In vitro screening for antiplasmodial activity of isoquinoline alkaloids from Brazilian plant species

In the search for new antimalarial agents, nine Brazilian plant species were selected, from the Annonaceae (6), Menispermaceae (2) and Siparunaceae (1) families naturally occurring at the cerrado and Atlantic rainforest regions, in order to investigate their in vitro antiplasmodial activity. The ethanol and the alkaloid extracts were tested against K1, chloroquine-resistant, and Palo Alto, chloroquine-sensitive, strains of Plasmodium falciparum. The majority of the alkaloid extracts were more active than the ethanol ones, with IC(50) ranging 0.3-8.2 microg/mL. The crude Guatteria australis alkaloids were the most active against K1 with an IC(50) = 0.3 microg/mL. The most promising total alkaloid fractions for further bioguided isolation are those with the IC(50) < or = 5 microg/mL: G. australis, Cissampelos ovalifolia and Duguetia lanceolata.

Analysis of genetic relatedness between populations of Aedes aegypti from different geographic regions of São Paulo state, Brazil

RAPD markers have been used for the analysis of genetic differentiation of Aedes aegypti, because they allow the study of genetic relationships among populations. The aim of this study was to identify populations in different geographic regions of the S o Paulo State in order to understand the infestation pattern of A. aegypti. The dendrogram constructed with the combined data set of the RAPD patterns showed that the mosquitoes were segregated into two major clusters. Mosquitoes from the Western region of the S o Paulo State constituted one cluster and the other was composed of mosquitoes from a laboratory strain and from a coastal city, where the largest Latin American port is located. These data are in agreement with the report on the infestation in the S o Paulo State. The genetic proximity was greater between mosquitoes whose geographic origin was closer. However, mosquitoes from the coastal city were genetically closer to laboratory-reared mosquitoes than to field-collected mosquitoes from the S o Paulo State. The origin of the infestation in this place remains unclear, but certainly it is related to mosquitoes of origins different from those that infested the West and North region of the State in the 80's.

Evaluation of a rapid dipstick test, Malar-Check, for the diagnosis of Plasmodium falciparum malaria in Brazil

The present study was carried out to evaluate the Malar-Check trade mark Pf test, an immunochromatographic assay that detects Plasmodium falciparum Histidine Rich Protein II, does not require equipment, and is easy and rapid to perform. In dilution assays performed to test sensitivity against known parasite density, Malar-Check were compared with thick blood smear (TBS), the gold standard for diagnosis. Palo Alto isolate or P. falciparum blood from patients with different parasitemias was used. The average cut-off points for each technique in three independent experiments were 12 and 71 parasites/mm3 (TBS and Malar-Check, respectively). In the field assays, samples were collected from patients with fever who visited endemic regions. Compared to TBS, Malar-Check yielded true-positive results in 38 patients, false-positive results in 3, true-negative results in 23, and false-negative result in 1. Malar-Check performed with samples from falciparum-infected patients after treatment showed persistence of antigen up to 30 days. Malar-Check should aid the diagnosis of P. falciparum in remote areas and improve routine diagnosis even when microscopy is available. Previous P. falciparum infection, which can determine a false-positive test in cured individuals, should be considered. The prompt results obtained with the Malar-Check for early diagnosis could avoid disease evolution to severe cases.