Purification and characterization of multifunctional peptides with in situ insulinotropic and antioxidative activity from a blue whiting (Micromesistius poutassou) protein hydrolysate

Two blue whiting protein hydrolysates (BWPHs) with potent in situ and in vitro antidiabetic and antioxidant activities were fractionated. Potent fractions were analysed using LC-MS/MS. Peptides VPVE and IPQD exhibited potent in situ DPP-IV inhibitory activity (Caco-2 cells) with IC₅₀ values of 88.79 ± 5.40 and 91.12 ± 19.73 µM, respectively. Significant decreases in ROS production observed (HepG2 cells) with MPKKE, GPAG and MPAH. MPAH and LPDDL significantly (p < 0.05) increased intracellular glutathione (GSH) concentration (150.22 and 155.80 %, respectively). MPAH (196.05 %), GPSQ (183.26 %), MPKKE (153.12 %), SPEELK (152.85 %), GPAG (144.66 %), and LPDDI (142.74 %) significantly (p < 0.05) increased intracellular catalase (CAT) activity in comparison to control. Significant increases (p < 0.05) in superoxide dismutase (SOD) activity were observed following treatment with IPDDL (118.69 %), SPEEIK (118.03 %), LPDDI (117.20 %) and APEEHTP (116.60 %). The results indicate that blue whiting-derived peptides may have potential applications as multifunctional health enhancing ingredients with a focus on glycaemic management and antioxidant activity.