Yuko Yoshioka

Relationship between conformation and biological response for (1→3)-β-d-glucans in the activation of coagulation Factor G from limulus amebocyte lysate and host-mediated antitumor activity. Demonstration of single-helix conformation as a stimulant.

The relationship between the conformation of (1----3)-beta-D-glucans in gel or hydrated form and the stimulation of two types of biological responses, namely, activation of coagulation Factor G from limulus amebocyte lysate (LAL) and host-mediated antitumor activity was examined. Both types were activated by the single-helical conformation, as revealed by high-resolution, solid-state 13C-n.m.r. spectroscopy. The potency of activation of Factor G was increased over 100-fold by treatment with a NaOH solution which leads to a complete or partial conversion from the triple to the single helix. Such a single-helix specific response was also demonstrated for the antitumor activity of curdlan, although the distinction was less pronounced for branched (1----3)-beta-D-glucans. The presence of the single-helix conformation was observed in schizophyllan gel, even though the triple helix is the most stable form of branched glucans in aqueous media.

Antitumor polysaccharides from P. ostreatus (Fr.) quél.: Isolation and structure of a β-glucan

We isolated an antitumor glucan (HA beta-glucan) from the neutral polysaccharide fraction (A3) of a hot-water extract of the edible mushroom P. ostreatus (Fr.) Quél. Purification was accomplished by extractions with 20% sodium chloride solution saturated with thymol and by precipitations with ethanol from dimethyl sulfoxide solution. The glucan showed marked antitumor activity at a dose of 0.1 mg/kg. It is a highly branched (1----3)-beta-glucan having an average structure represented by a pentasaccharide segment consisting of one nonreducing terminal, one 3,6-di-O-substituted, and three 3-mono-O-substituted beta-D-glucopyranosyl residues. This structure was confirmed by examining 13C-n.m.r. spectra taken at 75.46 MHz.

A 13C nuclear magnetic resonance study of a gel-forming branched (1→3)-β-D-glucan, A3, from Pleurotus ostreatus (Fr.) quél: Determination of side-chains and conformation of the polymer-chain in relation to gel-structure

In recent years, a number of gel-forming branched (1+3)

Isolation, purification, and structure of components from acidic polysaccharides of pleurotus ostreatus (Fr.) Quél.

-D&cans with anti-tumor activity were isolated from various natural sources [l-3] . Evidence was presented that conformation of polysaccharide is closely related to its biological activity [4] . Further, conformational studies of polysaccharides in relation to gel-structure are of considerable importance in view of their biological functions [5,6] . However, conformational behaviour of neutral polysaccharides, especially of (l-+3)

Effect of hydration on conformational change or stabilization of (1 .fwdarw. 3)-.beta.-D-glucans of various chain lengths in the solid state as studied by high-resolution solid-state carbon-13 NMR spectroscopy

-D-glucans, has not been fully investigated in comparison with that of polypeptides and polynucleotides. In this paper, we demonstrate that 13C n.m.r. measurements of polysaccharide A3 from P. ostreutus in the gel state are able to provide insight into structure and conformation.

Distinct gelation mechanism between linear and branched (1 3)-β-D-glucans as revealed by high-resolution solid-state 13C NMR

Isolation of an antitumor component from polysaccharide fraction A5 of some Basidiomyces was achieved by column chromatography on Sephadex G-200. A detection method based on the specific rotatory characteristics of the polysaccharide was applied to estimate components in effluent fractions from the chromatography, and it was confirmed that a series of eluates having similar specific rotation was made up of homogeneous polysaccharide. Three components (H51, H52, and H53) were isolated, in chromatographically pure state, from fraction A5. Component H51 consisted of a skeleton of beta-(1 leads to 3)-linked glucose residues, probably having branches of galactose and mannose residues, and also containing acidic sugars. Component H53 had a main structure similarly consisting of beta-(1 leads to 3)-linked glucose residues and a larger proportion of acidic sugar than H51. Component H52 was a heteropolysaccharide made up of alpha-linked galactose and mannose residues. Components H51 and H53 had a higher and a lower molecular weight, respectively, than H52. The only antitumor-active component was H51.