Heteroglycan from an alkaline extract of a somatic hybrid mushroom (PfloVv1aFB) of Pleurotus florida and Volvariella volvacea: structural characterization and study of immunoenhancing properties

A water soluble heteroglycan, isolated from the alkaline extract of the fruit bodies of the somatic hybrid mushroom (PfloVv1aFB), raised through protoplast fusion between the strains of Pleorutus florida and Volverilla volvacea, was found to consist of (1→3)-, (1→6)-, (1→3,4)-linked, and terminal β-d-Glcp along with (1→2,6)-α-d-Galp and terminal α-d-Manp in a relative proportion of approximately 1:1:1:1:1:1. This polysaccharide exhibited strong immunostimulating activity of macrophages as well as splenocytes and thymocytes. Structural investigation was carried out using sugar analysis, methylation analysis; periodate oxidation study, and NMR experiments (1H, 13C, DEPT-135, DQF-COSY, TOCSY, NOESY, ROESY, HMQC, and HMBC). On the basis of the above mentioned experiments, the structure of the repeating unit of the polysaccharide was established as: