Structural Characterization And Physicochemical Properties Of Polysaccharides From Huangshan Floral Mushroom

Huangshan floral mushroom, which grows in Huangshan Mountain in Anhui, is a kind of natural edible fungus. It’s famous for the high nutritional value, big fruiting body and delicious flavor. In this paper, the extraction and separation technologies, structural characterization methods, pharmacological experiments, rheological methods and macromolecular physics theory were used to study the polysaccharides, the main active chemical components, in Huangshan floral mushrooms. The research results were as following:(1) Four neutral polysaccharides, FMP1、FMP2-1、FMP3-1 and FMPS, were extracted and purified from Huangshan floral mushroom and their molecular weights were 9.21×106 Da、8.4×106 Da、5.74×105 Da and 7.2×105 Da, respectively. FMP1 was composed of mannose, glucose and galactose with the molar ratio 1.00:9.33: 1.02; FMP2-1 and FMPS were composed of glucose; FMP3-1 was composed of mannose, glucose and galactose with the molar ratio 1.00:9.23:0.5. Results of the structure analysis showed that:The backbone of FMP1 consisted of (1�'4)-β-D-Glcp and (1�'4)-α-D-Manp with the branched chains (1�'3)-β-D-Glcp、(1�'6)-β-D-Glcp、 T-α-D-Glcp and T-β-D-Galp substituted at O-2/O-3 position of (1�'4)-β-D-Glcp and O-3 position of (1�'4)-α-D-Manp. The backbone of FMP2-1 consisted of (1�'4)-α-D-Glcp and (1�'6)-β-D-Glcp with the branched chain T-β-D-Glcp substituted at O-6 position of (1�'4)-α-D-Glcp. The backbone of FMP3-1 consisted of (1�'4)-β-D-Glcp、(1�'6)-β-D-Glcp and (1�'6)-β-D-Manp with the branched chains T-β-D-Glcp and T-β-D-Galp substituted at O-3 position of (1�'6)-β-D-Glcp and (1�'6)-β-D-Manp. The backbone of FMPS consisted of (1�'3)-β-D-Glcp with the branched chain T-β-D-Glcp substituted at O-6 position of the backbone. The advanced structure studies indicated that FMPS was a triple-helical polysaccharide. (2) The rheological studies indicated that FMPS solution was a pseudoplastic fluid and the storage modulus G’and the loss modulus G" of FMPS exhibited strong dependences on the concentration and temperature. The exponent n of G’～ωn and tan δ exhibited strong dependences on the concentration and temperature. The gel point (cgel) of FMPS solution was 1.16×10-2 g/mL at 15℃, and the Tgel of 1.4×10-2 g/mL FMPS solution was 20.6℃. The FMPS gel system had no time dependence and was thermally reversible. (3) The optimal conditions of orthogonal test for sulfation of FMPS were reaction temperature of 100℃, reaction time of 2 h and chlorosulfonic acid-pyridine ratio of 1:4. The sulfuric acid group substitution degree of FMPS could reach 2.08 on this condition. (4) The immunoregulatory activity experiments showed that FMP1、FMP2-1 and FMP3-1 could promote the proliferation and NO production of macrophage RAW 264.7 and enhance the phagocytosis. The lack of branched chain could reduce this effect. The antioxidant experiments showed that FMPS exhibited high DPPH radical scavenging activities (79.46% at 5 mg/mL) and hydroxyl radical scavenging activities (74.18% at 5 mg/mL), as well as Fe2+ chelating activities and ABTS radical scavenging activities to some extent. The antitumor activity experiments indicated that different substitution degrees of FMPS-S had different inhibitory activities on liver cancer cells HepG2. The FMPS-S2 had the best tumor inhibitory activities at various concentrations and the highest inhibition rate could reach 42.30%. The results have a certain guiding significance for the development of Huangshan floral mushroom and the polysaccharides in it.