Glucan of a somatic hybrid mushroom, pfls1h: structural characterization and study of immunological activities

A water-soluble glucan (PS-I) was isolated from the aqueous extract of the fruit bodies of a hybrid mushroom, pfls1h of Pleurotus florida and Lentinus squarrosulus (Mont.) Singer. Structural characterization of PS-I was carried out using total hydrolysis, methylation analysis, periodate oxidation, and NMR experiments (1H, 13C, DEPT-135, DQF-COSY, TOCSY, NOESY, ROESY, HSQC, and HMBC). Methylation analysis revealed that PS-I was composed of (1→3, 6), (1→3), (1→6)-linked and terminal β-d-glucopyranosyl residues in a relative proportion of approximately 1:1:1:1. The repeating unit of the glucan consists of a backbone chain of two (1→6)-β-d-glucopyranosyl residues, one of which is branched at O-3 position with (1→3)-β-d-glucopyranosyl and terminated with a β-d-glucopyranosyl residue. Study of immunological activity revealed that PS-I stimulates the splenocytes, thymocytes and macrophages.