Novel Antihypertensive Peptides Derived from Adlay (Coix larchryma-jobi L. var. ma-yuen Stapf) Glutelin

Abstract

Our previous studies have shown that <i>Coix</i> glutelin pepsin hydrolysate can effectively inhibit angiotensin converting enzyme (ACE) activity in vitro. The main purpose of this study was to obtain potent anti-hypertensive peptides from <i>Coix</i> glutelin. The <i>Coix</i> glutelin hydrolysates (CGH) were prepared by pepsin catalysis and further separated by an ultrafitration (UF) system, gel filtration chromatography (GFC) and reversed-phase high performance liquid chromatography (RP-HPLC). As a result, the sub-fraction F5-3 had the highest ACE-inhibitory activity. Six ACE inhibitory peptides were identifiedusing nano-liquid chromatography coupled to tandem mass spectrometry. The most potent peptide GAAGGAF (IC₅₀ = 14.19 μmol·L^-1) was finally obtained by further molecular simulation screening and a series of division and optimization. Single oral administration of synthesized GAAGGAF at 15 mg/kg body weight (BW) in spontaneously hypertensively rats (SHR) could reduce the systolic blood pressure (SBP) around 27.50 mmHg and blood pressure-lowering effect lasted for at least 8 h. The study demonstrated for the first time that the ACE inhibitory peptide GAAGGAF from <i>Coix</i> glutelin has a significant antihypertensive effect, and it could be a good natural ingredient for pharmaceuticals against hypertension and the related diseases.