Multioxidized aromatic polyketides produced by a soil-derived fungus Penicillium canescens

Under OSMAC strategy, seven unreported multioxidized aromatic polyketides, penicanesins A‒G, were discovered from a soil-derived fungus Penicillium canescens along with seven known compounds. Their structures were assigned by extensive 1D and 2D NMR spectra in combination with HRESIMS and single crystal X-ray diffraction. Absolute stereochemistry of penicanesins A and D were elucidated by theoretical ECD calculation. (±)-Penicanesins A and B are two pairs of racemic aromatic polyketides with an unusual 6/6/6/6 heterotetracyclic ring core. In bioassay, (-)-penicanesin A shows potential cytotoxicity against human cancer cell lines HL-60 and SW480 with IC₅₀ values at 13.8 ± 0.6 and 12.5 ± 0.9 μM, respectively, whereas the enantiomer (+)-penicanesin A is less active.