Structurally diverse polyketides and alkaloids produced by a plant-derived fungus Penicillium canescens L1

A series of structurally diverse polyketides (1-3), sesterterpenoids (24 and 25), and alkaloids (26-34) were isolated from the fermentation of a plant-derived fungus Penicillium canescens L1 on solid rice medium. Among these secondary metabolites, penicanesols A-G (1-7) were new structures, which were elucidated by NMR, HR-ESI-MS, ECD calculation, and X-ray diffraction. Penicanesol A (1) represented a rare dimer derived from phthalan derivatives, characterized by a 5/6/6/6/5 heteropentacyclic core. The bioassay on the NCI-H1975 cell model showed that two compounds had good cytotoxic activities, and the most significant activate compound 13 had an IC₅₀ value of 4.24 ± 0.13 μM, more than the positive control drug (12.99 ± 0.13 μM).