Comparative Effects of Rothmannia Hispida Leaves Extract and Protamine-Zinc Insulin on Alloxan-Induced Diabetic Rats

Abstract

Diabetes mellitus (DM) is a metabolic disorder resulting from a defect in insulin secretion, insulin action, or both, manifesting in hyperglycaemia, polyuria, glucosuria etc. Various regimens have been used to alleviate the symptoms of this disorder; notable in orthodox medicine is insulin. Rothmannia hispida herb extract is also used to manage DM by traditional healers. This study was therefore designed to establish the relative potency of insulin and R. hispida leaves extract in alloxan-induced diabetic rats. 20 male albino Wistar rats were randomly assigned into 4 groups of 5 rats each. Group 1 (control) received normal rat chow + drinking water. Groups 2 - 4 in additional to control diet received alloxan treatment (150mg/kg i.p once). Seven days after, groups 3 (diabetic extract treated, DET) and 4 (diabetic insulin treated, DIT)) were further treated with R. hispida extract (100mg/kg, once daily) and protamine-zinc insulin (1unit) respectively. Their body weight, food intake, urine volume, urine and blood glucose levels were monitored daily. Results showed that after 7 days alloxan treatment, rats in groups 2 – 4 had significantly higher blood glucose, urine output, food intake, urine and blood glucose levels compared with controls. At day 14, the blood glucose level of DET (4.40 ± 0.52mmol/L) and DIT (4.10 ± 0.48mmol/L) were significantly (P<0.001) lower compared with diabetic untreated - DUT (22.00 ± 0.00mmol/L). Terminal urine glucose was absent in control, DET and DIT but was recorded in DUT (42.60 ± 6.14mmol/L). Terminal urine output was also significantly (P<0.001) lower in DET (8.60 ± 1.17ml) and DIT (8.80 ± 0.80ml) compared with diabetic untreated group (44.00 ± 1.48ml). The DUT and DIT were also observed to have negative growth rates (-4.86g/day and -0.29g/day respectively), whereas the controls and DET had positive growth rates (5.70g/day and 0.14g/day respectively). Terminal blood glucose levels and urine output were not significantly different between DET and DIT groups. We therefore conclude that both insulin and Rothmannia hispida leaves extract reverses symptoms (hyperglycaemia, polyuria, glucosuria) in diabetic rats, while the extract was more effective in restoring body weight than insulin. Therefore, 100mg/kg body weight of the Rothmannia hispida leaves extract is equally potent as 1 unit of protamine-zinc insulin as an anti-diabetic agent.

Key words: Insulin, Rothmannia Hispida, Diabetes mellitus, Rats