6,8-Dihydroxy-3-methylisocoumarin

The title compound, C10H8O4, was isolated from the fermentation culture of the endophytic fungus Cephalosporium sp. In the crystal structure, molecules are connected into a one-dimensional chain along [101] by intermolecular O—H...O hydrogen bonds involving the hydroxyl and carbonyl functionalities. The chains are linked by non-classical C—H...O interactions, forming extended two-dimensional layers approximately parallel to (11overline{2}).