Isolation and identification of dipeptidyl peptidase-IV inhibitory peptides from Sacha inchi meal

BACKGROUNDSacha inchi meal (SIM) is a by-product of oil processing. Our previous studies showed that SIM hydrolysates exhibited dipeptidyl peptidase-IV (DPP-IV) inhibition activity. The objective of the present work was to identify and characterize the bioactive peptides from protein hydrolysates of SIM; enzyme kinetics and peptide-enzyme interaction were also investigated. RESULTSFrom SIM hydrolysates, ten peptides responsible for the activity were identified: GPSRGF (GF-6), FPILSPDPA (FA-9), APYRRGGKI (AI-9), WPYH (WH-4), DPATWLALPT (DT-10), NPEDEFRQQ (NQ-9), APESKPVGV (AV-9), LEWRDR (LR-6), APVYWVQ (AQ-7) and LLMWPY (LY-6). The IC50 values of five peptides (GF-6, WH-4, AQ-7, AV-9 and LY-6) with better inhibitory activity on DPP-IV were within the range of 23.43-128.40 mu mol L-1. AQ-7 had the best activity, with an IC50 value of 23.43 mu mol L-1. Enzyme kinetics indicated the presence of various inhibition types (mixed, non-competitive and competitive). Isothermal titration microcalorimetry showed that the main forces of the binding sites between peptide (GF-6 or AQ-7) and DPP-IV were hydrogen bond, hydrophobic interaction and van der Waals force. The key residues involved in peptide-enzyme interaction were determined by molecular docking. Furthermore, at a concentration of 800 mu mol L-1, GF-6 was found to significantly increase the glucose consumption in insulin-resistant HepG2 cells (P < 0.05) compared with the model group. CONCLUSIONSacha inchi meal-derived peptides displayed potent DPP-IV inhibition activity and could be used in the health food industry and as lead compounds for diabetes therapy. (c) 2023 Society of Chemical Industry.

Automated summary

This study identified and characterized bioactive peptides derived from the by-product Sacha inchi meal, which showed potent DPP-IV inhibition activity. The inhibition types were mixed, non-competitive, and competitive. The binding sites between peptides and DPP-IV were determined through hydrogen bonding, hydrophobic interaction, and van der Waals force. The peptides could have potential applications in the health food industry and as lead compounds for diabetes therapy.