Boarfish (Capros aper) protein hydrolysate has potent insulinotropic and GLP-1 secretory activity in vitro and acute glucose lowering effects in mice

The anti-diabetic actions of a boarfish protein hydrolysate (BPH) were investigated in cultured cells and mice. A boarfish (Capros aper) muscle protein hydrolysate was generated using the enzymes Alcalase 2.4 L and Flavourzyme 500 L. Furthermore, the BPH was subjected to simulated gastrointestinal digestion (SGID). BPH and SGID samples (0.01–2.5 mg mL⁻¹) were tested in vitro for DPP-IV inhibition and insulin and GLP-1 secretory activity from BRIN-BD11 and GLUTag cells, respectively. The BPH and SGID samples, caused a dose-dependent increase (4.2 to 5.3-fold, P < 0.001) in insulin secretion from BRIN-BD11 cells and inhibited DPP-IV activity (IC₅₀ 1.18 ± 0.04 and 1.21 ± 0.04 mg mL⁻¹), respectively. The SGID sample produced a 1.3-fold (P < 0.01) increase in GLP-1 secretion. An oral glucose tolerance test (OGTT) was conducted in healthy mice (n = 8), with or without BPH (50 mg/kg bodyweight). BPH mediated an increase in plasma insulin levels (AUC_{(0–120 min),} P < 0.05) and a consequent reduction in blood glucose concentration (P < 0.01), after OGTT in mice versus controls. The BPH showed potent anti-diabetic actions in cells and improved glucose tolerance in mice.