Correlation between antitumor activity, molecular weight, and conformation of lentinan

Anticancer Activities of Mushrooms: A Neglected Source for Drug Discovery

Approximately 270 species of mushrooms have been reported as potentially useful for human health. However, few mushrooms have been studied for bioactive compounds that can be helpful in treating various diseases. Like other natural regimens, the mushroom treatment appears safe, as could be expected from their long culinary and medicinal use. This review aims to provide a critical discussion on clinical trial evidence for mushrooms to treat patients with diverse types of cancer. In addition, the review also highlights the identified bioactive compounds and corresponding mechanisms of action among the explored mushrooms. Furthermore, it also discusses mushrooms with anticancer properties, demonstrated either in vitro and/or in vivo models, which have never been tested in clinical studies. Several mushrooms have been tested in phase I or II clinical trials, mostly for treating breast cancer (18.6%), followed by colorectal (14%) and prostate cancer (11.6%). The majority of clinical studies were carried out with just 3 species: Lentinula edodes (22.2%), Coriolus versicolor, and Ganoderma lucidum (both 13.9%); followed by two other species: Agaricus bisporus and Grifola frondosa (both 11.1%). Most in vitro cell studies use breast cancer cell lines (43.9%), followed by lung (14%) and colorectal cancer cell lines (13.1%), while most in vivo animal studies are performed in mice tumor models (58.7%). Although 32 species of mushrooms at least show some promise for the treatment of cancer, only 11 species have been tested clinically thus far. Moreover, most clinical studies have investigated fewer numbers of patients, and have been limited to phase III or IV. Therefore, despite the promising preclinical and clinical data publication, more solid scientific efforts are required to clarify the therapeutic value of mushrooms in oncology.

Structure–immunomodulatory activity relationships of dietary polysaccharides

Polysaccharides are usually composed of more than ten monosaccharide units, which are connected by linear or branched glycosidic bonds. The immunomodulatory effect of natural polysaccharides is one of the most important bioactive function. In this review, molecular weight, monosaccharide (including galactose, mannose, rhamnogalacturonan-I arabinogalactan and uronic acid), functional groups (namely sulfate, selenium, and acetyl groups), types of glycoside bond connection (including β-1,3-D-glucosyl, α-1,4-D-glucosyl, β-1,4-D-glucosyl, α-1,6-D-glucosyl, β-1,4-D-mannosyl, and β-1,4-D-Xylopyranosyl), conformation and the branching degrees are systematically identified as their contribution to the immunostimulatory activity of polysaccharides. At present, studies on the structure-activity relationships of polysaccharides are limited due to their low purity and high heterogeneity. However, it is an important step in providing useful guidance for dietary supplements with polysaccharides. The chemical structures and the process of immune responses induced are necessary to be discussed. Polysaccharides may bind with the cell surface receptors to modulate immune responses. This review mainly discusses the structure-activity relationship of dietary polysaccharides.

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Structure - activity relationships of polysaccharides with immune-enhancing effect are proposed.

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Polysaccharides with the higher molecular weight are helpful to improve immunity.

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Higer galactose, mannose, rhamnogalacturonan-I, arabinogalacta,n and uronic acid contents have immunoregulation.

Different molecular sizes and chain conformations of water-soluble yeast β-glucan fractions and their interactions with receptor Dectin-1

Although β-glucan could bind to Dectin-1 to exert bioactivity, the influence of molecular size and chain conformation of β-glucan on its interaction with Dectin-1 is still unclear. This work investigated the molecular sizes and chain conformations of five water-soluble yeast β-glucan (WYG1-5) fractions as well as their interactions with Dectin-1 by fluorescence spectroscopy and microscale thermophoresis. Results revealed a spherical conformation for higher molecular weight WYG and a stiff chain conformation for smaller molecular weight WYG. The WYG and Dectin-1 interactions were in the order of WYG-2 > WYG-1 > WYG-3 > WYG-4 > WYG-5. The spherical WYG-2 exhibited the largest binding constant of 7.91 × 10⁵ M¹ and the lowest dissociation constant of 22.1 nM to Dectin-1. Additionally, the underlying interaction mechanism showed that it may be easier for spherical WYG with longer side chains to interact with receptor Dectin-1.

Interaction between polysaccharides and toll-like receptor 4: Primary structural role, immune balance perspective, and 3D interaction model hypothesis

Various structural types of polysaccharides are recognized by toll-like receptor 4 (TLR4). However, the mechanism of interaction between the polysaccharides with different structures and TLR4 is unclarified. This review summarized the primary structure of polysaccharides related to TLR4, mainly including molecular weight, monosaccharide composition, glycosidic bonds, functional groups, and branched-chain structure. The optimal primary structure for interacting with TLR4 was obtained by the statistical analysis. Besides, the dual-directional regulation of TLR4 signaling cascade by polysaccharides was also elucidated from an immune balance perspective. Finally, the 3D interaction model of polysaccharides to TLR4-myeloid differentiation factor 2 (MD2) complex was hypothesized according to the LPS-TLR4-MD2 dimerization model and the polysaccharides solution conformation. The essence of polysaccharides binding to TLR4-MD2 complex is a multivalent non-covalent bond interaction. All the arguments summarized in this review are intended to provide some new insights into the interaction between polysaccharides and TLR4.

