Bioactive constituents from Turkish Pimpinella species

A new 'phenylpropanoid', 4-(3-methyloxiran-2-yl)phenyl 2-methylbutanoate (1), a new trinorsesquiterpene, 4-(6-methylbicyclo[4.1.0]hept-2-en-7-yl)butan-2-one (2), and eight known compounds (3-10) were isolated from the essential oils of several Pimpinella species growing in Turkey. The structures of the new compounds were determined by 1D- and 2D-NMR analyses. The absolute configuration of 1 was established via comparison of its optical rotation with that of 'epoxypseudoisoeugenyl 2-methylbutyrate' (11), the absolute configuration of which was determined by chemical degradation and an appropriate Mosher ester formation. Direct bioautography revealed antifungal activity of 1 and 11 against Colletotrichum acutatum, C. fragariae, and C. gloesporioides. Subsequent evaluation of antifungal compounds in a 96-well microtiter assay showed that compounds 1 and 11 produced the most-significant growth inhibition in Phomopsis spp., Colletotrichum spp., and Botrytis cinerea. Compounds 1 and 6 displayed antimicrobial activities against Mycobacterium intracellulare, with IC50 values of 2.78 and 1.29 microM, respectively.