The title compound, C(7)H(5)NO(4), isolated from the leaves of Actephila merrilliana, is essentially planar (r.m.s. deviation = 0.026 Å). The conformation is supported by an intra-molecular O-H⋯O hydrogen bond, which generates an S(6) ring. In the crystal, C-H⋯O inter-actions and aromatic π-π stacking [centroid-centroid distance = 3.754 (4) Å] help to establish the packing.