2H-Pyranone and isocoumarin derivatives isolated from the plant pathogenic fungus Leptosphaena maculans

Two new 2H-pyranones and two new isocoumarin derivatives, maculanslines A-D (1-4), together with seven known compounds (5-11), were isolated from the plant pathogenic fungus Leptosphaena maculans. Their planar structures and absolute configuration were elucidated by comprehensive spectroscopic techniques including high-resolution electrospray ionization mass spectrum, 1D and 2D nuclear magnetic resonance, as well as electronic circular dichroism. All 11 compounds were tested for their inhibitory activity against alpha-glucosidase. Compound 1 showed moderate inhibitory activity against alpha-glucosidase with IC50 of 74.35 mu M.