Prasenjit Maity

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.

Structural, immunological, and antioxidant studies of β-glucan from edible mushroom Entoloma lividoalbum

A water soluble β-glucan having molecular weight ∼2×10(5)Da was isolated from hot water extract of the fruit bodies of an edible mushroom Entoloma lividoalbum (Kühner & Romagn) Kubička. This polysaccharide (ELPS) contains (1→3,6)-β-D-Glcp, (1→3)-β-D-Glcp, (1→6)-β-D-Glcp, and terminal β-D-Glcp moieties in a molar ratio of nearly 1:1:3:1. Chemical and spectroscopic analysis showed that the backbone of glucan consists of three (1→6)-β-D-glucopyranosyl and two (1→3)-β-D-glucopyranosyl residues, out of which one (1→3)-β-D-glucopyranosyl moiety was branched at O-6 with a terminal β-D-glucopyranosyl residue. This β-glucan exhibited macrophage, splenocyte, and thymocyte stimulations. It possesses promising antioxidant activities as evidenced from its hydroxyl and superoxide radical scavenging activities and reducing properties.

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.

Structural elucidation and immunostimulating property of a novel polysaccharide extracted from an edible mushroom Lentinus fusipes

A water soluble heteroglycan (PS-II) with an average molecular weight∼60kDa was isolated from the hot aqueous extract of an edible mushroom Lentinus fusipes. The structural characterization of PS-II was carried out using total acid hydrolysis, methylation analyses, periodate oxidation, Smith degradation and 1D/2D NMR experiments. Total acid hydrolysis indicated the presence of D-galactose and D-glucose in a molar ratio of approximately 1:1. The chemical and NMR analyses revealed that the proposed repeating unit of the PS-II had a backbone chain consisting of three (1→6)-linked α-d-galactopyranosyl residue and two (1→6)-linked β-d-glucopyranosyl residues, one of the β-d-glucopyranosyl residue was branched at O-3 position with a terminal β-d-glucopyranosyl. The PS-II exhibited significant in vitro splenocyte and macrophage activations with optimum dose of 20μg/ml and 80μg/ml respectively. Flow cytometry study revealed the protective role of the PS-II against nicotine stimulated lymphocytes. Moreover, the ROS scavenging property of PS-II was also established using DPPH radical scavenging assay.

Structural elucidation and biological studies of a novel exopolysaccaride from Klebsiella pneumoniae PB12

An exopolysaccharide (KNPS) of an average molecular weight ∼1.8×10(5) Da was isolated from the culture medium of Klebsiella pneumoniae PB12. Structural characterization of KNPS was carried out using sugar and methylation analysis, Smith degradation and 1D/2D NMR experiments. Sugar analysis showed that the KNPS composed of arabinose, galactose, 3-O-methyl-galctose and glucose in a molar ratio of nearly 4:3:1:1. The proposed repeating unit of the KNPS has a backbone chain consisting of two (1→6)-galactopyranosyl residues, two (1→5)-arabinofuranosyl residues, one (1→6)-glucopyranosyl residue and one (1→3)-arabinopyranosyl residue, out of which one (1→6)-galactopyranosyl residue was branched at O-2 position with a (1→2)-linked-galactopyranosyl residue terminated with non reducing arabinofuranosyl residue and one (1→5)-arabinofuranosyl residue branched at O-3 position with non reducing end 3-O-Me-galactopyranosyl residue. KNPS was found non-toxic toward human lymphocyte up to the dosage of 100 μg/ml. KNPS enhanced malondialdehyde (MDA), reactive oxygen species (ROS), and have the potential to alter the ratio of oxidized glutathione (GSSG) and reduced glutathione (GSH) levels in the cellular system.

Polysaccharide of an edible truffle Tuber rufum: Structural studies and effects on human lymphocytes.

A water-soluble heteroglycan (PS-II) with average molecular weight ∼7.27×104Da, was isolated from the fruiting bodies of an edible truffle mushroom Tuber rufum (Pico) var. by hot water extraction. The structural investigation of PS-II has been carried out using acid hydrolysis, methylation analysis, periodate oxidation, and 1D/2D NMR experiments. It was composed of d-glucose, d-galactose, l-fucose in a molar ratio of nearly 4:3:1 respectively. On the basis of these experiments, the repeating unit of the PS-II was found to contain a backbone of two (1→6)-α-d-galactopyranosyl, one (1→4)-α-d-glucopyranosyl, two (1→6)-β-d-glucopyranosyl, and one (1→4)-β-d-glucopyranosyl residues, out of which (1→4)-α-d-glucopyranosyl residue was branched at O-2 position with terminal α-l-fucopyranosyl residue and at O-6 position with terminal α-d-galactopyranosyl residue. Ameliorative activities of the PS-II was observed at different concentrations (25, 50, 100, 200, 400μg/ml) and it maintained the redox balance as well as reduced the lipid peroxidation to protect the cell damage.

Structural characterization and evaluation of prebiotic activity of oil palm kernel cake mannanoligosaccharides

In this study, mannanoligosaccharides (MOS) were isolated from palm kernel cake by aqueous extraction using high temperature and pressure. Structural characterization of MOS was carried out using acid hydrolysis, methylation analysis, ESI-MS/MS and 1D/2D NMR. The prebiotic activity of MOS was evaluated in vitro using two probiotic Lactobacillus strains. Sugar analysis indicated the presence of mannose in each of the oligomers. Methylation and 1D/2D NMR analysis indicated that the MOS have a linear structure consisting of (1→4)-β-d-mannopyranosyl residues. ESI-MS/MS results showed that the isolated mannan oligomers, MOS-III, MOS-IV, MOS-V and MOS-VI consist of tetra-, penta-, hexa-, and hepta-saccharides with molecular weights of 689, 851, 1013 and 1151Da, respectively. Based on the in vitro growth study, MOS-III and MOS-IV was found to be effective in selectively promoting the growth of Lactobacillus reuteri C1 strain as evidenced by the optical density of the culture broth.