treated with 2.5 mg/kg b.wt of glibenclamide (standard) compared with all the test groups. Significant reduction (p < 0.05) in the activities of ALT, ALT and total bilirubin concentration were observed in the test groups treated with the extracts compared with the diabetic untreated rats. ALT activity and total bilirubin level decreased significantly (p < 0.05) in groups 10, 11 and 12 administered a combination of leaf and fruit extracts as against groups 4-9 treated with either leaf or fruits only. The results suggest that management and prevention of diabetic complications can be achieved by the use of K. africana.

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