(1→3)-β-d-Glucans as biological response modifiers: a review of structure-functional activity relationships

Factor G utilizes a carbohydrate-binding cleft that is conserved between horseshoe crab and bacteria for the recognition of beta-1,3-D-glucans

In the horseshoe crab, the recognition of beta-1,3-D-glucans by factor G triggers hemolymph coagulation. Factor G contains a domain of two tandem xylanase Z-like modules (Z1-Z2), each of which recognizes beta-1,3-D-glucans. To gain an insight into the recognition of beta-1,3-D-glucans from a structural view point, recombinants of Z1-Z2, the C-terminal module Z2, Z2 with a Cys to Ala substitution (Z2A), and its tandem repeat Z2A-Z2A were characterized. Z2 and Z1-Z2, but not Z2A and Z2A-Z2A, formed insoluble aggregates at higher concentrations more than approximately 30 and 3 microM, respectively. Z1-Z2 and Z2A-Z2A bound more strongly to an insoluble beta-1,3-D-glucan (curdlan) than Z2A. The affinity of Z2A for a soluble beta-1,3-D-glucan (laminarin) was equivalent to those of Z1-Z2, Z2A-Z2A, and native factor G, suggesting that the binding of a single xylanase Z-like module prevents the subsequent binding of another module to laminarin. Interestingly, Z2A as well as intact factor G exhibited fungal agglutinating activity, and fungi were specifically detected with fluorescently tagged Z2A by microscopy. The chemical shift perturbation of Z2A induced by the interaction with laminaripentaose was analyzed by nuclear magnetic resonance spectroscopy. The ligand-binding site of Z2A was located in a cleft on a beta-sheet in a predicted beta-sandwich structure, which was superimposed onto cleft B in a cellulose-binding module of endoglucanase 5A from the soil bacterium Cellvibrio mixtus. We conclude that the pattern recognition for beta-1,3-D-glucans by factor G is accomplished via a carbohydrate-binding cleft that is evolutionally conserved between horseshoe crab and bacteria.

A novel beta-glucan produced by Paenibacillus polymyxa JB115 induces nitric oxide production in RAW264.7 macrophages

The effect of extracellular β-(1→3), (1→6)-glucan, produced by Paenibacillus polymyxa JB115, on nitric oxide (NO) production in RAW264.7 macrophages was investigated. β-glucan induced the production of NO by RAW264.7 macrophages in a concentration- and time-dependent manner. Moreover, β-glucan stimulation increased the mRNA expression of iNOS, COX-2 and IL-6 in RAW264.7 macrophages in a concentration-dependent manner.

Supramolecular structure and conformation of a (1-->3)(1-->2)-beta-D-glucan from Lactobacillus suebicus CUPV221 as observed by tapping mode atomic force microscopy

Tapping mode atomic force microscopy (TM-AFM) has been used to analyze the supramolecular structure and conformation of the (1-->3)(1-->2)-beta-D-glucan produced by Lactobacillus suebicus CUPV221 isolated from cider. Solutions for TM-AFM observation were prepared by dispersing the solid glucan in distilled water and in alkaline aqueous solutions. It was found that from the distilled water at 10 mg/L or higher concentrations, the (1-->3)(1-->2)-beta-D-glucan forms networks. The heat resistance of the networks depends on the concentration. From the alkaline aqueous solutions, different supramolecular structures were observed depending on the pH. From the weakest alkaline solution, a fairly rough morphology with a high density of spikelike growth features was revealed. As the ionic force of the medium increased, the sizes of the spikelike growth features diminished, and even many disaggregated fibers could be found. At 0.4 M NaOH (pH 13.16), the aggregates had disappeared almost totally. NaOH aqueous solutions (0.1 and 0.4 M) were used to carry out the study of conformation. At 0.1 M NaOH, the aggregates were partially detached, and many free microfibers were found to which a helical conformation could be assigned due to their stiffness and rodlike character. At 0.4 M NaOH, the beginning of the dissociation of the helical structures was seen.

