Biologically active polysaccharide from edible mushrooms: A review.

Mushrooms are renewable natural gift for humankind, furnished with unique taste, flavor and medicinal properties. For the last few decades study of mushroom polysaccharides has become a matter of great interest to the researchers for their immunomodulating, antimicrobial, antioxidant, anticancer, and antitumor properties. Molecular mass, branching configuration, conformation of polysaccharides and chemical modification are the major factors influencing their biological activities. The mechanism of action of mushroom polysaccharides is to stimulate T-cells, B-cells, natural killer cells, and macrophage dependent immune responses via binding to receptors like the toll-like receptor-2, dectin-1. The present review offers summarized and significant information about the structural and biological properties of mushroom polysaccharides, and their potential for development of therapeutic materials.

Structural features and antioxidant activity of a new galactoglucan from edible mushroom Pleurotus djamor.

A new water soluble galactoglucan with apparent molecular weight ~1.61 × 105 Da, was isolated from the edible mushroom Pleurotus djamor by hot water extraction followed by purification through dialysis tubing cellulose membrane and sepharose 6B column chromatography. The sugar analysis showed the presence of glucose and galactose in a molar ratio of nearly 3:1 respectively. The structure of the repeating unit in the polysaccharide was determined through chemical and NMR experiments as: In vitro antioxidant studies showed that the PDPS exhibited hydroxyl radical scavenging activity (EC50 = 1.681 ± 0.034 mg/mL), DPPH radical scavenging activity (EC50 = 3.83 ± 0.427 mg/mL), reducing power (EC50 = 4.258 ± 0.095 mg/mL), and ABTS radical quenching activity (EC50 = 0.816 ± 0.077 mg/mL). So, PDPS should be explored as a natural antioxidant.

Structure and biological properties of exopolysaccharide isolated from Citrobacter freundii.

This study aimed to investigate the molecular characterization, antioxidant activity in vitro, cytotoxicity study of an exopolysaccharide isolated from Citrobacter freundii. Firstly, the culture conditions were standardized by the Design of experiments (DoE) based approach, and the final yield of thecrude exopolysaccharide was optimized at 2568 ± 169 mg L-1. One large fraction of exopolysaccharide was obtained from the culture filtrate by size exclusion chromatography and molecular characteristics were studied. A new mannose rich exopolysaccharide (Fraction-I) with average molecular weight ~ 1.34 × 105 Da was isolated. The sugar analysis showed the presence of mannose and glucose in a molar ratio of nearly 7:2 respectively. The structure of the repeating unit in the exopolysaccharide was determined through chemical and 1D/2D- NMR experiments as: Finally, the antioxidant activity, and the cytotoxicity of the exopolysaccharide were investigated and the relationship with molecular properties was discussed as well.

Structural Characterization of an Exopolysaccharide Isolated from Enterococcus faecalis, and Study on its Antioxidant Activity, and Cytotoxicity Against HeLa Cells.

An exopolysaccharide (EPS-I) having the molecular weight ~ 2.6 × 105 Da, was isolated from a Zinc resistant strain of Enterococcus faecalis from costal area. The exopolysaccharide consists of D-mannose, D-glucose, and L-fucose in molar ratio of 9:4:1. The monosaccharide units in the EPS-1 were determined through chemical (total acid hydrolysis and methylation analysis) and spectroscopic (FTIR and 1H NMR experiment) analysis. The mannose-rich EPS-1 showed total antioxidant activity (1 mg mL-1 of EPS-I as functional as approximately to 500 ± 5.2 µM of ascorbic acid) and Fe2+ metal ion chelation activity (EC50 = 405.6 µg mL-1) and hydroxyl radical scavenging activity (EC50 = 219.5 µg mL-1). The in vitro cytotoxicity experiment of EPS-I against cervical carcinoma cell line, HeLa cells showed strong cytotoxic effect (LC50 = 267.3 µg mL-1) and at that concentration, it found almost nontoxic against normal healthy cells (HEK-293).

Green synthesis, characterization, antimicrobial and cytotoxic effect of silver nanoparticles using arabinoxylan isolated from Kalmegh.

A green synthesis of silver nanoparticles was synthesized by AgNO3 with arabinoxylan, isolated from green stem of Andrographis paniculata (Kalmegh). The synthesized Ag NPs-arabinoxylan conjugates were characterized by UV-vis spectroscopy, FE-SEM, TEM, XRD, TGA, EDX, and Zeta potential experiments. The Ag NPs formation was established by the surface plasmon resonance band ~410.25 nm. SEM image showed mostly spherical morphology of Ag NPs. The fcc crystalline nature was identified by XRD, SAED and the size were 24.5 and 25 nm from TEM and XRD analysis respectively. The prepared Ag NPs showed dose-dependent antimicrobial activity against Streptococcus pneumonia, Candida albicans and E. coli. The nanoparciles damage 4% hemolysis to human RBCs at 12.5 µg/mL. MTT assay of Ag NPs showed that half of the cell killed at 10 µg/mL and wound healing assay observed effective inhibition cell proliferation.

Structural studies of a water insoluble ß-glucan from Pleurotus djamor and its cytotoxic effect against PA1, ovarian carcinoma cells.

A water insoluble ß-glucan (PS), with molecular mass ∼9.16 × 104 Da was isolated from the 4% alkaline extract of an edible mushroom, Pleurotus djamor and found to consist of (1→3)-ß-d-glucopyranosyl moiety. The structure of the PS was elucidated on the basis of total hydrolysis, methylation analysis, periodate oxidation, and NMR experiments (1H, 13C, DQF-COSY, DEPT-135, and HSQC). The structure of the repeating unit of the polysaccharide was established as: →3)-ß-d-Glcp-(1→. The water insoluble ß-glucan showed cytotoxic effect against PA1 cells, where˜50% population was destroyed at 100 µg/mL concentration, and almost all cells at 250 µg/mL concentration. The wound healing assay showed significant anticarcinogenic effect against ovarian carcinoma PA1 cells after 48 h of treatment.

Structural and antioxidant studies of a new arabinoxylan from green stem Andrographis paniculata (Kalmegh).

A water soluble arabinoxylan (APPS), with a molecular weight ∼1.49 × 105 Da was isolated from the green stem of Andrographis paniculata. The APPS contained D-xylose, 2-methoxy D-xylose and L- arabinose in molar ratio of 3:1:1. The structure of the repeating unit in the polysaccharide was determined through several chemical (acid hydrolysis, Methylation analysis and periodate oxidation) and spectroscopic analysis (1D/2D NMR experiments) as: In vitro antioxidant assay, APPS was found to possess ferrous ion chelating activity (EC50 = 283 µg/ml), superoxide radical scavenging activity (EC50 = 470 µg/ml), and hydroxide radical scavenging activity (EC50 = 193 µg/ml). Thus, APPS could be used as a natural antioxidant agent for food and pharmaceutical industries.