Antiinflammatory constituents from Heterotheca inuloides

Three new compounds, cadalen-15-oic acid (1), 3,7-dihydroxy-3(4H)-isocadale n-4-one (2), and dicadalenol (3), were isolated from the aerial parts of He terotheca inuloides (Mexican arnica), together with the known compounds 7-h ydroxycadalene (4), 7-hydroxy-4 alphaH-3,4-dihydrocadalene (5), 1 alpha -hy droxy-1(4H)-isocadalen-4-one (6), 1 alpha -hydroxy-4 alphaH-1,2,3,4-tetrahy drocadalen-15-oic acid (7), 7-(3,3-dimethylallyloxy)coumarin, caryolan-1,9 beta -diol, and quercetin. The structures of the new compounds were elucida ted by spectroscopic methods. The antiinflammatory activities of the extrac ts and the isolated compounds were evaluated by determining the inhibition of TPA-induced mouse ear edema. The natural products 3, caryolan-1,9,beta - diol, and quercetin were the most active substances tested and displayed do se-dependent activities.