In vitro effect of Acanthospermum australe (Asteraceae) extracts on Acanthamoeba polyphaga trophozoites / Efeito in vitro de extratos de Acanthospermum australe (Asteraceae) sobre trofozoitos de Acanthamoeba polyphaga

Acanthamoeba is a free-living protozoan widely distributed in the environment, occurring in vegetative trophozoite and resistance cyst stages during its life cycle. It constitutes an etiological agent of Acanthamoeba keratitis, a disease that may cause severe ocular inflammation and blindness. New drugs can be developed from molecules found in plants and thus help in its difficult treatment. Acanthospermum australe (Asteraceae), a plant used in folk medicine, had its effect tested on Acanthamoeba polyphaga. Aqueous and ethanolic extracts of A. austral were obtained from aerial parts for infusion and static maceration, respectively. Concentrations of 10, 5, 2.5, 1.25 and 0.625 mg/ml of the extract were tested against Acanthamoeba polyphaga trophozoites. The cytotoxic effect of the extracts was tested in mammalian cells using the 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay. RESULTS: The 10 mg/ml concentration of ethanolic extract was lethal to 100% of the A. polyphaga trophozoites in 24 h and both extracts presented cytotoxic effect against mammalian cells. These findings suggest that the A. austral ethanolic extract may have compounds with relevance to the development of new amoebicidal drugs.

Acanthamoeba é um protozoário de vida livre amplamente distribuído no ambiente, ocorrendo sob a forma trofozoítica (metabolicamente ativa) e cística (de resistência), durante seu ciclo de vida. O protozoário constitui um agente etiológico da Ceratite Amebiana, uma doença que pode causar inflamação ocular severa e cegueira. Novos fármacos podem ser desenvolvidos a partir de moléculas encontradas em plantas e assim ajudar em seu difícil tratamento. Aqui, Acanthospermum australe (Asteraceae), uma planta utilizada na medicina popular, teve seu efeito sobre trofozoítos de Acanthamoeba polyphaga testado. O extrato aquoso e etanólico de A. australe foram obtidos das partes aéreas por infusão e maceração estática, respectivamente. As concentrações 10, 5, 2,5, 1,25 e 0,625 mg/ml dos extratos foram testadas contra trofozoítos do protozoário. O efeito citotóxico dos extratos foi testado em células de mamífero utilizando o ensaio de brometo de 3-[4,5-dimetiltiazol-2-il]-2,5-difeniltetrazólio (MTT). A concentração de 10 mg/ml do extrato etanólico foi letal a 100% dos trofozoítos de A. polyphaga em 24 h e ambos os extratos apresentaram efeito citotóxico contra as células de mamífero. Estes resultados sugerem que o extrato etanólico de A. australe pode ter componentes com relevância para o desenvolvimento de novos fármacos amebicidas.

Assessment of the antimicrobial effect of three plants used for therapy of community-acquired urinary tract infection in Rio Grande do Sul (Brazil).

ETHNOPHARMACOLOGICAL RELEVANCE: The urinary tract infections (UTI) are among the infectious diseases of bacterial origin most commonly diagnosed, and may result in a significant mortality. The microorganisms most frequently involved in community-acquired infections are Escherichia coli and Klebsiella pneumoniae, both Gram-negative bacillus of the Enterobacteriaceae family. In southern Brazil, it is common the treatment of UTI using herbs and teas, a tradition inherited from the ancient indigenous people. Nevertheless, there is still poor scientific information about the action of these plants. MATERIALS AND METHODS: Tests included the determination of minimum inhibitory concentration (MIC) by microdilution method at concentrations of 5000-156.25 µg/µL, and evaluation of antimicrobial activity by agar disc diffusion method at concentrations 500-12.5 µg/µL, against the microorganisms Escherichia coli and Klebsiella pneumoniae. RESULTS: In the tests for MIC and antimicrobial activity by disc diffusion method in agar, the growth of Escherichia coli and Klebsiella pneumoniae isolates were not inhibited by extracts from Piptochaetium montevidense, Bulbostylis capillaris and Juncus capillaceus employed in the study. CONCLUSIONS: Despite the popular use of the plants used in this study, there is no relation between the use and the expected antimicrobial activity. Prolonged use of these plants may worsen the disease and lead to kidney involvement, and in severe cases, lead to death.