Effect of angiotensin I-converting enzyme inhibitory peptide from rice dregs protein on antihypertensive activity in spontaneously hypertensive rats.

BACKGROUND Angiotensin I-converting enzyme (ACE) inhibitory peptide has good effect on blood pressure regulation. Therefore, research to find and develop safer, effective and economical ACE inhibitors is necessary for the prevention and remedy of hypertension. So food-derived ACE inhibitory peptides isolated from food or from enzymatic digestion of food proteins are the safe and efficient substitution for human health. OBJECTIVE To investigate the effect of rice dreg enzymatic hydrolysates as an anti-hypertensive in vivo with spontaneous hypertension rats (SHRs). DESIGN The once-oral administration experiments with rice dreg hydrolysates peptide (RDHP) in different doses were conducted using 6 weeks old spontaneous hypertension rats as the test model. Twenty five SHRs were randomized into five groups according to blood-pressure level. The group A is blank control group, the group B positive control group (Captopril), the group C (1.0 mg/kg), the group D (RDHP 10 mg/kg) and group E (RDHP 50 mg/kg). The administration approach is to fill in stomach by mouth. The blood pressure value was observed for each group. The long term oral administration design was conducted for one month. Twenty four SHRs were randomized into 3 groups. The first group is the blank control, the second group is low dose (RDHP 10 mg/kg) and the third group is high dose (RDHP 20 mg/kg). In administration period, blood pressure was measured for once a week. OUTCOMES The once-oral administration animal experiments showed that the blood pressure of SHR drop was 11 mmHg, 17 mmHg, 26.00 mmHg, 17 mmHg at a dosage of 1 mg/kg, 10 mg/kg, 50 mg/kg hydrolysates and 1 mg/kg captopril, respectively, after 1h administration. The results of long-term oral administration indicated that the blood pressure drop was 17 mmHg, 26 mmHg in 10 mg/kg and 20 mg/kg, respectively after 30 days administration. RDHP not only promoted the growth of SHR, but also had no adverse effect on heart rate. CONCLUSIONS The present study indicated the inhibitory peptides from rice dreg hydrolysate had significant antihypertensive action and no other side effects by oral administration in SHR.