Experimental Crystal data

R factor = 0.033; wR factor = 0.096; data-to-parameter ratio = 11.2. The title compound (AME; systematic name: 3,7-dihydroxy-9-methoxy-1-methyl-6H-benzo[c]chromen-6-one), C15H12O5, was isolated from an endophytic fungi Alternaria sp., from Catharanthus roseus (common name: Madagascar periwinkle). There is an intramolecular O—H O hydrogen bond in the essentially planar molecule (r.m.s. deviation 0.02 Å). In the crystal, the molecule forms an O—H O hydrogen bond with its centrosymmetric counterpart with four bridging inter-actions (two O—H O and two C—H O). The almost planar sheets of the dimeric units thus formed are stacked along b axis via C—H and – contacts [with C C short contacts between aromatic moieties of 3.324 (3), 3.296 (3) and 3.374 (3) Å]. Related literature Species of the fungal genus Alternaria are known producers of mycotoxins and have previously been described as plant endophytes. For the isolation of Alternariol (AOH) and Alternariol 9-O-methyl ether (AME) see: An et al. (1989); Wen (2009); Ashour et al. (2011). For 1H, 13C and two-dimensional experimental data analysis see: Koch et al. (2005); Siegel et al. (2010). For the biological activity see: Aly et al. (2008)