Abstract
Corn silk tea has been used in folk medicine for anti-hypertensive healthcare. Angiotensin-converting enzyme (ACE) plays a crucial role on the homeostasis of blood pressure. However, effects of corn silk tea on ACE activity and the presence of ACE inhibitory constituents in corn silk are still unknown. Here we applied proteomics and bioinformatics approaches to identify corn silk bioactive peptides (CSBps) that target ACE from the boiling water extract of corn silk (CSE). CSE significantly reduced systolic blood pressure (SBP) levels in spontaneously hypertensive rats and inhibited the ACE activity. By proteomics coupled with bioinformatics analyses, we identified a novel ACE inhibitory peptide CSBp5 in CSE. CSBp5 significantly inhibited the ACE activity and decreased SBP levels in a dose-dependent manner. Docking analysis showed that CSBp5 occupied the substrate-binding channel of ACE and interacted with ACE via hydrogen bonds. In conclusion, we identified that CSE exhibited anti-hypertensive effects in SHRs via the inhibition of ACE, the target of most anti-hypertensive drugs. In addition, an ACE inhibitory phytopeptide CSBp5 that decreased SBP levels in rats was newly identified. Our findings supported the ethnomedical use of corn silk tea on hypertension. Moreover, the identification of ACE inhibitory phytopeptide in corn silk further strengthened our findings.
Highlights
Hypertension is the most common serious chronic health problem in the world
In comparison of Angiotensin-converting enzyme (ACE) inhibitory peptides in corn, our findings suggested that CSBp5 showed more effective ACE inhibitory activity and anti-hypertensive abilities in SHRs
Micronucleus assay and sperm malformation assay showed corn silk is not a genotoxic substance [46]. These studies suggested that corn silk tea is an herbal remedy with low toxicity
Summary
Hypertension is the most common serious chronic health problem in the world. The World. Inhibition of ACE activity decreases the production of angiotensin II, leading to vasodilation and reduced blood pressure. Val-Pro-Pro (VPP) and Ile-Pro-Pro (IPP), identified from sour milk, inhibit the ACE activity and protect the endothelial function in vitro, and exhibit anti-hypertensive effects in SHRs [11]. Clinical trials on subjects with blood pressure ranging from normal to mild hypertension show that intake of tablets containing VPP and IPP leads to a mild improvement in hypertension without side effects [12] These results suggest that the presence of food-derived ACE inhibitory peptides makes foods show anti-hypertensive potentials. We evaluated the effects of corn silk tea on ACE activity in vitro and hypertension in SHRs. Captopril, lisinopril, and enalapril, the well-known ACE inhibitors, are amino acid or dipeptide drugs. Of ACE and decreased systolic blood pressure (SBP) levels in rats
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