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 Chán 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.