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

Three previously uncharacterized lactones, namely penicianstinoid L (1), talaromyketide J (2) and peniciisocoumarin K (3), along with twenty-eight known compounds (4–31), were yielded from the mangrove-derived fungus Talaromyces 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 2 and 3 being confirmed by single-crystal X-ray crystallographic analysis. Furthermore, compounds 1–31 were evaluated in terms of their neuraminidase (NA) inhibitory activities. These bioassay results revealed that three lactones (11, 15, and 16) 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.