Penioxalone A: A new isocoumarine derivative fromPenicillium oxalicum with potent cytotoxic effects on A549 cells

A chemical analysis of Penicillium oxalicum, a fungus isolated from saline soil, resulted in the discovery of four bioactive compounds (1–4), including a new resorcylic acid lactone, named penioxalone A (1). The structural characterization of penioxalone A was achieved through comprehensive spectroscopic techniques, including 1D and 2D NMR spectroscopy, coupled with HRESIMS data. To determine its absolute configuration, experimental data from ECD and ORD were compared with theoretical calculations. The cytotoxicity of compounds 1, 3, and 4 was assessed against A549 human lung carcinoma cells, revealing IC₅₀ values of 3.6, 0.23, and 0.35 μM, respectively. These compounds exhibited enhanced potency compared to cisplatin, a standard chemotherapy drug, which had an IC₅₀ of 4.2 μM.