Anti-diabetic Effects of the Aqueous and Ethanol Extracts of Ipomoea batatas Tubers on Alloxan Induced Diabetes in Wistar Albino Rats

Background: Diabetes mellitus continues to remain the number one cause of mortality among the low- and mid-income populations. Hence, the need for cost-effective, available and accessible novel drug agents for improved health outcomes. This study was undertaken to investigate the antidiabetic effects of the aqueous and ethanol extracts of Ipomoea batatas tubers on alloxan induced diabetes in Wistar albino rats.

Methods: Proximate analysis was conducted directly on the sweet potato tubers using the method of AOAC (2004) while ethanol and aqueous extracts obtained from the Ipomoea batatas tubers were subjected to phytochemical analysis using various standard methods. Seven groups of 5 albino Wistar rats each were used for the study as follows: the negative control group, the standard drug group treated with Glibenclamide, the 200 mg/kg aqueous extract group, the 400 mg/kg aqueous extract group, the 200 mg/kg ethanol extract group, the 400 mg/kg ethanol extract group and the untreated group. The rats were induced to diabetes by administering alloxan (130 mg/kg) intraperitoneally. Further, the extracts were orally administered to the four treatment groups while changes in both weights and blood glucose levels were closely monitored. After 28 days, blood samples were collected and assayed for the activities of superoxide dismutase, glutathione peroxidase and catalase. Data were further subjected to statistical analysis using ANOVA (Analysis of Variance).

Results: The proximate analysis of I. batatas showed a high carbohydrate content of 86.37 ± 0.04 while the fat amount was lowest with 0.58 ± 0.18. The phytochemical analysis indicated a high tannin concentration for both aqueous and ethanol extracts at 87.83 ± 2.91 and 89.05 ± 2.53 respectively whereas the lowest content was found for terpernoids in the aqueous extract and total flavonoids in the ethanol extract. Remarkable recovery from weight loss was more rapid in the 400 mg/kg ethanol extract group (29.09% increase) than the other groups. There was no significant difference (P > 0.05) in the initial and final weights of the animals. The difference in final glucose levels were significant (P < 0.05) across treatment groups when compared with the negative control group. The 400 mg/kg ethanol extract had the highest percentage reduction in glucose level (53.21%) in 28 days, even more than the standard drug group (24.74 %). The 200 mg/kg ethanol extract gave the least percentage reduction. The results showed that there was no significant difference (P > 0.05) in the activities of the three antioxidant enzymes across treatment groups.

Conclusion: The relatively rapid recovery of weight and reduction in blood glucose levels of the animals observed with the 400 mg/kg ethanol extract showed that it is more potent in the management of diabetes mellitus when compared with the other dosage preparations.