Chemical Modification of Rosa roxbunghii Tratt. Polysaccharide and Their Antioxidant and Hypoglycemic Activities

To enhance the functional properties of Rosa roxbunghii Tratt. polysaccharide (RTFP), the polysaccharide was prepared through water extraction. The polysaccharide and its derivatives (RTFP-40, S-RTFP-40, P-RTFP-40, RTFP-60, S-RTFP-60, P-RTFP-60) were obtained through isolation, purification, and chemical modification. The effects of chemical modification on the structure and biological activity of the polysaccharide were investigated through in vitro antioxidant and hypoglycemic experiments. The results indicated that sulfuric and phosphoric acid groups were successfully introduced into the polysaccharide via sulfation and phosphorylation modifications, respectively, enhancing the biological activity of the polysaccharide. Both modification methods significantly enhanced the in vitro hypoglycemic activity of prickly rose polysaccharide, with S-RTFP-40 and S-RTFP-60 exhibiting increases of 18.04% and 8.27%, respectively, and P-RTFP-40 and P-RTFP-60 showing increases of 15.44% and 3.73%, respectively. All four derivatives enhanced α-amylase inhibition, with S-RTFP-40 exhibiting an increase of 94.94%, while S-RTFP-40 and S-RTFP-60 showed increases of 15.19% and 41.53%, respectively. In conclusion, sulfation modification enhanced the antioxidant and hypoglycemic activities of the polysaccharide, which is attributed to the introduction of sulfuric acid groups into its structure.