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.