1. The synthetic peptide GPNAV exerted an endothelium-independent vasorelaxation action (EC₅₀: 0.41 ± 0.05 μM, Value was means ± standard deviation (n = 3)), while a mixture of the corresponding amino acids (i.e., Gln, Cys, Pro, Ala, Asn, and Val) was used as a negative control and did not show vasodilation. So this data suggested that the peptide was a potent vasorelaxant.
   

2. Vasorelaxation action of GPNAV was also examined in the endothelium-denuded aortic rings. The absence of the endothelium layer was confirmed by no vascular response against 1.0 mM ACh. Vascular relaxation determined in the endothelium denuded aorta ring also observed a dose-dependent vasorelaxation, while there was no difference between the aorta ring with or without endothelium. According to this result, the endothelium is not involved in the underlying mechanism of soy peptide induced vasorelaxation.
   

Fermentation and Enzymatic hydrolysis

Soy meal  was fermented with Bacillus subtilis from Douchi and then was hydrolyzed by thermolysin, and the water extraction was then separated into four fractions using ultrafiltration membranes.