Sulfonation and anticoagulant activity of botryosphaeran from Botryosphaeria rhodina MAMB-05 grown on fructose

Botryosphaeran (EPS(FRU)), an exopolysaccharide of the beta-(1-->3,1-->6)-d-glucan type with 31% branching at C-6, is produced by the fungus Botryosphaeria rhodina MAMB-05 when grown on fructose as carbon source. Botryosphaeran was derivatized by sulfonation to induce anticoagulant activity. The effectiveness of the sulfonation reaction by chlorosulfonic acid in pyridine was monitored by the degree of substitution and FT-IR analysis of the sulfonated EPS(FRU) (once sulfonated, EPS(FRUSULF); and re-sulfonated, EPS(FRURESULF)). Activated partial thromboplastin time (APTT) and thrombin time (TT) tests of EPS(FRURESULF) indicated significant in vitro anticoagulant activity that was dose-dependent. EPS(FRU) did not inhibit any of the coagulation tests.

Characterization and anti-tumor activities of sulfated polysaccharide SRBPS2a obtained from defatted rice bran

A novel chemically sulfated polysaccharide SRBPS2a with potent anti-tumor activity was derived from defatted rice bran by chlorosulfonic acid-pyridine (CSA-Pyr) method. The average molecular weight of SRBPS2a was 3.5 x 10(5) Da and the degree of sulfation (DS) was 1.29. The Fourier-transform infrared spectra (FT-IR) and 13C NMR spectroscopy analysis revealed that SRBPS2a was mainly consist of beta-(1-->3)-D-galactopyranosyl residues, the sulfate substitution site was on C-2 and C-4 while the side chains were cut off during the sulfated reaction. Furthermore, SRBPS2a exhibited evident growth inhibition on mouse mammary tumor EMT-6 cells both in vitro and in vivo.

The effects of beta-glucan on human immune and cancer cells

Non-prescriptional use of medicinal herbs among cancer patients is common around the world. The alleged anti-cancer effects of most herbal extracts are mainly based on studies derived from in vitro or in vivo animal experiments. The current information suggests that these herbal extracts exert their biological effect either through cytotoxic or immunomodulatory mechanisms. One of the active compounds responsible for the immune effects of herbal products is in the form of complex polysaccharides known as beta-glucans. beta-glucans are ubiquitously found in both bacterial or fungal cell walls and have been implicated in the initiation of anti-microbial immune response. Based on in vitro studies, beta-glucans act on several immune receptors including Dectin-1, complement receptor (CR3) and TLR-2/6 and trigger a group of immune cells including macrophages, neutrophils, monocytes, natural killer cells and dendritic cells. As a consequence, both innate and adaptive response can be modulated by beta-glucans and they can also enhance opsonic and non-opsonic phagocytosis. In animal studies, after oral administration, the specific backbone 1-->3 linear beta-glycosidic chain of beta-glucans cannot be digested. Most beta-glucans enter the proximal small intestine and some are captured by the macrophages. They are internalized and fragmented within the cells, then transported by the macrophages to the marrow and endothelial reticular system. The small beta-glucans fragments are eventually released by the macrophages and taken up by other immune cells leading to various immune responses. However, beta-glucans of different sizes and branching patterns may have significantly variable immune potency. Careful selection of appropriate beta-glucans is essential if we wish to investigate the effects of beta-glucans clinically. So far, no good quality clinical trial data is available on assessing the effectiveness of purified beta-glucans among cancer patients. Future effort should direct at performing well-designed clinical trials to verify the actual clinical efficacy of beta-glucans or beta-glucans containing compounds.

Supplements for immune enhancement in hematologic malignancies

This brief review aims to discuss the various cellular immunological aspects and related mechanisms of the use of specific components from traditional herbal medicines. We begin with lessons learned from thalidomide as an effective single drug with multiple mechanisms of action to treat multiple myeloma. Examples of “supplements” or integrative therapy will be drawn from arsenic trioxide, medicinal mushrooms including Coriolus vesicular and Ganoderma lucidum, followed by the discussion of beta-glucans affecting various immunological important cellular subsets. Different classes of compounds may enhance distinct immune cell populations that might contribute to a multi-targeted holistic effects on anti-cancer treatment. Finally, we conclude by highlighting an herbal formulation PHY906 as a potential adjunct to chemotherapy that might become one of the first US Food and Drug Administration (FDA) approved oral herbal medicines for anti-cancer adjunct treatment.

