Elsinopirins A-D, Decalin Polyketides from the Ascomycete Elsinoё pyri

In course of our screening for new secondary metabolites from ecological niche specialized, phytopathogenic fungi, the plant pathogen Elsinoё pyri, strain 2203C, was found to produce four novel compounds (1-4), which were named elsinopirins A-D, in addition to the known metabolite elsinochrome A (5). After isolation by preparative high-performance liquid chromatography (HPLC), their structures, including relative stereochemistry, were elucidated by 1D and 2D nuclear magnetic resonance (NMR) and mass spectrometry (MS) data. Finally, absolute stereochemistry was assigned by chemical shifts of Mosher's esters (α-methoxy-α-trifluoromethylphenylacetic acid; MTPA) derivatives of elsinopirin B (2). The compounds were found to be devoid of significant antibacterial, antifungal, and cytotoxic activities.