Structural characterization of a heteroglycan from an edible mushroom Termitomyces heimii.

A water soluble heteroglycan (THPS) of an average molecular weight ~1.98 × 105 Da was isolated from the aqueous extract of the fruit bodies of an edible mushroom Termitomyces heimii. Structural characterization of THPS was carried out using acid hydrolysis, methylation analysis, periodate oxidation, Smith degradation and 1D/2D NMR studies. Sugar analysis indicated the presence of glucose, mannose, galactose, and fucose in a molar ratio of nearly 6:2:2:1. The repeating unit of the THPS had a backbone consisting of four (1 â†’ 3)-ß-d-glucopyranosyl, one (1 â†’ 6)-ß-d-glucopyranosyl, two (1 â†’ 3)-α-D-manopyranosyl, and two (1 â†’ 6)-α-D-galactopyranosyl residues, out of which one (1 â†’ 3)-ß-d-glucopyranosyl residue was branched at O-6 position with terminal ß-d-glucopyranosyl residue and one (1 â†’ 6)-α-D-galactopyranosyl residue was branched at O-2 position with terminal α-L-fucopyranosyl residue.

Studies on structure and antioxidant properties of a heteroglycan isolated from wild edible mushroom Lentinus sajor-caju.

A water-soluble heteroglycan (PS-I) isolated from the aqueous extract of a wild edible mushroom Lentinus sajor-caju showed average molecular weight ∼1.79×105Da. The structure of the polysaccharide was determined using chemical and 1D/2D NMR experiments. Acid hydrolysis indicated the presence of d-glucose, d-galactose, d-mannose, and l-fucose in a molar ratio of nearly 4:4:1:1 respectively. The presence of terminal Fucp, terminal Galp, (1→3)-Glcp, (1→6)-Galp, (1→6)-Glcp, (1→4,6)-Galp, and (1→2,4)-Manp moieties were established from methylation analysis. The chemical and NMR analyses indicated that the PS-I was a heteroglycan composed of a repeating unit with backbone chain of three (1→6)-α-d-galactopyranosyl residues, two (1→6)-ß-d-glucopyranosyl residues, one (1→4)-α-d-mannopyranosyl residue, and two (1→3)-ß-d-glucopyranosyl residues where one (1→6)-α-d-galactopyranosyl residue was branched at O-4 position with terminal α-l-fucopyranosyl residue and (1→4)-α-d-mannopyranosyl residue was branched at O-2 position with terminal α-d-galactopyranosyl residue and the structure was proposed as; The PS-I is a moderate antioxidant compound which showed DPPH radical scavenging activity, hydroxyl radical scavenging activity, ABTS radical scavenging property, reducing power, and ferrous ion chelating ability.

GBF1 differentially regulates CAT2 and PAD4 transcription to promote pathogen defense in Arabidopsis thaliana.

G-BOX BINDING FACTOR 1 (GBF1) influences light-regulated seedling development in Arabidopsis, and inhibits CATALASE 2 (CAT2) expression during senescence. CAT2 functions as a scavenger of hydrogen peroxide. The role of GBF1 in the defense response is not known. We report here that GBF1 positively influences the defense against virulent and avirulent strains of Pseudomonas syringae. The gbf1 mutants are susceptible, whereas GBF1 over-expresser transgenic plants are resistant to bacterial pathogens. GBF1 negatively regulates pathogen-induced CAT2 expression and thereby positively regulates the hypersensitive response. In addition to CAT2 promoter, GBF1 binds to the G-box-like element present in the intron of PHYTOALEXIN DEFICIENT 4 (PAD4). This association of GBF1 with PAD4 intron is enhanced upon pathogenesis. GBF1 positively regulates PAD4 transcription in an intron-dependent manner. GBF1-mediated positive regulation of PAD4 expression is also evident in gbf1 mutant and GBF1 over-expression lines. Similar to pad4 mutants, pathogen-induced camalexin and salicylic acid (SA) accumulation, and expression of SA-inducible PATHOGENESIS RELATED1 (PR1) gene are compromised in the gbf1 mutant. Exogenous application of SA rescues the loss-of-defense phenotypes of gbf1 mutant. Thus, altogether, our results demonstrate that GBF1 is an important component of the plant defense response that functions upstream of SA accumulation and, by oppositely regulating CAT2 and PAD4, promotes disease resistance in Arabidopsis.

Structural characterization and antioxidant activity of a glucan from Meripilus giganteus.

