Open Access
Highlights
• Peptides in walnut dreg proteins are efficiently released by alcalase.
• Alcalase hydrolysate (Al-WPH) inhibits cyclooxygenase-2 (COX-2) activity.
• Four novel peptides (AGFP, FPGA, LFPD, and VGFP) were identified in Al-WPH.
• AGFP, FPGA, LFPD, and VGFP showed potential COX-2 inhibitory activity.
• Walnut dreg protein is an excellent low-cost source of anti-inflammatory peptides.
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 in silico and in vitro 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 in vitro evaluation allows for rapid screening of COX-2 inhibitory peptides in walnut protein dregs.