Flavonoid Glucuronides from the Flowers of Arnica montana1

Five flavonoid glucuronides were identified from flowers of ARNICA MONTANA L. The structures were established on the basis of total acid hydrolysis and spectral data (UV, (1)H-NMR, (13)C-NMR, mass) as 3- O-beta- D-glucuronides of quercetin, kaempferol, isorhamnetin, patuletin, and 6-methoxykaempferol. The last one is a new natural compound. This is the first report on glucuronides in the genus ARNICA. Additionally, tricin and 3,5,7-trihydroxy-6,3',4'-trimethoxyflavone were identified. Up to now these two flavonoid aglycones have been rarely found in the family of the Asteraceae.