In the octa-hydroxanthenedione unit of the title compound, C31H27NO6, the central di-hydro-pyran ring shows an envelope conformation, while the bilateral cyclo-hexene and cyclo-hexane rings adopt a half-boat conformation and a chair conformation, respectively. The nitro-benzene ring is twisted with respect to the two benzene rings, making dihedral angles of 63.1 (1) and 63.0 (1)°. In the crystal, O-H⋯O hydrogen bonds link the mol-ecules into supra-molecular chains propagating along the a-axis direction.
Keywords: crystal structure; hydrogen bonding; xanthene.