A new water soluble glucan (MGPS), with a molecular weight ∼1.48×105Da, was isolated from the fruit bodies of Meripilus giganteus by hot water extraction followed by purification through dialysis tubing cellulose membrane and sepharose 6B column chromatography. Its structural characteristics were investigated by acid hydrolysis, methylation analysis, Smith degradation and 1D/2D NMR experiments. The monosaccharide composition analysis showed that MGPS contain only glucose. The backbone of MGPS was composed of two (1→3)-ß-d-glucopyranosyl, two (1→6)-ß-d-glucopyranosyl, two (1→6)-α-d-glucopyranosyl, and one (1→4)-α-d-glucopyranosyl residues, out of which one (1→3)-ß-d-glucopyranosyl residue was branched at O-6 position with terminal α-d-glucopyranosyl residue and one (1→4)-α-d-glucopyranosyl residue branched at O-6 position with terminal ß-d-glucopyranosyl residue. In vitro antioxidant studies showed that the MGPS exhibited hydroxide radical scavenging activity (IC50=390µg/mL), superoxide radical scavenging activity (IC50=70µg/mL), and ferrous ion chelating activity (IC50=290µg/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 ß-d-glucopyranosyl residues, one of the ß-d-glucopyranosyl residue was branched at O-3 position with a terminal ß-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.

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)-ß-d-glucopyranosyl, and one (1→4)-ß-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.

Heteroglycan of an edible mushroom Pleurotus cystidiosus: Structural characterization and study of biological activities.

A water soluble heteroglycan (PCPS) was isolated from the aqueous extract of an edible mushroom Pleurotus cystidiosus. Structural characterization of the heteroglycan was carried out using total hydrolysis, methylation analysis, periodate oxidation, Smith degradation, and 1D/2D NMR experiments. Sugar analysis indicated the presence of glucose, galactose, and mannose in a molar ratio of nearly 6:2:1 respectively. The chemical and NMR analysis of the PCPS indicated the presence of a repeating unit with a backbone consisting of one unit of (1→6)-ß-d-glucopyranosyl, two (1→3)-ß-d-glucopyranosyl, one (1→3)-α-d-glucopyranosyl, one (1→6)-α-d-glucopyranosyl, and two (1→6)-α-d-galactopyranosyl moieties respectively, out of which one (1→3)-ß-d-glucopyranosyl residue was branched at O-6 with terminal ß-d-glucopyranosyl and another (1→6)-α-d-galactopyranosyl residue was branched at O-2 with terminal ß-d-mannopyranosyl moiety. The polysaccharide was found to exhibit cellular activities at different concentrations (10, 25, 50, 100, 200, 400µg/mL) and maintained the redox balance as well as reduced lipid per oxidation which protect the cell destruction.

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

A water soluble ß-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 ß-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)-ß-D-glucopyranosyl residues, one of which was branched at O-3 position with the side chain consisting of two (1 → 3)-ß-D-glucopyranosyl and a terminal ß-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.

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.

Heteroglycan of an edible mushroom Termitomyces clypeatus: structure elucidation and antioxidant properties.

A water-soluble heteroglycan (PS) of an average molecular weight ∼1.98 ×10(5) Da was isolated from the aqueous extract of an edible mushroom Termitomyces clypeatus (R. Heim). The structure of the polysaccharide (PS) was established using total hydrolysis, methylation analysis, Smith degradation, and 1D/2D NMR experiments. Total hydrolysis indicated the presence of d-glucose, d-galactose, d-mannose, and l-fucose in a molar ratio of 4.10:1.95:1.0:0.95, respectively. The chemical and NMR analysis indicated the presence of a repeating unit with a backbone consisting of one each of the residues (1→3)-α-d-galactopyranosyl, (1→3)-α-d-mannopyranosyl, (1→3)-α-d-glucopyranosyl, (1→3)-ß-d-glucopyranosyl, (1→6)-ß-d-glucopyranosyl, and (1→6)-α-d-galactopyranosyl, respectively. The (1→3)-α-d-mannopyranosyl residue was found branched at O-2 with terminal α-l-fucopyranosyl moiety and (1→3)-ß-d-glucopyranosyl residue was branched at O-6 with terminal α-d-glucopyranosyl residue. The PS exhibited antioxidant properties.

Interconnection between flowering time control and activation of systemic acquired resistance.

