Immunomodulatory potential of dietary soybean-derived saponins

Abstract

Soybeans are widely recognized as a valuable crop, often included as a high-quality protein source in production animal diets. In addition to contributing to the macronutrient composition of the diet, soybeans also contain many minor bioactive components which can influence the health and growth of animals. This review examined the immunomodulatory potential of soy saponins and their specific effects on the inflammatory response, oxidative stress, and intestinal barrier function. Saponins are amphiphilic molecules, a property imparted by their polar carbohydrate chains that attach to a nonpolar aglycone backbone. This structure also complicates their isolation, thus most research investigating soy saponins has been performed in models that only require small amounts of isolated material. Many experiments conducted in vitro or in rodents reported that saponins can reduce damage, particularly in conditions where a challenge was first introduced to stimulate inflammation or oxidative stress. It appears that saponins can exert their anti-inflammatory effects through modulation of the NF-κB pathway, reducing its activation and the release of pro-inflammatory molecules later in the cascade. Furthermore, soy saponins can influence levels of important antioxidative enzymes and reduce the generation of reactive oxygen species, thus attenuating levels of oxidative stress in the model. As these results were obtained from experiments done in vitro or in rodents, they neglect to provide a good representation of how soy saponins may affect some of the greatest consumers of soy-based products, with those being production animals. The work that has been done seems to indicate that soy saponins may exert similar anti-inflammatory and anti-oxidative effects in production animals as those observed in other research models along with immunostimulatory activity that may help boost host defense systems. Overall, there is a dearth of research regarding the effects of soy saponins on species that commonly consume soy products, which begins by developing more effective methods of saponin extraction.