Conformation of grifolan in the fruit body of Grifola frondosa assessed by carbon-13 cross polarization-magic angle spinning nuclear magnetic resonance spectroscopy.

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Abstract
Grifola frondosa produces an antitumor (1 .fwdarw. 3)-.beta.-D-glucan, grifolan, which possesses two kinds of conformations in the solid state, i.e., helix (curdlan type) and native (laminaran type) (Ohno et al., Chem. Pharm. Bull., 34, 2555 (1986)). In this paper, the glucan conformation in the fruit body was examined by using carbon-13 cross polarization-magic angle spinning (CP/MAS) nuclear magnetic resonance (NMR) spectroscopy. Before analysis, the fruit body was treated as follows: amylase digestion, amylase digestion-periodate-borohydride treatment, hot water extraction, cold alkali extraction, or hot alkali extraction. Except for the cold and the hot alkali-extracted fruit bodies, all preparations showed C-3 signals at about 86 ppm, resembling those of the native form. These findings suggested that the (1 .fwdarw. 3)-.beta.-D-glucan conformation in the fruit body is the "native form".