Pythium aphanidermatum: culture, cell-wall composition, and isolation and structure of antitumour storage and solubilised cell-wall(1 → 3),(1 → 6)-β-d-glucans

Abstract

Under optimal conditions for the culture of the fungus Phytium aphanidermatum, no polysaccharides were excreted into the medium. The mycelium contained up to 38% of a slightly branched, storage (1 → 3),(1 → 6)-β-d-glucan with a MW of 20 000. The cell=wall polysaccharides of the mycelium comprised 18% of cellulose and 82% of (1 → 3),(1 → 6)-β-d-glucans. Of the non-cellulosic glucans, ∼ 33% could be solubilised by extraction with water at 121°, and they had a MW of 10 000, were highly branched, and contained 6% (of (1 → 6) linkages. Treatment of the cell wall with 0.1 M trifluoroacetic acid released ∼ 50% of the non-cellulosic glucans. The acid-soluble cell-wall (1 → 3),-(1 → 6)-β-d-glucans of lower MW (6000) were still highly branched and contained 14% of (1 → 6) and 8% of (1 → 4) linkages. The storage glucan and the hot-water-soluble cell-wall glucan exhibited strong activity against the Sarcoma 180 in CD-1 mice, whereas the acid-soluble cell-wall glucans were inactive. The hot-water-soluble cell-wall was also active against the DBA/2-MC.SC-1 fibrosarcoma in DBA/2 mice.