Protein Isolates from Fermented Melon Seeds Promoted Differential Expression in Liver and Pancreas of Streptozotocin Induced Diabetic Male Wistar Rats

Diabetes mellitus (DM) is the most common endocrine disorder of human. However, the anti-diabetic activity of protein isolates from fermented plants seed for DM remains enigmatic. The prevalence of diabetes in Africa is exponentially increasing with more deaths occurring directly from diabetes mellitus or from its associated complications. The current study investigated the effect of Protein isolate from fermented melon seeds (Ogiri; OPI) of Cucumeropsis manni on blood glucose, hepatic and pancreatic protein profile, histopathological parameters, identification and characterisation of expressed proteins in streptozotocin (STZ)-induced diabetic rats. Thirty Male wistar rats were divided into nondiabetic control, STZ-diabetic control, STZ-Ogiri protein isolate supplemented group (STZ-OPI; 200 mg/kg diet), STZ-Ogiri protein isolate supplemented group (STZ-OPI; 600 g/kg diet) and STZ-glibenclamide treated group (STZ-GBN; 0.5 mg/kg diet). Diabetes was induced by a single injection of STZ (60 mg/kg BW) freshly dissolved in 0.1 mol/L citrate buffer (pH 4.5) into the intraperitonium. Diabetes was confirmed by measuring the fasting blood glucose concentration 48-h post-injection. The rats with blood glucose level above 290 mg/dL were considered to be diabetic. Ogiri protein isolates was supplemented in the diet for 6 weeks. The supplementation OPI reduced (P< 0.05) the blood glucose concentration of the STZ-induced diabetic rats. OPI supplemented groups had significantly higher percentage body weight gain. The high dose OPI supplemented group had a lowest liver protein concentration (19.39 mg/dl) but a significantly (P< 0.05) higher pancreas protein concentration when compared to all the diabetic control. Histological sections of examined tissue revealed accumulation of fat in the liver of diabetic rats and necrosis of the islet of Langerhans were observed in the pancreas. 1DE SDS-PAGE of hepatic and pancreatic tissue homogenates revealed differential expression of 150 kDa proteins in rats treated with 200 mg/kg body weight of OPI only and 20-25 kDa proteins in rats treated with 600 mg/kg body weight of OPI respectively. This result show that OPI supplementation may impose a direct or indirect inhibitory or post translational modification on specific proteins implicated in hyperglycemia and diabetes and as such be a potential antihyperglycemic agent in the management of diabetes.