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Antihypertensive Effects, Molecular Docking Study, and Isothermal Titration Calorimetry Assay of Angiotensin I-Converting Enzyme Inhibitory Peptides from Chlorella vulgaris

Xie, Jingli, Chen, Xujun, Wu, Junjie, Zhang, Yanyan, Zhou, Yan, Zhang, Lujia, Tang, Ya-Jie, Wei, Dongzhi
Journal of agricultural and food chemistry 2018 v.66 no.6 pp. 1359-1368
Chlorella vulgaris, active sites, angiotensin-converting enzyme inhibitors, animal disease models, antihypertensive effect, body weight, calorimetry, digestion, gastrointestinal system, hydrogen bonding, hydrolysis, hypertension, inhibitory concentration 50, molecular models, peptides, peptidyl-dipeptidase A, proteins, rats, systolic blood pressure, titration, tryptophan
The aim of this work is to explore angiotensin I-converting enzyme (ACE) inhibitory peptides from Chlorella vulgaris (C. vulgaris) and discover the inhibitory mechanism of the peptides. After C. vulgaris proteins were gastrointestinal digested in silico, several ACE inhibitory peptides with C-terminal tryptophan were screened. Among them, two novel noncompetitive ACE inhibitors, Thr-Thr-Trp (TTW) and Val-His-Trp (VHW), exhibited the highest inhibitory activity indicated by IC₅₀ values 0.61 ± 0.12 and 0.91 ± 0.31 μM, respectively. Both the peptides were demonstrated stable against gastrointestinal digestion and ACE hydrolysis. The peptides were administrated to spontaneously hypertensive rats (SHRs) in the dose 5 mg/kg body weight, and VHW could decrease 50 mmHg systolic blood pressure of SHRs (p < 0.05). Molecular docking displayed that both TTW and VHW formed six hydrogen bonds with active site pockets of ACE. Besides, isothermal titration calorimetry assay discovered that VHW could form more stable complex with ACE than TTW. Therefore, VHW was an excellent ACE inhibitor.