Sulfonated and Carboxymethylated β-Glucan Derivatives with Inhibitory Activity against Herpes and Dengue Viruses

The infection of mammalian cells by enveloped viruses is triggered by the interaction of viral envelope glycoproteins with the glycosaminoglycan, heparan sulfate. By mimicking this carbohydrate, some anionic polysaccharides can block this interaction and inhibit viral entry and infection. As heparan sulfate carries both carboxyl and sulfate groups, this work focused on the derivatization of a (1→3)(1→6)-β-D-glucan, botryosphaeran, with these negatively-charged groups in an attempt to improve its antiviral activity. Carboxyl and sulfonate groups were introduced by carboxymethylation and sulfonylation reactions, respectively. Three derivatives with the same degree of carboxymethylation (0.9) and different degrees of sulfonation (0.1; 0.2; 0.4) were obtained. All derivatives were chemically characterized and evaluated for their antiviral activity against herpes (HSV-1, strains KOS and AR) and dengue (DENV-2) viruses. Carboxymethylated botryosphaeran did not inhibit the viruses, while all sulfonated-carboxymethylated derivatives were able to inhibit HSV-1. DENV-2 was inhibited only by one of these derivatives with an intermediate degree of sulfonation (0.2), demonstrating that the dengue virus is more resistant to anionic β-D-glucans than the Herpes simplex virus. By comparison with a previous study on the antiviral activity of sulfonated botryosphaerans, we conclude that the presence of carboxymethyl groups might have a detrimental effect on antiviral activity.

Combining the Anticancer and Immunomodulatory Effects of Astragalus and Shiitake as an Integrated Therapeutic Approach

Astragalus root (Huang Qi) and Shiitake mushrooms (Lentinus edodes) are both considered medicinal foods and are frequently used in traditional Chinese medicine due to their anticancer and immunomodulating properties. Here, the scientific literatures describing evidence for the anticancer and immunogenic properties of Shiitake and Astragalus were reviewed. Based on our experimental data, the potential to develop medicinal food with combined bioactivities was assessed using Shiitake mushrooms grown over Astragalus beds in a proprietary manufacturing process, as a novel cancer prevention approach. Notably, our data suggest that this new manufacturing process can result in transfer and increased bioavailability of Astragalus polysaccharides with therapeutic potential into edible Shiitake. Further research efforts are required to validate the therapeutic potential of this new Hengshan Astragalus Shiitake medicinal food.

A polysaccharide of PFP-1 from Pleurotus geesteranus attenuates alcoholic liver diseases via Nrf2 and NF-κB signaling pathways

A polysaccharide named PFP-1 was isolated from the Pleurotus geesteranus fruiting body, and potential investigations on ameliorating oxidative stress and liver injury against alcoholic liver disease (ALD) were performed in mice. The animal studies demonstrated that PFP-1 had hepatoprotective effects by improving hepatocellular histopathology, modulating alcohol metabolisms and restoring the serum lipid levels. Besides, PFP-1 could attenuate oxidative stress and inflammatory responses by activating the Nrf2-mediated signal pathways and regulating the TLR4-mediated NF-κB signal pathways. The characterization indicated that PFP-1 was a typical pyranose-polysaccharide in a triple-helical conformation, which was linked by t-β-Glcp, 1,6-α-Glcp and 1,2,6-α-Galp. And the characteristic properties of higher water solubility and appropriate molecular weights contributed to the superior bioactivities. The results demonstrated that PFP-1 could be used as a supplement for alleviating alcohol-induced liver damage.

Biological activities of Pleurotus spp. polysaccharides: A review

Mushrooms are consumed for their nutrients and therapeutic bioactive compounds and are used medicinally in Chinese and Japanese medicine traditions since time immemorial. Members of the genus Pleurotus form a heterogeneous group of edible species with outstanding nutritional profiles rich in fiber, vitamins (thiamine, riboflavin, ascorbic acid, ergosterine, and niacin), micro and macro-elements (phosphorus and iron), and carbohydrates. Pleurotus is one of the most diversified medicinal and edible mushrooms related to the composition of chemical structures such as polysaccharides, glycoproteins, and secondary metabolites such as alkaloids and betalains. The cultivation of Pleurotus spp. on lignocellulosic wastes represents one of the most economically and cost-effective organic recycling processes, especially for the utilization of different feasible and cheap recyclable residues. Also, several Pleurotus spp. have the ability to remove phenolic compounds from wastewater with the action of phenoloxidase activity. Here, we have reviewed the chemistry of such polysaccharides and their reported biological activities, namely, anti-inflammatory, immunomodulatory, anti-diabetic, anti-tumor, antioxidant, etc. The mechanism of action and effects of novel polysaccharides extracted from various species of Pleurotus have been studied. The current study will be beneficial for guiding future research projects on the above concept and investigating more deeply the health of human beings. PRACTICAL APPLICATIONS: Mushrooms are one of the most delicious foods around the globe and have many medicinal properties for decades. Various Pleurotus species have been in focus in recent years because of their palatability and medicinal importance too. It contains many bioactive compounds among which polysaccharides are valued to a great extent. Many biological activities are exerted by polysaccharides derived from the Pleurotus spp., namely, anti-tumor, antioxidant, and many more. They are responsible for significant physiological responses in animals, animal-alternative in vitro models, and humans. Their important physicochemical characteristics benefit their use in the food industry as well. So, the biological activities of these Pleurotus spp. polysaccharides will provide an insight to develop Pleurotus spp. as functional foods, because of their nutritional value and presence of bioactive components.

