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The search for new therapeutic strategies for leishmaniasis treatment is essential due to the side effects of available drugs and the increasing incidence of resistance to them. Marine sponges use chemical compounds as a defense mechanism, and several of them present interesting pharmacological properties. The aim of this study was to evaluate the in vitro activity of the aqueous extract of the marine sponge Dercitus (Stoeba) latex against Leishmania amazonensis. MIC and toxicity against mammal cells were evaluated through broth microdilution assays. Transmission electron microscopy analysis was performed to assess possible effects on L. amazonensis ultrastructure. Arginase and proteolytic activities were measured by spectrometric methodologies. The extract of Dercitus (Stoeba) latex displayed antileishmanial activity and moderate toxicity against peritonial macrophages. Ultrastructural changes were observed after the growth of L. amazonensis promastigotes in the presence of the extract at 150 µg.ml-1 (IC50), mainly on acidocalcysomes. The extract was able to inhibit the activity of arginase and serine proteases. This study shows that Dercitus (Stoeba) latex aqueous extract may be a novel potential source of protozoa protease inhibitors and drugs that are less toxic to be used in the treatment of L. amazonensis infections.

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Several research groups have explored the repositioning of human immunodeficiency virus aspartyl peptidase inhibitors (HIV-PIs) on opportunistic infections caused by bacteria, fungi and protozoa. In Trypanosoma cruzi, HIV-PIs have a high impact on parasite viability, and one of the main alterations promoted by this treatment is the imbalance in the parasite's lipid metabolism. However, the reasons behind this phenomenon are unknown. In the present work, we observed by transmission electron microscopy (TEM) that the treatment of T. cruzi epimastigotes with the HIV-PIs lopinavir and nelfinavir induced a huge accumulation of crystalloid-shaped lipids within the reservosomes, most of them deforming these key organelles. As previously reported, those structures are characteristic of lipid inclusions formed mostly of cholesterol and cholesterol-esters. The fractionation of nontreated epimastigotes generated two distinct fractions enriched in reservosomes: one mostly composed of lipid inclusion-containing reservosomes (Fraction B1) and one where lipid inclusions were much less abundant (Fraction B2). Interestingly, the extract of Fraction B2 presented enzymatic activity related to aspartyl-type peptidases 3.5 times higher than that found in the extract obtained from Fraction B1. The cleavage of cathepsin D substrate by this class of peptidases was strongly impaired by pepstatin A, a prototypical aspartyl PI, and the HIV-PIs lopinavir and nelfinavir. In addition, both HIV-PIs also inhibited (to a lesser extent) the cruzipain activity present in reservosomes. Finally, our work provides new evidence concerning the presence and supposed participation of aspartyl peptidases in T. cruzi, even as it adds new information about the mechanisms behind the alterations promoted by lopinavir and nelfinavir in the protozoan.

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In the protozoan pathogen Leishmania, endocytosis, and exocytosis occur mainly in the small area of the flagellar pocket membrane, which makes this parasite an interesting model of strikingly polarized internalization and secretion. Moreover, little is known about vesicle recognition and fusion mechanisms, which are essential for both endo/exocytosis in this parasite. In other cell types, vesicle fusion events require the activity of phospholipase A2 (PLA2), including Ca2+-independent iPLA2 and soluble, Ca2+-dependent sPLA2. Here, we studied the role of bromoenol lactone (BEL) inhibition of endo/exocytosis in promastigotes of Leishmania amazonensis. PLA2 activities were assayed in intact parasites, in whole conditioned media, and in soluble and extracellular vesicles (EVs) conditioned media fractions. BEL did not affect the viability of promastigotes, but reduced the differentiation into metacyclic forms. Intact parasites and EVs had BEL-sensitive iPLA2 activity. BEL treatment reduced total EVs secretion, as evidenced by reduced total protein concentration, as well as its size distribution and vesicles in the flagellar pocket of treated parasites as observed by TEM. Membrane proteins, such as acid phosphatases and GP63, became concentrated in the cytoplasm, mainly in multivesicular tubules of the endocytic pathway. BEL also prevented the endocytosis of BSA, transferrin and ConA, with the accumulation of these markers in the flagellar pocket. These results suggested that the activity inhibited by BEL, which is one of the irreversible inhibitors of iPLA2, is required for both endocytosis and exocytosis in promastigotes of L. amazonensis.

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Capping and shedding of ectodomains in Trypanosoma cruzi may be triggered by different ligands. Here, we analysed the mobility and shedding of cell surface components of living trypomastigotes of the Y strain and the CL Brener clone in the presence of poly-L-lysine, cationized ferritin (CF) and Concanavalin A (Con A). Poly-L-lysine and CF caused intense shedding in Y strain parasites. Shedding was less intense in CL Brener trypomastigotes, and approximately 10% of these parasites did not show any decrease in poly L-lysine or CF labelling. Binding of Con A induced low-intensity shedding in Y strain and redistribution of Con A-binding sites in CL Brener parasites. Trypomastigotes of the Y strain showed intense labelling with anti-〈-galactosyl antibodies, resulting in the lysis of approximately 30% of their population, in contrast with what was observed in CL Brener parasites. Incubation with Con A and CF protected trypomastigotes of the Y strain from lysis by anti-αGal. The last treatment did not interfere with the survival of the CL Brener parasites. This study corroborates with the idea that a ligand can differentially modulate the cell surface of T. cruzi, depending on the strain used, resulting in variable immune system responses and recognition by host cells.