The ability to avoid or neutralize pathogens is inherent to all higher organisms including plants. Plants recognize pathogens through receptors, and mount resistance against the intruders, with the help of well-elaborated defense arsenal. In response to some localinfections, plants develop systemic acquired resistance (SAR), which provides heightened resistance during subsequent infections. Infected tissues generate mobile signaling molecules that travel to the systemic tissues, where they epigenetically modify expression o a set of genes to initiate the manifestation of SAR in distant tissues. Immune responses are largely regulated at transcriptional level. Flowering is a developmental transition that occurs as a result of the coordinated action of large numbers of transcription factors that respond to intrinsic signals and environmental conditions. The plant hormone salicylic acid (SA) which is required for SAR activation positively regulates flowering. Certain components of chromatin remodeling complexes that are recruited for suppression of precocious flowering are also involved in suppression of SAR in healthy plants. FLOWERING LOCUS D, a putative histone demethylase positively regulates SAR manifestation and flowering transition in Arabidopsis. Similarly, incorporation of histone variant H2A.Z in nucleosomes mediated by PHOTOPERIOD-INDEPENDENT EARLY FLOWERING 1, an ortholog of yeast chromatin remodeling complex SWR1, concomitantly influences SAR and flowering time. SUMO conjugation and deconjugation mechanisms also similarly affect SAR and flowering in an SA-dependent manner. The evidences suggest a common underlying regulatory mechanism for activation of SAR and flowering in plants.

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) Kubicka. 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)-ß-d-glucopyranosyl, one (1→6)-ß-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)-ß-d-glucopyranosyl residue was branched at O-6 position with terminal ß-d-glucopyranosyl residue and one (1→6)-α-d-galactopyranosyl residue was branched at O-2 position with terminal ß-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.

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.

Structure elucidation and antioxidant properties of a soluble ß-D-glucan from mushroom Entoloma lividoalbum.

A water soluble branched ß-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) Kubicka which consists of terminal ß-D-glucopyranosyl, (1→3)-ß-D-glucopyranosyl, (1→6)-ß-D-glucopyranosyl, and (1→3,6)-ß-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)-ß-D-glucopyranosyl residues, one of which was branched at O-3 position with the side chain consisting of three (1→3)-ß-D-glucopyranosyl and a terminal ß-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.

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

A water soluble ß-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 ß-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)-ß-D-glucopyranosyl residues, one of which was branched at O-3 position with the side chain consisting of two (1 → 3)-ß-D-glucopyranosyl and a terminal ß-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.

Structural characterization of an immunoenhancing glucan isolated from a mushroom Macrolepiota dolichaula.

A water soluble branched glucan (PS-I) was isolated from aqueous extract of the fruit bodies of an edible mushroom Macrolepiota dolichaula, having average molecular weight ~2.02×10(5) Da. The structure of this PS-I was determined using total hydrolysis, methylation analysis, Smith degradation, partial hydrolysis, and 1D/2D NMR experiments. Total hydrolysis and methylation analysis results showed the presence of (1→3, 6)-, (1→6)-, (1→4)-, (1→3)-linked and terminal ß-D-glucopyranosyl residues in a relative proportion of nearly 1:2:1:1:1. All the chemical and NMR results indicated that the PS-I was a branched glucan, and the repeating unit of this glucan consisted of a backbone chain of three (1→6)-linked-ß-D-glucopyranosyl residues where one of the backbone residues is branched at O-3 with (1→3)- moiety which is further attached to another (1→4)- residue and terminated with a non-reducing ß-D-glucopyranosyl residue. The PS-I exhibited in vitro macrophage activation in RAW 264.7 cell line as well as splenocyte and thymocyte activation in mouse cell culture medium.

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)-ß-d-glucopyranosyl, two (1→6)-α-d-galactopyranosyl, and one (1→2)-α-l-fucopyranosyl residues, out of which one (1→3)-ß-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.

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.

Pectic polysaccharide from immature onion stick (Allium cepa): structural and immunological investigation.

The structure of a water-soluble pectic polysaccharide (PS) isolated from immature onion stick (Allium cepa) was investigated using acid hydrolysis, methylation analysis, periodate oxidation study, and NMR studies ((1)H, (13)C, DQF-COSY, TOCSY, NOESY, ROESY, HSQC, and HMBC). The results of the above experiments indicated that the PS contained d-galactose, 6-O-Me-D-galactose, 3-O-acetyl-D-methyl galacturonate and D-methyl galacturonate in a molar ratio of nearly 1:1:1:1 and possesses a backbone of [→4)-α-D-GalpA6Me-(1→4)-α-D-GalpA6Me-(1→] in which one methyl galacturonate was substituted at O-3 position by an acetyl group and the neighboring methyl galacturonate being substituted at O-2 with a side chain, α-D-Galp-(1→4)-6-O-Me-ß-D-Galp-(1→. The probable structure of repeating unit of the pectic polysaccharide was established as: [formula in text] The pectic polysaccharide showed in vitro splenocyte, thymocyte as well as macrophage activations.

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.