Effect of alkali-neutralization treatment on triple-helical aggregates and independent triple helices of curdlan

Triple-helical aggregates (THAs) have been proven to affect the biological activities and functional properties of triple-helix polysaccharides. Thus, it's urgent to seek a method to reduce the size of THAs while preserving independent triple helices (ITHs). In this study, the effects of alkali-neutralization (AN) treatment on THAs and ITHs of curdlan were studied. The positive values of the Congo red test data (R²>0.99) fitted using a Logistic model indicated that AN treatment (C_NaOH/HCl>0.28 mol/L) facilitated the disaggregation of THAs. Congo red test, sedimentation test, and turbidity test showed that AN treatment (C_NaOH/HCl = 1.0 mol/L) significantly reduced the size of THAs to approximately 1 μm while effectively increasing the relative amount of ITHs to approximately 199 %. Fourier transform infrared spectroscopy and X-ray diffraction analysis showed that AN treatment basically unchanged the primary structure of curdlan chains, but affected the crystalline structure and the intermolecular and intramolecular hydrogen bonding of curdlan.

Recent advances in polysaccharides from Lentinus edodes (Berk.): Isolation, structures and bioactivities

Lentinus edodes, an important edible mushroom cultivated in East Asia for thousands of years, has been widely used as food and medicinal ingredient worldwide. Modern phytochemistry studies have demonstrated that L. edodes is very rich in bioactive polysaccharides, especially the β-glucans. Over the past two decades, the isolation, chemical properties, and bioactivities of polysaccharides from fruiting bodies, mycelium and fermentation broth of L. edodes have been drawing much attention from scholars around the world. It has been demonstrated that L. edodes polysaccharides possess various remarkable biological activities, including anti-oxidant, anti-tumor, anti-aging, anti-inflammation, immunomodulatory, antiviral, and hepatoprotection effects. This review summarizes the recent development of polysaccharides from L. edodes including the isolation methods, structural features, bioactivities and mechanisms, and their structure-activity relationship, which can provide useful research underpinnings and update information for their further application as therapeutic agents and functional foods.

Purification and characterization of a novel mixed-linkage α,β-d-glucan from Arca subcrenata and its immunoregulatory activity

Arca subcrenata Lischke is a seafood with high nutritional value. In this study, we purified and characterized a novel water-soluble polysaccharide (ASPG-2) from Arca subcrenata with significant immunoregulatory effects and no apparent cell toxicity. ASPG-2 is a class of mixed-linkage α,β-d-glucan backbones with α-linked side chains with a molecular weight of 4.39 × 10⁵ Da. Its structure was characterized as a repeating unit consisting of (1 → 3)-β-d-Glcp, (1 → 4)-α-d-Glcp, (1 → 4,6)-α-d-Glcp and (1 → 6)-α-d-Glcp. Using mouse RAW264.7 macrophages, we demonstrated that ASPG-2 exerted marked immunoregulatory effects by promoting the secretion of NO and increasing the phagocytosis of RAW264.7 cells in vitro. Moreover, flow cytometry analysis of the expression of the cell surface molecule CD86 revealed that ASPG-2 could polarize RAW264.7 cells into the M1 type. The immunomodulatory mechanism of ASPG-2 in macrophages was associated with the activation of the TLR4-MAPK/Akt-NF-κB signalling pathways. These results indicated that ASPG-2 might be researched and developed as a potential immunomodulatory agent or health product from marine organisms.

Effects of Medicinal Fungi-Derived β-Glucan on Tumor Progression

β-Glucans have been studied in animal species, from earthworms to humans. They form a heterogenous group of glucose polymers found in fungi, plants, bacteria, and seaweed. β-Glucans have slowly emerged as an important target for the recognition of pathogens. In the current review, we highlight the major roles of mushroom-derived β-glucans on cancer progression.

Triple-helix polysaccharides: Formation mechanisms and analytical methods

Triple helix conformation of polysaccharides is generally believed to be associated with their biological activities. However, the formation mechanisms and analytical methods for the triple helix polysaccharides, to our best knowledge, have not been systematically investigated. This article reviews specifically the literature on the formation and characterization of triple-helix polysaccharides. The formation mechanisms and related structural-conformation-bioactivity relationships are discussed; various analytical methods for characterizing triple-helix polysaccharides are summarized. This review devotes to a better understanding of the formation of polysaccharides based triple-helix structure and related analytical methods. These could provide some insights and inspirations for their applications in both food and pharmaceutical industries.

Molar mass effect in food and health

It is demanded to supply foods with good quality for all the humans. With the advent of aging society, palatable and healthy foods are required to improve the quality of life and reduce the burden of finance for medical expenditure. Food hydrocolloids can contribute to this demand by versatile functions such as thickening, gelling, stabilising, and emulsifying, controlling texture and flavour release in food processing. Molar mass effects on viscosity and diffusion in liquid foods, and on mechanical and other physical properties of solid and semi-solid foods and films are overviewed. In these functions, the molar mass is one of the key factors, and therefore, the effects of molar mass on various health problems related to noncommunicable diseases or symptoms such as cancer, hyperlipidemia, hyperglycemia, constipation, high blood pressure, knee pain, osteoporosis, cystic fibrosis and dysphagia are described. Understanding these problems only from the viewpoint of molar mass is limited since other structural characteristics, conformation, branching, blockiness in copolymers such as pectin and alginate, degree of substitution as well as the position of the substituents are sometimes the determining factor rather than the molar mass. Nevertheless, comparison of different behaviours and functions in different polymers from the viewpoint of molar mass is expected to be useful to find a common characteristics, which may be helpful to understand the mechanism in other problems.

