Immunomodulatory effects of pepsin-educed soy protein hydrolysate in rats and murine cells

Abstract

Background: There has been an increase in demand for soy and its products, with soy protein having a huge market in particular. Several reports have established how soy protein hydrolysates (SPHs) yield better physiological properties and play essential functional roles than the crude soy protein. Objective: To investigate the immunomodulatory and acute toxicity of soy protein hydrolysate (SPH) produced with pepsin protease in mice and rats. Methods: Soy protein hydrolysate was enzymatically produced using pepsin, with E/S (enzyme to substrate ratio) of 0.5% (250 u/mg) and hydrolysis time of 4h. Afterwards, the SPH effects on murine spleen lymphocyte proliferation, and peritoneal macrophage phagocytosis were investigated in vitro. Confirmation studies were explored in rats' sera IgG and IgA, and the acute toxic effect of SPH was observed in mice subjects. Results: The hydrolysate increased the levels of splenocytes (stimulative index of 10.141 - 10.811) and peritoneal macrophages (phagocytic index of 1.285 - 1.721). Furthermore, the concentrations of sera IgG and IgA obtained from SPH-fed rats ranged from 0.198 - 0.345 mg/ml and 0.0184 - 0.0194 mg/ml, respectively in comparison with the soy protein isolate (SPI) -fed rats (0.208 - 0.322 mg/ml and 0.0188 - 0.0189 mg/ml, respectively). Additionally, 10 mg dose of SPH stably elicited serum IgG in contrast to other doses, while there was a general decrease in the amounts of IgA obtained in the rat subjects. Moreover, there was no acute toxic effect recorded in the mice subjects. Conclusion: In light of the results, it is possible that SPH prepared with pepsin has the potential of improving the immune system, and may therefore be used as immunomodulatory or functional food product