Our previous studies have shown that Coix 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 Coix glutelin. The Coix 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 Coix glutelin has a significant antihypertensive effect, and it could be a good natural ingredient for pharmaceuticals against hypertension and the related diseases.
Keywords: Coix larchryma-jobi L. var. ma-yuen Stapf; angiotensin I-converting enzyme; antihypertensive peptide; glutelin; molecular simulation.