Angiotensin-I-converting enzyme inhibitory peptides from eel (Anguilla japonica) bone collagen: preparation, identification, molecular docking, and protective function on HUVECs.

Abstract

Introduction: Hypertension is a chronic cardiovascular disease, which can trigger some disease such as heart failure, loss of vision or kidney. There were various peptides derived from food that are recognized for their ability to inhibit ACE activity, potentially leading to a reduction in blood pressure levels in vivo. The primary objective of this research is to discover ACE inhibitory peptides from protein hydrolysates of eel bone collagen (EBCHs).

Methods: To begin, EBCHs were created and then divided through the process of ultrafiltration. The second step involved screening of peptides capable of inhibiting ACE by combining peptidomics and molecular docking. And the mechanism by which ACE interacts with peptides has been studied. Finally, the hypotensive mechanism of identified peptide through cell experiments with HUVEC (Human Umbilical Vein Endothelial Cells).

Results: Eel (Anguilla japonica) bone collagen was hydrolyzed by alcalase and the hydrolysate was separated into three fractions, among which the F2 displayed a higher level of ACE inhibitory activity. According to molecular docking calculations, a total of 615 peptides were identified through nano-HPLC-MS/MS, with the prediction of seven newly discovered ACE inhibitory peptides (PMGPR, GPMGPR, GPAGPR, GPPGPPGL, GGPGPSGPR, GPIGPPGPR, GPSGAPGPR). Notably, GPPGPPGL had the lowest IC₅₀ value of 535.84 μM among the identified peptides, indicating its potency as an ACE inhibitor. The ACE S2 pocket formed hydrogen and hydrophobic interactions with GPPGPPGL. Lineweaver-Burk plots revealed that GPPGPPGL competitively bound to ACE's active site residues. Treatment with GPPGPPGL significantly increased nitric oxide secretion (p < 0.01) and decreased endothelin-1 (ET-1) production in HUVECs.

Discussion: Our findings suggest that combining peptidomics with molecular docking is effective for rapidly screening ACE inhibitory peptides. Future studies should assess the bioavailability and in vivo activity of the identified peptide GPPGPPGL from EBCHs.