Structural elucidation and antioxidant activity a novel Se-polysaccharide from Se-enriched Grifola frondosa

Se-GFP-22, a heteropolysaccharide, with a weight-average M-w of 4.13 x 10(6) Da, was purified from the crude Se-polysaccharide (Se-GFP) isolated from fruit bodies of Se-enriched Grifola frondosa. Selenium was accumulated efficiently in Grifola frondosa during cultivation with Na2SeO3. The structure was investigated through FT-IR, GC, GC-MS, NMR, HPSEC-MALL-RI, particle size, Conge-red test, CD, AFM and SEM. Se-GFP-22 was deduced as a backbone chain of 1,4-alpha-D-Glcp units with a branched point at C6 of both 1,3,6-beta-D-Manp and 1,4,6-alpha-D-Galp units. A typical absorption for selenium ester was existed in SeGFP-22. Se-GFP-22 adopted as a spherical conformation with random coils. A novel Se-polysaccharide of different monosaccharide constituents, molecular weight, linkage types and high content of selenium has been isolated from G. frondosa. The antioxidant effect of Se-GFP-22 was more potent than that of G. frondosa polysaccharide (GFP-22), which may be influenced by the co-effect of polysaccharide and Se, molecular weight, degree of branching and configuration. (C) 2016 Elsevier Ltd. All rights reserved.