Fracionamento do extrato diclorometânico de Senecio desiderabilis Vellozo e avaliação da atividade antimicrobiana / Fractionation of dichlorometane extract from Senecio desiderabilis Vellozo and evaluation of the antimicrobial activity

O presente trabalho descreve a avaliação da atividade antimicrobiana de uma fração sesquiterpênica, obtida a partir do extrato CH2Cl2 de Senecio desiderabilis Vellozo (Asteraceae), e do germacreno D, isolado a partir desta. A fração e o germacreno D foram obtidos mediante cromatografia em coluna e analisados por CG-EM e também por RMN, no caso da substância isolada. A atividade antimicrobiana foi avaliada frente a leveduras e bactérias pelo método de microdiluição em caldo, conforme preconizado pelo NCCLS, nos documentos M27-A2 para fungos leveduriformes, e M7-A4 para bactérias. A fração sesquiterpênica evidenciou moderada atividade antimicrobiana, enquanto que o germacreno D não inibiu o crescimento dos microrganismos testados.

The present work describes the evaluation of the antimicrobial activity of a sesquiterpene fraction obtained from CH2Cl2 extract of Senecio desiderabilis Vellozo (Asteraceae), and of germacrene D isolated from it. The sesquiterpene fraction and the isolated substance were obtained by column chromatography and analysed by GC-MS. Substance identification was carried out by NMR. The antimicrobial activity was assayed by broth microdilution method, as preconized by NCCLS in the documents M27-A for yeasts and M7-A4 for bacteria. The sesquiterpene fraction showed moderated antimicrobial activity, and germacrene D did not inhibit the tested microorganisms.

Saponins from maté (Ilex paraguariensis) amd other South American Ilex species: ten years research on Ilx saponins

Ilex paraguariensis is widely used in South Brazil, Argentinna, Paraguay and Uruguay as a beverage (maté) and also as a traditional medicinal plant. During the past ten years, we have systematically studied the saponins of the leaves of genuine maté (Ilex paraguariensis) and the other Ilex species reported as adulterants, searching for chemical differences. Here we give a brief account of the elucidated saponin structures. Ilex paraguariensis and Ilex dumosa can be considered as saponin rich species, containing between 5-10 per cent of crude saponins in the leaves, in opposition to other species that showed a lower saponin content. All the saponins from Ilex paraguariensis leaves identified up to now are glycosides of ursolic or oleanolic acid. From Ilex dumosa, the most frequently quoted maté adulterant, we have isolated and elucidated the structures of ten saponins, almost all of them being glycosides of oleanolic acid and one of 29-hydroxyoleanolic acid. In comparison, the saponin pattern for the other South American Ilex species investigated up to now is different. The saponins from I. pseudobuxus, I. argentina, I. taubertiana and I. theezans all have the aglycones derived from the 19alpha-hydroxyursolic acid. Saponins containing this type of aglycone were not found in the leaves of Ilex paraguariensis and Ilex dumosa. These are important features, that may have taxonomical significance. Furthermore, this knowledge is necessary to develop methodologies for quality control of maté products and to identify the compounds involved in the tast, flavor and pharmacological properties.