Nuevas lactonas sesquiterpénicas de Perymenium grande
Three new sesquiterpenes lactonaes were isolated from the aerial parts of Perymenium grande Hemsl. (Asteraceae), collected around Rincón de la Vieja Volcano, Costa Rica. In addition to the three new lactones 1, 3 and 5; were isolated the additional five known sesquiterpenes lactones. The separation were performed with chromatographic techniques and the structures were elucidated by one- and two-dimensional nuclear magnetic resonance techniques.