Structural elucidation of a 3-O-methyl-d-galactose-containing neutral polysaccharide from the fruiting bodies of Phellinus igniarius

PIP60-1, a novel heteropolysaccharide isolated from fruiting bodies of the medicinal fungus, Phellinus igniarius, has a molecular weight of 1.71 × 104 Da and is composed of l-fucose, d-glucose, d-mannose, d-galactose and 3-O-Me-d-galactose in a ratio of 1:1:1:2:1. A structural investigation of PIP60-1 carried out using sugar and methylation analyses, combined with 1H and 13C NMR spectroscopy, including COSY, TOCSY, NOESY, HSQC and HMBC experiments, established the repeating unit of the polysaccharide as the following:

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