Sporulosol, a New Ketal from the Fungus Paraconiothyrium sporulosum

Abstract

Sporulosol (<b>1</b>), a new ketal, together with four known compounds, has been isolated from the liquid fermentation cultures of a wetland-soil-derived fungus, <i>Paraconiothyrium sporulosum</i>. Its structure was elucidated primarily by NMR experiments, and was further confirmed by X-ray crystallography. Sporulosol was obtained as a racemic mixture and the resolved two enantiomers racemized immediately after chiral separation. Sporulosol appears to be the first ketal derived from a 6<i>H</i>-benzo[<i>c</i>]chromen-6-one and a benzofuranone unit. The compound showed modest cytotoxicity toward the human tumor cell line T24, with an IC₅₀ value of 18.2 µM.