1,3-Dihydr-oxy-9,10-dioxo-9,10-di-hydro-anthracene-2-carbaldehyde.

The title compound, C(15)H(8)O(5), also known as nordamnacanthal, was isolated from the Malaysian Morinda citrifolia L. The 20 non-H atoms are coplanar. The structure is stabilized by intra-molecular O-H⋯O hydrogen bonds and inter-molecular O-H⋯O and C-H⋯O hydrogen bonds, forming bilayers of mol-ecular tapes with alternating stacking directions along the a axis.