Ten new pentapeptides from protein hydrolysate of miiuy croaker (Miichthys miiuy) muscle: Preparation, identification, and antioxidant activity evaluation

In the report, five proteases including alcalase, trypsin, neutrase, papain, and pepsin were screened to hydrolyze the muscle protein of miiuy croaker (Miichthys miiuy), respectively, and papain hydrolysate (MPH) showed higher 2,2-Diphenyl-1-picrylhydrazyl radical (DPPH) radicals scavenging activity (52.28 +/- 2.80%) than other hydrolysates did. Ten pentapeptides were isolated from MPH using ultrafiltration membrane and chromatographic methods, and identified as Tyr-Ala-Ser-Val-Val (YASVV), Asn-Phe-Trp-Trp-Pro (NFWWP), Phe-Trp-LysVal-Val (FWKVV), Thr-Trp-Lys-Val-Val (TWKVV), Phe-Met-Pro-Leu-His (FMPLH), Tyr-Phe-Leu-Trp-Pro (YFLWP), Val-Ile-Ala-Pro-Trp (VIAPW), Trp-Val-Trp-Trp-Trp (WVWWW), Met-Trp-Lys-Val-Trp (MWKVW), and Ile-Arg-Trp-Trp-Trp (IRWWW) with molecular weights of 739.88 Da, 569.64 Da, 611.66 Da, 625.73 Da, 1092.23 Da, 527.58 Da, 578.67 Da, 831.98 Da, 559.53 Da, and 574.64 Da, respectively. The isolated pentapeptides especially FWKVV and FMPLH exhibited strong scavenging activity on DPPH radical (EC(50)( )0.85 mg/mL and 0.48 mg/mL), hydroxyl radical (EC50 0.97 mg/mL and 0.80 mg/mL), and superoxide anion radical (EC50 0.29 mg/mL and 0.15 mg/mL). In addition, FWKVV and FMPLH exhibited strong reducing power and lipid peroxidation inhibition abilities. Therefore, the isolated pentapeptides from miiuy croaker muscle could be served as promising candidates applied in health-promoting functional foods and therapeutic products.