A xylan from the fresh leaves of Piper betle: Structural characterization and studies of bioactive properties.

A pure water soluble xylan (PS-I) with an average molecular weight ~1.1 × 105 Da was isolated from the hot water extraction of fresh leaves of Piper betle (paan). The xylan was found to be composed of xylose, galactose and methyl galacturonate in a molar ratio of nearly 3:1:1. The repeating unit was composed of a backbone containing three (1 â†’ 4)-α-D-Xylp residues, one of which was branched at O-2 position with the side chain consisting of (1 â†’ 4)-α-D-GalpA6Me and terminal ß-D-Galp residues. This xylan exhibited macrophage, splenocyte, and thymocyte stimulatory activities. In vitro antioxidant studies demonstrated that the xylan has DPPH radical scavenging potential (EC50 = 148 µg/mL), ABTS radical quenching activity (EC50 = 188 µg/mL) and ferrous ions chelating activity (EC50 = 370 µg/mL). These findings elicit the need for further exploration of the xylan as a natural antioxidant and a potent immunostimulating agent.

A review on antiviral and immunomodulatory polysaccharides from Indian medicinal plants, which may be beneficial to COVID-19 infected patients.

The emergence of the novel coronavirus, SARS-CoV-2 has pushed forward the world to experience the first pandemic of this century. Any specific drug against this RNA virus is yet to be discovered and presently, the COVID-19 infected patients are being treated symptomatically. During the last few decades, a number of polysaccharides with potential biological activities have been invented from Indian medicinal plants. Many polysaccharides, such as sulfated xylomannan, xylan, pectins, fucoidans, glucans, glucoarabinan, and arabinoxylan from Indian medicinal plants, have been shown to exhibit antiviral and immunomodulating activities. Plant polysaccharides exhibit antiviral activities through interference with the viral life cycle and inhibition of attachment of virus to host cell. Intake of certain immune stimulating plant polysaccharides may also protect from the virus to a certain extent. In process of continuous search for most potent drug, Indian plant polysaccharides may emerge as significant biomaterial to combat COVID-19. This review explores a number of polysaccharides from Indian medicinal plants which showed antiviral and immunomodulating activities. It is aimed to provide an overview about the composition, molecular mass, branching configuration and related bioactivities of polysaccharides which is crucial for their classification as possible drug to induce immune response in viral diseases.

Structural studies of immunomodulatory (1 → 3)-, (1 → 4)-α glucan from an edible mushroom Polyporus grammocephalus.

A water soluble polysaccharide (PGPS) with molecular weight ~ 1.4 × 105 Da was isolated by alkali treatment from an edible mushroom Polyporus grammocephalus and purified by gel chromatography using sepharose-6B column. Monosaccharide analysis revealed that PGPS was made up of glucose only. PGPS contained (1 â†’ 3)-α-D-Glcp and (1 â†’ 4)-α-D-Glcp moieties in a molar ratio of nearly 1:2. Through a series of chemical and spectroscopic (1D/2D NMR) investigations, the repeating unit of the glucan was established as: →3)-α-D-Glcp(1 â†’ [4)-α-D-Glcp(1]2→ This α-glucan was observed to stimulate some prime components of immune system, namely, macrophages, splenocytes, and thymocytes.

A ß-glucan from the alkaline extract of a somatic hybrid (PfloVv5FB) of Pleurotus florida and Volvariella volvacea: structural characterization and study of immunoactivation.

A water soluble polysaccharide isolated from the alkaline extract of the somatic hybrid mushroom (PfloVv5FB), obtained through protoplast fusion between Pleurotus florida and Volvariella volvacea strains was found to contain d-glucose only. Structural investigation was carried out using acid hydrolysis, methylation analysis; periodate oxidation, and NMR studies ((1)H, (13)C, DEPT-135, TOCSY, DQF-COSY, 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 strong immunoactivation of macrophages, splenocytes as well as thymocytes.

A heteroglycan from the mycelia of Pleurotus ostreatus: structure determination and study of antioxidant properties.

