The leishmaniases are severe parasitic diseases that occur worldwide, caused by protozoa of the genus Leishmania. Studies with medicinal plants can lead to a range of possibilities for treating and improving the patients' quality of life. Research on Azadirachta indica fractions and extracts has shown that they have excellent anti-leishmanial activity based on bioactivity-guided fractionation of ethanolic extracts of leaves and seeds and in vitro activity against promastigotes. In this research the most efficient extracts and fractions were selected for tests on intracellular amastigotes of Leishmania amazonensis. The ethanolic extract of the leaves and dichloromethane and chloroform fractions had IC50 values of 38, 3.9 and 1.2 μg/mL for promastigotes and 9.8, 1.1 and 0.6 μg/mL for amastigotes, respectively, at 72 hours. For the ethanolic extract and dichloromethane fraction from nut tegument, the IC50 was 2.7 and 2.1 μg/mL for promastigotes and 0.4 and 0.6 μg/mL for amastigotes. The cytotoxicity of the fractions presented selectivity that was between 8 to 32 times more toxic to promastigotes and 15 to 72 times to amastigotes than to macrophages. The extracts and fractions from leaves and fruits were more effective against amastigotes, and the fractionation increased activity against both promastigotes and amastigotes, enabling us to obtain potentially active fractions with low toxicity.

RNAs não codificadores (ncRNAs) têm sido recentemente objeto de atenção muito maior devido aos avanços técnicos no sequenciamento que expandiram a caracterização dos transcritomas em diferentes organismos. ncRNAs possuem diferentes comprimentos (22 nt a >1.000 nt) e mecanismos de ação que essencialmente compreendem uma sofisticada rede de regulação de expressão gênica. A publicação recente dos genomas e transcritomas dos esquistossomos aumentou a descrição e caracterização de um grande número de genes do parasita. Aqui nós revisamos o número de genes preditos e a cobertura das bases do genoma em face dos ESTs públicos disponíveis, incluindo uma avaliação crítica da evidência e caracterização de ncRNAs em esquistossomos. Nós mostramos dados de expressão de ncRNAs em Schistosoma mansoni. Nós analisamos três conjuntos diferentes de dados de experimentos com microarranjos: (1) medidas de expressão em larga escala de vermes adultos; (2) genes diferencialmente expressos de S. mansoni regulados por uma citocina humana (TNF-α) no parasita em cultura; e (3) expressão estágio-especifica de ncRNAs. Todos estes dados apontam para ncRNAs envolvidos em diferentes processos biológicos e respostas fisiológicas que sugerem funcionalidade destes novos personagens na biologia do parasita. Explorar este mundo é um desafio para os cientistas sob uma nova perspectiva molecular da interação parasita-hospedeiro e do desenvolvimento do parasita.

Non-coding RNAs (ncRNAs) were recently given much higher attention due to technical advances in sequencing which expanded the characterization of transcriptomes in different organisms. ncRNAs have different lengths (22 nt to >1, 000 nt) and mechanisms of action that essentially comprise a sophisticated gene expression regulation network. Recent publication of schistosome genomes and transcriptomes has increased the description and characterization of a large number of parasite genes. Here we review the number of predicted genes and the coverage of genomic bases in face of the public ESTs dataset available, including a critical appraisal of the evidence and characterization of ncRNAs in schistosomes. We show expression data for ncRNAs in Schistosoma mansoni. We analyze three different microarray experiment datasets: (1) adult worms' large-scale expression measurements; (2) differentially expressed S. mansoni genes regulated by a human cytokine (TNF-α) in a parasite culture; and (3) a stage-specific expression of ncRNAs. All these data point to ncRNAs involved in different biological processes and physiological responses that suggest functionality of these new players in the parasite's biology. Exploring this world is a challenge for the scientists under a new molecular perspective of host-parasite interactions and parasite development.

It has been shown previously that the laticifer fluid of Calotropis procera (Ait.) R.Br. is highly toxic to the egg hatching and larval development of Aedes aegypti L. In the present study, the larvicidal potential of other laticifer fluids obtained from Cryptostegia grandiflora R.Br., Plumeria rubra L. and Euphorbia tirucalli L. was evaluated. We attempted to correlate larvicidal activity with the presence of endogenous proteolytic activity in the protein fraction of the fluids. After collection, the fluids were processed by centrifugation and dialysis to obtain the soluble laticifer protein (LP) fractions and eliminate water insoluble and low molecular mass molecules. LP did not visibly affect egg hatching at the doses assayed. LP from Cr. grandiflora exhibited the highest larval toxicity, while P. rubra was almost inactive. E. tirucalli was slightly active, but its activity could not be correlated to proteins since no protein was detected in the fluid. The larvicidal effects of LP from C. procera and Cr. grandiflora showed a significant relationship with the proteolytic activity of cysteine proteinases, which are present in both materials. A purified cysteine proteinase (papain) from the latex of Carica papaya (obtained from Sigma) was similarly effective, whereas trypsin and chymotrypsin (both serine proteinases) were ineffective. The results provide evidence for the involvement of cysteine proteinase activity in the larvicidal action of some laticifer fluids. C. procera is an invasive species found in areas infested with Ae. aegypti and thus could prove useful for combating mosquito proliferation. This is the first report to present evidence for the use of proteolytic enzymes as chemical agents to destroy Ae. aegypti larvae.