Penicyclones A–E, Antibacterial Polyketides from the Deep-Sea-Derived Fungus Penicillium sp. F23‑2

Five new ambuic acid analogues, penicyclones A–E (1–5), were isolated from the extract of the deep-sea-derived fungus Penicillium sp. F23-2. The structures including the absolute configurations were established by interpretation of NMR and MS data, as well as the application of ECD, X-ray crystallography, and a chemical conversion, as well as the TDDFT-ECD calculations. Penicyclones A–E (1–5) exhibited antimicrobial activity against the Gram-positive bacterium Staphylococcus aureus with MIC values ranging from 0.3 to 1.0 μg/mL.