Identification, characterization and hypolipidemic effect of novel peptides in protein hydrolysate from Protaetia brevitarsis larvae

The proteins were mainly derived from Protaetia brevitarsis larval extracts obtained using two empty intestine methods (traditional static method: TSM or salt immersion stress method: SISM) and extraction solvents (water: W or 50 % water-ethanol: W:E), and the proteins were used as objects to investigate the effect of emptying intestine methods on hypolipidemic peptides. The results revealed that the F-2 fractions of protein hydrolysate had stronger in vitro hypolipidemic activity, with the peptides obtained by SISM possessing a stronger cholesterol micelle solubility inhibition rate, especially in SISM-W:E-P. Moreover, a total of 106 peptides were tentatively identified, among which SISM identified more peptides with an amino acid number < 8. Meanwhile, five novel peptides (YPPFH, YPGFGK, KYPF, SPLPGPR and VPPP) exhibited good hypolipidemic activity in vitro and in vivo, among which YPPFH, VPPP and KYPF had strong inhibitory activities on pancreatic lipase (PL) and cholesteryl esterase (CE), and KYPF, SPLPGPR and VPPP could significantly reduce the TG content in Caenorhabditis elegans. Thus, P. brevitarsis can be developed as a naturally derived hypolipidemic component for the development and application in functional foods.