Molecular approaches for structural characterization of Bothrops L-amino acid oxidases with antiprotozoal activity: cDNA cloning, comparative sequence analysis, and molecular modeling

Two L-amino acid oxidases (LAAOs) were identified by random sequencing of cDNA libraries from the venom glands of Bothrops moojeni (BmooLAAO) and Bothrops jararacussu (Bjussu LAAO). Phylogenetic analysis involving other SV-LAAOs showed sequence identities within the range 83-87% being closely related to those from Agkistrodon and Trimeresurus. Molecular modeling experiments indicated the FAD-binding, substrate-binding, and helical domains of Bmoo and Bjussu LAAOs. The RMS deviations obtained by the superposition of those domains and that from Calloselasma rhodostoma LAAO crystal structure confirm the high degree of structural similarity between these enzymes. Purified BjussuLAAO-I and BmooLAAO-I exhibited antiprotozoal activities which were demonstrated to be hydrogen-peroxide mediated. This is the first report on the isolation and identification of cDNAs encoding LAAOs from Bothrops venom. The findings here reported contribute to the overall structural elucidation of SV-LAAOs and will advance the understanding on their mode of action. (c) 2006 Elsevier B.V. All rights reserved.

Antiprotozoal Sesquiterpene Pyridine Alkaloids from Maytenus ilicifolia

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Antiprotozoal activity of quinonemethide triterpenes from Maytenus ilicifolia (Celastraceae)

The present study describes the leishmanicidal and trypanocidal activities of two quinonemethide triterpenes, maytenin (1) and pristimerin (2), isolated from Maytenus ilicifolia root barks (Celastraceae). The compounds were effective against the Trypanosomatidae Leishmania amazonensis and Leishmania chagasi and Trypanosoma cruzi, etiologic agents of leishmaniasis and Chagas' disease, respectively. The quinonemethide triterpenes 1 and 2 exhibited a marked in vitro leishmanicidal activity against promastigotes and amastigotes with 50% inhibitory concentration (IC50) values of less than 0.88 nM. Both compounds showed IC50 lower than 0.3 nM against Trypanosoma cruzi epimastigotes. The selectivity indexes (SI) based on BALB/c macrophages for L. amazonensis and L. chagasi were 243.65 and 46.61 for (1) and 193.63 and 23.85 for (2) indicating that both compounds presented high selectivity for Leishmania sp. The data here presented suggests that these compounds should be considered in the development of new and more potent drugs for the treatment of leishmaniasis and Chagas' disease. © 2013 by the authors.

New drugs with antiprotozoal activity from marine algae: a review

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

On the release of metronidazole from natural rubber latex membranes

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Cell cycle arrest evidence, parasiticidal and bactericidal properties induced by L-amino acid oxidase from Bothrops atrox snake venom

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Piperamides and their derivatives as potential anti-trypanosomal agents

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Trypanocidal activity of Brazilian plants against epimastigote forms from Y and Bolivia strains of Trypanosoma cruzi

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Atividade tripanocida de Piper arboreum e Piper tuberculatum (Piperaceae)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Efeito do praziquantel incorporado a lipossomas nos diferentes estágios de desenvolvimento dos ovos de Schistosoma mansoni

Mansonian schistosomiasis is caused by an intravascular digenetic trematode Schistosoma mansoni. Praziquantel (PZQ) and oxamniquine (OXA) are the drugs of choice for the treatment of this disease. However, both drugs are subject to some limitations in their action and cases of tolerance and resistance have been reported. Moreover, tolerance and resistance cases have been reported. For this reason, there is an urgent need for research on new alternatives aimed at improving the action of existing drugs, such as the incorporation of these drugs into liposomes. In this study, the efficiency of action of liposome- encapsulated praziquantel (lip.PZQ) on oviposition by S. mansoni, strain BH, was assessed in Mus musculus mices (SPF Swiss mice). Four PZQ and lip.PZQ doses (47; 60; 250 e 300mg/kg) were tested. Some mice were treated 30 days post-infection and others after 45 days. The oogram analyses showed that the most effective lip.PZQ treatment was 300mg/kg dose given on the 45th day post infection, which reduced the number of S. mansoni eggs per gram of tissue.

