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Russula virescens is an edible wild mushroom that is widely distributed in south of China. This research aimed to analyze the structure characterization and evaluate the hypoglycemic, anticancer and immunological activities of two water soluble polysaccharides RVP-1 and RVP-2 from R. virescens. The results showed RVP-1 and RVP-2 were non-triple helix structured hetero-polysaccharides with different weight-average molecular weight 14,883 and 13,301 Da, respectively. Both RVP-1 and RVP-2 were composed of galactose, glucose, mannose and fructose, and the sugar residues were mainly linked by 1,6→, 1,2→, 1→ and 1,3,6→ glycosidic bonds. Moreover, the antidiabetic, anticancer and immune activities of RVP-1 and RVP-2 were explored in vitro methods. The two polysaccharides have potential for inhibiting α-glucosidase and α-amylase activities, suppressing HepG-2, A549 and MCF-7 cancer cells proliferation, and activating macrophage RAW 264.7 cells to secret immune cytokines for mediating cellular immune response. These findings provided a scientific basis for further utilization of polysaccharide from R. virescens.

The water-soluble polysaccharide from fruiting bodies of Russula virescens (RVP) was sulfated using sulfur trioxide·pyridine complex method under different reaction conditions. Five sulfated RVP derivatives (SRVP1-5, SRV1-10, SRVP1-15, SRVP1-20 and SRVP1-25) with different degrees of substitution (DS) ranging from 0.34 to 0.73 were prepared. Several structural features of RVP and SRVPs including chemical structure, monosaccharide composition, molecular weight and chain conformation were investigated. The spectra results indicated that the sulfate groups were successfully introduced on RVP. The molecular weights of SRVP decreased with the increasing DS. Both RVP and SRVPs were mainly composed of mannose, glucose and galactose, with different molar ratios. The triple-helical conformation was broken down into a random coil when the DS exceeded 0.34. In vitro activity test results indicated that the SRVPs showed better antioxidant, anticoagulant, antibacterial and anti-tumor activities compared with RVP. Among the five sulfated derivatives, SRVP1-25 exhibited the strongest ABTS and hydroxyl radical scavenging activities and anticoagulant activity, while SRVP1-20 showed the best antibacterial activity and anti-tumor activity. These results demonstrated that the SRVPs could be developed as one of potential antioxidant, anticoagulant, antibacterial and anti-tumor agents for industrial and biomedical use.

Water-soluble crude polysaccharide named as RVP was obtained from the fresh fruiting bodies of Russula virescens by boiling-water extraction. DEAE-Sepharose CL-6B column chromatography was used for the fractionation of polysaccharide RVP. Two fractions were obtained, namely RVP-1 and RVP-2. RVP-1 and RVP-2 were composed mainly of glucose, with the estimated equivalent dextran molecular weights of 3.1 × 10 5 and 4.2 × 10 5 Da, respectively. Analysis by Periodate oxidation–Smith degradation indicated that RVP-1 was composed of 68.3% (1 →)- or ((1 → 6)-glycosidic linkages and 31.7% (1 → 3)-glycosidic linkages, and RVP-2 7.9% (1 →)- or (1 → 6)-glycosidic linkages, 9.6% (1 → 2)-glycosidic linkages, 35.7% (1 → 4)-glycosidic linkages, and 46.8% (1 → 3)-glycosidic linkages. RVP-1 exhibited equivalent inhibiting power for self-oxidation of 1,2,3-phentriol to vitamin C (Vc), a little higher scavenging activity of superoxide radical and hydroxyl radical than Vc. The reducing power of RVP-1 at 20.0 mg/ml was 0.77, and RVP-1 was a good chelating agent for ferrous ions. Overall, RVP-1 possessed good antioxidant properties and should be developed as a novel potential antioxidant.

The metal (Cu, Ni, Cd, Hg, As, Pb) contents in wild edible mushrooms collected from three different sites in China were determined by atomic absorption spectrometry and atomic fluorescence spectrometry. All element concentrations were determined on a dry weight basis. A total of 11 species was studied, five being from the urban area and six from rural areas in China. The As content ranged from 0.44 to 1.48 mg/kg. The highest As content was seen in Macrolepiota crustosa from the urban area, and the lowest in Russula virescens from rural areas. A high Ni concentration (1.35 mg/kg) was found in Calvatia craniiformis from the urban area. The lowest Ni level was 0.11 mg/kg, for the species R. virescens and Cantharellus cibarius. The Cu content ranged from 39.0 to 181.5 mg/kg. The highest Cu content was seen in Agaricus silvaticus and the lowest in C. cibarius. The Pb content ranged from 1.9 to 10.8 mg/kg. The highest Pb value was found in C. craniiformis. The Cd content ranged from 0.4 to 91.8 mg/kg. The highest Cd value was found in M. crustosa. The Hg content ranged from 0.28 to 3.92 mg/kg. The highest Hg level was found in Agaricus species. The levels of the heavy metals Cd, Pb, and Hg in the studied mushroom species from urban area can be considered high. The metal-to-metal correlation analysis supported they were the same source of contamination. High automobile traffic was identified as the most likely source of the contamination. Based upon the present safety standards, consumption of those mushrooms that grow in the polluted urban area should be avoided.

A monomeric feruloyl esterase (FAE) with a molecular mass of 62 kDa was acquired from fresh fruiting bodies of the edible mushroom Russula virescens. The isolation procedure involved ion exchange chromatography on CM-cellulose, Q-Sepharose, and SP-Sepharose and finally fast protein liquid chromatography-gel filtration on Superdex 75. Two amino acid sequences were obtained after tryptic digestion, and they both showed some homology with the esterase of some fungi. Maximal activity was observed at pH 5.0 and at 50 °C. The enzyme displayed relatively high thermostability as evidenced by over 70 % residual activity at 70 °C and about 34 % residual activity at 80 °C. The K m and V max for this enzyme on methyl ferulate were 0.19 mM and 1.65 U/mg proteins, respectively. The purified FAE prefers methyl ferulate over methyl caffeate and is least active on methyl p-coumarate. The FAE activity was not significantly affected by the presence of cations such as Mn(2+), Ca(2+), Cd(2+), Zn(2+), Mg(2+), Cu(2+), and K(+) ions but inhibited by Al(3+), Hg(2+), Fe(2+), and Pb(2+) ions at a tested concentration of 2. 5 mM.