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Background: The drugs available for the treatment of Chagas disease are ineffective in its chronic phase and produce many adverse effects, making the search for new drugs an urgent medical need. Objective: This study aimed to design, synthesize, and evaluate the trypanocidal and cytotoxic profiles of new 4-nitroimidazole prototypes. Method: The new compounds were synthesized in overall yields ranging from 31-to 52% through the use of classical and reproducible methodologies. Their trypanocidal profile and cytotoxicity were assayed against trypomastigote forms of T. cruzi and mammalian macrophages, respectively. Results: The best trypanocidal activity was evidenced in compounds that present lipophilic and electronegative substituents, e.g. 4-chlorophenyl derivative (5), with an IC50 = 206.98 μM; Conclusion: The new benznidazole N-glycinyl-hydrazone analogues demonstrated a very significant reduction in the trypanocidal activity compared to benznidazole, which seems to be related to the position occupied by the nitro group in the imidazole ring.

Background: Near to 5-7 million people are infected with T. cruzi in the world, and about 10,000 people per year die of problems associated with this disease. Method: Herein, the synthesis, antitrypanosomal and antimycobacterial activities of seventeen coumarinic N-acylhydrazonic derivatives have been reported. Results: These compounds were synthesized using methodology with reactions global yields ranging from 46%-70%. T. cruzi in vitro effects were evaluated against trypomastigote and amastigote, forming M. tuberculosis activity towards H37Rv sensitive strain and resistant strains. Discussion: Against T. cruzi, the more active compounds revealed only moderate activity IC50/96h~20 μM for both trypomastigotes and amastigotes intracellular forms. (E)-2-oxo-N'- (3,4,5-trimethoxybenzylidene)-2H-chromene-3-carbohydrazide showed meaningful activity in INH resistant/RIP resistant strain. Conclusion: These compound acting as multitarget could be good leads for the development of new trypanocidal and bactericidal agents.

Ortho-Quinones represent a special class of redox active compounds associated with a spectrum of pronounced biological activities, including selective cytotoxicity and antimicrobial actions. The modification of the quinone ring by simple nitrogen and sulphur substitutions leads to several new classes of compounds with their own, distinct redox behaviour and equally distinct activities against cancer cell lines and Trypanosoma cruzi. Some of the compounds investigated show activity against T. cruzi at concentrations of 24.3 and 65.6 μM with a selectivity index of around 1. These results demonstrate that simple chemical modifications on the ortho-quinone ring system, in particular, by heteroatoms such as nitrogen and sulphur, transform these simple redox molecules into powerful cytotoxic agents with considerable “potential”, not only in synthesis and electrochemistry, but also, in a broader sense, in health sciences.

Chagas disease is a neglected illness endemic in Latin America that mainly affects rural populations. The etiological agent of Chagas disease is the protozoan Trypanosoma cruzi, which has three different parasite stages and a dixenous life cycle that includes colonization of the vertebrate and invertebrate hosts. During its life cycle, T. cruzi is subjected to stress conditions, including variations in nutrient availability and pH, which impact parasite survival and differentiation. The plasticity of mitochondrial function in trypanosomatids has been defined as mitochondrial activity related to substrate availability. Thus, mitochondrial remodeling and autophagy, which is a constitutive cellular process of turnover and recycling of cellular components, may constitute a response to the nutritional and pH stress in the host. To assess these processes, epimastigotes were subjected to acidic, alkaline, and nutritional stress conditions, and mitochondrial function and its influence on the autophagic process were evaluated. Our data demonstrated that the three stress conditions affected the mitochondrial structure, inducing organelle swelling and impaired oxidative phosphorylation. Stressed epimastigotes produced increased ROS levels and overexpressed antioxidant enzymes. The stress conditions resulted in an increase in the number of autophagosomes and exacerbated the expression of different autophagy-related genes (Atgs). A correlation between mitochondrial dysfunction and autophagic phenotypes was also observed. After 24 h, acid stress and nutritional deprivation induced metacyclogenesis phenotypes (mitochondrial remodeling and autophagy). On the other hand, alkaline stress was transient due to insect blood feeding and culminated in an increase in autophagic flux as a survival mechanism.

BACKGROUND Chagas disease, which is caused by the protozoan Trypanosoma cruzi, is endemic to Latin America and mainly affects low-income populations. Chemotherapy is based on two nitrocompounds, but their reduced efficacy encourages the continuous search for alternative drugs. Our group has characterised the trypanocidal effect of naphthoquinones and their derivatives, with naphthoimidazoles derived from β-lapachone (N1, N2 and N3) being the most active in vitro. OBJECTIVES In the present work, the effects of N1, N2 and N3 on acutely infected mice were investigated. METHODS in vivo activity of the compounds was assessed by parasitological, biochemical, histopathological, immunophenotypical, electrocardiographic (ECG) and behavioral analyses. FINDINGS Naphthoimidazoles led to a decrease in parasitaemia (8 dpi) by reducing the number of bloodstream trypomastigotes by 25-50% but not by reducing mortality. N1 protected mice from heart injury (15 dpi) by decreasing inflammation. Bradycardia was also partially reversed after treatment with N1 and N2. Furthermore, the three compounds did not reverse hepatic and renal lesions or promote the improvement of other evaluated parameters. MAIN CONCLUSION N1 showed moderate trypanocidal and promising immunomodulatory activities, and its use in combination with benznidazole and/or anti-arrhythmic drugs as well as the efficacy of its alternative formulations must be investigated in the near future.

