Diverse and Bioactive Lactones from the Sri Lankan Mangrove-Derived Fungus Talaromyces sp. SCSIO41445

Three previously uncharacterized lactones, namely penicianstinoid L (<b>1</b>), talaromyketide J (<b>2</b>) and peniciisocoumarin K (<b>3</b>), along with twenty-eight known compounds (<b>4</b>-<b>31</b>), were yielded from the mangrove-derived fungus <i>Talaromyces</i> sp. SCSIO41445, collected from Mangrove Park (NARA), Sri Lanka. Their structures were established by HRESIMS and NMR spectroscopic analysis (including ¹H and ¹³C NMR, HSQC, and HMBC), with the stereostructures of <b>2</b> and <b>3</b> being confirmed by single-crystal X-ray crystallographic analysis. Furthermore, compounds <b>1</b>-<b>31</b> were evaluated in terms of their neuraminidase (NA) inhibitory activities. These bioassay results revealed that three lactones (<b>11</b>, <b>15</b>, and <b>16</b>) of them exerted NA inhibitory effects, with IC₅₀ values of 46.66 ± 2.31, 20.78 ± 1.89, and 34.14 ± 2.56 µM, respectively. Moreover, molecular docking analysis demonstrated the potential of these compounds to inhibit NA enzymes, revealing specific interactions between the compounds and target proteins.