A Novel ACE Inhibitory Peptide Ala-His-Leu-Leu Lowering Blood Pressure in Spontaneously Hypertensive Rats.

Ala-His-Leu-Leu (AHLL) was isolated and purified from the loach (Misgurnus anguillicaudatus) hydrolysate in our previous study. The aim of this study was to investigate the antihypertensive effects of angiotensin-I-converting enzyme (ACE) inhibitory peptide AHLL in spontaneously hypertensive rats (SHRs). AHLL showed good antihypertensive effects in SHRs during the long-term oral administration and no allergic reactions or coughing were observed. After 2 months of oral administration of AHLL, the body weight growth was normal. The decrements in systolic blood pressure of the high dose (5 mg/kg bw) and the low dose of AHLL (1 mg/kg bw) treatment groups were 22.1 and 5.0 mmHg at week 8, respectively. Compared to the control group, the concentrations of triglyceride and sodium in serum were reduced significantly in the high-dose group after 2 months. The ACE activity of kidney and lung decreased significantly, which indicated that AHLL exerted an antihypertensive effect on kidney and lung and they were the target sites of AHLL. These results strongly supported the in vivo antihypertensive mechanism of AHLL.