Trehalose dihydrate from Tremella fuciformis

The title compound, C₁₂H₂₂O₁₁·2H₂O {systematic name: 6,6′-oxybis[2-(hy­droxy­meth­yl)-3,4,5,6-tetra­hydro-2H-pyran-3,4,5-triol] dihydrate}, is a disaccharide, which was isolated from Tremella fuciformis. The mol­ecule contains two six-membered rings, both of which adopt a chair conformation. Extensive O—H...O hydrogen bonds occur in the crystal structure.