Structure characterization and in vitro immunomodulatory activities of carboxymethyl pachymaran

Carboxymethyl pachymaran (CMP) was prepared from Poria cocos polysaccharide by carboxymethylation. Two types of CMP (CMP-1 and CMP-2) were further purified by DEAE-52 anion-exchange chromatography. The structure characteristics and immunomodulatory activities of CMP-1 and CMP-2 were investigated. CMP-1 was determined as β-(1 → 3)-d-glucan. A β-(1 → 3)-d-glucan backbone structure was also found in CMP-2, which was mainly consistent of mannose and glucose, with the mole ratio of 0.03:1. The molecular weight of CMP-1 was 126.1 kDa with a 30.4 nm irregular sphere in distilled water. However, the molecular weight of CMP-2 was 172.6 kDa in a 19.9 nm spherical structure in water solution. Both CMP-1 and CMP-2 had triple helical structure, which can promote the proliferation and the phagocytosis of macrophages. Moreover, CMP-1 and CMP-2 both could improve the secretions of NO, TNF-α and IL-6 by increasing the expression of iNOS, TNF-α and IL-6 mRNA, but CMP-1 exhibited a stronger immunomodulatory ability than that of CMP-2. Our results indicated that CMP-1 and CMP-2 can act as potential immunomodulatory agents.

Effect of exopolysaccharides from cariogenic bacteria on human gingival fibroblasts

Bacterial biofilm (dental plaque) plays a key role in caries etiopathogenesis and chronic periodontitis in humans. Dental plaque formation is determined by exopolysaccharides (EPSs) produced by cariogenic and periopathogenic bacteria. The most frequent cariogenic bacteria include oral streptococci (in particular S. mutans) and lactobacilli (most frequently L. acidophilus). In turn, the dominant periopathogen in periodontitis is Porphyromonas gingivalis. Development of dental caries is often accompanied with gingivitis constituting the mildest form of periodontal disease. Basic cellular components of the gingiva tissue are fibroblasts the damage of which determines the progression of chronic periodontitis. Due to insufficient knowledge of the direct effect of dental plaque on metabolic activity of the fibroblasts, this work analyses the effect of EPSs produced by S. mutans and L. acidophilus strains (H₂O₂-producing and H₂O₂-not producing) on ATP levels in human gingival fibroblasts (HGF-1) and their viability. EPSs produced in 48-hours bacterial cultures were isolated by precipitation method and quantitatively determined by phenol - sulphuric acid assay. ATP levels in HGF-1 were evaluated using a luminescence test, and cell viability was estimated using fluorescence test. The tests have proven that EPS from S. mutans did not affect the levels of ATP in HGF-1. Whereas EPS derived from L. acidophilus strains, irrespective of the tested strain, significantly increased ATP levels in HGF-1. The analysed EPSs did not affect the viability of cells. The tests presented in this work show that EPSs from cariogenic bacteria have no cytotoxic effect on HGF-1. At the same time, the results provide new data indicating that EPSs from selected oral lactobacilli may have stimulating effect on the synthesis of ATP in gingival fibroblasts which increases their energetic potential and takes a protective effect.

Molecular Properties of Flammulina velutipes Polysaccharide-Whey Protein Isolate (WPI) Complexes via Noncovalent Interactions

Whey protein isolate (WPI) has a variety of nutritional benefits. The stability of WPI beverages has attracted a large amount of attention. In this study, Flammulina velutipes polysaccharides (FVPs) interacted with WPI to improve the stability via noncovalent interactions. Multiple light scattering studies showed that FVPs can improve the stability of WPI solutions, with results of radical scavenging activity assays demonstrating that the solutions of the complex had antioxidant activity. The addition of FVPs significantly altered the secondary structures of WPI, including its α-helix and random coil. The results of bio-layer interferometry (BLI) analysis indicated that FVPs interacted with the WPI, and the equilibrium dissociation constant (K_D) was calculated as 1.736 × 10^-4 M in this study. The in vitro digestibility studies showed that the FVPs protected WPI from pepsin digestion, increasing the satiety. Therefore, FVPs effectively interact with WPI through noncovalent interactions and improve the stability of WPI, with this method expected to be used in protein-enriched and functional beverages.

Advances in the extraction, purification, structural-property relationships and bioactive molecular mechanism of Flammulina velutipes polysaccharides: A review

With the further research in recent years, Flammulina velutipes (F. velutipes), an edible mushroom, has great application value in many fields. As one of the main bioactive components in F. velutipes, polysaccharide has a series of functions such as anti-oxidation, immune regulation, anti-inflammation, liver protection, anti-tumor, anti-hyperlipidemia and so on. In this paper, the current progress in the extraction, purification, structural characteristics and bioactivities of F. velutipes polysaccharides (FVPs) were reviewed. Meanwhile, the structural-property relationships of FVPs were further discussed. In addition, based on in vitro and in vivo experiments, the possible mechanisms of bioactivities of FVPs were summarized. In order to understand FVPs more comprehensively, the application status and the future research work of FVPs were also introduced. Finally, we hope that our research can provide a reference for further research and development of FVPs.