Chemical and biological characterization of four new linear cationic α-helical peptides from the venoms of two solitary eumenine wasps

Four novel peptides were isolated from the venoms of the solitary eumenine wasps Eumenes rubrofemoratus and Eumenes fraterculus. Their sequences were determined by MALDI-TOF/TOF (matrix assisted laser desorption/ionization time-of-flight mass spectrometry) analysis, Edman degradation and solid-phase synthesis. Two of them, eumenitin-R (LNLKGLIKKVASLLN) and eumenitin-F (LNLKGLFKKVASLLT), are highly homologous to eumenitin, an antimicrobial peptide from a solitary eumenine wasp, whereas the other two, EMP-ER (FDIMGLIKKVAGAL-NH 2) and EMP-EF (FDVMGIIKKIAGAL-NH 2), are similar to eumenine mastoparan-AF (EMP-AF), a mast cell degranulating peptide from a solitary eumenine wasp. These sequences have the characteristic features of linear cationic cytolytic peptides; rich in hydrophobic and basic amino acids with no disulfide bond, and accordingly, they can be predicted to adopt an amphipathic α-helix secondary structure. In fact, the CD (circular dichroism) spectra of these peptides showed significant α-helical conformation content in the presence of TFE (trifluoroethanol), SDS (sodium dodecylsulfate) and asolectin vesicles. In the biological evaluation, all the peptides exhibited a significant broad-spectrum antimicrobial activity, and moderate mast cell degranulation and leishmanicidal activities, but showed virtually no hemolytic activity. © 2011 Elsevier Ltd.

Trypanosoma cruzi: Evaluation of (-)-cubebin derivatives activity in the messenger RNAs processing

No fully effective treatment has been developed since the discovery of Chagas' disease. Since drug-resistant Trypanosoma cruzi strains are occurring and the current therapy is effective in the acute phase but with various adverse side effects, more studies are needed to characterize the susceptibility of T. cruzi to new drugs. Pre-mRNA maturation in trypanosomatids occurs through a process called trans-splicing, which is unusual RNA processing reaction, and it implies the processing of polycistronic transcription units into individual mRNAs; a short transcript spliced leader (SL RNA) is trans-spliced to the acceptor pre-mRNA, giving origin to the mature mRNA. Cubebin derivatives seem to provide treatments with less collateral effects than benznidazole and showed similar or better trypanocidal activities than benznidazole. Therefore, the cubebin derivatives ((-)-6,6′-dinitrohinokinin (DNH) and (-)-hinokinin (HQ)) interference in the mRNA processing was evaluated using T. cruzi permeable cells (Y and BOL (Bolivia) strains) following by RNase protection reaction. These substances seem to intervene in any step of the RNA transcription, promoting alterations in the RNA synthesis, even though the RNA processing mechanism still occurs. Furthermore, HQ presented better activity against the parasites than DNH, meaning that BOL strain seems to be more resistant than Y. © 2011 Springer-Verlag.

American visceral leishmaniasis: Factors associated with lethality in the state of São Paulo, Brazil

Objectives. To identify factors associated with death in visceral leishmaniasis (VL) cases. Patients and Methodology. We evaluated prognostic factors for death from VL in São Paulo state, Brazil, from 1999 to 2005. A prognostic study nested in a clinical cohort was carried out by data analysis of 376 medical files. A comparison between VL fatal cases and survivors was performed for clinical, laboratory, and biological features. Association between variables and death was assessed by univariate analysis, and the multiple logistic regression model was used to determine adjusted odds ratio for death, controlling confounding factors. Results. Data analysis identified 53 fatal cases out of 376 patients, between 1999 and 2005 in São Paulo state. Lethality was 14.1 (53/376), being higher in patients older than fifty years. The main causes of death were sepsis, bleeding, liver failure, and cardiotoxicity due to treatment. Variables significantly associated with death were severe anemia, bleeding, heart failure, jaundice, diarrhea, fever for more than sixty days, age older than fifty years, and antibiotic use. Conclusion. Educational health measures are needed for the general population and continuing education programs for health professionals working in the affected areas with the purpose of identifying and treating early cases, thus preventing the disease evolution towards death. © 2012 Geraldine Madalosso et al.

Synthesis, cytotoxicity and in vitro antileishmanial activity of naphthothiazoles

The leishmaniasis is a spectral disease caused by the protozoan Leishmania spp., which threatens millions of people worldwide. Current treatments exhibit high toxicity, and there is no vaccine available. The need for new lead compounds with leishmanicidal activity is urgent. Considering that many lead leishmanicidal compounds contain a quinoidal scaffold and the thiazole heterocyclic ring is found in a number of antimicrobial drugs, we proposed a hybridization approach to generate a diverse set of semi-synthetic heterocycles with antileishmanial activity. We found that almost all synthesized compounds demonstrated potent activity against promastigotes of Leishmania (Viannia) braziliensis and reduced the survival index of Leishmania amastigotes in mammalian macrophages. Furthermore, the compounds were not cytotoxic to macrophages at fivefold higher concentrations than the EC50 for promastigotes. All molecules fulfilled Lipinski's Rule of Five, which predicts efficient orally absorption and permeation through biological membranes, the in silico pharmacokinetic profile confirmed these characteristics. The potent and selective activity of semi-synthetic naphthothiazoles against promastigotes and amastigotes reveals that the 2-amino-naphthothiazole ring may represent a scaffold for the design of compounds with leishmanicidal properties and encourage the development of drug formulation and new compounds for further studies in vivo. © 2013 John Wiley & Sons A/S.