Exploration of cyclooxygenase-2 inhibitory peptides from walnut dreg proteins based on <i>in silico</i> and <i>in vitro</i> analysis

Abstract

Walnut dreg protein hydrolysates (WDPHs) exhibit a variety of biological activities, however, the cyclooxygenase-2 (COX-2) inhibitory peptide of WDPHs remain unclear. The aim of this study was to rapidly screen for such peptides in WDPHs through a combination of <i>in silico</i> and <i>in vitro</i> analysis. In total, 1262 peptide sequences were observed by nano liquid chromatography/tandem mass spectrometry (nano LC-MS/MS) and 4 novel COX-2 inhibitory peptides (AGFP, FPGA, LFPD, and VGFP) were identif ied. Enzyme kinetic data indicated that AGFP, FPGA, and LFPD displayed mixed-type COX-2 inhibition, whereas VGFP was a non-competitive inhibitor. This is mainly because the peptides form hydrogen bonds and hydrophobic interactions with residues in the COX-2 active site. These results demonstrate that computer analysis combined with <i>in vitro</i> evaluation allows for rapid screening of COX-2 inhibitory peptides in walnut protein dregs.