Antihypertensive Effect of the Peptides Derived from Casein by an Extracellular Proteinase from Lactobacillus helveticus CP790

Peptides derived from αs1- and β-caseins by the Lactobacillus helveticus CP790 proteinase were investigated for their inhibitory activities against angiotensin I-converting enzyme. The antihypertensive effect of casein hydrolysates in strain SHR spontaneously hypertensive rats was also investigated. Both αs1 and β-casein hydrolysates inhibited this enzyme. Some of these peptides showed enzyme inhibitory activity, and one of them from β-casein inhibited the enzyme greatly; the concentration of an angiotensin I-converting enzyme inhibitor needed to inhibit 50% of the enzyme activity was 4 μM. The hydrolysate of casein demonstrated antihypertensive activity in spontaneously hypertensive rats at an orally administered dosage of 15 mg/kg of body weight. Milk fermented with L. helveticus CP790, containing about .3% peptides, also showed antihypertensive activity in SHR rats with 5 ml/kg of body weight (15mg of peptide/kg); however, the milk fermented with L. helveticus CP791, a variant defective for proteinase activity, did not show this activity. Results suggested that the peptides liberated from casein by the proteinase in the culture medium showed antihypertensive effect in SHR rats.