A heteroglycan (PS) isolated from the mycelia of Pleurotus ostreatus was found to consist of l-fucose, d-mannose, and d-glucose in a molar ratio of nearly 1:2:3. On the basis of acid hydrolysis, methylation analysis, periodate oxidation, and NMR studies (1H, 13C, TOCSY, DQF-COSY, NOESY, ROESY, HSQC, HMBC, and DEPT), the structure of the repeating unit of the PS was determined. The repeating unit had a branched backbone composed of (1→6)-linked α and ßd-glucose and (1→2)-linked α-l-fucose. Branching occurred at C-4 position of (1→6)-linked α-d-glucopyranosyl residue with terminal ß-d-mannose and C-3 position of (1→6)-linked ß-d-glucopyranosyl residue with (1→6)-α-d-mannopyranosyl moiety terminated by α-d-glucose. The structure of the repeating unit of the PS was proposed as: [formula: see text]. The antioxidant properties of the PS were studied. The scavenging activity of hydroxyl free radicals whose EC50 value of PS at 943 µg/mL was determined. Further, EC50 value of the PS at 53 µg/mL was observed for scavenging activity of superoxide free radicals. Chelating effects (54.82%) of ferrous ions were observed at 1mg/mL of the PS.

Structure and immunology of a heteroglycan from somatic hybrid mushroom of Pleurotus florida and Calocybe indica var. APK2.

A water soluble polysaccharide was isolated from the aqueous extract of the fruit bodies of somatic hybrid mushroom PCH3FB, obtained through protoplast fusion between the strains Pleurotus florida and Calocybe indica var. APK2. On the basis of sugar analysis, methylation analysis, periodate oxidation, and NMR studies ((1)H, (13)C, DEPT-135, DQF-COSY, TOCSY, NOESY, ROESY, HMQC and HMBC), the structure of the repeating unit of the polysaccharide was established as: [formula, see text] This molecule showed macrophage, splenocyte and thymocyte activations.

Heteroglycan from an alkaline extract of a somatic hybrid mushroom (PfloVv1aFB) of Pleurotus florida and Volvariella volvacea: structural characterization and study of immunoenhancing properties.

A water soluble heteroglycan, isolated from the alkaline extract of the fruit bodies of the somatic hybrid mushroom (PfloVv1aFB), raised through protoplast fusion between the strains of Pleorutus florida and Volverilla volvacea, was found to consist of (1→3)-, (1→6)-, (1→3,4)-linked, and terminal ß-D-Glcp along with (1→2,6)-α-D-Galp and terminal α-D-Manp in a relative proportion of approximately 1:1:1:1:1:1. This polysaccharide exhibited strong immunostimulating activity of macrophages as well as splenocytes and thymocytes. Structural investigation was carried out using sugar analysis, methylation analysis; periodate oxidation study, and NMR experiments ((1)H, (13)C, DEPT-135, DQF-COSY, TOCSY, NOESY, ROESY, HMQC, and HMBC). On the basis of the above mentioned experiments, the structure of the repeating unit of the polysaccharide was established as: [formula see text].

Glucans of Pleurotus florida blue variant: isolation, purification, characterization and immunological studies.

Two different glucans (PS-I and PS-II) were isolated from the alkaline extract of the fruiting bodies of an edible mushroom, Pleurotus florida blue variant and the PS-I showed macrophage, splenocyte and thymocyte activations. On the basis of sugar analysis, methylation analysis, periodate oxidation, and NMR studies ((1)H, (13)C, DEPT-135, DQF-COSY, TOCSY, NOESY, ROESY, HMQC and HMBC), the structure of the repeating unit of these polysaccharides were established.

Structural characterization and study of immunoenhancing properties of heteroglycan isolated from a somatic hybrid mushroom (PfloVv1aFB) of Pleurotus florida and Volvariella volvacea.

A water soluble polysaccharide isolated from the hot aqueous extract of the fruit bodies of the somatic hybrid mushroom (PfloVv1aFB), raised through protoplast fusion between the strains of Pleurotus florida and Volvariella volvacea was found to consist of d-glucose, d-galactose, and d-mannose in a molar ratio of nearly 4:1:1 and showed macrophage, splenocyte, and thymocyte activation. On the basis of sugar analysis, methylation analysis, periodate oxidation, and NMR studies ((1)H, (13)C, DEPT-135, DQF-COSY, TOCSY, NOESY, ROESY, HMQC and HMBC), the structure of the repeating unit of the polysaccharide was established as: [structure: see text].

Isolation and characterization of an immunoenhancing glucan from alkaline extract of an edible mushroom, Lentinus squarrosulus (Mont.) Singer.

