Antihypertensive effect and purification of an ACE inhibitory peptide from sea cucumber gelatin hydrolysate

Abstract Gelatin from the sea cucumber ( Acaudina molpadioidea ) was hydrolyzed sequentially with bromelain and alcalase. The hydrolysate was fractionated into three ranges of molecular weight (GH-I, 50 value of 0.35 mg/ml. An ACE inhibitory peptide was isolated from the GH-III, using the chromatographic methods including ion-exchange chromatography, gel filtration and reversed phase high-performance liquid chromatography. The purified ACE inhibitory peptide with a molecular weight of 840 Da consisted of five main amino acids (Glu, Asp, Pro, Gly and Ala), and its IC 50 value was 0.0142 mg/ml. This sea cucumber gelatin hydrolysate (GH-III) was used as drinks administered to renal hypertensive rats (RHR) for 1 month. The systolic blood pressure and diastolic blood pressure of the RHR were significantly reduced, which indicates an antihypertensive effect by oral administration.