Heteroglycan of an edible mushroom Entoloma lividoalbum: Structural characterization and study of its protective role for human lymphocytes

Isolation, structural characterization of (1 → 4), (1 → 6)-α-D-glucan from Dioscorea Alata and synthesis and catalytic activity studies of (1 → 4), (1 → 6)-α-D-glucan derived carbon dots

Herein, a straightforward, productive protocol was adopted for the synthesis of carbon dots (CDs) by a simple microwave-assisted technique from (1 → 4), (1 → 6)-α-D-glucan polysaccharide (DAPS). The isolation and structural characterization of (1 → 4), (1 → 6)-α-D-glucan from the aqueous extracting of the Diascorea Alata was described here. The photo-physical and morphological studies of the prepared high quantum yield (27.70 %) CDs were systematically characterized using different analytical techniques: TEM, DLS, XPS, XRD, FT-IR, TCSPC, EDX, Fluorescence and UV-vis spectroscopy. In our study the carbon dots (CDs) obtained are non-toxic, highly water-soluble, spherical-shaped negatively charged particles with an average diameter of 3.28 nm. The photo-catalytic activity of carbon dots (CDs) was tested under the sunlight for photo-degradation of crystal violet (CV), a pollutant organic dye. Carbon dots (CDs) showed outstanding results regarding the photo degradation of CV (achieving 99.9 % degradation within 8 min) under sunlight.

A highly branched glucomannan from the fruiting body of Schizophyllum commune: Structural characteristics and antitumor properties analysis

In this study, a highly branched glucomannan (SCP-1) from Schizophyllum commune fruiting body with good solubility was isolated, and its structural characteristics and antitumor properties were analyzed. The monosaccharides of SCP-1 were fucose, glucosamine hydrochloride, galactose, glucose and mannose with a relative molar ratio of 14:6:210:593:177, and the molecular weight (Mw) of SCP-1 was 15.1 kDa. SCP-1 showed a rough and dense surface, and it was aggregated to particles in distilled water, though it might have triple-helix conformation. The main backbone chain of SCP-1 was →[3)-β-D-Glcp-(1]3→3)-β-D-Glcp-(1→2)-α-D-Manp-(1→2)-α-D-Manp-(1→3)-α-D-Glcp-(1→ and three sides chains including α-D-Glcp-(1→[6)-β-D-Glcp-(1]2→, α-D-Glcp-(1→3)-α-D-Manp-(1→ and α-D-Glcp-(1→[6)-α-D-Galp-(1]3→ were linked with 1,6-glycosidic bond, which was significantly different with the schizophyllan isolated from the mycelia of S. commune. SCP-1 could significantly inhibit the growth of A549 cells, the inhibition rate reached 41.62 % and the percentage of cells in S phase increased from 27.17 % to 56.40 % (400 μg/mL, 48 h). Moreover, SCP-1 could induce cell apoptosis and the total apoptosis rate reached 28.13 %. SCP-1 exerted apoptosis inducing effect probably by reducing the expression ratio of Bcl-2/Bax and the p-PI3K, p-Akt and p-mTOR expression level. The results showed that SCP-1 might have the potential to act as an antitumor agent for lung cancer therapy.

An alkali-extracted neutral heteropolysaccharide from Phellinus nigricans used as an immunopotentiator in immunosuppressed mice by activating macrophages

A neutral heteropolysaccharide (PNANb) was isolated with alkali (0.1 M NaOH) from mycelia of Phellinus nigricans, and the structure, immunostimulating activity and some of the underlying molecular mechanisms of action of PNANb were explored in the current study. PNANb (14.95 kDa) predominantly consisted of Gal, Glc, and Man with minor Fuc. GC-MS and NMR analyses indicated that the backbone of PNANb was mainly composed of 6-α-Galp, 2,6-α-Galp with minor 3,6-β-Glcp, which was substituted with complex side chains at C-2 of 2,6-α-Galp and C-3 of 3,6-β-Glcp. Notably, PNANb (50 or 100 mg/kg) possessed immunoprotective effects in cyclophosphamide (Cy)-induced immunosuppressed C57BL/6 mice, which was supported by evidence including the enhancement of spleen and thymus indices, levels of serum immunoglobulins (IgG, IgM) and cytokines (IFN-γ, IL-2, IL-4, IL-10), and macrophage activity. However, the immunostimulation effects of PNANb were decreased when macrophages were depleted, underscoring the essential role of macrophages in the beneficial effects of PNANb in Cy-induced immunosuppressed mice. Further investigations in vitro indicated that PNANb activated macrophages through MAPK/NF-κB signaling pathways mediated by Toll-like receptor 4. Therefore, PNANb can serve as a prospective immunopotentiator in immunosuppression.

