Examples of homopolysaccharides .
Mushrooms have been used as a common folk medicine due to their effective bioactive compounds including polysaccharides. It is known that the glucans are the main bioactive mushroom polysaccharides. This review study explains the method of isolation, structural characterization, and antitumor activities of mushroom polysaccharides. In many laboratories, these trials are still underway, and the function of polysaccharides as an antitumor agent is particularly under intense discussion. This review aims to summarize the accessible data and reflect this study area’s current status with a perspective to future direction.
- edible mushrooms
Polysaccharides obtained from mushrooms have played a significant role as food and medicinal agent in the therapy of cancer in Asian nations such as China and Japan . The consumption of fresh or dried mushroom powder in pre- and postmenopausal females might prevent breast cancer . Mushrooms with distinctive fruiting bodies that have an impact on cancer curing belong to
2. Chemistry of polysaccharides
Polysaccharides are the most recognized and powerful mushroom-derived substances with antitumor and immunomodulating characteristics. Because of its wide biological range, polysaccharide β-glucan is the most versatile metabolite. The β-glucans consist of a backbone of glucose residue associated with β-(1 to 3) glycosidic bonds, often connected by β-(1 to 6) linkages with the adjoining side-chain glucose residue . It may be linear or branched to polysaccharides. Polysaccharides are split into two groups according to the number of distinct monomers: homopolysaccharides consist of only one type of monosaccharides, whereas heteropolysaccharides consists of two more types of monosaccharides . Homopolysaccharides and heteropolysaccharides may have homolinkages or heterolinkages in configuration and/or position of connection. Polysaccharides with a powerful antitumor action vary significantly in their chemical structure. Antitumor activity is shown by a broad spectrum of glycans ranging from homopolymers to extremely complicated heteropolymers . A broad variety of antitumor or immunostimulating polysaccharides were explored from distinct chemical structures from greater
|Amylose||α-(1 → 4)-Glc|
|Xylan||β-(1 → 4)-Xyl|
|β-Glucan||β-(1 → 4, 1 → 3)-Glc|
|Amylopectin||α-(1 → 4, 1 → 6)-Glc|
|Glycogen||α-(1 → 4, 1 → 6)-Glc|
Antitumor polysaccharides comprise monosaccharides like glucose, mannose, xylose, fucose, arabinose, galactose, glucuronic acid, and ribose. In few mushrooms, polysaccharides are conjugated with peptides or proteins which exhibited potent anticancer activity . The origin, type, and bioactivity of the most common edible mushrooms, in Bangladesh, are given in Table 2. Some of them have been sold for clinical treatment in patients receiving anticancer treatment with polysaccharides and polysaccharide conjugates.
Glycans are structurally diversified. There are no unique protocols for the analysis of glycans. The primary structure of mushroom polysaccharide comprises the sequence and composition of monosaccharide, position, and configuration of monosaccharide, nature, and number of noncarbohydrate moieties.
During structure analysis, the composition of monosaccharide gives information on the molar ratio of monomers and nature and the location of glycosidic linkages, detection, and quantification of monomers. In Table 3, we represented the analytical methods that are used to analyze the primary structures of polysaccharides.
