A novel angiotensin I-converting enzyme (ACE) inhibitory peptide from Wuyi rock tea residue: Preparation, identification, and its potential molecular mechanism

Wuyi rock tea residue is rich in protein, making them a valuable protein source for producing angiotensin I-converting enzyme (ACE) inhibitory peptides. In the present research, five novel ACE inhibitory peptides were isolated and identified from protein hydrolysate of Wuyi rock tea residue using Sephadex G-15, reversed phase high-performance liquid chromatography (RP-HPLC), and quadrupole time-of-flight mass spectrometry. The peptide sequences were identified as FPFPRPP, PPPRGP, PFPRPPH, LGHPW and LKFPDF, with IC 50 values ranged from 0.271 mg/mL to 1.018 mg/mL, with FPFPRPP demonstrating the strongest activity. As indicated by the Lineweaver–Burk plot, FPFPRPP was a mixed-type inhibitor against ACE. Molecular docking studies further confirmed that FPFPRPP forms five hydrogen bonds with residues near the active sites of ACE, with a binding energy of -10.5 kcal/mol. Functional assay in human umbilical vein endothelial cells (HUVECs) showed that FPFPRPP significantly upregulated nitric oxide production and downregulated reactive oxygen species and endothelin-1 levels induced by angiotensin II, indicating its potential antihypertensive effect. These findings highlight Wuyi rock tea residue as a promising source of ACE inhibitory peptides and suggest FPFPRPP could be developed as a functional food ingredient with possible applications in hypertension management. • Five ACE inhibitory peptides were purified and identified from Wuyi rock tea residues. • FPFPRPP showed the highest ACE inhibitory activity with an IC 50 of 0.271 ± 0.021 mg/mL. • FPFPRPP acts as a mixed-type inhibitor against ACE. • FPFPRPP forms complex interactions with amino acid residues near the active sites of ACE. • FPFPRPP increased NO production and decreased ROS and ET-1 levels in Ang II-induced HUVECs.