Setosphlides A–D, New Isocoumarin Derivatives from the Entomogenous Fungus Setosphaeria rostrate LGWB-10

ABSTRACT: Investigation of the entomogenous fungus Setosphaeria rostrate LGWB-10 from Harmonia axyridis led to the isolation of four new isocoumarin derivatives, setosphlides A–D (1–4), and four known analogues (5–8). Their planar structures and the relative configurations were elucidated by comprehensive spectroscopic methods. The absolute configurations of isocoumarin nucleus for 1–4 were elucidated by their ECD spectra. The C-10 relative configurations for the pair of C-10 epimers (1 and 2) were established by comparing the magnitude of the computed (13)C NMR chemical shifts (Δδ(calcd.)) with the experimental (13)C NMR values (Δδ(exp.)) for the epimers. All of the isolated compounds (1–8) were evaluated for their cytotoxicities against four human tumor cell lines MCF-7, MGC-803, HeLa, and Huh-7. GRAPHIC ABSTRACT: [Image: see text] SUPPLEMENTARY INFORMATION: The online version of this article (10.1007/s13659-020-00292-8) contains supplementary material, which is available to authorized users.