Résumé
A recent reinvestigation of aerial parts of Wedelia paludosa D.C. is described and reports, for the first time, the isolation of iso-kaurenoic acid from this species.
Uma recente reinvestigação das partes aéreas de Wedelia paludosa D.C. é descrita e relata, pela primeira vez, o isolamento do ácido iso-caurenóico desta espécie.
Sujets)
Diterpènes/isolement et purification , Extraits de plantes/isolement et purification , Wedelia/composition chimique , Diterpènes/composition chimique , Diterpènes/pharmacologie , Extraits de plantes/composition chimique , Extraits de plantes/pharmacologieRésumé
A systematic investigation on the trypanocidal effect of several natural products isolated from Brazilian plant species has been carried out. In this paper we report on the results obtained from the screening of 26 diterpenes from natural sources or of synthetic/microbial transformations origin (mainly derivatives of kaurenoic acid) against trypomastigote forms of Trypanosoma cruzi, the causative agent of Chagas'disease. In the in vitro assays, kaurenoic acid, kaurenol, acutifloric acid and stemodin showed a complete elimination of parasites from the blood. Therefore, such diterpenoids can be considered as starting materials for molecular modification in the search for lead compounds for clearance of infected blood to be used in transfusions. Blood previously treated with active compounds was submitted to an infectivity test. Samples proceeded from treatment with kaurenol and kaurenoic acid showed to be completly clean from T. cruzi as no infection was observed in mice inoculated with contaminated blood treated by these compounds.
Résumé
Ethanol extracts of 83 plants species belonging to the Asteraceae (Compositae) family, collectes in the State of Minas Gerais, Brazil, were tested for larvicidal activity against the mosquito Aedes fluviatilis - Diptera: Culicidae). The extract from Tagetes minuta was the most active with LC90 of 1.5 mg/l and LC50 of 1.0 mg/l. This plant been the object of several studies by other groups and its active components have already been identified as thiophene derivates, a class of compounds present in many Asteraceae species. The extract of Eclipta paniculata was also significantly active, with a LC90 of 17.2 mg/l and LC50 of 3.3 mg/l and no previous studies on its larvicidal activity or chemical composition could be found in the literature. Extracts of Achryrocline satureoides, Gnaphalium spicatum, Senecio brasiliensis, Trixis vauthieri, Tagetes patula and Vernonia ammophila were less active, killing more than 50 per cent of the larvae only at the higher dose tested (100 mg/l)