|GLC-FID, GLC-MS, HPLC||Monosaccharide compositions|
|IR, NMR||Glycosidic bonds, configuration|
3. Purification of polysaccharides
Mushroom polysaccharide consists of two main polysaccharide kinds as the structural elements of the fungal cell wall. The celluloses and matrix-like glycoprotein are a rigid cellulose fibrilla, α-glucan or β-glucan. The selection of mushroom polysaccharides is usually based on the cell wall structure. A reliable procedure has been developed for successful polysaccharide mining of either cultivar mycelia or fruit body . The process of extraction usually involves 80% ethanol to remove low molecular substances from the pest material and 3–5 repeated water extractions (100°C, 2–4 h). Alternatively, 5% sodium hydroxide (80°C, 6 h) or 2% ammonium oxalate (100°C, 6 h) is used. Using a mixture of methods such as ethanol precipitation, fractional precipitation, acidic precipitation with acetic acid, ion-exchange chromatography, gel filtration, and chromatography of affinity, extracted polysaccharides can be further purified. The precipitation of ethanol excludes polysaccharides from the impurities. Acidic and neutral polysaccharides can be separated on a DEAE-cellulose column by anion-exchange chromatography. First, a suitable running buffer elucidates the neutral polysaccharide in the blend; then the acid polysaccharide is eluted at a greater salt concentration . Using gel filtration and affinity chromatography, neutral polysaccharides can be further divided into α-glucans (adsorbed fraction) and β-glucans (non-adsorbed fraction). Affinity chromatography is a selective adsorption method and the subsequent regeneration from an immobilized ligand of a compound. This method now enables some carbohydrates to be extremely specific and efficiently purified . Previous studies have indicated that the mushroom sample fractionation for polysaccharides usually began with the extraction of warm water. Pk et al. described the isolation and characterization and anticancer effect of antioxidant polysaccharide from
4. Anticancer role
The antimicrobial activity of
GLP shows activity against cancer by inducing immune responses and directly cytotoxic effects on tumor cells. GLP blocked the proliferation of mouse melanoma cells (B16F10) and human bladder cancer cells (HUC-PC and MTC-11). Several studies have found the mechanism of GLP anticancer role .
It has been shown that many plants contain high levels of natural antioxidants that can scavenge free radicals . In addition, this property may well decrease the level of DNA damage caused by oxidative stress and thus partially account for chemopreventive mechanisms that are attributed to antioxidants derived from plants . Both the extracts of triterpene and polysaccharide have an antioxidant effect on pyrogallol-induced membrane oxidation and lipid peroxidation mediated by Fe(II)-ascorbic acid . The findings of this study showed that GL extracts displayed dose-dependent antioxidant activity by increasing the expression of SOD and catalase . Figure 3 shows the expression patterns of SOD and CAT genes.
As edible and medicinal tools,
5. Chemical structure
The chemical structure of lentinan has a main chain consisting of β-D-(1 → 3)-linked D-glucopyranosyl residues with two (1 → 6)-β-glucoside branches for every five D-glucose residues, and the side chains of lentinan consist of β-D-(1,6)-linked and β-D-(1 → 3)-linked glucose residues  (Figure 4).
It has been shown that many mushroom β-glucans stimulate production of interferons (IFNs), interleukins (ILs), and other cytokines . It is based mainly on the activation of T and B lymphocytes, macrophages, and natural killer cells . Studies have found that the proliferation of mononuclear blood cells including lymphocytes, monocytes, and macrophages is induced by lentinan . In addition, the production and differentiation of cells involved in the host defense mechanisms are encouraged. Lentinan can also improve immune cell reactivity and activate cytokines, hormones, and/or other biologically active substances to secrete. Lentinan increases the resistance of the body to malignant transformation by these properties . Lentinan therapy has also been shown to inhibit prostaglandin synthesis, which often leads to a slowing of the differentiation of T lymphocytes and inhibition of Treg cell activities, in patients suffering from stomach cancer . Increased levels of activated and cytotoxic T lymphocytes in spleen and peripheral cell mononuclear blood stimulation were also observed in generating interleukin 1α (IL-1α), IL-1β, and TNF-α . Certain tumor forms have demonstrated the ability of lentinan in stimulating IL-1 release . In addition to the indirect action, most polysaccharides had direct effects on cancer cells. Many researches about the tumor cell proliferation and/or apoptotic deaths in vitro and in vivo indicate that polysaccharides inhibit tumor cell growth . The modulation of NF-β activity is one of the best-described mechanisms for direct anticancer action of polysaccharides derived from
Polysaccharides’ anticancer properties depend on sugar composition , molecular weight , water solubility , glucose relation , tertiary structure , branching frequency and shape , chemical modification , and ligand presence . Scientific approaches to mushroom compounds have allowed the isolation of many of the important active substances used in lifestyle disease prevention and treatment, including cancer. The immune system was strengthened by various polysaccharides from different mushroom varieties. Their ability to stimulate the host’s immune system, rather than direct cytotoxicity, all has demonstrated strong antitumor activity. Chemotherapy or radiation therapy seem to withstand and compatible mushroom polysaccharides. Nonetheless, there are urgent needs to be studied that describe the molecular mechanism of mushroom polysaccharides such as receptors and downstream events induced by these polymers being bound to their target cells.