Effect of gamma irradiation on the efficacy of beta-glucan against acetaminophen induced toxicity in mice

The present study was conducted to compare the efficacy of unirradiated beta-glucan (UBG) and gamma irradiated beta-glucan (GIBG) against acetaminophen (APAP) induced hepatotoxicity in mice. Mice of BALB/c strain were pretreated with UBG and GIBG (50mg/kg, p.o.) for 7 days and on the 8th day they received an overdose of APAP (500 mg/kg, i.p.). Eight hours after the APAP injection, the levels of serum aminotransferase (AST) and alanine aminotransferase (ALT) were measured and liver, kidney and lung tissue were examined for morphological changes. A significant elevation (p<0.001) of the levels of AST and ALT was observed in mice toxicated with APAP. Histology data revealed severe liver centrilobular necrosis, portal vein damage with apparent toxicity in renal glomerulus and lung inflammation associated with edema. However, a significant inhibition (p<0.05) in the elevation of AST and ALT was observed in mice that received UBG and GIBG compared with APAP-treated mice. Histology examination revealed the non-statistical difference between the protective effects of GIBG and UBG against acetaminophen challenge. In conclusion, it was demonstrated that gamma irradiation induced no severe alteration in the protective activity of beta-glucan against APAP-induced hepatotoxicity.

Structural stability of Sclerotium rolfsii ATCC 201126 beta-glucan with fermentation time: a chemical, infrared spectroscopic and enzymatic approach

AIMS

Sclerotium rolfsii ATCC 201126 exopolysaccharides (EPSs) recovered at 48 h (EPS I) and 72 h (EPS II) of fermentation, with differences in rheological parameters, hydrogel topography, salt tolerance, antisyneresis, emulsifying and suspending properties, were subjected to a polyphasic characterization in order to detect structural divergences.

METHODS AND RESULTS

Fermenter-scale production led to productivity (P(r)) and yield (Y(P/C)) values higher at 48 h (P(r) = 0.542 g l(-1) h(-1); Y(P/C) = 0.74) than at 72 h (P(r) = 0.336 g l(-1) h(-1); Y(P/C) = 0.50). Both EPSs were neutral glucose-homopolysaccharides with a beta-(1,3)-glycosidic backbone and single beta-(1,6)-glucopyranosyl sidechains regularly attached every three residues in the main chain, as revealed by chemical analyses. The infra-red diagnostic peak at 890 cm(-1) confirmed beta-glycosidic linkages, while gentiobiose released by beta-(1,3)-glucanases confirmed single beta-1,6-glycosidic branching for both EPSs.

CONCLUSIONS

The true modular repeating unit of S. rolfsii ATCC 201126 scleroglucan could be resolved. Structural stability was corroborated and no structural differences could be detected as to account for the variations in EPSs behaviour.

SIGNIFICANCE AND IMPACT OF THE STUDY

Recovery of S. rolfsii ATCC 201126 scleroglucan at 48 h might be considered based on better fermentation kinetic parameters and no detrimental effects on EPS structural features.

Effect of beta-glucans on an ETEC infection in piglets

The effect of orally administered beta-glucans in protecting pigs against an ETEC infection after weaning was analysed in this study. Three beta-glucans that differed in origin (Saccharomyces cerevisiae (MCG (Macrogard) and G2) or Sclerotium rolfsii (G3)) and/or extraction procedure were tested. Pigs fed for 2 weeks after weaning with these glucans were less susceptible to an F4+ ETEC infection in comparison with the control group. This was evidenced by a reduction in the faecal excretion of F4+ Escherichia coli as well as a reduced F4-specific serum antibody response. This decrease in faecal excretion was statistically significant for pigs fed with the MCG glucan in a first experiment and with the G3 glucan in a second experiment; diarrhoea was milder in the glucan-supplemented groups and was significantly reduced in the MCG-supplemented group. Furthermore, a lower amount of F4-specific IgM antibody-secreting cells (ASC) was found in the lymphoid tissues of pigs fed with G2 or G3 glucans in comparison with the control pig, as well as lower F4-specific IgA ASC in G3-fed pigs in comparison with the control pig. This study showed that beta-glucans can protect against an ETEC infection. Both MCG from S. cerevisiae and G3 from S. rolfsii, resulted in significant effects. To our knowledge, this is the first in vivo study, in which the use of beta-glucans as feed ingredient for just-weaned piglets was tested for their protective effects against ETEC infection.

