An angiotensin-converting enzyme inhibitory peptide (Val-Trp) from cauliflower by-products exerts an antihypertensive effect <i>via</i> the eNOS/NO/cGMP pathway

Val-Trp (VW) has been identified as an angiotensin-converting enzyme (ACE) inhibitory peptide from cauliflower by-products by our previous research. The aim of this study is to investigate the antihypertensive activity and mechanism of VW. The results showed that oral administration of VW (40 mg kg^-1) could effectively reduce the systolic and diastolic blood pressure in SHRs. The underlying mechanisms of VW were further investigated. The generation of cGMP was promoted by VW in an Ang I-induced HUVEC model, leading to a decrease in intracellular calcium concentration, thus facilitating vascular relaxation and lowering blood pressure. Additionally, VW significantly increased the content of the vasodilator factor NO, inhibited the production of the vasoconstrictor factor ET-1, and induced eNOS phosphorylation. Based on these findings, it can be inferred that VW exerted its antihypertensive effects by inhibition of ACE and activation of the eNOS/NO/cGMP signaling pathway. Furthermore, the inhibitory mechanism of VW on ACE was investigated. Isothermal titration calorimetry results revealed that the binding of VW to ACE was a spontaneous exothermic process driven by enthalpy and entropy, which involved hydrogen bonding and hydrophobic effects. The peptide VW had a static fluorescence quenching effect on ACE, involving secondary structure changes, and molecular docking showed that VW attached to the active pocket of ACE, consequently preventing the substrate from binding to ACE. The present study provides evidence for the antihypertensive effect of VW through the ACE-mediated eNOS/NO/cGMP pathway, and promotes the recycling of cauliflower by-products.