Three new compounds, cadalen-15-oic acid (1), 3,7-dihydroxy-3(4H)-isocadalen-4-one (2), and dicadalenol (3), were isolated from the aerial parts of Heterotheca inuloides (Mexican arnica), together with the known compounds 7-hydroxycadalene (4), 7-hydroxy-4alphaH-3,4-dihydrocadalene (5),
Heterotheca inuloides Cass. (Asteraceae) is used in the traditional medicine of Mexico. The aqueous extract obtained from the flowers of H. inuloides was assessed for anti-inflammatory activity by carrageenan-induced edema test. At 100 mg/kg, i.p, it produced 29% inhibition of inflammation. Ethyl