Structural characterization and antioxidant activities of the degradation products from Porphyra haitanensis polysaccharides

摘要

In this study, crude polysaccharides fromPorphyra haitanensis(CPP) were obtained by water extraction and alcohol precipitation. The CPP were separated and purified by DEAE-cellulose column chromatography to give five components (PP1, PP2, PP3, PP4, and PP5) whose physicochemical properties were characterized. The sulfate-group content (20.1%) of PP3 was higher than those of the other four components. PP3 was treated with H2O2-VC, and then dialyzed to obtain degradation products PP3-1 (102 kDa), PP3-2 (72 kDa), PP3-3 (39 kDa), and PP3-4 (20 kDa). The antioxidant activities of the degradation products and PP3 were assessed, which revealed that PP3-4 was significantly more active than the other four components. PP3-4 was purified by Sephadex G-100 to give PP3-4a. The molar ratio of galactose to 3,6-anhydro-α-L-galactose in PP3-4a was 10:1. The structure of PP3-4a was characterized by FT-IR and 1D/2D NMR spectroscopies. The results reveal that the structure of PP3-4a contains two →3) β-D-galactose (1→4) 3,6-anhydro-α-L-galactose (1 →, and → 3) β-D-galactose (1→4) α-L-galactose-6-S (1 → repeating structural units, with the latter structural units dominating and partially substituted with methoxy groups at some C-6 positions of the β-D-galactose and C-2 positions of 3,6-anhydro-α-L-galactose. The anomeric glycosidic bonds include both α and β types.