A demethylation chloroisosulochrin and a chromone metabolite from the endophytic fungus <i>Penicilium</i> sp.

A newly discovered chloroisosulochrin derivative, involving demethychloroisosul (<b>1</b>), and a novel chromone metabolite, reduchromone (<b>2</b>), were extracted from <i>Penicilium</i> sp., an endophytic fungus residing in <i>Rhododendron molle</i>. The structures of these compounds were elucidated through a comprehensive analysis of their 1D and 2D NMR and HRESIMS data. In addition, the X-ray diffraction analysis of demethychloroisosul (<b>1</b>) is the first example to confirm the structure of chloroisosulochrin by single-crystal data. Notably, demethychloroisosul (<b>1</b>) exhibited moderate cytotoxic efficacy against HepG2 liver cancer cells, with a half-maximal inhibitory concentration value of 30.18 μM.