39 / 2021-10-09 19:24:47

Study on the Mechanisms of Urechis Unicinctus Peptides’ ACE inhibitory effects

Urechis Unicinctus,ACE inhibitor,Oligopeptide,Mechanism,ROS

Urechis Unicinctus were used as raw material to screen for enzymatic peptides with ACE inhibitory activity. A series of separation, purification and identification techniques have been performed to obtain 7 peptides, and their mechanisms of ACE inhibitory activities were studied at the molecular and protein levels. Based on enzyme kinetics and computer-simulated molecular docking, we explored the mode of action of peptides with ACE. The main research contents and results are as follows:

(1) ACE inhibitory rate were used as indicator, 7 peptides were determined by mass spectrometry and amino acid sequence analysis as Gln-Pro-Met-*-* (F1), Ile-Val-Lys-*-* (F2), Phe-Pro-Tyr-*-* (F3), Trp-Pro-Gly-*-* (F4), Gly-Leu-Thr-*-* (F5), Met-Pro-Gln-Gly-Ile-*-* (F6), Ile-Val-Met-*-* (F7).

(2) According to enzyme kinetics and computer-simulated molecular docking technology, we found that oligopeptides F2, F4, F5 and F7 are competitive inhibitors while F3 is non-competitive inhibitor of ACE enzyme.

(3) These 5 oligopeptides can not only inhibit the generation of endogenous contraction factor endothelin (ET-1), promote the release of diastolic factor nitric oxide (NO), but also activate endothelial nitric oxide synthase (eNOS) to a certain extent, inhibit the activity of induced nitrogen monoxide synthase (iNOS), and thus release more NO to improve endothelial cell dysfunction caused by norepinephrine.

(4) F4 and F5 with better clearance rate of superoxide anion (O₂^-) were selected for further experiments. Both of them can promote the release of NO and increase the activity of SOD and CAT in cells, at the same time, reduce the content of MDA and LDH in the extracellular medium. DCFH-DA staining observations show that F4 and F5 can also reduce the increase of ROS in H₂O_2-induced HUVECs, and the activity increased in a concentration-dependent manner.

Therefore, F4 and F5 as competitive inhibitors of ACE enzymes, can promote the release of NO and inhibit the production of ET-1, thereby lowering blood pressure. At the same time, they can reduce the damage of ROS to HUVECs and reduce the risk of cardiovascular disease. They are expected to provide candidates in the development of antihypertensive drugs.