Structure of rutin pentamethanol.

The crystal structure of rutin, 3-[(6-O-(6-deoxy-α-L-mannopyranosyl)-β-D-glucopyranosyl)oxy]-2-(3, 4-dihydroxy-phenyl)-5, 7-dihydroxy-4H-1-benzopyran-4-one, has been determined by the X-ray diffraction method. The crystals are orthorhombic with a=8.748 (3), b=23.567 (10), c=36.052 (12) Å and the space group is C2221. The final R value is 0.102 for 1789 observed reflections after full-matrix least-squares refinement. The dihedral angle between the benzopy-ran and the phenyl rings is 19.0 (7)°, and the quercetin and the rutinose portions are linked together with the torsion angles of 114.1 (18)°and 143.1 (15)°, around the C(3)-O(3) and O(3)-C(1') bonds, respectively. There are two kinds of intramolecular hydrogen bonds between the quercetin and glucose moieties. The structure-function relationship of the flavonoids involving rutin as inhibitors of aldose reductase is also discussed.