Six new heptaketides, pleosporalins A-F (1-5, and 7), and a new heptaketide derivative, pleosporalin G (9), together with four biosynthetically related known compounds (6, 8, 10, and 11), were isolated from an endophytic fungus, Pleosporales sp. F46, found in the medicinal plant Mahonia fortunei. The structures and stereochemistry of these compounds were established by extensive spectroscopic analyses including LC-HRMS, NMR spectroscopy, optical rotations, ECD calculations, and single-crystal X-ray diffraction. The antifungal activities of isolated compounds 1-11 were investigated against Candida albicans, and their cytotoxic activities were evaluated against A549, SMMC-721, and MDA-MB-231 cancer cell lines. Compound 1 was active against C. albicans with an MIC80 of 128 μg mL-1, and compound 7 showed moderate cytotoxicity against MDA-MB-231 with an IC50 of 22.4 ± 1.1 μM. By comparing compounds 1 and 7 with structurally related metabolites, it was revealed that alterations to their C-1 or C-2 substitutions could significantly influence their antifungal or cytotoxic efficacies.
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