Immunomodulatory activity of ß-glucan-containing exopolysaccharides from Auricularia auricular in phagocytes and mice infected with Cryptococcus neoformans.

Current antifungal drugs present poor effectiveness and there is no available vaccine for fungal infections. Thus, novel strategies to treat or prevent invasive mycosis, such as cryptococcosis, are highly desirable. One strategy is the use of immunomodulators of polysaccharide nature isolated from mushrooms. The purpose of the present work was to evaluate the immunostimulatory activity of ß-(1,3)-glucan-containing exopolysaccharides (EPS) from the edible mushrooms Auricularia auricula in phagocytes and mice infected with Cryptococcus neoformans. EPS triggered macrophages and dendritic cell activation upon binding to Dectin-1, a pattern recognition receptor of the C-type lectin receptor family. Engagement of Dectin-1 culminated in pro-inflammatory cytokine production and cell maturation via its canonical Syk-dependent pathway signaling. Furthermore, upon EPS treatment, M2-like phenotype macrophages, known to support intracellular survival and replication of C. neoformans, repolarize to M1 macrophage pattern associated with enhanced production of the microbicidal molecule nitric oxide that results in efficient killing of C. neoformans. Treatment with EPS also upregulated transcript levels of genes encoding products associated with host protection against C. neoformans and Dectin-1 mediated signaling in macrophages. Finally, orally administrated ß-glucan-containing EPS from A. auricular enhanced the survival of mice infected with C. neoformans. In conclusion, the results demonstrate that EPS from A. auricula exert immunostimulatory activity in phagocytes and induce host protection against C. neoformans, suggesting that polysaccharides from this mushroom may be promising as an adjuvant for vaccines or antifungal therapy.

Safe therapeutics of murine melanoma model using a novel antineoplasic, the partially methylated mannogalactan from Pleurotus eryngii.

A heteropolysaccharide was isolated by cold aqueous extraction from edible mushroom Pleurotus eryngii ("King Oyster") basidiocarps and its biological properties were evaluated. Structural assignments were carried out using mono- and bidimensional NMR spectroscopy, monosaccharide composition, and methylation analyses. A mannogalactan having a main chain of (1→6)-linked α-d-galactopyranosyl and 3-O-methyl-α-d-galactopyranosyl residues, both partially substituted at OH-2 by ß-d-Manp (MG-Pe) single-unit was found. Biological effects of mannogalactan from P. eryngii (MG-Pe) were tested against murine melanoma cells. MG-Pe was non-cytotoxic, but reduced in vitro melanoma cells invasion. Also, 50mg/kg MG-Pe administration to melanoma-bearing C57BL/6 mice up to 10days decreased in 60% the tumor volume compared to control. Additionally, no changes were observed when biochemical profile, complete blood cells count (CBC), organs, and body weight were analyzed. Mg-Pe was shown to be a promising anti-melanoma molecule capable of switching melanoma cells to a non-invasive phenotype with no toxicity to melanoma-bearing mice.

A 3-O-methylated mannogalactan from Pleurotus pulmonarius: structure and antinociceptive effect.

A polysaccharide (Mw 2.39x10(4)g/mol) was extracted with cold water from the basidiomycete Pleurotus pulmonarius, and its antinociceptive and anti-inflammatory properties were evaluated. It was a mannogalactan (MG), whose structure was characterized using mono- and two-dimensional NMR spectroscopy, methylation analysis, and a controlled Smith degradation. It had a main chain of (1-->6)-linked alpha-D-galactopyranosyl and 3-O-methyl-alpha-D-galactopyranosyl units, both of which are partially substituted at O-2 by beta-D-mannopyranosyl non-reducing ends. The MG was tested for its effects on the acetic acid-induced writhing reaction in mice, a typical model for inflammatory pain, causing a marked and dose-dependent inhibition of the nociceptive response, with ID50 of 16.2 (14.7-17.7)mg/kg and inhibition of 93+/-3% at a dose of 30mg/kg. An inflammatory response was not inhibited.

Anticoagulant and antithrombotic activities of a chemically sulfated galactoglucomannan obtained from the lichen Cladonia ibitipocae.

A galactoglucomannan (GGM), isolated from the lichen Cladonia ibitipocae, consisted of a (1-->6)-linked main chain of alpha-mannopyranose units, substituted by alpha- and beta-D-galacto (alpha- and beta-D-Galp)-, beta-D-gluco (beta-D-Glcp)- and alpha-D-mannopyranosyl (alpha-D-Manp) groups, and was sulfated giving a sulfated polysaccharide (GGM-SO4) with 42.2% sulfate corresponding to a degree of substitution of 1.29. NMR studies indicated that after sulfation, the OH-6 groups of galactopyranosyl and mannopyranosyl units were preferentially substituted. GGM-SO4 was investigated in terms of its in vitro anticoagulant and in vivo antithrombotic properties. Those of the former were evaluated by its activated partial thromboplastin (APTT) and thrombin time (TT), using pooled normal human plasma, and compared with that of 140 USP units mg(-1) for a porcine intestinal mucosa heparin. Anticoagulant activity was detected in GGM-SO4, but not in GGM. The in vivo antithrombotic properties of GGM-SO4 were evaluated using a stasis thrombosis model in Wistar rats, intravenous administration of 2 mg kg(-1) body weight totally inhibiting thrombus formation. It caused dose-dependent increases in tail transection bleeding time. The results obtained showed that this sulfated polysaccharides is a promising anticoagulant and antithrombotic agent.

Comparative studies of the polysaccharides isolated from lichenized fungi of the genus Cladonia: significance as chemotypes.

Beta-D-glucans of the laminaran type were prepared from 15 Cladonia spp., Cladonia bellidiflora, Cladonia boryi, Cladonia clathrata, Cladonia connexa, Cladonia crispatula, Cladonia furcata, Cladonia gracilis, Cladonia ibitipocae, Cladonia imperialis, Cladonia miniata, Cladonia penicillata, Cladonia salmonea, Cladonia signata, Cladonia substellata and Cladonia uncialis. They were extracted with 10% aqueous KOH at 100 degrees C, giving polysaccharides with varying yields and proportions of mannose, galactose and glucose. Their aqueous solutions were freeze-thawed giving precipitates of mixed alpha-glucan (nigeran) and beta-glucans, which were isolated and suspended in aqueous 0.5% KOH at 50 degrees C, which preferentially dissolved the beta-glucan. In the case of the C. uncialis product, it was subjected to methylation analysis, which gave rise to 2,4,6-tri-O-methylglucitol acetate only, corresponding to (1-->3)-linkages. Its specific rotation (+4 degrees ) and one- and two-dimensional nuclear magnetic resonance (NMR) spectra were consistent with beta-linkages. 13C and (1)H-1 signals were observed, respectively, at delta 102.8 (C-1), 86.0 (C-3), 76.2 (C-5), 72.6 (C-2), 68.3 (C-4) and 60.7 (C-6), and 4.55 (H-1), 3.31 (H-2), 3.49 (H-3), 3.27 (H-4), 3.27 (H-5), 3.48 (H-6) and 3.72 (H-6'). Similar (13)C-NMR spectra were obtained from the glucans from the other 14 Cladonia spp. The beta-D-glucans of the laminaran type seems to be present in all Cladonia spp. being significant for chemotyping since it was observed in every species studied.