5,3′-Di­hydroxy-3,7,4′,5′-tetra­methoxy­flavone

The title compound, C₁₉H₁₈O₈ [systematic name: 5-hydroxy-2-(3-hydroxy-4,5-di­methoxy­phenyl)-3,7-di­methoxy­chromen-4-one], an extract from Premna tomentosa willd, is used in the Siddha system of medicine practiced in South India. The dihedral angle between the mean planes through the benzo­pyran moiety and benzene ring is 38.60 (7)°. A strong O—H...O intramolecular hydrogen bond is observed in the molecular structure. O—H...O and C—H...O hydrogen bonds and π–π interactions stabilize the mol­ecules in the crystal packing.