Talaromyoxaones A and B: Unusual Oxaphenalenone Spirolactones as Phosphatase Inhibitors from the Marine-Derived Fungus Talaromyces purpureogenus SCSIO 41517

(+)- and (-)-talaromyoxaones A and B (1 and 2, respectively), two new oxaphenalenone derivatives with a hemiacetal frame and an unprecedented spirolactone frame of a 2'H,3H,4'H-spiro[isobenzofuran-1,3'-pyran]-3-one unit that show biosynthetic enantiodivergence, and two new oxaphenalenone analogues (±)-11-apopyrenulin (3) and (+)- or (-)-abeopyrenulin (4) were isolated from the marine-derived fungus Talaromyces purpureogenus SCSIO 41517. Their structures were elucidated by spectroscopic analysis, single-crystal X-ray diffraction, and quantum chemical calculations of ECD spectra. Compounds 1 and 2 showed selective inhibitory activity against phosphatases SHP1, SHP2, and MEG2 with IC50 values of 1.3-3.4 μM, and the potential modes of action for 1 were investigated by a preliminary molecular docking study.