Isolation, Characterization and Bioactive Properties of Alkali-Extracted Polysaccharides from Enteromorpha prolifera

Four new purified polysaccharides (PAP) were isolated and purified from the Enteromorpha prolifera by alkali extraction, and further characterization was investigated. Their average molecular weights of PAP-1, PAP-2, PAP-3, and PAP-4 were estimated as 3.44 × 104, 6.42 × 104, 1.20 × 105, and 4.82 × 104 Da, respectively. The results from monosaccharide analysis indicated that PAP-1, PAP-2, PAP-3 were acidic polysaccharides and PAP-4 was a neutral polysaccharide. PAP-1 and PAP-2 mainly consist of galacturonic acid, while PAP-3 and PAP-4 mainly contained rhamnose. Congo red test showed that no triple helical structure was detected in the four polysaccharides. The antioxidant activities were investigated using 1,1-diphenyl-2-picrylhydrazyl (DPPH), Superoxide, and 2, 2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical assay. In vitro antitumor activities were evaluated by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. PAP-1 exhibited relatively stronger antioxidant activities among the four polysaccharides in a dose-dependent manner. At a concentration of 1.00 mg/mL, the antioxidant activities of PAP-1 on the DPPH radical scavenging rate, superoxide anion radical scavenging rate, and ABTS radical rate at 1.00 mg/mL were 56.40%, 54.27%, and 42.07%, respectively. They also showed no significant inhibitory activity against MGC-803, HepG2, T24, and Bel-7402 cells. These investigations of polysaccharides provide a scientific basis for the use of E. prolifera as an ingredient in functional foods and medicines.

Structural investigation and comparative cytotoxic activity of water-soluble polysaccharides from fruit bodies of the medicinal fungus quinine conk

The structures and cytotoxic activities of water-soluble polysaccharides were investigated to search for biologically active polysaccharides from the fruit bodies of quinine conks (Fomitopsis officinalis). The decoctions of this medical fungus are actively used in folk medicine in many countries and traditional Chinese medicine. From the fungal extract we prepared, only branched β-glucan had cytotoxic activity among all the water-soluble polysaccharides. This glucan is characterized by a regular structure. Its backbone is formed by 1,3-linked β-D-Glcp residues, of which every third residue is substituted at O-6 by a single β-D-Glcp residue. It has a triple helix conformation according to the data obtained from a colorimetric assay with Congo red dye and is characterized by a high-weight average molar mass (Mw > 800 kDa). β-Glucan possessed cytotoxic activity against HeLa cells (IC₅₀ = 318 ± 47 μg/mL) and induced the formation of apoptotic bodies around most cancer cells at a concentration of 200 μg/mL. It should be noted that extraction with boiling water, which is usually used to obtain extracts and decoctions, is unable to isolate active β-glucan. Active β-glucan can be obtained in an individual state by cold alkali extraction after dehydration of the fruit bodies and removal of the components extractable by boiling water.

Quality control and immunological activity of lentinan samples produced in China

Lentinan is widely used as a therapeutic agent for treatment of malignant tumors in clinical practice. The chemical structure of lentinan is highly associated with its biological activity. In this study, the correlation between the structure of lentinan and its immune activity was investigated to assess the function of key parameters that can influence quality control of lentinan. The results showed that the batch-to-batch consistency of two lentinan samples was satisfactory, indicating the stability of production process of lentinan. However, although the chemical composition and triple-helical conformation (THC) of the tested samples were relatively similar, their Mw, polydispersity index (PDI), and Rg_z remarkably varied due to different production processes. In vitro immunomodulatory assay reflects that lentinan could stimulate the macrophages phagocytic capacity. Meanwhile, lentinan samples could improve the spleen and thymus indices, promote the proliferation of lymphocytes and adjust for the percentages of CD4+ and CD8+ T cells in vivo. Furthermore, the immunomodulatory effect of lentinan sample B (Mw: 650,700 g/mol) was superior than that of the sample A (Mw: 4,818,700 g/mol). It was noted that the Mw should be detected as a necessary index for quality control of lentinan to ensure stability and effectiveness of the production process.

Structure-Functional Activity Relationship of β-Glucans From the Perspective of Immunomodulation: A Mini-Review

β-Glucans are a heterogeneous group of glucose polymers with a common structure comprising a main chain of β-(1,3) and/or β-(1,4)-glucopyranosyl units, along with side chains with various branches and lengths. β-Glucans initiate immune responses via immune cells, which become activated by the binding of the polymer to specific receptors. However, β-glucans from different sources also differ in their structure, conformation, physical properties, binding affinity to receptors, and thus biological functions. The mechanisms behind this are not fully understood. This mini-review provides a comprehensive and up-to-date commentary on the relationship between β-glucans' structure and function in relation to their use for immunomodulation.