The Measurement and Health Impact of Endotoxin Contamination in Organic Dusts from Multiple Sources: Focus on the Cotton Industry

Endotoxin is derived from Gram-negative bacterial membranes, and its inflammatory effects following inhalation are well characterized. The significance of this fact becomes apparent when the wide-ranging environments containing high levels of this microbial product are considered. Endotoxin is present in numerous industrial environments, especially where organic fibers are processed. Microbial contamination of these fibers mainly occurs at the agricultural stage. Materials such as flax and hemp are affected in this way, but the most important product in this context is cotton, from which chronic dust inhalation causes the disease byssinosis. Despite the fact that endotoxin constitutes a significant threat to public health, there are currently no occupational exposure limits for this toxicant. This communication describes the toxicology of endotoxin, and its role in inhalation-induced disease, focusing on measurement of airborne endotoxin in the occupational and domestic environments using the Limulus amebocyte lysate (LAL) enzyme assay. Following the success of the LAL assay for measuring endotoxin in dusts, our laboratory has examined its application to aqueous washes from cotton fibers. Reproducibility of the results was high, and data are presented displaying levels of endotoxin contamination in fibers from different cotton producing countries. Hence, worldwide comparison of industrial endotoxin concentrations can be readily made using this test. It would be highly desirable if the performance of the LAL assay facilitated introduction of industrial endotoxin safety limits, and in spite of minor surmountable shortcomings, the test is accurate, reliable, and well field-tested, so its continued widespread use may achieve this goal.

Physiological activities of a beta-glucan produced by Panebacillus polymyxa

In vitro bioactivities of a beta-glucan produced by Panebacillus polymyxa JB115 were investigated. Nitric oxide production by RAW 264.7 macrophage cells pre-treated with beta-glucan JB115 (from 0.1 to 1 mg ml(-1)) was significantly increased, compared to that in untreated cells (P < 0.001). The beta-glucan JB115 increased superoxide radical-scavenging activity by 66% at 1 mg ml(-1). It also suppressed hyaluronidase (32%) and collagenase (33%) activities and, additionally, displayed antitumor activity, blocking the growth of Sarcoma 180 cells in a concentration-dependent manner. The immune-stimulatory, antioxidant, collagenase inhibitory and hyaluronidase inhibitory effects of the beta-glucan support its potential role in the prevention of bacterial disease against fish and in the protection of skin against aging.

Tissue culture of some lichens and screening of their antioxidant, antityrosinase and antibacterial properties

Lichen species Usnea ghattensis, Heterodermia podocarpa, Arthothelium awasthii and Parmotrema tinctorum have been cultured in vitro and screened for their antioxidant, antimicrobial and antityrosinase potential using different assay systems. The methanol extract of lichens showed antioxidant, antimicrobial and antityrosinase activities according to the order Usnea ghattensis > Arthothelium awasthii > Heterodermia podocarpa > Parmotrema tinctorum. The IC(50) values for the antioxidant and antityrosinase activities of U. ghattensis and A. awasthii were less than or equivalent to that of standard antioxidants and tyrosinase inhibitors. The methanol extracts of the lichen cultures Usnea ghattensis and Arthothelium awasthii were effective against Bacillus licheniformis, Bacillus megaterium, Bacillus subtilis and Staphylococcus aureus. The minimum inhibitory concentration (MIC) of the extract was found to be between 5 and 10 microg extract/mL. The results suggested that the extract of lichen cultures, U. ghattensis and A. awasthii, could be of use as an easily accessible source of natural antioxidants, tyrosinase inhibitory and antimicrobial properties as possible food supplements or in the pharmaceutical industry.