Dendrobium officinale polysaccharides-chemical properties and pharmacodynamic effects on the airways in experimental conditions

The study aimed to analyze the effects of Dendrobium polysaccharides on the cough and airway reactivity and compare them with the effects of clinically used antitussives (codeine phosphate and butamirate citrate) and bronchodilators (salbutamol), using the guinea pig test system. Dendrobium officinale polysaccharides contained proteins (4.0 wt%) and phenolic compounds (1.7 wt%) with a molecular weight of 25,000 g/mol. The sugar analysis revealed a dominance of glucose (93.7 wt%) and a lesser amount of mannose (5.1 wt%) while other sugar quantities were negligible. Methylation analysis indicated the presence of highly branched polysaccharides. Glucose was found mainly as terminal, 1,4- and 1,6-linked. Furthermore, some 1,4- and 1,6-linked glucose units were found branched at O2, O3, and O6/O4. Mannose was terminal and 1,4-linked. NMR spectra signals indicate the presence of the (1→4)-linked α-d-glucan, (1→4)-linked β-d-glucan branched at position O6, (1→6)-linked β-d-glucan branched at position O3 and (1→4)-linked glucomannan. Pharmacological studies showed statistically significant antitussive activity of Dendrobium polysaccharides, exceeding the effect of clinically used antitussives, which may be partially associated with confirmed bronchodilation and the ability of polysaccharides to increase the threshold of cough receptor activation. Dendrobium polysaccharides may increase the possibility of symptomatic treatment of cough, especially in asthmatics.

Extraction and immunomodulatory activity of the polysaccharide obtained from Craterellus cornucopioides

In this study, we investigated the structural features of the polysaccharide obtained from Craterellus cornucopioides (CCP2) by high-performance liquid chromatography, Fourier transform infrared spectroscopy and ion chromatography. The results showed that CCP2 was a catenarian pyranose that principally comprised of mannose, galactose, glucose, and xylose in the ratio of 1.86: 1.57: 1.00: 1.14, with a molecular weight of 8.28 × 10⁴ Da. Moreover, the immunoregulation effect of CCP2 was evaluated both in vitro and in vivo. It displayed a remarkable immunological activity and activation in RAW264.7 cells by enhancing the phagocytosis of macrophages in a dose-dependent manner without showing cytotoxicity at the concentrations of 10–200 μg/mL in vitro. Additionally, Histopathological analysis indicated the protective function of CCP2 against immunosuppression induced by cyclophosphamide (Cy). Meanwhile, the intake of CCP2 had better immunoregulatory activity for immunosuppression BALB/c mice model. After prevention by CCP2, the spleen and thymus weight indexes of BALB/c mice model were significantly increased. The RT-qPCR and Western Blot results provided comprehensive evidence that the CCP2 could activate macrophages by enhancing the production of cytokines (IL-2, IL-6, and IL-8) and upregulating the protein expression of cell membrane receptor TLR4 and its downstream protein kinase (TRAF6, TRIF, and NF-κB p65) production of immunosuppressive mice through TLR4-NFκB p65 pathway. The results demonstrated that CCP2 could be a potential prebiotic and might provide meaningful information for further research on the immune mechanism.

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.

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 → 3)-α-D-Glcp and (1 → 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 → [4)-α-D-Glcp(1]₂→ This α-glucan was observed to stimulate some prime components of immune system, namely, macrophages, splenocytes, and thymocytes.

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 → 3)-β-d-glucopyranosyl, one (1 → 6)-β-d-glucopyranosyl, two (1 → 3)-α-D-manopyranosyl, 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 α-L-fucopyranosyl residue.

A 3-O-methylated heterogalactan from Pleurotus eryngii activates macrophages

Mushroom-derived polysaccharides exhibit various biological activities owing to their diverse structural features. Here, we purified a 3-O-methylated heterogalactan (WPEP-N-b, Mw 21.4 kDa) from the fruiting bodies of Pleurotus eryngii. WPEP-N-b is composed primarily of galactose (43.8%), mannose (39.3%), methyl-galactose (11.7%) and glucose (9.2%) residues, with the main chain being composed of α-1,6-linked D-Galp and 3-O-Me-D-Galp, branched at O-2 with single t-β-D-Manp as major the side chain. β-1,6-D-Glcp residues are present as minor components either in side-chains or backbone. WPEP-N-b increases macrophage phagocytosis and secretion of NO, TNF-α, IL-6 and IL-1β. Mechanistic studies demonstrate that WPEP-N-b promotes the degradation of IκB-α, and enhances phosphorylation of MAPKs and the NF-κB p65 subunit. Our results also indicate that this polysaccharide activates RAW264.7 cells via MAPK and NF-κB signaling pathways and the Toll-like receptor 2(TLR2). These results increase our understanding as to how mushroom-derived polysaccharides modulate the immunologic process.

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)-β-d-glucopyranosyl residues, one (1→4)-α-d-mannopyranosyl residue, and two (1→3)-β-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.