Purification, Characterization and Immunomodulatory Activities of Polysaccharides from Mulberry Leaf Fermented with Phellinus igniarius

Abstract

Phellinus igniarius is a rare and precious medicinal fungus, displaying an outstanding physiological effect, especially the immunomodulatory effects. Previous studies indicated that water-soluble crude polysaccharide (MPFP) was obtained from mulberry leaf fermented with Phellinus igniarius. In vitro cell assay revealed that MPFP showed higher immunomodulatory activity than that of mulberry leaves polysaccharide (MP) and Phellinus igniarius mycelial polysaccharide (PP). Therefore, in this study, structure and immunomodulatory activity of MPFP were measured, a novel polysaccharide named MPFP2-1 was separated through DEAE-52 cellulose column and SephadexG-100 gel-filtration chromatography. Monosaccharide composition analysis showed that MPFP2-1 was mainly composed of L-rhamnose and D-glucose with the molar ratio of 1.0:5.4. The average molecular weight was 50.3 kDa by high performance gel permeation chromatography (HPGPC). FT-IR spectrum showed that MPFP2-1 contained a characteristic absorption peak of polysaccharide. The NMR spectrum indicated MPFP2-1 contained 1 → 6 glucosidic bond. In vitro immunomodulatory assay revealed that MPFP2-1 significantly enhanced the macrophages proliferation, stimulated the macrophages phagocytic capacity, as well as induced NO and TNF-a generation. We further discovered that MPFP2-1 stimulated iNOS and TNF-α protein expression in RAW264.7 cells by western blotting. The results are in agreement with ELISA. All the results suggest that MPFP2-1 possesses potent immunomodulatory activity and could be taken forward as new products for medicines.