Structural and physiological studies on the storage beta-polyglucan of haptophyte Pleurochrysis haptonemofera

The storage beta-polyglucan and catabolic enzyme activities of the haptophyte Pleurochrysis haptonemofera were characterized. The storage beta-polyglucan was prepared by the dimethylsulfoxide-extraction method. (13)C- and (1)H-NMR spectroscopy revealed that the polyglucan consists of beta-(1-->3)- and beta-(1-->6)-linked glucose polymers, with a beta-(1-->6)- to beta-(1-->3)-linkage ratio of 1.5. Gel permeation chromatography showed that the molecular weight of the polyglucan is 1.1-8.4 x 10(4) Da, with a peak at 3.4 x 10(4) Da. The degree of polymerization, which was estimated from the amounts of total carbohydrate and reduced ends, was 203, corresponding to 3.3 x 10(4) Da. A method for measurement of the beta-polyglucan in a small amount of liquid culture involving a mixture of beta-glucanases, Westase, was established. The beta-polyglucan was localized in the soluble fraction of cells. The amount of beta-polyglucan per cell increased at the stationary phase under continuous illumination and decreased in the dark, like those of storage alpha-polyglucans, starch of green algae and glycogen of cyanobacteria. The activities of beta-1,3- and beta-1,6-glucanases involved in the degradation of the storage beta-polyglucan were assayed in vitro, both being optimal at pH 5.0. The beta-1,3-glucanase activity, which was detected on active staining after native polyacrylamide gel electrophoresis, was partially purified by ammonium sulfate precipitation and anion exchange chromatography.

Alternative medium for production of Pleurotus ostreatus biomass and potential antitumor polysaccharides

Pleurotus species are recognized for producing beta-glucans with important medicinal properties as a constituent of the cellular wall of the fruiting body or of the mycelium. The aims of this work were to select a culture medium that maximized the production of biomass and polysaccharides produced by Pleurotus ostreatus DSM 1833 and to evaluate the selected medium in two values of initial oxygen transfer rate -K(L)a (10.2 and 19.3 h(-1)). A 2* *4 factorial design was constructed to evaluate the supplementation of wheat extract with corn steep liquor--CSL (10 or 20 g L(-1)), yeast extract--YE (2 or 5gL(-1)), ammonium sulfate--AS (0 or 5 g L(-1)) and glucose (20 or 40 g L(-1)). In terms of maximum productivity in biomass and global productivity in polysaccharides, the best values were obtained when 5 g L(-1) of YE and 40 g L(-1) of glucose were used. In terms of maximum concentration of biomass, the best results were obtained when 20 g L(-1) of CSL and 40 g L(-1) of glucose were used. The best results in terms of production of biomass and polysaccharides were achieved when lower initial K(L)a (10.2 h(-1)) was used.

Dietary modulation of immune function by beta-glucans

The immune response can be modulated by nutrients like beta-glucans, which are glucose polymers that are major structural components of the cell wall of yeast, fungi, and bacteria, but also of cereals like oat and barley. There is a lot of structural variation in the beta-glucans from these different sources, which may influence their physiological functions. In this review the current status concerning possibilities to modulate immune function by beta-glucans is discussed. In vitro as well as in vivo studies in animals and humans show that especially beta-glucans derived from fungi and yeast have immune modulating properties. Most frequently evaluated are effects on leukocyte activity, which has been suggested to contribute to the increased resistance against infections observed after beta-glucan interventions. Although most studies supply the beta-glucans parenteral (e.g. intravenous or subcutaneous), also enteral administrated (dietary) beta-glucan influence the immune response. Although more human studies are needed, it is tempting to suggest that dietary beta-glucans may be a useful tool to prime the host immune system and increase resistance against invading pathogens.

