Constituintes químicos de óleos voláteis de plantas medicinais do Rio Grande do Sul: isolamento, determinação estrutural e atividade biológica.

Abstract

The essential oils of six species of plants wild in south Brazil, were investigated as for its chemical composition, antibacterial activity and antioxidant potential. The selected species for this study were Calea clematidea (Asteraceae), Acanthospermum australe (Asteraceae), Tagetes minuta (Asteraceae), Julocroton humilis (Euphorbiaceae), Nectandra megapotamica (Lauraceae) e Nectandra lanceolata (Lauraceae). In this work, the essential oil of each specie was submitted to chromatographic procedures to isolate its constituents in pure form. The structural determination of isolated components were realized through chromatographic technics, obtainment of Kovats indices, GC-MS and RMN of 1H and 13C uni- and bi dimensional. So that, were possible to identify two inedited sesquiterpenes of essential oil from Nectandra megapotamica denominated in this work as PF1 and PF2. From essential oil of Acanthospermum australe were isolated its principal constituent, the mix of Carvacrol isobutirate and Timol isobutirate. In conclusion, the essential oil obtained as well as, the isolated components through chromatographic methods were submitted to antibacterial and antifungical tests, using the microdiluition methods, through which is possible to observe that the essential oils were active against a greater number of microorganisms. The results, between 6,5 a 100 μg/ mL, showed that the PF1 and PF2 have a excellent antimicrobial activity against the tested microorganisms. Furthermore, the antioxidant activity was accessed by the reducing power assay, the scavenging effect on DPPH (2,2-diphenyl-1-picrylhydrazyl) radicals model system. In a general way, the essential oils from Acanthospermum australe presented moderate antioxidant activity.