Screening, ACE-inhibitory mechanism and structure-activity relationship of a novel ACE-inhibitory peptide from Lepidium meyenii (Maca) protein hydrolysate

Maca is an edible functional plant with antihypertensive activity. However, there is still no clear understanding of angiotensin-converting enzyme (ACE) inhibitory substances in maca. In the present study, six novel angiotensin-converting enzyme inhibitor (ACEI) peptides (RSRGVFF, LGHPVFRNK, HGSCNYR, KANLGFRF, GGGHKRLY and SSYLGRN) were found in maca protein hydrolysates using in silico tools and molecular docking. RSRGVFF revealed prominent ACE inhibitory activity with an IC50 value of 5.01 μM as a mixed-type ACE inhibitor. An analysis of the structure-activity connection demonstrated that the arginine at N-terminal is the most likely active residue in RSRGVFF, and two phenylalanines at the C-terminal also contributed to its inhibitory activity. Thus, these results indicate that maca protein may be one of the substances that leads to antihypertensive activity. This provides a new perspective to understanding the ACE inhibitory activity of maca and offers valuable insights to enlighten the structure-activity relationship of ACEI peptides.