A polysaccharide from Lichina pygmaea and L. confinis supports the recognition of Lichinomycetes.

The lichen-forming order Lichinales, generally characterized by prototunicate asci and the development of thalli with cyanobacteria, has recently been recognized as a separate class of ascomycetes, Lichinomycetes, as a result of molecular phylogenetic studies. As alkali and water-soluble (F1SS) polysaccharides reflect phylogeny in other ascomycetes, a polysaccharide from Lichina pygmaea and L. confinis was purified and characterized to investigate whether these F1SS compounds in the Lichinomycetes were distinctive. Nuclear magnetic resonance (NMR) spectroscopy and chemical analyses revealed this as a galactomannan comprising a repeating unit consisting of an alpha-(1-->6)-mannan backbone, mainly substituted by single alpha-galactofuranose residues at the O-2- or the O-2,4- positions linked to a small mannan core. With the exception of the trisubstituted mannopyranose residues previously described in polysaccharides from other lichens belonging to orders now placed in Lecanoromycetes, the structure of this galactomannan most closely resembles those found in several members of the Onygenales in Eurotiomycetes. Our polysaccharide data support molecular studies showing that Lichina species are remote from Lecanoromycetes as the galactofuranose residues are in the alpha-configuration. That the Lichinomycetes were part of an ancestral lichenized group can not be established from the present data because the extracted polysaccharide does not have the galactofuranose residue in the beta configuration; however, the data does suggest that an ancestor of the Lichinomycetes contained a mannan and was part of an early radiation in the ascomycetes.

Structure of a galactomannan isolated from the cell wall of the fungus Lineolata rhizophorae.

The structure of an alkali-extracted water-soluble polysaccharide isolated from the cell wall of the marine fungus Lineolata rhizophorae has been elucidated by chemical and spectroscopic means. The idealized repeating unit of this novel structure is [carbohydrate structure: see text] being m approximately 41, n approximately 2, and p approximately 5.

Potential antioxidant capacity of sulfated polysaccharides from the edible marine brown seaweed Fucus vesiculosus.

Fucus vesiculosus was sequentially extracted with water at 22 degrees C (fraction 1 (F1)) and 60 degrees C (F2), and with 0.1 M HCl (F3) and 2 M KOH (F4) at 37 degrees C. Soluble fractions (42.3% yield) were composed of neutral sugars (18.9-48 g/100 g), uronic acids (8.8-52.8 g/100 g), sulfate (2.4-11.5 g/100 g), small amounts of protein (< 1-6.1 g/100 g), and nondialyzable polyphenols (0.1-2.7 g/100 g). The main neutral sugars were fucose, glucose, galactose, and xylose. Infrared (IR) spectra of the fractions showed absorption bands at 820-850 and 1225-1250 cm(-1) for sulfate. F1, F2, and F4 also exhibited an absorption band at 1425 cm(-1), due to uronic acids, and their IR spectra resembled that of alginate. F3 had an IR spectrum similar to that of fucoidan with an average molecular weight of 1.6 x 10(6) Da, calculated by molecular exclusion high-performance liquid chromatography. The presence of fucose in this polysaccharide was confirmed by (1)H NMR spectroscopy. This fraction showed the highest potential to be antioxidant by the ferric reducing antioxidant power (FRAP) assay, followed by the alkali- and water-soluble fractions. Sulfated polysaccharides from edible seaweeds potentially could be used as natural antioxidants by the food industry.

Comparison of cell-wall polysaccharides from Nectria cinnabarina with those from the group of Nectria with Sesquicillium anamorphs.

Alkali-extractable and water-soluble polysaccharides were purified from cell walls of five species of Sesquicillium or its teleomorphs, Nectria lasiacidis and Nectria impariphialis, and from Nectria cinnabarina, the type species of Nectria, a heterogeneous genus that belongs to the Hypocreales. Methylation and NMR analyses for determination of linkage types and structure were performed and indicated differences between the polysaccharides purified during the present study and those isolated from other nectrioid fungi, namely the presence of 5-O-substituted galactofuranose (-->5)-Galf-(1-->) in the main chain together with 2,6-di-O-substituted galactofuranose (-->2,6)-Galf-(1-->) residues in Sesquicillium buxi and Sesquicillium pseudosetosum. The polysaccharide from N. impariphialis was similar to those obtained from the above species, although an additional residue of 6-O-substituted glucopyranose (-->6)-Glcp-(1-->), was detected in some side chains. In N. lasiacidis and Sesquicillium candelabrum the polysaccharide contained an additional branching point of 5,6-di-O-substituted galactofuranose (-->5,6)-Galf-(1-->) linked to terminal N-acetylglucosamine GlcNAc-(1-->). These chains were linked to a small mannan core. All these polysaccharides showed major differences to the polysaccharide of N. cinnabarina, which was formed by a main chain of (1-->6)-beta-linked galactofuranose units almost fully branched at positions 2-O by either single residues of glucopyranose or acidic chains containing glucuronic acid and mannose.