ABSTRACT
This study evaluate toxicity profiling and biochemical effect of methanol extract of moringa oleifera leaves (MEMO)in diabetic rats. Sprague Dawley rats (n = 24) weighing between 180 and 250 g were used in this study. In the acute toxicity with MEMO in rats, the result shows that there was no mortality observed in the first phase of acute toxicity study, while in phase II, mortality was observed in 2900 and 5000 mg extract treated groups. The rats were randomly assigned to six groups of 4 rats each: normal control, metformin group, 100mg MEMO/kg bwt group, 200mg MEMO/kg bwt group, 250mg MEMO/kg bwt and 300mg MEMO/kg bwt group. With the exception of normal control group, diabetes mellitus was induced in the rats via intraperitoneal injection of STZ at a dose of 55 mg/kg body weight (bwt). The diabetic rats were then treated with either Glibeclamide (5mg/kg bwt), 100mg/MEMO, 200mg/bwt MEMO, 250mg MEMO/kg bwt and 300mg MEMO/kg bwt for 21 days. In the sub chronic toxicity with MEMO in rats, treatment of normal Wistar rats with MEMO for 28 days led to significant increase in the activity of ALT and AST in rat serum, except the 100 mg/kg bwt group where AST activity was reduced (p < 0.05). Urea levels were mostly reduced in 100 and 200 mg/kg bwt groups, when compared to the 250 and 300 mg/kg bwt groups (p < 0.05). The results of phytochemical screening shows that alkaloids, flavonoids, saponins and other phenolic compounds were present in aqueous, methanol and ethanol extracts of M. oleifera leaves. Tannins were present only in the aqueous extract, while steroids were present only in the ethanol extract. Moreover, terpenoids were conspicuously absent in the three extracts. The results showed that intraperitoneal administration of streptozotocin (STZ) caused a significant elevation in fasting blood glucose (FBG) level (p< 0.05). This elevated blood glucose level was however significantly reduced after daily treatment with methanol extract of Moringa oleifera leaves (MEMO). The reduction was highest in 300mg of methanol extract of Moringa Oleifera leaves (MEMO) group and no significant reduction with Glibenclamide treatment group. The biochemical effect of MEMO in diabetics rats shows there was nosignificant differences in the levels of total protein in the kidney, heart and pancreas of diabetic rats treated with MEMO (p > 0.05), but its level was significantly reduced in the treatment groups, with the 100 and 200 mg/kg bwt groups being the most reduced (p < 0.05). The activity of ALT was also significantly reduced by MEMO (p < 0.05). Aspartate aminotransferase (AST) activity was reduced significantly in the 250 and 300 mg/kg bwt groups, but it was increased in the 100 and 200 mg/kg bwt groups (p < 0.05). In addition, MEMO did not significantly alter the levels of urea and creatinine (p > 0.05). There were no significant differences in the levels of MDA in the kidney, heart and pancreas of diabetic rats treated with MEMO (p > 0.05), but its level was significantly reduced in the 100 and 200 mg/kg bwt groups (p < 0.05). The results of this study appear to suggest that MEMO may not be safe at any dose higher than 2500 mg/kg bwt, daily administration of MEMO shows its effectiveness in ameliorating streptozotocin-induced diabetic rats. It may be toxic to the liver at very high doses. However, further studies are required to establish the safety of the crude drug.
