Isolation, identification, and in vivo evaluation of the novel antihypertensive peptide, VSKRLNGDA, derived from chicken blood cells

Angiotensin I-converting enzyme (ACE)-inhibitory peptides from Alcalase-hydrolyzed chicken blood cells were isolated and characterized. The nonapeptide VSKRLNGDA was identified as the most potent peptide, with an increase in inhibition after in vitro gastrointestinal (GI) digestion with an IC50 of 26.46 µM. The oral administration of VSKRLNGDA reduced the systolic blood pressure (SBP) in spontaneously hypertensive rats (SHRs) by 41.83 mmHg at 50 mg/kg within 12 h of administration. Blood pressure reduction was also maintained in rats fed 50 mg/kg VSKRLNGDA for 4 weeks. After 4-week feeding trials, the expression of genes encoding renin and angiotensin II type-1 receptor (AT-1) was downregulated, while that of adrenoceptor β-3 (AR-β3) and peroxisome proliferator-activated receptor δ (Pparδ) was upregulated. Therefore, the oral intake of VSKRLNGDA modulated expression various genes involved in blood pressure control, which could critically contribute to its antihypertensive effect.