"Carqueja-amarga" [Baccharis trimera (Asteraceae)] is a species from the central south of South America. Qualitative and quantitative analyses were performed using the technique gas chromatography coupled to mass spectrometry to evaluate the effect of different post-harvest processing forms of drugs constituted of parts of "carqueja" on the chemical composition of its essential oil. The variation in the chemical composition of the essential oil stored at -6ºC for up to eight months was also evaluated. Storage of powdered drug significantly reduced the essential oil content, which was not observed for fragmented drug. The concentration of the major constituents of "carqueja" essential oil, spathulenol and ledol, was not affected by the post-harvest treatment, although they presented distinct variations, with ledol concentrations reducing and spathulenol concentrations increasing. We found that fragmented drugs can be stored for up to 12 months and powdered at the moment of extraction, without reducing the concentration of the essential oil or its chemical constituents. Storage at -6ºC for eight months caused quantitative variations in some minor constituents of the essential oil such as a-guaiene, b-selinene, germacrene B and espathulenol.
Baccharis; Asteraceae; medicinal plants; essential oil; post-harvest
