Ashis K. Nandi

Antioxidant and immunostimulant β-glucan from edible mushroom Russula albonigra (Krombh.) Fr.

A water soluble β-glucan (PS) with an average molecular weight ∼1.95 × 10(5)Da was isolated from the alkaline extract of ectomycorrhizal edible mushroom, Russula albonigra (Krombh.) Fr. and found to consist of terminal, (1 → 3)-, (1 → 6)-, and (1 → 3,6)-linked β-D-glucopyranosyl moieties in a ratio of nearly 1:2:2:1. The structure of this PS was elucidated on the basis of total hydrolysis, methylation analysis, Smith degradation, partial hydrolysis, and 1D/2D NMR experiments. On the basis of these experiments, the repeating unit of the PS was found to contain a backbone of three (1 → 6)-β-D-glucopyranosyl residues, one of which was branched at O-3 position with the side chain consisting of two (1 → 3)-β-D-glucopyranosyl and a terminal β-D-glucopyranosyl residue. This PS showed in vitro macrophage activation by NO production as well as splenocytes and thymocytes proliferation. Moreover, it also exhibited potent antioxidant activities.

Structure elucidation and antioxidant properties of a soluble β-d-glucan from mushroom Entoloma lividoalbum

A water soluble branched β-D-glucan (PS-I) with an average molecular weight ~2.1×10(5) Da was isolated from alkaline extract of the fruit bodies of the edible mushroom Entoloma lividoalbum (Kühner & Romagn) Kubička which consists of terminal β-D-glucopyranosyl, (1→3)-β-D-glucopyranosyl, (1→6)-β-D-glucopyranosyl, and (1→3,6)-β-D-glucopyranosyl moieties in a molar ratio of nearly 1:3:2:1. The structure of PS-I was elucidated using acid hydrolysis, methylation analysis, periodate oxidation study, partial hydrolysis, and 1D/2D NMR experiments. The repeating unit of the polysaccharide (PS-I) contains a backbone chain of three (1→6)-β-D-glucopyranosyl residues, one of which was branched at O-3 position with the side chain consisting of three (1→3)-β-D-glucopyranosyl and a terminal β-D-glucopyranosyl residues. Total antioxidant capacity of 1mg PS-I was measured and found equivalent to 70±15 μg of ascorbic acid. The PS-I was found to possess hydroxyl and superoxide radical-scavenging activities with EC50 values of 480 and 150 μg/mL, respectively. The reducing power of PS-I was determined 0.5 at 480 μg/mL.

Glucan from hot aqueous extract of an ectomycorrhizal edible mushroom, Russula albonigra (Krombh.) Fr.: structural characterization and study of immunoenhancing properties

A water soluble glucan (PS-I) was isolated from the hot aqueous extract of the fruit bodies of an ectomycorrhizal edible mushroom, Russula albonigra (Krombh.) Fr. The total hydrolysis, methylation analysis, periodate oxidation, and NMR ((1)H, (13)C, DEPT-135, TOCSY, DQF-COSY, NOESY, ROESY, HSQC, and HMBC) studies revealed the presence of the following repeating unit in the polysaccharide: This glucan showed excellent activation of macrophages as well as splenocytes and thymocytes in vitro.

Structural and immunological studies of hetero polysaccharide isolated from the alkaline extract of Tricholoma crassum (Berk.) Sacc.

An immunoenhancing water-soluble hetero polysaccharide was isolated from an alkaline extract of the fruit bodies of an ectomycorrhizal edible mushroom, Tricholoma crassum (Berk.) Sacc. The structure of the molecule was investigated using acid hydrolysis, methylation analysis; periodate oxidation study, and NMR spectroscopy techniques ((1)H, (13)C, DEPT-135, DQF-COSY, TOCSY, NOESY, ROESY, HSQC, and HMBC). On the basis of the above-mentioned experiments the structure of the repeating unit of the polysaccharide was established as: This polysaccharide exhibited splenocyte, thymocyte as well as macrophage activations.

A glucan from an ectomycorrhizal edible mushroom Tricholoma crassum (Berk.) Sacc.: isolation, characterization, and biological studies

A water soluble glucan of average molecular weight ∼1.74×10(5)Da was isolated from hot aqueous extract of the fruiting bodies of an ectomycorrhizal edible mushroom Tricholoma crassum (Berk.) Sacc. The structure of this glucan was elucidated on the basis of total hydrolysis, methylation analysis, Smith degradation, and 1D/2D NMR studies. Based on the above experiments the repeating unit of the glucan was established as: [formula see text]. This glucan showed macrophage activation in vitro by NO production in a dose dependent manner and strong splenocyte and thymocyte immunostimulation in mouse cell culture medium. It also exhibited good inhibition activity toward lipid peroxidation.

Structural elucidation of an immunoenhancing heteroglycan isolated from Russula albonigra (Krombh.) Fr.

