Chemical structure of a novel heteroglycan polysaccharide isolated from the biomass of Ophiocordyceps Sobolifera

Abstract

This study aims at identifying the structure of polysaccharide (PS) extracted from the biomass of Vietnam-grown Ophiocordyceps sobolifera for the first time. The molecular weight of the obtained polysaccharide (denoted as PS-T100) is found to be 2.29 × 105 Da using gel permeation high-performance liquid chromatography. The structural investigations of the sample PS-T100 unveil a novel structure composed of a heteropolysaccharide with the appearance of two main sugars, D-glucose and D-mannose, in the backbone. Indeed, methylation analysis indicates that PS-T100 is mainly composed of (1→3)-linked glucosyl and (1→3)-linked mannosyl units. Moreover, 1D and 2D nuclear magnetic resonance spectroscopy interpretations of the sample PS-T100 prove the repeating unit of the isolated polysaccharide is [→3)-β-D-Glcp-(1→3)-α-D-Manp-(1→3)-β-D-Glcp-(1→3)-α-D-Manp-(1→3)-β-D-Glcp-(1→]n. Such a structure appears to be a novel polysaccharide. The obtained results contribute to enriching the database of Ophiocordyceps sobolifera- extracted PSs and open up a new pathway toward the production of PS-T100 for biomedical applications. © 2021 Elsevier B.V.