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

Abstract BACKGROUND Sacha 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. RESULTS From 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 IC 50 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 μmol L −1 . AQ‐7 had the best activity, with an IC 50 value of 23.43 μmol 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 μmol 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. CONCLUSION Sacha 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. © 2023 Society of Chemical Industry.