Somanjana Khatua

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.

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 βd-glucose and (1→2)-linked α-l-fucose. Branching occurred at C-4 position of (1→6)-linked α-d-glucopyranosyl residue with terminal β-d-mannose and C-3 position of (1→6)-linked β-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.

Selective inhibition of Leishmania donovani by active extracts of wild mushrooms used by the tribal population of India: An in vitro exploration for new leads against parasitic protozoans

The study was intended at evaluating the anti-proliferating effect of mushrooms used in traditional folklore of Santal tribal population in India against Leishmania donovani (MHOM/IN/83/AG83). A total of eighteen extracts, three estracts from each mushroom [(80% ethanol extracted; Fa), (water-soluble polysaccharide fraction; Fb), (polyphenolic fraction; Fc)], from six wild mushrooms were obtained. These extracts were tested against the promastigotes and amastigotes for their antileishmanial capacity. Fa fractions (250 μg/mL) of Astraeus hygrometricus and Tricholoma giganteum significantly inhibited the growth of L. donovani promastigotes and interfered in lipid biosynthesis. Moreover, both fractions induced apoptosis in promastigotes. Water soluble Fb fractions of A. hygrometricus, Russula laurocerasi, Russula albonigra, Termitomyces eurhizus, Russula delica and polyphenolic Fc fraction of R. laurocerasi were found to inhibit the replication of intracellular amastigotes in macrophages dose dependently. Significantly, 50% inhibitory concentration of the active extracts against intracellular amastigotes induced release of nitric oxide and IL-12 in murine macrophages and dendritic cells assay and also found considerably non-toxic on murine splenocytes. Results of this study can be used as a basis for further phytochemical and pharmacological investigations in the effort for search of novel anti-leishmanial leads.

Pectic polysaccharide from the green fruits of Momordica charantia (Karela): structural characterization and study of immunoenhancing and antioxidant properties

A water soluble pectic polysaccharide (PS) isolated from the aqueous extract of the green fruits of Momordica charantia contains D-galactose and D-methyl galacturonate in a molar ratio of nearly 1:4. It showed splenocyte, thymocyte as well as macrophage activations. Moreover, it exhibited potent antioxidant activities. On the basis of total acid hydrolysis, methylation analysis, periodate oxidation, and 1D and 2D NMR studies, the structure of the repeating unit of the pectic polysaccharide was established as: [Formula: see text].

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.

Influence of a blend of guar gum and poly(vinyl alcohol) on long term stability, and antibacterial and antioxidant efficacies of silver nanoparticles

This paper describes a detailed procedure for the synthesis of highly stable (almost for 60 days) and monodispersed silver nanoparticles (average particle size of 16 nm which changed to 42 nm only on the 60th day of standing under refrigeration) in the presence of a blend of a polysaccharide (guar gum) and a hydrophilic synthetic polymer (poly(vinyl alcohol)) where both the polymers provided synergistic effects in reduction and stabilization of incipient nanoparticles. Time dependant stability of aqueous dispersions of silver nanoparticles in various compositions of polymeric matrices was studied from UV-Vis spectroscopy, DLS and zeta potential characterization data. An FTIR spectrum and HRTEM image along with EDX results of the best optimized compositions in respect of particle size and particle size distribution of silver nanoparticles were also obtained. A study displayed how viscosity of the polymeric matrices played a vital role in the long term stabilization of aqueous dispersions of silver nanoparticles. For the first time we are reporting that silver nanoparticles synthesized by a green technique, using a blend of two highly viscous polymers, exhibited excellent stability. The aqueous dispersions of silver nanoparticles also displayed strong antibacterial and antioxidant properties. Hence our synthesized silver nanoparticles may be suitable for commercialization in future.

Prospecting Russula senecis: a delicacy among the tribes of West Bengal.

