Alternatone A, an Unusual Perylenequinone-Related Compound from a Soft-Coral-Derived Strain of the Fungus .

A novel perylenequinone-related compound, alternatone A (), with an unprecedented tricyclo[6.3.1.0] dodecane skeleton, together with three known perylenequinones, altertoxin I (), stemphyperylenol (), and alterperylenol (), was isolated from the soft-coral-derived fungus L3111'. Their structures including absolute configurations were elucidated on the basis of comprehensive spectroscopic analysis, electronic circular dichroism calculations, and X-ray diffraction data. Compound showed cytotoxicity against A-549, HCT-116, and HeLa cell lines with IC values of 2.6, 2.4, and 3.1 μM, respectively. A possible biosynthetic pathway of was proposed.