Effects of simulated saliva-gastrointestinal digestion on the physicochemical properties and bioactivities of Siraitia grosvenorii polysaccharides

The aim of this study was to investigate the effect of simulated saliva-gastric digestion (SGID) on the physicochemical properties and bioactivity of Siraitia grosvenorii polysaccharides (SGPs). The results revealed that the digestibility (bioavailability) of SGPs was approximately 16.81%, 43.86%, and 52.38% after saliva digestion (SD), saliva-gastric digestion (SGD), and SGID, respectively. SGID significantly altered the physicochemical properties of SGPs, such as total polysaccharide content (from 88.25% to 69.26%) and molecular weight (from 23.00 to 7.82). The structure of SGPs was significantly altered after digestion. In addition, SGID affected the biological activity of SGPs. after SGID, SGPs still had strong antioxidant activity, as well as alpha-glucosidase, alpha-amylase inhibition, and cellular hypoglycemic activity. However, the ability to bind bile acids and cholesterol in vitro was not affected. In conclusion, these results could provide a theoretical basis for investigating the mechanism of action of SGPs during digestion in vivo.