Immunomodulatory potential of protein hydrolysate by-products derived from skipjack (Katsuwonus pelamis (Linnaeus, 1758)) against nicotinamide-streptozotocin induced diabetic rat

Type 2 diabetes mellitus (T2DM) is determined by glucose intolerance and low-grade chronic inflammation that might be partially controlled using nutritional interventions. Skipjack tuna (Katsuwonus pelamis) by-products are processed by enzyme hydrolysis, providing many essential elements with health-promoting benefits. Herein, the study aimed to investigate the effect of dietary supplementation of fish protein hydrolysate (FPH) derived from skipjack tuna on diabetes rat models. Twenty-five male Sprague-Dawley rats were separated into five groups: (1) normal group, (2) DM (diabetes mellitus) group, (3) DM + Imunos 0.8 g/kg BW (positive control) group, (4) DM + FPH 0.8 g/kg BW, and (5) DM + FPH 1.6 g/kg BW. The DM groups consecutively gave a high-fat diet (HFD) for twelve weeks. Nicotinamide (NA) (120 mg/kg BW) and streptozotocin (60 mg/kg BW) were then injected to induce diabetic animal models. The treatment was given orally each day for two weeks. Fasting blood glucose, insulin, homeostasis model assessment of insulin resistance (HOMA-IR), HOMA-β, GLUT4, and malondialdehyde (MDA) were measured. Our result suggested that FPH administration increased the body weight of DM rats significantly (p<0.05). FPH also reduced the fasting blood glucose, HOMA-IR, HOMA-β, improved insulin and GLUT4 levels, and decreased MDA significantly (p<0.05) than DM groups. Our finding suggests FPH derived from skipjack tuna ameliorates DM progression by controlling glucose homeostasis and oxidative stress. Biopeptides from FPH might be a promising candidate as food nutraceuticals that can be involved in DM management.