Hypolipidemic Effects of β-Glucans, Mannans, and Fucoidans: Mechanism of Action and Their Prospects for Clinical Application

The search for lipid-lowering drugs is important for clinical medicine. This review summarizes our research findings regarding the hypolipidemic activity of polysaccharides. There are several validated agents altering lipid levels which reduce the risk of atherosclerotic cardiovascular events. Nonetheless, for many people, the risk of such an event remains unacceptably high despite treatment with these agents. This situation has prompted the search for new therapies to reduce the residual cardiovascular risk. The lipid-lowering effect of β-glucans consumed with food was demonstrated in patients with atherosclerosis. The mechanism of the protective effect of β-glucans is poorly studied. The effects of β-glucans are mediated by Toll-like receptors, by dectin-1, and possibly by other receptors. Nevertheless, the mechanism of the protective action of β-glucan in lipemic mice has been studied insufficiently. This review will present up-to-date information regarding experimental hypolipidemic polysaccharide compounds that hold promise for medicine. Phagocyte-specific chitotriosidase in humans contributes to innate immune responses against chitin-containing fungi. This enzyme has been first described in patients with Gaucher disease and serves as an important diagnostic biomarker. It has been reported that, in mice, chitin particles of certain size are recognized by macrophages through Toll-like receptors, dectin-1, and to a lesser extent through mannose receptor.

Size distribution and chain conformation of six different fucoidans using size-exclusion chromatography with multiple detection

Fucoidans represent an intriguing class of fucose-containing sulfated polysaccharides. The biological activities of these polysaccharides are related to their compositional and structural parameters, whereby their degree of sulfation, as well as molecular weight (MW) distribution and chain conformation play important roles. Modern NMR and mass spectrometry techniques allow elucidating details of the glycan structure, but not the structure of the whole molecules in their native state. Accordingly, the knowledge about the latter of the fucoidans is currently still limited. Contrary to traditional MW determination by SEC with column calibration, SEC with triple detection provides not only the absolute Mw, but can also give information on additional molecule characteristics. In the present study, we used this method to compare six fucoidans extracted from Fucus vesiculosus (FV), F. serratus (FS), F. evanescens (FE), Dictyosiphon foeniculaceus (DF), Laminaria digitata (LD), and Saccharina latissima (SL) concerning their molar mass (Mw, Mn, Mp, dispersity) and size (rms radius, Rh) characteristics and distribution as well as their chain conformation in solution. The tested fucoidans displayed considerable structural diversity including large differences in their MW profiles and showed to be heterogeneously composed. Fuc-FV and Fuc-SL showed the broadest MW distributions, those from Fuc-FE and Fuc-DF the narrowest ones. Most of the fucoidan fractions (except for Fuc-DF) turned out to exist as expanded flexible chains in PBS solution. The conformation data suggest branched structures with partly long side chains. The knowledge obtained by this study is useful for further fractionation and structural characterization as well as the interpretation of the bioactivity differences between the various fucoidans.

Recent Advances in Chain Conformation and Bioactivities of Triple-Helix Polysaccharides

Natural polysaccharides derived from renewable biomass sources are regarded as environmentally friendly and sustainable polymers. As the third most abundant biomacromolecule in nature, after proteins and nucleic acids, polysaccharides are also closely related with many different life activities. In particular, β-glucans are one of the most widely reported bioactive polysaccharides and are usually considered as biological response modifiers. Among them, β-glucans with triple-helix conformation have been the hottest and most well-researched polysaccharides at present, especially lentinan and schizophyllan, which are clinically used as cancer therapies in some Asian countries. Thus, creation of these active triple-helix polysaccharides is beneficial to the research and development of sustainable "green" biopolymers in the fields of food and life sciences. Therefore, full fundamental research of triple-helix polysaccharides is essential to discover more applications for polysaccharides. In this Review, the recent research progress of chain conformations, bioactivities, and structure-function relationships of triple-helix β-glucans is summarized. The main contents include the characterization methods of the macromolecular conformation, proof of triple helices, bioactivities, and structure-function relationships. We believe that the governments, enterprises, universities, and institutes dealing with the survival and health of human beings can expect the development of natural bioproducts in the future. Hence, a deep understanding of β-glucans with triple-helix chain conformation is necessary for application of natural medicines and biologics for a sustainable world.

A β-glucan from Grifola frondosa effectively delivers therapeutic oligonucleotide into cells via dectin-1 receptor and attenuates TNFα gene expression

Grifola frondosa is an edible and medicinal mushroom with great nutritional values and bioactivities. In the present study, a soluble homogeneous β-glucan, GFPS, with high molecular mass of 5.42 × 10⁶ Da was purified from the fruit bodies of Grifola frondosa using 5% cold NaOH. The structure of GFPS was determined with FT-IR, NMR, and monosaccharide composition analysis, and was identified to be a β-D-(1-3)-linked glucan backbone with a single β-D-(1-6)-linked glucopyranosyl residue branched at C-6 on every third residue. Our results indicated that GFPS had a triple helical structure and could form complex with polydeoxyadenylic acid (poly[A]). Further studies demonstrated that GFPS could interact with poly[A] moiety of a designed antisense oligonucleotide (ASO) targeting the primary transcript of proinflammatory cytokine TNFα (TNFα-A60). This GFPS-based complex could incorporate TNFα-A60 into the macrophage cells via dectin-1 receptor and attenuate lipopolysaccharide-induced secretion of TNFα. Our results suggested that GFPS could be applied to deliver therapeutic oligonucleotides for the treatment of diseases such as inflammation and cancers.

Natural polysaccharides with different conformations: extraction, structure and anti-tumor activity

Natural polysaccharides as sustainable polymers are rich sources with good biological safety and various biological functions, which are important research topics in the fields of food and medicine.

