[[#1987-05] Conformational Changes of the Two Different Conformers of Grifolan in Sodium Hydroxide, Urea or Dimethylsulfoxide Solution, N. Ohno et al.

Conformational Changes of the Two Different Conformers of Grifolan in Sodium Hydroxide, Urea or Dimethylsulfoxide Solution

Ohno, N (a), Adachi, Y(a), Ohsawa, M (b), Sato, K (b),Oikawa, S (b), Yadomae, T (b)

a) Tokyo College of Pharmacy, b) Nippon Beet Sugar Mfg. Co. Ltd.

Grifolan is an antitumor (1–>3)-β-D-glucan with a β-glucosyl substitution at C-6 of every three main chain units, and is produced by Grifola frondosa ( maitake ). Grifolan possesses two different solid-state conformations, N (native) and H (helix) (N. Ohno et al., Chem. Pharm. Bull. 34, 2555 (198 6)), and both form a gel in an aqueous neutral media. In this study, the gel-to-sol or sol-to-gel transition of these forms in sodium hydroxide, urea and dimethylsulfoxide solutions were examined by carbon-13 nuclear magnetic resonance spectroscopy. The N gel showed C13 signals in sodium- hydroxide of more than 0.15N, and the H gel showed them at more than 0.05N. Gel-to-sol transitions of the N and H gels in urea were induced at 8 and 2M, respectively. Sol-to-gel transitions of the glucans in dimethylsulfoxide were induced by the addition of more than 20% of water. These results suggested firstly that the architecture of the two gels is different because the gel-to-sol transition occurred more easily in the case of the H gel than the N gel, and secondly that the structure of the two glucans in the sol state is essentially the same.