Plant mucilages. XXVII. Isolation and characterization of a mucous polysaccharide, "Narcissus-T-glucomannan," from the bulbs of Narcissus tazetta var. chinensis

A mucous polysaccharide, named Narcissus-T-glucomannan, was isolated from the bulbs of Narcissus tazetta L. var. chinensis ROEMER. The final preparation was homogeneous as determined by ultracentrifugal analysis, glass-fiber electrophoresis, and gel chromatography. It was composed of D-mannose and D-glucose in the molar ratio of 5 : 1, and its molecular weight was estimated to be 119000. The O-acetyl groups in the glucomannan was identified and the content amounted to 22.7%. They were located at positions 6 and 2, 6 of most of the D-mannose units. Methylation, periodate oxidation, partial acetolysis, and enzymatic degradation studies showed that the glucomannan is mainly composed of β-1→4 linked aldohexopyranose residues, and that it contains about 42 aldohexose units per non-reducing group on average. D-Mannose units occupy non-reducing terminal positions and branching points linked through position 3.