Chihiro Hara

An antitumor, branched (1 → 3)-β-d-glucan from a water extract of fruiting bodies of Cryptoporus volvatus

A water-soluble, (1-->6)-branched (1-->3)-beta-D-glucan (H-3-B) was isolated from a hot-water extract of the fruiting bodies of the fungus, Cryptoporus volvatus (Basidiomycetes). Enzymatic analysis using exo-(1-->3)-beta-D-glucanase and methylation analysis indicated that this polysaccharide has a main chain composed of beta-(1-->3)-linked D-glucopyranosyl residues, and single, beta-(1-->6)-linked D-glucopyranosyl residues attached as side chains to, on average, every fourth sugar residue of the main chain. This structure was confirmed by 13C NMR spectra of the glucan in Me2SO-d6. The weight-average molecular weight (Mw) of H-3-B was determined to be 44.0 x 10(4) by gel permeation chromatography equipped with a low-angle laser-light-scattering photometer. The electron microscopic observations showed that H-3-B and its sonicated sample (S-H-3-B, Mw = 13.7 x 10(4)) can be described as linear worm-like chains. The mass per unit length for native and sonicated H-3-B was determined to be 1750 and 1780 g mol-1 nm-1, respectively, from the contour lengths obtained by electron microscopy and the molecular weights. These values are in good agreement with that expected for the triple stranded structure. A sample denatured in 0.1 M NaOH and subsequently renatured by neutralization showed a mixture of linear and cyclic structures, and larger aggregates with less well-defined morphology. The H-3-B and S-H-3-B had antitumor activity against the Sarcoma 180 tumor.

(1→3)-α-d-glucan from an alkaline extract of Agrocybe cylindracea, and antitumor activity of its O-(carboxymethyl)ated derivatives

The structure of an alkali-soluble D-glucan (AG-AL) from the fruit body of Agrocybe cylindracea was investigated by a combination of chemical and spectroscopic methods indicating that it was a linear (1----3)-alpha-D-glucan (molecular weight, approximately 560,000), [alpha]20D +195 degrees (c 0.5, M sodium hydroxide). Both water-soluble and gelatinous products obtained by O-(carboxymethyl)ation of AG-AL showed potent antitumor activity against the solid form of Sarcoma 180 in mice, although the native D-glucan had little effect on the tumor.

A minor, protein-containing galactomannan from a sodium carbonate extract of Cordyceps sinensis☆

Abstract A water-soluble, minor, protein-containing galactomannan (CT-4N), [α] D −29.6°, isolated from a 5% sodium carbonate extract of Cordyceps sinensis , showed a homogeneous pattern in gel filtration and one spot in glass-fiber paper-electrophoresis. The molecular weight was estimated by gel filtration to be ∼23,000. It was mainly composed of d -mannose and d -galactose in the molar ratio of 3:5, and contained a small proportion of protein. From the results of methylation analysis, Smith degradation, stepwise hydrolysis, and 13 C-n.m.r. spectroscopy, it was concluded that the polysaccharide has a highly branched structure, and is composed of (1→6)- and (1→2)-linked α- d -mannopyranosyl residues in the main chain. Some of the residues are present as branching points of (1→2,6) and (1→4,6) linkages and the branches contain short chains having a large proportion of (1→5)-linked β- d -galactofuranosyl residues and a small proportion of (1→6)-linked α- d -galactopyranosyl resdues, and the (nonreducing) terminal groups consist of a large proportion of β- d -galactofuranosyl and a small proportion of α- d -mannopyranosyl groups.

A branched (1→3)-β-d-glucan from a water extract of Dictyophora indusiata Fisch

Abstract A water-soluble, (1→6)-branched, (1→3)-β- d -glucan (T-3-G), [α]D27 +40.8° (c 0.123, water), was isolated from a hot-water extract of the fruit bodies of Dictyophora indusiata Fisch. T-3-G was homogeneous as judged by ultracentrifugal analysis, Tiselius-type electrophoresis, and gel filtration. By gel filtration on Sepharose CL-2B, with 0.25 m sodium hydroxide as the eluant, the molecular weight ( M w) of T-3-G was estimated to be ∼5.1 × 105. From the results of methylation analysis, periodate oxidation, Smith degradation, and enzymic hydrolysis, it was concluded that T-3-G has a main chain composed of β-(1→3)-linked d -glucopyranosyl residues, and two single, β-(1→6)-linked d -glucopyranosyl groups attached as side chains to, on average, every five sugar residues of the main chain. In addition, the results of enzymic hydrolysis indicated that the branching of T-3-G occurs regularly at O-6 of the β-(1→3)-linked backbone. The results of optical rotatory measurements and complex-formation with Congo Red suggested that T-3-G probably takes a triple-helical conformation.

Minor, protein-containing galactomannans from the insect-body portion of the fungal preparation Chán huā (Cordyceps cicadae)☆

Abstract Two minor, water-soluble, protein-containing galactomannans, CI-P ([α]D +15.3°) and CI-A ([α]D +10.6°), isolated from the insect-body portion of the fungal preparation Chan huā (Cordyceps cicadae) showed single peaks on gel filtration, and one spot on glass-fiber paper electrophoresis. The polymers are composed of d -mannose and d -galactose in the molar ratios of 1:0.85 for CI-P and 1:0.57 for CI-A, together with traces of d -glucose, and small proportions of protein. Although both polysaccharides have a molecular weight of ∼25,000, the affinity of CI-A for Con A was stronger than that of CI-P. From the results of methylation analysis, Smith degradation, stepwise hydrolysis, and 13C-n.m.r. spectroscopy, it was concluded that the polysaccharides are highly branched, with structures composed of (1→6)-linked α- d -mannopyranosyl main chains, having most residues substituted at O-2 with single α- or β- d -galactofuranosyl groups, short chains of (1→2)-linked β- d -galactofuranosyl residues, or chains of (1→2)-linked α- d -mannopyranosyl residues. CI-A has fewer and shorter d -galactofuranosyl side-chains and longer (1→2)-linked α- d -mannopyranosyl side-chains than CI-P.