Investigation of the fungal strain
Monodictys putredinis isolated from the inner tissue of a marine green alga led to theisolation of four new monomeric xanthones and a benzophenone. All structures were elucidated by extensive spectroscopicmeasurements. The relative configuration of compound
1 was determined by X-ray crystal structure analysis, while for
2 and
3 configurations were confirmed by NOE experiments. Absolute configurations for compounds
1-
3 were deducedby comparing experimental circular dichroism spectroscopic data with those calculated employing quantum-chemicaltime-dependent density functional theory (TDDFT). The compounds were examined for their cancer chemopreventivepotential. Xanthone
2 was shown to inhibit cytochrome P450 1A activity with an IC
50 value of 3.0
M. Compounds
2and
3 displayed moderate activity as inducers of NAD(P)H:quinone reductase (QR) in cultured mouse Hepa 1c1c7cells, with CD values (concentration required to double the specific activity of QR) of 12.0 and 12.8
M, respectively.Compound
3 showed weak inhibition of aromatase activity.