RESUMO
This paper describes the development of a novel microfluorimetric assay to measure the inhibition of Plasmodium falciparum based on the detection of parasitic DNA by intercalation with PicoGreen. The method was used to determine parasite inhibition profiles and 50% inhibitory concentration values of known or potential antimalarial drugs. Values for parasite inhibition with known anti-malarial drugs using the PicoGreen assay were comparable with those determined by the standard method based upon the uptake of 3H-hypoxanthine and the Giemsa stain microscopic technique. The PicoGreen assay is rapid, sensitive, reproducible, easily interpreted, and ideally suited for screening of large numbers of samples for anti-malarial drug development.
Assuntos
Antimaláricos/farmacologia , DNA de Protozoário/análise , Testes de Sensibilidade Parasitária/métodos , Plasmodium falciparum/efeitos dos fármacos , Animais , Citofotometria , Relação Dose-Resposta a Droga , Eritrócitos/parasitologia , Corantes Fluorescentes , Humanos , Compostos Orgânicos , Extratos Vegetais/farmacologia , Plasmodium falciparum/genética , Plasmodium falciparum/crescimento & desenvolvimento , Reprodutibilidade dos Testes , Contagem de Cintilação , Sensibilidade e EspecificidadeRESUMO
A colorimetric method for measuring the viability of Leishmania promastigotes is described that is based on the reduction of the tetrazolium salt, XTT, to a water-soluble formazan. Values obtained by the XTT method correlated well with parasite number (r=0.965) and with methods that rely upon the reduction of MTT or MTS (r=0.96 and 0.97, respectively). The IC(50) values obtained by XTT method with amphotericin-B, miltefosine and ketoconazole were similar to those previously reported by other methods. The XTT method proved to be a reliable and convenient method for the screening of methanolic extracts from 1059 plants and was used for the bioassay-guided fractionation of the alkaloid aegeline from Sarcorhachis naranjoana.