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Lipoprotein lipase (LPL) mRNA expression in chronic lymphocytic leukaemia (CLL) is associated with an unmutated immunoglobulin profile and poor clinical outcome. We evaluated the subcellular localization of LPL protein in CLL cells that did or did not express LPL mRNA. Our results show that LPL protein is differently located in CLL cells depending on whether it is incorporated from the extracellular medium in mutated CLL or generated de novo by leukaemic cells of unmutated patients. The specific quantification of endogenous LPL protein correlates with mRNA expression levels and mutational IGHV status, suggesting LPL protein as a possible reliable prognostic marker in CLL.

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Leishmaniases is a tropical disease caused by protozoa of the genus Leishmania for which the current treatment is expensive, besides increasing reports of parasite resistance. This study investigated the anti-Leishmania amazonensis activity of the essential oil from Aloysia gratissima (AgEO) and guaiol, the major sesquiterpene constituent in the oil. Our results showed that AgEO killed promastigotes and intracellular amastigotes at an IC50 of 25 and 0·16 µg mL-1, respectively, while guaiol killed amastigotes at an IC50 of 0·01 µg mL-1. Both AgEO and guaiol were safe for macrophages up to 100 µg mL-1, as evaluated by the dehydrogenase activity, membrane integrity and phagocytic capacity. AgEO and guaiol did not induce nitrite oxide (NO) in resting macrophages and inhibited the production of NO in lipopolysaccharide-stimulated macrophages. The ultrastructural analysis suggested that AgEO and guaiol act directly on parasites, affecting promastigotes kinetoplast, mitochondrial matrix and plasma membrane. Together, these results pointed out that AgEO and guaiol could be promising candidates to develop anti-Leishmania drugs.

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Triatoma infestans is a mandatory haematophagous vector of Chagas disease in Brazil. Despite a large number of studies on the anti-haemostatic molecules present in its saliva, the role of its salivary components on parasite transmission is poorly understood. Here, we show that the bioactive lipid molecule, lysophosphatidylcholine (LPC), is present in the salivary gland of T. infestans. We characterized the lipid profiles of each unit of the T. infestans salivary gland. We noticed that LPC is present in the three units of the salivary gland and that the insect feeding state does not influence its proportion. T. infestans saliva and LPC can enhance T. cruzi transmission to mice by dramatically altering the profile of inflammatory cells at the site of inoculation on mouse skin, facilitating the transmission of T. cruzi to the vertebrate host. Consequently, the mortality curves of either saliva- or LPC-injected mice display significant higher mortality rates than the control. Altogether, these results implicate LPC as one of key salivary molecule involved in Chagas disease transmission.

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Hyicin 4244 is a small antimicrobial peptide with a broad spectrum of activity that was found in the culture supernatant of Staphylococcus hyicus 4244, the genome of which was then sequenced. The bacteriocin gene cluster (hyiSABCDEFG) was mined from its single chromosome and exhibited a genetic organization similar to that of subtilosin A. All genes involved in hyicin 4244 biosynthesis proved to be transcribed and encode proteins that share at least 42% similarity to proteins encoded by the subtilosin A gene cluster. Due to its resemblance to subtilosin A and the presence of three thioether bonds in its structure, hyicin 4244 is assumed to be a 35-amino acid circular sactibiotic, the first to be described in staphylococci. Hyicin 4244 inhibited 14 staphylococcal isolates from either human infections or bovine mastitis, all biofilm formers. Hyicin 4244 significantly reduced the number of colony-forming units (CFU) and the biofilm formation by two strong biofilm-forming strains randomly chosen as representatives of the strains involved in human infections and bovine mastitis. It also reduced the proliferation and viability of sessile cells in established biofilms. Therefore, hyicin 4244 proved not only to prevent biofilm formation by planktonic cells, but also to penetrate the biofilm matrix in vitro, exerting bactericidal activity against staphylococcal sessile cells. This bacteriocin has the potential to become an alternative antimicrobial for either prevention or treatment of biofilm-related infections caused by different staphylococcal species.

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Couroupita guianensis is known in Brazil as 'Abricó-de-Macaco' and it has some attributes such as: antihypertensive, analgesic and anti-inflammatory activities. This study evaluated the antimicrobial activity of ethanolic extract and fractions of C. guianensis flowers and isolation of bioactive component. These extracts and fractions were subjected to agar diffusion, MIC, TLC and bioautography to bacteria, filamentous fungi and yeasts. Among the fractions of EtOH extract, the DCM fraction was the most active, particularly against Methicillin-resistant Staphylococcus aureus (MRSA) with MIC of 156 µg/mL. The active compound in this fraction was identified as Tryptanthrin, which showed promising antibacterial activity for MRSA showing MIC of 62.5 µg/mL. Ultrastructural analysis of MRSA incubated in the presence of Tryptanthrin by transmission electron microscope showed significant alterations in the cellular structure. Cytotoxicity tests demonstrated that DCM fraction and Tryptanthrin showed low toxicity, which makes it a promising candidate for alternative therapies to control and combat diseases.

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Leishmania (Leishmania) infantum chagasi is one of the agents that cause visceral leishmaniasis. This disease occurs more frequently in third world countries, such as Brazil. The treatment is arduous, and is dependent on just a few drugs like the antimonial derivatives and amphotericin B. Moreover, these drugs are not only expensive, but they can also cause severe side effects and require long-term treatment. Therefore, it is very important to find new compounds that are effective against leishmaniasis. In the present work we evaluated a new group of synthetic amides against the promastigote and amastigote forms of L. infantum chagasi. The results showed that one of these amides in particular, presented very effective activity against the promastigotes and amastigotes of L. infantum chagasi at low concentrations and it also presented low toxicity for mammal cells, which makes this synthetic amide a promising drug for combating leishmaniasis.

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