The non-pathogenic, saprophytic fungus Clonostachys rosea is a mycoparasite of several plant pathogenic fungi. A chemical investigation was carried out on this ascomycete in order to determine the structures of its carbohydrates. The mycelium of C. rosea was first extracted with 2:1 (v/v) CHCl₃-MeOH at 25 ºC for 24 h (x 2). The residue was submitted to sequential extraction with water at 25 ºC for 24 h (Fraction A) and at 100 ºC for 6 h each (x 7) (Fraction B corresponds to the first three extractions and Fraction C corresponds to the four last extractions), 2% aq. KOH at 100 ºC for 6 h each (x 3) (Fractions K1, K2 and K3) and 10% aq. KOH in the same conditions (Fraction K10). Fractions obtained by aqueous extraction (A, B and C) were precipitated with excess ethanol 3:1 (v/v). The precipitate obtained was dialyzed, while fractions extracted with KOH were neutralized with HOAc before being dialyzed. Each fraction obtained (Fractions A, B, C, K1, K2, K3 and K10) was partially purified through a freeze-thawing procedure furnished precipitates (PB, PC, PK1, PK2, PK3 and PK10) and supernatants (SB, SC, SK1, SK2, SK3 and SK10). All the water-soluble fractions contained glucose (70-80%), mannose and galactose, while the insoluble fractions had glucose (~90%) as the main monosaccharide component suggesting the presence of a glucan. Due to the similarity shown by GC-MS, the insoluble-water fractions were combined, giving a fraction denominated PGD. The ¹³C-NMR spectrum of the PGD fraction showed C-1 signals at low field at d 102.6-102.9 consistent with a b-configuration. The signal observed at ~ d 85.0 suggests a substitution at C-3. The ¹³C-NMR spectrum of the SK1 fraction showed C-1 signals at d 101.3-100.6, which corresponds to a-Glcp units, while signals at d 108.6 and 106.1 are characteristic of galactofuranosyl units. The water-soluble fractions are heterogeneous as shown by HPSEC-MALLS. Currently, they are being purified by dialysis and ultrafiltration. Additional studies are being carried out in order to determine the fine chemical structure of these fractions.

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