Photoprotective effects of glucomannan isolated from Candida utilis

Glucomannans belong to yeast and fungal cell wall polysaccharides with known immunostimulatory and radioprotective effects. However, glucomannan protective effects against pathological consequences of skin exposure to short wavelength solar light, ultraviolet (UV) radiation, are unclear. Herein, a highly branched glucomannan (GM) isolated from the cell wall of Candida utilis, a member of the alpha-(1-->6)-D-mannan group, was tested for its photoprotective effects in an in vitro model of UVB-irradiated human keratinocytes and an in vivo model of UV-induced erythema formation in human volunteers. GM suppressed the UVB-induced decrease of keratinocyte viability, which was connected with the suppression of UVB-induced keratinocyte apoptosis. GM reduced UVB-mediated caspase activation together with suppression of DNA fragment release into the cytoplasm. Furthermore, GM suppressed UVB-induced gene expression of pro-inflammatory markers including nuclear factor kappa B, inducible nitric oxide synthase, interleukins 8 and 1, together with suppression of prostaglandin E2 and interleukin 1alpha protein release. In vivo, GM decreased UV-induced skin erythema formation, which was correlated with a decrease of phosholipase A(2) activity within the stratum corneum. It could be concluded that GM isolated from C. utilis possesses significant photoprotective effects on human keratinocytes in vitro as well as in vivo.

Relationship between structure and immunostimulating activity of enzymatically synthesized glycogen

Glycogen acts as energy and carbon reserves in animal cells and in microorganisms. Although anti-tumor activity has recently been reported for shellfish glycogen and enzymatically synthesized glycogen, the activity of glycogen has not yet been fully clarified. We enzymatically prepared various sizes of glycogens with controlled structures to investigate the relationship between the structure and immunostimulating activity of glycogen. The results revealed that glycogens with a weight-average molecular weight (M(w)) of more than 10,000K hardly activated RAW264.7, a murine macrophage cell line, whereas glycogens of M(w) 5000K and 6500K strongly stimulated RAW264.7 in the presence of interferon-gamma (IFN-gamma), leading to augmented production of nitric oxide (NO), tumor necrosis factor-alpha (TNF-alpha), and interleukin-6 (IL-6). Comparing the fine structure of the glycogens, the average-number of chain length, as well as the exterior and the interior chain lengths of the glycogens, had minor correlation between active and less-active glycogen derivatives. The available evidence suggests that the macrophage-stimulating activity of glycogen is strictly related to its molecular weight rather than to any fine structural property.

Determinants of microbial exposure in grain farming

OBJECTIVES

Exposure to organic dust containing high concentrations of microorganisms is common in grain farming, although the farmers have practices to counteract microbial growth to obtain optimal grain yields. We investigated the influence of weather and production practices on personal microbial exposure during grain work.

METHODS

Airborne dust was collected by personal sampling during threshing and storage work on 92 Norwegian farms. The personal exposure for bacteria, endotoxin, fungal spores and hyphae, beta-(1-->3)-glucans and actinomycetes was quantified and compared with climatic data expressed as fungal forecasts from the grain growth season and production practices as reported by farmers.

RESULTS

Farmers were exposed to a geometrical mean of 4.4 mg m(-3) inhalable dust [geometrical standard deviation (GSD) = 4.0], 4 x 10(6) m(-3) bacteria and fungal spores (GSD = 5.2 and 5.9, respectively), 5.9 x 10(3) EU m(-3) of endotoxins (GSD = 8.6), 2 x 10(5) m(-3) actinomycetes (GSD = 15.3), 120 mug m(-3) beta-(1-->3)-glucans (GSD = 4.7) and 5 x 10(5) AU m(-3) of hyphae (GSD = 4.4). Univariate associations were found between one or several of these microbial factors and work operation, visible fungal damage, grain species, lodging of grain, storage technology or harvester type. As assessed by general linear models, storage work was the main predictive determinant for microbial exposure, although grain species and visible fungal damage also were also important. Wet and warm weather throughout the grain growth season were associated with elevated exposure for inhalable dust, beta-(1-->3)-glucans, endotoxins and hyphae during threshing. The beta-(1-->3)-glucan exposure could biologically be explained by the fungal spore and hyphal exposure, both variables contributing equally. However, spores were most important during storage work, whereas only hyphae were predictive during threshing.

CONCLUSIONS

Farmers were exposed to high levels of microorganisms and their components during dusty grain work. Dust prevention and protection may reduce microbial exposure, and may be particularly important in areas with frequent fungal forecasts, when fungal damage has been observed, during storage work or when handling barley.

