Antidiabetic potential of Moringa oleifera Lam. leaf extract in type 2 diabetic rats, and its mechanism of action

Purpose: To explore the antidiabetic potential of Moringa oleifera leaf extract in type 2 diabetic rats, and the underlying mechanisms.Methods: Streptozotocin (STZ) at a dose of 40 mg/kg was given to high fat diet (HFD)- fed rats to induce type 2 diabetes. M. oleifera leaf extract at doses 100, 200 and 400 mg/kg were given to 3 groups of type 2 diabetic rats. The area under curve (AUC) of glucose and homeostasis model assessment of insulin resistance (HOMA-R) were calculated using appropriate formulas, whereas levels of glucose,insulin, peroxisome proliferator activated receptor-γ (PPARγ, dipeptidyl peptidase-IV (DPP-IV) and inflammatory cytokines (IL-6, IL-1β and TNFα) were assayed using ELISA kits.Results: The leaf extract of M. oleifera significantly reduced the levels of glucose, insulin and cytokines in treated type 2 diabetic groups (p < 0.05). DC group had significantly increased AUC for glucose, whereas the extract-treated groups showed significant  decrease in glucose AUC. There was significant decrease in insulin sensitivity parameters, as indicated by increase in HOMA-R and decrease in PPARγ levels in the DC group (p < 0.05). However, treatment with the M. oleifera extract reversed this trend via marked decrease in HOMA-R level and significant rise in PPARγ level. In contrast, the extract had no effect on DPP-IV concentration in diabetic treated groups (p < 0.05).Conclusion: These results indicate that M. oleifera leaf extract mitigates hyperglycemia in type 2 DM by modulating hyperinsulinemia, PPARγ and inflammatory cytokines. Thus, the extract is a potential source of drug for the management of type 2 DM. Keywords: Moringa oleifera, Diabetes mellitus, Streptozotocin, Peroxisome proliferator activated receptor-γ, Dipeptidyl peptidase IV