Bioactive Peptides Derived from Soy Protein
This chapter describes the physiological effects that are truly attributable to protein and peptides in soy. The hypocholesterolemic nature of soy proteins is the highest among plant proteins. Iwami found that the hydrophobicity of pepsin, and the bile acid-binding ability of pepsin digest of soy protein were the highest among proteins. Proteins and polypeptides in soy might be effective for cancer chemoprevention. It has been suggested that the Bowman–Birk trypsin inhibitor might suppress carcinogenesis induced by chemicals or radiation. The antialopecia effect of orally administered soymetide-4 is reversed by indomethacin, a cyclooxigenase (COX) inhibitor, suggesting the involvement of COX metabolites in the antialopecia effect. The shape of the hair follicles in rats given both etoposide and soymetide-4 was normal. Immunomodulating peptides have been found in soy proteins. Proteins and polypeptides in soy might be effective for cancer chemoprevention. Commercial soy products contain amounts of lunacin, ranging from 5.48 mg/g of protein to 16.52 mg/g protein.