Identification Of Boletus Reticulatus Schaeff And Studies On Structure Identification,Immunological Activity And The Mechanism Of Anti-tumor Activity Of The Polysaccharide(BRS-X)

Boletus reticulatus Schaeff belongs to Boletales,Boletaceae and Boletus.B.reticulatus Schaeff has medium to large fruiting bodies,which are edible and delicious.In this paper,we studied the structure,immunological activities and the mechanism of antitumor activities of the polysaccharide of B.reticulatus Schaeff fruiting bodies collected from Xiaojin County of Sichuan Province.The results were as follows:(1)The wild edible fungi collected from Xiaojin County of Sichuan Province were identified as B.reticulatus Schaeff by combining morphological characteristics and the result of ITS sequence analysis.(2)The isolated and purified homogeneous polysaccharide was named BRS-X and its molecular weight was 150,935 Da.(3)Based on experimental results of fourier transform infrared spectroscopy(FT-IR),high performance liquid chromatography(HPLC),nuclear magnetic resonance(NMR)and gas chromatography-mass spectrometry(GC-MS),the structure of BRS-X was that the main chain was(1→6)-α-D-Galactopyranose and the side chain was →4)-β-D-Glucopyranose attached to the C2 of Galactopyranose,and the ratio of Galactopyranose to Glucopyranose was 5:1.(4)The results of immunological activities assays showed that the BRS-X group could significantly promote the proliferation activities of T cells,B cells and RAW264.7 cells compared with the blank control group.When the concentration of BRS-X was 20 μg/mL,it had the greatest influence on the proliferation activity of T cells and B cells,and the proliferation rate reached 38.88% and 30.97%,respectively.Moreover,compared with the blank control group,BRS-X could promote the secretion of immunoglobulins by B cells.When the concentration of BRS-X was 10 μg/mL,it had the greatest influence on the proliferation activity and phagocytic activity of RAW264.7 cells.The proliferation rate reached 122.49%,and the phagocytosis rate reached 67.74%.(5)The results of in vitro antitumor activity assay showed that the BRS-X group could significantly inhibit the growth of S180 cells compared with the blank control group.When the concentration of BRS-X was 10 μg/mL,the inhibitory effect on S180 cells was the strongest,and the inhibition rate was 39.74%.The experimental results of S180-bearing mice model in vivo showed that the BRS-X group had significant anti-tumor activity compared with the model group,and the inhibition rate was 37.86%.(6)KEGG signaling pathways analysis of transcriptome sequencing results revealed that the genes were mainly concentrated in the mitogen-activated protein kinase(MAPK)signaling pathway and the phosphatidylinositol 3-kinase/protein kinase B(PI3K/AKT)signaling pathway.The results of enzyme-linked immunosorbent assay(ELISA)of tumor tissues showed that in the BRS-X group,the expression levels of TNF-α and IL-1? were significantly increased,and the expression levels of VEGFR,VEGF and IL-6 were significantly decreased.A novel polysaccharide(BRS-X)from B.reticulatus Schaeff fruiting bodies was introduced in this paper.It has been found that BRS-X had significant immunological and antitumor activities,and the molecular mechanism of its antitumor activity had been preliminarily revealed.The above research contributes to the development and utilization of B.reticulatus Schaeff,and provides a scientific basis for the medicinal value of BRS-X.