Characterization and angiotensin-converting enzyme inhibitory activity of peptides of seabuckthorn ( Hippophae rhamnoides L.) seed meal

Abstract

Given the side effects associated with synthetic antihypertensive drugs, there is a growing need among researchers to investigate angiotensin-converting enzyme (ACE) inhibitory peptides derived from food protein as safer therapeutic alternatives. This study used seabuckthorn ( Hippophae rhamnoides L.) seed meal as the raw material, and the protein was extracted by alkaline extraction and acid precipitation. After enzymatic digestion, peptides with molecular weight less than 3 kDa were selected for study. The screened peptide had an IC ₅₀ value of 4.358 mg/mL on ACE with a non-competitive inhibition mechanism and good inhibition stability. By employing infrared (IR) analysis, exclusively β-fold and β-helix structures were identified in the hydrolysate, while no other structural motifs were detected. X-ray diffraction revealed that it had an irregular amorphous structure. The peptide contains 17 amino acids that are both highly acidic and hydrophobic, with glutamic acid ranking first in terms of the number of individual amino acids. Compared with the database (NCBI, Uniport), ten peptides with ACE inhibitory activity were detected, and molecular docking showed the mechanism of each peptide inhibiting ACE, FRVAWTEKNDGQRAPLANN, LIISVAYARVAKKLWLCNMIGDVT-TEQY, VIRSRASDGCLEVKEFEDIPP, AGGGG-GGGGGGSRRL, LQPREGPAGGTT-ALREELSLGPEAALDTPPAGP, DDEARINQLFL, FAVSTLTSYDWSDRDDATQGR-KL, RQLSLEGSGLGVEDLKDN, GGGGGGGGGGGGGGGIGGGGGGGGGGGAR, and KEALGEGCFGNRIDRIGD. According to the results, AGGGGGG-GGGGSRRL is more stable in binding to ACE and may have better inhibitory activity. It has been shown that seabuckthorn protein can be an alternative source of ACE inhibitory peptides.

Keywords

Seabuckthorn / Angiotensin-converting enzyme (ACE) / Inhibitory activity / Molecular docking