Toxicological assessment of a particulate yeast (1,3/1,6)-β-d-glucan in rats

This study investigates the toxicity of WGP 3-6, a yeast-derived beta-glucan ingredient, during single-dose acute and sub-chronic toxicity studies in rats. For the acute study, Fisher-344 rats were administered WGP 3-6 via gavage at a dose of 2000 mg/kg body weight, and any evidence of toxicity was monitored over a 14-day period. WGP 3-6 was well tolerated, indicating that the LD(50) value is greater than 2000 mg/kg body weight. For the sub-chronic study, Fisher-344 rats (10/sex/group) were randomly allocated to receive daily gavage treatment with WGP 3-6 at doses of 0, 2, 33.3, or 100 mg/kg body weight. Control and high-dose satellite recovery groups of each sex also were included. Full toxicological monitoring and endpoint investigations were performed throughout and upon completion of the study. No negative effects on animal weights or food consumption attributable to WGP 3-6 were evident at any dose. In addition, no mortality, clinical pathology, functional/behavioral, microscopic, or gross observations indicating toxicity were observed. Sporadic changes in some biochemical and hematological parameters were observed; however, since the effects were within the physiological ranges in historical controls, were not dose-responsive, or were not observed in both sexes, they were determined to be of no toxicological significance. In conclusion, no adverse or toxic effects were observed after subchronic oral administration of 2, 33.3, or 100mg/kg body weight/day of WGP 3-6 in Fisher-344 rats, and therefore, a no observed adverse effect level (NOAEL) of 100 mg/kg body weight/day, the highest dose tested, was determined.

Carboxymethylated (1 --> 3)-beta-D-glucan protects liposomes against ultraviolet light-induced lipid peroxidation

In this study we have analyzed antioxidant capabilities of the carboxymethylated (1 --> 3)-beta-D-glucan (M(w) = 5.88 x 10(5)) against lipid peroxidation induced by ultraviolet (UV) radiation--UVA (320-400 nm), which is known to produce mainly singlet oxygen, (1)O(2) . Lipid peroxidation was monitored by measuring the absorption spectra of the conjugated dienes and quantified by Klein oxidation index. The results imply that the (1 --> 3)-beta-D-glucan derivative studied is an antioxidant with the scavenging ability lying between alpha-tocopherol and hyaluronic acid. Thus, glucan as a potential safe and effective dietary supplement may be used for a prolonged time for a systemic photoprotection of humans.

beta-Glucans in promoting health: prevention against mutation and cancer

The polysaccharides beta-glucans occur as a principal component of the cellular walls. Some microorganisms, such as yeast and mushrooms, and also cereals such as oats and barley, are of economic interest because they contain large amounts of beta-glucans. These substances stimulate the immune system, modulating humoral and cellular immunity, and thereby have beneficial effect in fighting infections (bacterial, viral, fungal and parasitic). beta-Glucans also exhibit hypocholesterolemic and anticoagulant properties. Recently, they have been demonstrated to be anti-cytotoxic, antimutagenic and anti-tumorogenic, making them promising candidate as pharmacological promoters of health.

beta-Glucan of Candida albicans cell wall causes the subversion of human monocyte differentiation into dendritic cells

The functional consequences of treating human monocytes with purified and chemically characterized Candida albicans beta-glucan -- a major microbial pathogen associated molecular pattern -- on their differentiation into dendritic cells (DC) were investigated. We show here that beta-glucan-treated monocytes differentiated into mature DC (Glu-MoDC) with altered phenotype and functional behavior, similarly to DC derived from C. albicans germ-tubes-infected monocytes (Gt-MoDC). They failed to express CD1a and to up-regulate CD80 and DR molecules. Moreover, they produced IL-10 but not IL-12 and primed naive T cells without inducing their functional polarization into effector cells. Since C. albicans beta-glucan is a mixture of both beta-(1,3) and beta-(1,6) glucan, we investigated their relative contribution by the use of non-Candida beta-glucan structural analogs. We found that high molecular weight (MW) glucans beta-(1,6) pustulan and beta-(1,3) curdlan totally mimicked the effect of C. albicans beta-glucan, while the low MW beta-(1,3) glucan laminarin did not have any effect. Because beta-glucan is a common constituent of all fungi and is abundantly released in vivo during systemic fungal infection, this novel effect of beta-glucan has potential implications for host-parasite relationship in candidiasis and other mycoses. In particular, our data suggest that beta-glucan could bias noninfected, bystander monocytes, thus aggravating the general immunodeficiency, predisposing to systemic fungal infection.

