Antihypertensive effects of peptides in autolysate of bonito bowels on spontaneously hypertensive rats.

An autolysate of bonito bowels was treated with ultrafiltration, loose RO concentration, ion-exchange chromatography, and reverse phase chromatography to increase its potency to inhibit angiotensin I-converting enzyme (ACE) activity by 16-fold. Oral administration of the partially purified autolysate decreased the systolic blood pressure of spontaneously hypertensive rats (SHR) in a dose-dependent manner at the doses of 1 g peptides/kg or higher. The relationship between the antihypertensive activity (in vivo) of the partially purified preparation and its ACE inhibitory activity (in vitro) in comparison with previously reported ACE inhibitory peptides is discussed.