Chemical structure elucidation and functional activities comparison of two polysaccharides purified from Citrus reticulata Blanco peels

Abstract Background The Citrus reticulata Blanco peels have been widely adopted as functional food or nutraceuticals for thousands of years. In our study, two polysaccharides from the C. reticulata Blanco peels were obtained and named as CRP-WA and CRP-02A, respectively. After characterization by monosaccharide composition, methylation and NMR, chemical structures of CRP-WA and CRP-02A were elucidated. Results As a result, CRP-WA with Mw of 32.8 kDa was an arabinogalactan polysaccharide composed of (β1 → 3) (β1 → 3,6)-D-Gal p , (β1 → 4)-D-Man p and (β1 → 4)-D-Glc p units in the backbone. The CRP-02A with Mw of 70.5 kDa was an arabinogalacturonan type pectin formed by (α1 → 4) (α1 → 3,4)-D-Gal p A units in the backbone. Moreover, the surface morphologies and rheological properties of CRP-WA and CRP-02A were quite different from each other. Both of these two polysaccharides possessed good antioxidant activities and immunoregulatory effects on RAW 264.7 cells, in which CRP-02A behaved remarkable antioxidant feature, whereas CRP-WA showed relatively high immunoregulatory activity. Conclusion Our study will provide fundamental information for C. reticulata Blanco-based nutritional foods development. Graphical Abstract