Mapping of B cell epitopes in an immunodominant antigen of Trypanosoma cruzi using fusions to the Escherichia coli LamB protein

The JL8 protein antigen from Trypanosoma cii , a dominant immunogen in man, has been characterized as containing tandem amino acid repeats. Here, we describe the use of the LamB protein of Escherichia coli as a carl icr of JL8 derived sequences in order to map the immunodominant B cell epitopes in this antigen. Five different sequences of JL8 were inserted in the LamB protein and the JL8-LamB fusion proteins were tested by ELISA with human chronic chagasic sera. the fusion carrying the sequence AEKQKAAEATKVAE was recognized by most sera. This protein was also capable of inhibiting the binding of human chagasic antibodies to GST-JL8 in competitive ELISA suggesting that it contains an immunodominant B cell epitope of JL8. (C) 1998 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.Universidade Federal de São Paulo, Escola Paulista Med, Dept Microbiol Imunol & Parasitol, BR-04023062 São Paulo, BrazilIngebi, RA-1428 Buenos Aires, DF, ArgentinaUniversidade Federal de São Paulo, Escola Paulista Med, Dept Microbiol Imunol & Parasitol, BR-04023062 São Paulo, BrazilWeb of Scienc

In vitro and in vivo assessment of the anti-malarial activity of Caesalpinia pluviosa

<p>Abstract</p> <p>Background</p> <p>To overcome the problem of increasing drug resistance, traditional medicines are an important source for potential new anti-malarials. <it>Caesalpinia pluviosa</it>, commonly named "sibipiruna", originates from Brazil and possess multiple therapeutic properties, including anti-malarial activity.</p> <p>Methods</p> <p>Crude extract (CE) was obtained from stem bark by purification using different solvents, resulting in seven fractions. An MTT assay was performed to evaluate cytotoxicity in MCF-7 cells. The CE and its fractions were tested <it>in vitro </it>against chloroquine-sensitive (3D7) and -resistant (S20) strains of <it>Plasmodium falciparum</it> and <it>in vivo </it>in <it>Plasmodium chabaudi</it>-infected mice. <it>In vitro </it>interaction with artesunate and the active <it>C. pluviosa </it>fractions was assessed, and mass spectrometry analyses were conducted.</p> <p>Results</p> <p>At non-toxic concentrations, the 100% ethanolic (F4) and 50% methanolic (F5) fractions possessed significant anti-malarial activity against both 3D7 and S20 strains. Drug interaction assays with artesunate showed a synergistic interaction with the F4. Four days of treatment with this fraction significantly inhibited parasitaemia in mice in a dose-dependent manner. Mass spectrometry analyses revealed the presence of an ion corresponding to <it>m/z </it>303.0450, suggesting the presence of quercetin. However, a second set of analyses, with a quercetin standard, showed distinct ions of <it>m/z </it>137 and 153.</p> <p>Conclusions</p> <p>The findings show that the F4 fraction of <it>C. pluviosa </it>exhibits anti-malarial activity <it>in vitro </it>at non-toxic concentrations, which was potentiated in the presence of artesunate. Moreover, this anti-malarial activity was also sustained <it>in vivo </it>after treatment of infected mice. Finally, mass spectrometry analyses suggest that a new compound, most likely an isomer of quercetin, is responsible for the anti-malarial activity of the F4.</p

Trypanocidal activity of eErythrina speciosa Andr. (Leguminosae)

Investigation of the bioactive crude extracts from the leaves of Erythrina speciosa Andr. (Leguminosae-Papilionoideae) from Brazil led to the isolation of nororientaline as a new alkaloid in this plant. The activity of crude extract and alkaloids, isolated from leaves of E. speciosa were evaluated against Trypanosoma cruzi epimastigotes and trypomastigotes in vitro. Our results show that crude alcoholic extract of E. speciosa (Et-Es) and alkaloids containing nororientaline at 250 μg/mL, 500 μg/mL and 1000 μg/mL inhibited 50, 60 and 80 % of epimastigote growth, respectively (p < 0.001). Et-Es showed activity against trypomastigote forms in 80 % and 60 % at 1000 μg/mL and 500 μg/mL, respectively. When tested against macrophages, the same extract did not affect the cell viability as measured by luminescent assay, suggesting that it should be considered as a leading structure for further research.Colegio de Farmacéuticos de la Provincia de Buenos Aire