Effect of the Modifications on the Physicochemical and Biological Properties of β-Glucan-A Critical Review

β-Glucan exhibits many biological activities and functions such as stimulation of the immune system and anti-inflammatory, anti-microbial, anti-infective, anti-viral, anti-tumor, anti-oxidant, anti-coagulant, cholesterol-lowering, radio protective, and wound healing effects. It has a wide variety of uses in pharmaceutical, cosmetic, and chemical industries as well as in food processing units. However, due to its dense triple helix structure, formed by the interaction of polyhydroxy groups in the β-d-glucan molecule, it features poor solubility, which not only constrains its applications, but also inhibits its physiological function in vivo. One aim is to expand the applications for modified β-glucan with potential to prevent disease, various therapeutic purposes and as health-improving ingredients in functional foods and cosmetics. This review introduces the major modification methods required to understand the bioactivity of β-glucan and critically provides a literature survey on the structural features of this molecule and reported biological activity. We also discuss a new method to create novel opportunities to exploit maximally various properties of β-glucan, namely ultrasound-assisted enzymatic modification.

Structural Characterization and Chain Conformation of Water-Soluble β-Glucan from Wild Cordyceps sinensis

Water-soluble β-d-glucan was obtained from wild Cordyceps sinensis by alkali solution and ethanol precipitation. The structure characteristics were determined using high-performance anion-exchange chromatography coupled with pulsed amperometric detection (HPAEC-PAD), methylation combined with gas chromatography-mass spectrometry, and one-/two-dimensional nuclear magnetic resonance spectroscopy. Results showed that β-d-glucan had a structure of every seven (1→3)-β-d-Glcp backbone residues with two (1→6)-β-d-Glcp branches. Additionally, conformation properties in different solvents were investigated by static light scattering, dynamic light scattering, and HPSEC with multiple detectors. It was found that β-d-glucan in 0.5 M NaOH had a narrow unimodal distribution of hydrodynamic radius displaying a spherical coil conformation, whereas it formed severe aggregation in dimethyl sulfoxide. In 0.1 M NaNO₃, β-d-glucan mainly existed as a rod-like conformation corresponding to a helical structure together with small aggregates (10%). This work added more information to the understanding of C. sinensis polysaccharides.

Characterization of a polysaccharide with antioxidant and anti-cervical cancer potentials from the corn silk cultivated in Jilin province

Corn silk polysaccharides (CSPs) were extracted from the corn silk cultivated in Jilin province, China, where is one of the golden corn belts worldwide. Three fractions (CSP-1, CSP-2 and CSP-3) were obtained by DEAE-52 cellulose and the former two fractions were further purified by Sephadex G-150 column chromatography to obtain CSP-S-1 and CSP-S-2. The molecular weights of CSP-S-1 and CSP-S-2 were calculated to be 586 kDa and 813 kDa, respectively. CSP-S-1 was composed of galactose, arabinose, xylose and rhamnose at a molar ratio of 4.16:1.00:1.01:6.32 and CSP-S-2 was composed of galactose, arabinose, glucose and rhamnose at a molar ratio of 8.71:3.58:0.169:1.00. CSP-S-2 outperformed CSP-S-1 in scavenging DPPH, ABTS and hydroxyl radicals, and significantly inhibited the proliferation of HeLa cells. IR and NMR analysis indicated that CSP-S-2 was pyranose. CSP-S-2 consisted of 1 → 4 and 1 → 6 linkages and exhibited a triple helix configuration. In summary, CSP-S-2 possesses high potential to be developed as a novel antioxidant and anti-cervical cancer agent.

Fungal polysaccharides

Fungal bioactive polysaccharides are well known and have been widely used in Asia as a part of the traditional diet and medicine. In fact, some biopolymers (mainly β-glucans or glycoconjugate) have already made their way to the market as antitumor or immunostimulating drugs. In the last decades, the relationship between structure and activity of polysaccharides and their detailed mode of action have been the core of intense research to understand and utilize their medicinal properties. Most of the antitumor polysaccharides belong to conserved β-glucans, with a linear β-(1→3)-glucan backbone and attached β-(1→6) branch. Structurally different β-glucans appear to have different affinities toward their receptors and thus generate markedly different host responses. However, their antitumor activities are mainly influenced by molecular mass, degree of branching, conformation, and structure modification of the polysaccharides. β-Glucans act on several immune receptors including Dectin-1, complement receptor (CR3) and TLR-2/6, then trigger both innate and adaptive response and enhance opsonic and nonopsonic phagocytosis. Various receptor interactions explain the possible mode of actions of polysaccharides.

Anti-tumor effect of volatile oil from Houttuynia cordata Thunb. on HepG2 cells and HepG2 tumor-bearing mice