A water soluble heteroglycan (PS-II) of average molecular weight ∼1.45 × 10(5)Da was isolated from the aqueous extract of an ectomycorrhizal edible mushroom, Russula albonigra (Krombh.) Fr. Structural characterization of PS-II was carried out using acid hydrolysis, methylation analysis, periodate oxidation, and 1D/2D NMR studies. Structural analysis revealed that PS-II was composed of terminal 2-O-methyl-Fucp, terminal Manp, (1→2)-Fucp, (1→3)-Glcp, (1→3,4)-Glcp, (1→6)-Galp, and (1→2,6)-Galp residues in a relative proportion of approximately 1:1:1:1:1:1:1. The proposed repeating unit of the PS-II had a backbone consisting of two (1→3)-β-d-glucopyranosyl, two (1→6)-α-d-galactopyranosyl, and one (1→2)-α-l-fucopyranosyl residues, out of which one (1→3)-β-d-glucopyranosyl residue was branched at O-4 position with terminal 2-O-methyl-α-l-fucopyranosyl and one (1→6)-α-d-galactopyranosyl residue was branched at O-2 position with terminal α-d-mannopyranosyl residue. This PS-II showed in vitro macrophage activation by NO production as well as splenocytes and thymocytes proliferation.

Heteroglycan of an edible mushroom Entoloma lividoalbum: Structural characterization and study of its protective role for human lymphocytes

A water soluble heteroglycan (PS-II) of an average molecular weight ∼5.2×10(4)Da was isolated from the alkaline extract of an edible mushroom Entoloma lividoalbum (Kühner & Romagn) Kubička. Structural characterization of PS-II was carried out using sugar and methylation analysis, periodate oxidation study, and 1D/2D NMR experiments. Sugar analysis indicated the presence of glucose, mannose, galactose, and fucose in a molar ratio of nearly 5:1:2:1. The repeating unit of the PS-II had a backbone consisting of two (1→3)-β-d-glucopyranosyl, one (1→6)-β-d-glucopyranosyl, one (1→2)-α-L-fucopyranosyl, one (1→6)-α-d-glucopyranosyl, and two (1→6)-α-d-galactopyranosyl residues, out of which one (1→3)-β-d-glucopyranosyl residue was branched at O-6 position with terminal β-d-glucopyranosyl residue and one (1→6)-α-d-galactopyranosyl residue was branched at O-2 position with terminal β-d-mannopyranosyl residue. PS-II showed ameliorative activities at different concentrations (50, 100, 200, 400μg/ml) and maintained the redox balance as well as reduced the lipid peroxidation to protect the cell destruction.

Studies on antioxidative and immunostimulating fucogalactan of the edible mushroom Macrolepiota dolichaula

A water soluble fucogalactan (PS-II) of an average molecular weight ∼1.2×10(5) Da was isolated from the aqueous extract of an edible mushroom Macrolepiota dolichaula. It was composed of fucose, galactose and 3-O-methyl galactose in a molar ratio of nearly 1:4:1. Structural characterization of PS-II was carried out using total hydrolysis, methylation analysis, Smith degradation, and 1D/2D NMR experiments. These results indicated that the proposed repeating unit of the PS-II had a backbone chain consisting of four (1→6)- linked α-d-Galp residues, one residue methylated at O-3, and another one substituted at O-2 by (1→2)-α-d-Galp residue, which is terminated with a α-l-Fucp moiety. The PS-II exhibited the antioxidant properties in different in vitro test systems, and also showed in vitro macrophage activation in RAW 264.7 cell line as well as splenocyte and thymocyte activation in mouse cell culture medium.

A partially methylated mannogalactan from hybrid mushroom pfle 1p: purification, structural characterization, and study of immunoactivation

A new water-soluble heteropolysaccharide (PS-II) with apparent molecular weight ∼1.65×10(5) Da, was isolated from the fruiting bodies of hybrid mushroom pfle 1p by hot aqueous extraction. It is composed of d-mannose, d-galactose, and 3-O-Me-d-galactose in a molar ratio of 1.0:0.99:1.1. The structural investigation of PS-II has been carried out using acid hydrolysis, methylation analysis, periodate oxidation study, and 1D/2D NMR experiments. Based on the results of these experiments, it was established that PS-II contained a main chain of (1→6) linked α-d-galactopyranosyl residues, one of which was substituted at C-2 by a terminal mannopyranosyl residue and also methylated at C-3 position. This heteropolysaccharide (PS-II) exhibited macrophage activation by NO production as well as in vitro splenocyte and thymocyte stimulation.

A water soluble β-glucan of an edible mushroom Termitomyces heimii: Structural and biological investigation.

A water soluble β-glucan (PS-I) with an average molecular weight ∼ 1.48 × 10(5)Da was isolated from the alkaline extract of an edible mushroom Termitomyces heimii. PS-I contained (1 → 3)-, (1 → 6)-, (1 → 3, 6)-linked and terminal β-d-glucopyranosyl moieties in a ratio of nearly 2:1:1:1. Based on the total hydrolysis, methylation analysis, periodate oxidation, Smith degradation, partial hydrolysis and 1D/2D NMR experiments the structure of the PS-I was elucidated. On the basis of these experiments, the repeating unit of the polysaccharide was found to consist of a backbone chain of two (1 → 6)-β-D-glucopyranosyl residues, one of which was branched at O-3 position with the side chain consisting of two (1 → 3)-β-D-glucopyranosyl and a terminal β-D-glucopyranosyl residue. Cytotoxic effect of PS-I on human blood lymphocytes at varied concentrations was studied. Moreover, it also exhibited potent antioxidant activities by diminishing the ROS and NO in the nicotine stimulated lymphocytes up to 200 μg/ml.