Soybean protein-derived hydrolysate affects blood pressure in spontaneously hypertensive rats

The aim of this study was to investigate the inhibitory activity of angioten-sin-converting enzyme (ACE) and antihypertensive effects of soybean protein hydrolysate in spontaneously hypertensive rats (SHRs). The inhibitory activities against ACE with an IC₅₀ of the peptidic fraction were 0.82 (casein), 0.73 (soybean protein isolate), and 0.48 mg/mL (soybean acid-precipitated protein), respectively. Peptic hydrolysate containing 1% NaCl was added to the SHRs' feed (5% of each protein hydrolysate). Systolic blood pressure of the soybean protein hydrolysate-supplemented groups were significantly lower than that of the casein hydrolysate-supplemented group in the study period. These data suggested that soybean protein hydrolysate may retard the development of hypertension in SHRs by its ACE inhibitory effect in vivo.