Chromone derivatives from a sponge-derived strain of the fungus Corynespora cassiicola.

Twelve new chromone derivatives, corynechromones A-L (1-12), were isolated from the sponge-derived fungus Corynespora cassiicola XS-200900I7. Among them, 1/2, 3/4, 5/6, and 7/8 were pairs of epimers. The planar structures were determined by extensive NMR spectroscopic data. The absolute configurations of 1-10 were assigned by the modified Mosher's method and TDDFT ECD calculations together with comparison of their CD spectra. These are the first chromone derivatives reported from the genus Corynespora. A possible rule to determine the absolute configurations at C-2 in chromone derivatives by CD was proposed.