Bioactive Isobenzofuranone and Isochromenones From a Marine‐Derived Fungus Penicillium sp.: Isolation, Characterization, and Inhibitory Activity Against α ‐Glucosidase

The chemical investigation of the marine-derived fungus Penicillium sp. led to the isolation of three new secondary metabolites, including one isobenzofuranone (1) and two isochromenones (2 and 3), along with five known compounds (4-8). The structures of the new compounds, including their absolute configurations, were elucidated through comprehensive nuclear magnetic resonance, optical rotatory dispersion, and electronic circular dichroism spectral analyses. The antibacterial, cytotoxic, and α-glucosidase inhibitory activity of all compounds was assessed. Compounds 1 (IC₅₀ = 76.4 µM), 3 (IC₅₀ = 95.4 µM), and 4 (IC₅₀ = 88.3 µM) exhibited inhibitory effects against α-glucosidase, showing comparable activity to the positive control acarbose (IC₅₀ = 67.7 µM). Molecular docking revealed that these structurally analogous compounds exhibited similar binding modes within the active site.