α-Glucosidase Inhibitors from Preussia minimoides ‡.

Extensive fractionation of an extract from the grain-based culture of the endophytic fungus Preussia minimoides led to the isolation of two new polyketides with novel skeletons, minimoidiones A (1) and B (2), along with the known compounds preussochromone C (3), corymbiferone (4), and 5-hydroxy-2,7-dimethoxy-8-methylnaphthoquinone (5). The structures of 1 and 2 were elucidated using 1D and 2D NMR data analysis, along with DFT calculations of 1H NMR chemical shifts. The absolute configuration of 1 was established by a single-crystal X-ray diffraction analysis and TDDFT-ECD calculations. Compounds 1-4 significantly inhibited yeast α-glucosidase.