Russula senecis, a worldwide distributed mushroom, is exclusively popular among the tribal communities of West Bengal for food purposes. The present study focuses on its reliable taxonomic identification through macro- and micro-morphological features, DNA barcoding, confirmation of its systematic placement by phylogenetic analyses, myco-chemicals and functional activities. For the first time, the complete Internal Transcribed Spacer region of R. senecis has been sequenced and its taxonomic position within subsection Foetentinae under series Ingratae of the subgen. Ingratula is confirmed through phylogenetic analysis. For exploration of its medicinal properties, dried basidiocarps were subjected for preparation of a heat stable phenol rich extract (RusePre) using water and ethanol as solvent system. The antioxidant activity was evaluated through hydroxyl radical scavenging (EC50 5 µg/ml), chelating ability of ferrous ion (EC50 0.158 mg/ml), DPPH radical scavenging (EC50 1.34 mg/ml), reducing power (EC50 2.495 mg/ml) and total antioxidant activity methods (13.44 µg ascorbic acid equivalent/mg of extract). RusePre exhibited antimicrobial potentiality against Listeria monocytogenes, Bacillus subtilis, Pseudomonas aeruginosa and Staphylococcus aureus. Furthermore, different parameters were tested to investigate its chemical composition, which revealed the presence of appreciable quantity of phenolic compounds, along with carotenoids and ascorbic acid. HPLC-UV fingerprint indicated the probable existence of at least 13 phenolics, of which 10 were identified (pyrogallol > kaempferol > quercetin > chlorogenic acid > ferulic acid, cinnamic acid > vanillic acid > salicylic acid > p-coumaric acid > gallic acid). Result from the present work suggests that the fraction, RusePre, may open novel prospect as a functional ingredient in antioxidant supplements and in drugs to treat infectious disease.

Influence of extraction parameters on physico-chemical characters and antioxidant activity of water soluble polysaccharides from Macrocybe gigantea (Massee) Pegler & Lodge

Polysaccharides from mushrooms are potentially active pharmaceutical ingredients and their action is dependent upon conformation, composition, size etc. In this context, three water soluble crude polysaccharide rich fractions viz. hot water extracted polysaccharide (HWP), cold alkaline extracted polysaccharide (CAP) and hot alkaline extracted polysaccharide (HAP) have been isolated using varying extraction parameters from Macrocybe gigantea, a well-known edible mushroom collected from Gangetic plain of West Bengal and authenticated by DNA barcoding of nrDNA ITS region. Physico-chemical investigation revealed that the fractions were mainly composed of β-configuration in pyranose form of sugars conjugated with small amount of protein. Further analysis presented that polysaccharides were composed of same monosaccharide even in similar order of ratio (D-glucose > D-galactose > D-mannose > D-xylose). However, D-glucose as well as β-glucan were found to be in the highest amount in CAP. The helical structure was determined by Congo red assay which indicated that polysaccharides were in aggregate forms except HWP which consisted of tertiary structure. These diverse structural features may have imparted effect on free radical scavenging activity of polysaccharides where HWP was the most active in all assays. HWP was proved to be a good scavenger of free radicals, strong chelator of ferrous ion and had high reducing power. Thus it can be inferred that HWP may foster further studies for searching active compound which might be used as ingredients of functional foods, nutraceuticals and pharmaceuticals. Moreover, to the best of our knowledge this is the first report on chemical composition and antioxidant activity of different crude polysaccharides from M. gigantea.

In Vitro Protective Ability of Ramaria aurea Against Free Radical and Identification of Main Phenolic Acids by HPLC

Free radical scavenging activity of Ramaria aurea, an edible mushroom, naturally grown in Shilong, India, was evaluated. A heat-stable, polyphenol-rich extract (RauPre) was prepared from the dried basidiocarps and analyzed. The major chemical constituent of RauPre was phenols (26.86 μg gallic acid equivalents [GAE] mg−1 of dry extract); flavonoids, β-carotene, lycopene, and ascorbic acid were present in minor amounts. Main phenolic acids identified by high performance liquid chromatography (HPLC) were caffeic acid > cinnamic acid > gallic acid. Results from antioxidant assays demonstrated potential for superoxide and DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging activity (EC50 0.283 mg mL−1 and 0.384 mg mL−1, respectively). RauPre chelated ferrous ion (EC50 0.95 mg mL−1) and had Fe3+ to Fe2+ reducing power (EC50 1.025 mg mL−1). The activity of 1 mg of RauPre was equivalent to 86.7 μg ascorbic acid for total antioxidant capacity.

Alkaline extractive crude polysaccharide from Russula senecis possesses antioxidant potential and stimulates innate immunity response

Over past decades, investigation on bioactive polysaccharides extracted from mushroom by heated water reflux has been an emerging field of biomedicine especially in the area of immune stimulation. While studies with macromolecules isolated from remainder residue of aqueous extraction are scarce. In this context, crude polysaccharide from a traditionally edible macrofungus, Russula senecis, was prepared (RuseCap) by alkaline solvent using leftover residue of that conventional process and its structural along with therapeutic properties were evaluated.