Two new sesquiterpene lactones: 8 alpha-(4'-acetoxymethacryloyloxy)-3 alpha
,9 beta -dihydroxy-1(10)E,4Z,11(13)-germacratrien- 12,6 alpha -olide (1) a
nd 8 alpha-(2'E)-(2'-acetoxymethyl-2'-butenoyloxy)-3 alpha ,9 beta -dihydro
xy-1 (10)E,4Z,11 (13)-germacratrien-12,6 alpha -olide (2), together with th
e known zoapatanolide A were isolated from the aerial parts of Montanoa tom
entosa Cerv. in La Llave et Lex ssp. microcephala (Sch. Bip. In K. Koch) V.
A. Funk (Asteraceae). The structures of all compounds were established on t
he basis of 1D, 2D NMR, and EIMS analysis.