Goldenrod Root Compounds Active against Crop Pathogenic Fungi.

Root extracts of three goldenrods were screened for antimicrobial compounds. 2,8- and 2,8-matricaria esters from European goldenrod () and - and -dehydromatricaria esters from grass-leaved goldenrod () and first from showy goldenrod () were identified by high-performance thin-layer chromatography combined with effect-directed analysis and high-resolution mass spectrometry or nuclear magnetic resonance spectroscopy after liquid chromatographic fractionation and isolation. Next to their antibacterial effects (against , , and pv. ), they inhibited the crop pathogenic fungi and with half maximal inhibitory concentrations (IC) between 31 and 107 μg/mL. Benzyl 2-hydroxy-6-methoxybenzoate, for the first time found in showy goldenrod root, showed the strongest antifungal effect, with IC of 25-26 μg/mL for both fungal strains.