Two different conformations of antitumor glucans obtained from Grifola frondosa.

Abstract

Several antitumor glucan fractions obtained by various extraction procedures from Grifola frondosa were compared by solution and solid (cross polarization, magic angle spinning (CP/MAS)) carbon-13 nuclear magnetic resonance (13C-NMR) spectroscopy. The fractions prepared under milder conditions, i.e., hot water extract (AHW), liquid culture filtrated (LLFD), and extracellular polysaccharide (LELFD), showed a C-3 signal at the same chemical shift as that in DMSO-d6 solution (native form) in 13C CP/MAS NMR spectroscopy. However, the fractions prepared under drastic conditions, i.e., cold alkali extract (NMF-5, grifolan), showed a C-3 signal at 89 ppm, similar to those of curdlan and attributable to helix structure (helix form). After dissolution of LELFD in 8 M urea followed by dialysis, LELFD also showed a C-3 signal at 89 ppm. These results suggest that the polysaccharides obtained from G. frondosa possess two kinds of conformations.