The aim of this paper is to study the anti-tumor mechanism of volatile oil from Houttuynia cordata Thunb. (sodium new houttuyfonate, SNH). In vitro, SNH exhibited a concentration-dependent cytotoxic effect against four human cancer lines (HepG2, A2780, MCF-7, SKOV-3). SNH treatment with different concentrations induced HepG2 cells to exhibit varying degrees of morphological changes in apoptotic features, such as round shape, cell shrinkage and formation of apoptotic body. It was observed that SNH caused the decrease in Bcl-2 mRNA expression and triggered the apoptosis of HepG2 cells. Wound healing assay and RT-PCR results showed that the decrease in the expression level of MMP9 and VEGF was observed in HepG2 cells after treatment with SNH for 48 h, suggesting that the extracellular matrix pathway degradation was involved in the HepG2 cells migration. Moreover, we got an insight into the binding mode of SNH into the MMP9 active site through 3D pharmacophore models. Docking study and molecular dynamics (MD) simulation analysis sheds light on that SNH was completely embedded into the MMP9 active site and formed hydrogen bonds with key catalytic residues of MMP9, including Ala191, His190, Ala189 and Glu227. The prediction of SNH binding interaction energies in the MMP9 was almost in good agreement with the original inhibitor EN140. In vivo experiments, both SNH and cyclophosphamide significantly reduced tumor weights and their tumor inhibitory rates were 50.78% and 82.61% respectively. This study demonstrated that SNH was an apoptosis inducer in HepG2 cells. SNH has four possible functions, that it could induce apoptosis by mitochondria pathway in HepG2 cells, inhibit the tumor growth, regulate Bcl-2 family mRNA expression and effectively subdue migration of hepatocellular carcinoma cells by decreasing the expression of MMP9 and VEGF. Therefore, SNH might be a potential candidate drug for the treatment of hepatocellular carcinoma, which could provide a reference for further clinical research.

Chain conformation and rheological properties of an acid-extracted polysaccharide from peanut sediment of aqueous extraction process

A polysaccharide (PPS) in peanut sediment of aqueous extraction process was obtained at pH4.0, purified via anion-exchange chromatography. The composition, chain conformation and rheological properties were investigated. PPS mainly consisted of arabinose, galacturonic acid, xylose, and rhamnose. The intrinsic viscosity [η] was 0.71 dL/g in 0.1 M NaNO₃ solution. The weight-average molar mass Mw and polydispersity index were 3.77 × 10⁵ g/mol and 1.25, suggesting high homogeneity. The average radius of gyration (R_g), hydrodynamic radius (R_h), R_g/R_h ratio and conformation parameter v were 25.5, 18.2, 1.40 and 0.21, respectively, indicating compact coil chain conformation with branched structure. Molecular morphology revealed that PPS displayed chain shape comprised of spheres with a diameter range of 15-50 nm and apparent length of chains mainly ranged from 100 to 300 nm. The aggregation caused by molecular self-association enhanced with concentration increasing. Additionally, Newtonian behavior was observed at various concentrations. Increase in temperature effectively broke this behavior. 10.0 wt.% PPS possessed activation energy of 21.7 KJ/mol, was structured liquid and almost fitted Cox-Merz rule. These closely related with its conformation and molecular self-association behavior.

A Concise Review on the Molecular Structure and Function Relationship of β-Glucan

β-glucan is a non-starch soluble polysaccharide widely present in yeast, mushrooms, bacteria, algae, barley, and oat. β-Glucan is regarded as a functional food ingredient due to its various health benefits. The high molecular weight (Mw) and high viscosity of β-glucan are responsible for its hypocholesterolemic and hypoglycemic properties. Thus, β-glucan is also used in the food industry for the production of functional food products. The inherent gel-forming property and high viscosity of β-glucan lead to the production of low-fat foods with improved textural properties. Various studies have reported the relationship between the molecular structure of β-glucan and its functionality. The structural characteristics of β-glucan, including specific glycosidic linkages, monosaccharide compositions, Mw, and chain conformation, were reported to affect its physiochemical and biological properties. Researchers have also reported some chemical, physical, and enzymatic treatments can successfully alter the molecular structure and functionalities of β-glucan. This review article attempts to review the available literature on the relationship of the molecular structure of β-glucan with its functionalities, and future perspectives in this area.

C-type lectin receptor-mediated immune recognition and response of the microbiota in the gut

C-type lectin receptors (CLRs) are powerful pattern-recognition receptors that discern ‘self’ and ‘non-self’ in our body and protect us from invasive pathogens by mediating immune recognition and response. The gastrointestinal tract is very important for the maintenance of homeostasis; it is the largest shelter for the billions of microorganisms in the body and CLRs play a crucial regulatory role in this system. This study focuses on several CLRs, including Dectin-1, Dectin-2, Dectin-3 and Mincle. We summarize the roles of CLRs in maintaining gastrointestinal immune-system homeostasis, especially their functions in mediating immune recognition and responses in the gut, discuss their relationships to some diseases, highlight the significance of CLR-mediated sensing of microbial and non-microbial compounds in the gut immune system and identify new therapeutic targets.

Ginger polysaccharides induced cell cycle arrest and apoptosis in human hepatocellular carcinoma HepG2 cells

In this study, ginger polysaccharide (GP) was obtained from ginger by enzymatic method, its chemical properties and antitumor activity were investigated. The results indicated that the composition and proportion of GP were l‑rhamnose, d‑arabinose, d‑mannose, d‑glucose and d‑galactose in a molar ratio of 3.64:5.37:3.04:61.03:26.91, GP had the characteristic absorption peak of polysaccharide. Congo red experiment showed that GP had a triple helix structure, which could have anti-tumor effect. Furthermore, MTT assay, cell morphology observation, nuclear morphology observation and reactive oxygen species observation demonstrated that GP had significant antitumor effect. Flow cytometry suggested that GP could promote apoptosis and arrest cells in G0-G1 phase. Real-time fluorescence quantification and Western blot revealed that GP could up-regulate the expression of Bax, Fas, FasL, caspase-3, p21 and p53, and down-regulate the expression of Bcl-2. These studies suggested that GP would be used as an antitumor drug in foods to promote the development of functional foods.