Structural characterization and bioactivities of a novel polysaccharide obtained from Lachnum YM38 together with its zinc and selenium derivatives

To prepare zinc and selenium modified polysaccharides derivatives (ZnLEP-1a and SeLEP-1a), a novel polysaccharide (LEP-1a) isolated from Lachnum YM38 was chosen. Following that, the structural characterization and in vitro bioactivities of LEP-1, ZnLEP-1a and SeLEP-1a were investigated. Results revealed that LEP-1a had a molecular weight of 5.69 × 104 Da and was composed of mannose, galactose and glucose. The linkage types of LEP-1a were proved to be (1→)-α-D-Manp, (1→3)-α-D-Manp, (1→2)-α-D-Galp, (1→2)-α-D-Glcp, (1→2,6)-α-D-Manp. Zinc content of ZnLEP-1a was 0.69 mg/g, while selenium content of SeLEP-1a was 206.99 µg/g. Compared with LEP-1a, ZnLEP-1a and SeLEP-1a had a lower molecular weight, same monosaccharides in different molar ratios. The results of FT-IR, DSC, NMR, SEM and AFM suggested that there were obvious changes in structural characteristics after LEP-1a was modified with zinc and selenium. ZnLEP-1a and SeLEP-1a had stronger antioxidant, hypoglycemic, antitumor activities in vitro in comparison with LEP-1a. As a result, ZnLEP-1a and SeLEP-1a showed great potential to develop into a natural antioxidant, hypoglycemic and low-toxic antitumor drug.