Fecal water from ileostomic patients consuming oat beta-glucan enhances immune responses in enterocytes

Yeast, fungal, and dietary beta-glucans have immune-modulating effects in vitro and in vivo, as thought, mainly by affecting leukocytes; however, effects of oat beta-glucan on enterocytes have never been studied. As recognized, supplying oat beta-glucans as such to cells in culture directly is difficult because of solubility problems. Therefore, six ileostomic patients consumed, in random order, a control diet or an oat beta-glucan enriched diet (5 g) and from the collected ileostomic content, fecal water was prepared and added to two small intestinal cell lines (INT407, Caco-2) and two colon cell lines (HT29, T84) together with a cytokine cocktail (IL-1beta + INFgamma + TNFalpha). Several parameters reflecting immune-modulation were measured. As compared to placebo fecal water, beta-glucan enriched fecal water significantly increased IL-8 production in HT29 (5.0%; p = 0.046) and INT407 cells (22.0%; p = 0.028). Intercellular adhesion molecule (ICAM)-1 expression increased in T84 (11.0%; p = 0.028) and Caco-2 cells (20.4%; p = 0.075). These immune-stimulating effects were confirmed by enhancement of inflammatory expression profiles, as determined with an antibody array. Our findings show immune enhancement by fecal water from ileostomic patients consuming oat beta-glucan both in small intestinal and colon cell lines after stimulation, which is in agreement with documented effects in leukocytes. Whether these immune-stimulating effects on enterocytes contribute to the enhanced protection of the host against invading pathogens as observed both in animals and in humans, as well as the underlying mechanism, needs further evaluation.

Structure of the fungal beta-glucan-binding immune receptor dectin-1: implications for function

The murine molecule dectin-1 (known as the beta-glucan receptor in humans) is an immune cell surface receptor implicated in the immunological defense against fungal pathogens. Sequence analysis has indicated that the dectin-1 extracellular domain is a C-type lectin-like domain, and functional studies have established that it binds fungal beta-glucans. We report several dectin-1 crystal structures, including a high-resolution structure and a 2.8 angstroms resolution structure in which a short soaked natural beta-glucan is trapped in the crystal lattice. In vitro characterization of dectin-1 in the presence of its natural ligand indicates higher-order complex formation between dectin-1 and beta-glucans. These combined structural and biophysical data considerably extend the current knowledge of dectin-1 structure and function, and suggest potential mechanisms of defense against fungal pathogens.

Immunomodulating and anticancer agents in the realm of macromycetes fungi (macrofungi)

Nowadays macrofungi are distinguished as important natural resources of immunomodulating and anticancer agents and with regard to the increase in diseases involving immune dysfunction, cancer, autoimmune conditions in recent years, applying such immunomodulator agents especially with the natural original is vital. These compounds belong mainly to polysaccharides especially beta-d-glucan derivates, glycopeptide/protein complexes (polysaccharide-peptide/protein complexes), proteoglycans, proteins and triterpenoids. Among polysaccharides, beta(1-->3)-d-glucans and their peptide/protein derivates and among proteins, fungal immunomodulatory proteins (Fips) have more important role in immunomodulating and antitumor activities. Immunomodulating and antitumor activity of these metabolites related to their effects to act of immune effecter cells such as hematpoietic stem cells, lymphocytes, macrophages, T cells, dendritic cells (DCs), and natural killer (NK) cells involved in the innate and adaptive immunity, resulting in the production of biologic response modifiers. In this review we have introduced the medicinal mushrooms' metabolites with immunomoduling and antitumor activities according to immunological evidences and then demonstrated their effects on innate and adaptive immunity and also the mechanisms of activation of immune responses and signaling cascade. In addition, their molecular structure and their relation to these activities have been shown. The important instances of these metabolites along with their immunomodulating and/or antitumor activities isolated from putative medicinal mushrooms are also introduced.