A water-soluble glucan, isolated from the alkaline extract of the fruit bodies of an edible mushroom, Lentinus squarrosulus (Mont.) Singer was found to consist of (1→3,6)-linked, (1→3)-linked, (1→6)-linked, and terminal ß-d-glucopyranosyl moieties in a relative proportion of approximately 1:2:1:1. This polysaccharide showed optimum activation of macrophages as well as splenocytes and thymocytes at 10µg/mL. Structural investigation was carried out using sugar analysis, methylation analysis, periodate oxidation study, and NMR experiments ((1)H, (13)C, DEPT-135, DQF-COSY, TOCSY, NOESY, ROESY, HMQC, and HMBC). On the basis of above-mentioned experiments, the structure of the repeating unit of the polysaccharide was established as:

A heteropolysaccharide from aqueous extract of an edible mushroom, Pleurotus ostreatus cultivar: structural and biological studies.

A water soluble polysaccharide isolated from the hot aqueous extract of Pleurotusostreatus cultivar was found to contain d-glucose and d-galactose in a molar ratio of nearly 7:1. Structural investigation was carried out using acid hydrolysis, methylation analysis, periodate oxidation, Smith degradation, and NMR studies ((1)H, (13)C, DEPT-135, TOCSY, DQF-COSY, NOESY, ROESY, HMQC, and HMBC). On the basis of the above mentioned experiments the structure of the repeating unit of the polysaccharide was established as: This heteroglycan stimulates macrophages, splenocytes, and thymocytes.

Chemical analysis of new water-soluble (1→6)-, (1→4)-α, ß-glucan and water-insoluble (1→3)-, (1→4)-ß-glucan (Calocyban) from alkaline extract of an edible mushroom, Calocybe indica (Dudh Chattu).

Two different glucans (PS-I, water-soluble; and PS-II, water-insoluble) were isolated from the alkaline extract of fruit bodies of an edible mushroom Calocybe indica. On the basis of acid hydrolysis, methylation analysis, periodate oxidation, and NMR analysis ((1)H, (13)C, DEPT-135, TOCSY, DQF-COSY, NOESY, ROESY, HMQC, and HMBC), the structure of the repeating unit of these polysaccharides were established as: PS-I: →6)-ß-D-Glcp-(1→6)-ß-D-glcp-(1→6)-)-ß-D-Glcp-(1→ α-D=Glcp (Water-soluble glucan). PS-II: →3)-ß-D-Glcp-(1→3)-ß-D-glcp-(1→3)-)-ß-D-Glcp-(1→3)-ß-D-Glcp-(1→ ß-D-Glcp (Water-insoluble glucan, Calocyban).

Chemical analysis of an immunoenhancing water-soluble polysaccharide of an edible mushroom, Pleurotus florida blue variant.

An immunoenhancing polysaccharide isolated from the aqueous extract of the fruit bodies of the mushroom, Pleurotus florida blue variant, was found to consist of d-glucose and d-galactose in a molar ratio of nearly 5:1. On the basis of sugar analysis, methylation analysis, periodate oxidation, Smith degradation, and NMR studies ((1)H, (13)C, DEPT-135, DQF-COSY, TOCSY, NOESY, ROESY, HMQC, and HMBC), the structure of the repeating unit of the polysaccharide was established as: →6)-ß-D-Glcp-(1→3)-α-D-glcp-(1→[6)-ß-D-Glcp-(1]3→ α-D=Glcp. The molecule activated macrophages, splenocytes, and thymocytes.

Structural characterization of an immunoenhancing heteroglycan isolated from an aqueous extract of an edible mushroom, Lentinus squarrosulus (Mont.) Singer.

A water-soluble polysaccharide, isolated from the hot water extract of the fruiting bodies of an edible mushroom, Lentinus squarrosulus (Mont.) Singer was found to contain d-galactose, l-fucose, and d-glucose in a molar ratio of nearly 1:1:5. Structural investigation of the polysaccharide was carried out using acid hydrolysis, methylation analysis, periodate oxidation study, and NMR experiments ((1)H, (13)C, DQF-COSY, TOCSY, NOESY, ROESY, HMQC, and HMBC). On the basis of above-mentioned experiments, the structure of the repeating unit of the polysaccharide was established as: This polysaccharide showed macrophage as well as splenocyte and thymocyte activation.