DITERPENES FROM ARNICA-ANGUSTIFOLIA

From flowerheads of Arnica angustifolia ssp. attenuata the labdane dit erpenes labd-13(Z)-ene-8 alpha, 15-diol (main component) and (13R,14R) 8,13-epoxylabdane-14,15-diol were isolated and their structures establ ished by extensive NMR and MS measurements. Both compounds are reporte d as natural products for the first time. Oxidative degradation of the main component was observed and the oxidation products 8 alpha-hydrox ylabd-13(Z)-ene-15-al, 8 alpha-hydroxylabd-13(E)-ene-15-al and 8,13-ep oxylabdane-15-al were identified. Additionally, the tetranoriabdanolid e norambreinolide, most probably also derived from the labdanes, was d etected in minor amounts. A search for diterpenes in flowers of A. mon tana revealed the presence of small amounts of labd-13(Z)-ene-8 alpha, 15-diol.