Isolation and Identification of Novel Angiotensin I-converting Enzyme (ACE) Inhibitory Peptides from Pony Seed and Evaluation of the Inhibitory Mechanisms

In this work, four novel angiotensin I-converting enzyme inhibitory (ACEI) peptides were isolated and identified from peony (Paeonia suffruticosa Andr.) seed hydrolysate (PSH) by consecutive chromatography and UPLC-ESIQTOF-MS/MS. The IC50 values of HWS (0.640 +/- 0.016 mg/mL) and VLSGF (0.328 +/- 0.040 mg/mL) were significantly (p < 0.05) lower than those of the other two peptides. The Lineweaver-Burk plots showed that VLSGF is competitive inhibition against ACE and HWS acted as a mixed-type inhibitor. Meanwhile, the results of molecular docking showed hydrogen interactions between VLSGF/HWS and ACE. In human endothelial cells, the pretreatments of VLSGF and HWS could increase the production of nitric oxide (NO) and the expression of endothelial nitric oxide synthase (eNOS). In addition, they also decreased the reactive oxygen species (ROS) production. These results indicated that it may be possible to use peony seed protein hydrolysate to create ingredients for functional foods.