In this paper, we describe the synthesis and the action against of the trypomastigote form of Trypanosoma cruzi of a new class of nitroimidazole-2-carbaldehyde O-benzyloximes. These derivatives were designed through the application of molecular hybridization concept between two potent antiprotozoal compounds, the 5-nitrothiophene-2-carbaldehyde O-oxime 6 and the trypanocidal piperidinyl-4-carbaldehyde O-benzyloxime 7 with the intention of reaching two distinct molecular targets of T. cruzi. The activity of these benzyl ether derivatives was tested against the infective trypomastigote forms of T. cruzi, and the derivative (E)-1-methyl-5-nitro-1H-imidazole-2-carbaldehyde O-(4-nitrobenzyl) oxime (1) presented moderate trypanocidal activity (IC50 = 12.7 μM) when compared with the standard drug benznidazole, which showed to be a good starting point for the design of more effective trypanocide agents.

Chagas disease, caused by Trypanosoma cruzi, stands out due to its socio- economic effects on low-income tropical populations. This disease affects millions of people worldwide. The current chemotherapy for it is based on benznidazole (Bz) and nifurtimox (Nif) and is unsatisfactory. In this review, we will focus on the search for potential target organelles and molecules for the chemotherapy of Chagas disease. We consider as potential target organelles those that are absent or significantly different in host cells and present in the clinically relevant forms of the parasite (trypomastigotes and amastigotes), which are the mitochondrion, cytoskeletal- related structures, the acidocalcisomes/contractile vacuole complex and glycosomes. Most molecular targets are key enzymes involved in processes that are essential to parasite survival, such as sterol biosynthesis, antioxidant defences and bioenergetic pathways. Among the molecular targets, enzymes of the sterol pathway, particularly C14α-sterol demethylase, are still the most promising target, even if clinical trials with posaconazole and E1224 have failed to sustain efficacy. We believe that in the near future, the Chagas community will have a “clear shot” at new drug candidates for Chagas disease based on the accumulated knowledge about trypanosomatid biochemistry, preclinical studies, advances in screening technologies, the efforts of medicinal chemists in the synthesis of both azolic and non-azolic inhibitors, and the interest of pharmaceutical companies in the development of new antifungal agents, which form a critical mass of information.

Phenazinic ligands and Ru(II)-based complexes were synthesized from natural products lapachol and lawsone and evaluated against T. cruzi, the etiological agent of Chagas disease. These new ruthenium compounds could provide promising trypanocidal drugs. Besides synthesis and trypanocidal activity, this paper reports photophysical features and computational details of the compounds. The fluorescent trypanocidal substances are promising derivatives for further studies aiming to find molecules active against parasites associated with neglected diseases.

The current treatment of Chagas disease is based on the use of two drugs, nifurtimox (Nfx) and benznidazole (Bnz), both of which present limited efficacy in the chronic stage of the disease and toxic side effects. Thus, the discovery of novel compounds is urgently required. Herein, we report the successful synthesis of 4-nitroimidazole analogs of Bnz via nucleophilic aromatic substitution or cycloaddition reactions. The analogs were biologically evaluated, and compound 4 (4-cyclopropyl-1-(1-methyl-4-nitro1H-imidazole-5-yl)-1H-1,2,3-triazole) was identified as the most potent against both the trypomastigote (IC50 ¼ 5.4 mM) and amastigote (IC50 ¼ 12.0 mM) forms of T. cruzi, showing activity in the same range as Bnz (IC50 ¼ 8.8 and 8.7 mM, respectively). The cytotoxic and genotoxic activities of compounds 5, 4 and 11 were assessed. These three compounds were cytotoxic and genotoxic to RAW and HepG2 cells and mutagenic to Salmonella enterica strains. However, 4 exhibited toxic effects only at concentrations higher than those needed for trypanocidal activity. Molecular docking of 4 showed the importance of the size and p-p interactions between the nitroimidazole and the cofactor (flavin mononucleotide) of T.cruzinitroreductase (TcNTR). Moreover, the residues His503 and Tyr545 are relevant for binding to TcNTR. Our design strategy was capable of generating novel and active Bnz analogs.

BACKGROUND Only benznidazole (Bnz) (1) and nifurtimox (Nfx) (2) are licensed for the treatment of Chagas disease although their safety and efficacy profile are far from ideal. Farmanguinhos from Fiocruz has developed seven nitroimidazole compounds (4-10) analogs of megazol (3). OBJECTIVES To evaluate whether the genotoxic effect of 3 was abolished in the seven nitroimidazoles (4-10) analogs using the in vitro alkaline comet assay (CA) and the in vitro cytokinesis-block micronucleus assay (CBMN) in whole human blood cells (WHBC) and correlate this effect with their trypanocidal activity using bloodstream trypomastigote forms of Trypanosoma cruzi. METHODS The toxicity of 3-10 to WHBC in the in vitro CA was determined using the fluorescein diacetate/ethidium bromide assay. DNA damage in the in vitro CA was evaluated according to tail size in four classes (0-3) and methyl methane-sulfonate (MMS) was used as a positive control. The cytotoxicity of 3-10 to WHBC in the CBMN was measured using the cytokinesis-block proliferation index and the replication index. The number of the micronucleate cells in 2,000 binucleate cells by experimental group was determined. Mitomycin C and N-deacetyl-N-methylcolchicine were used as positive controls. FINDINGS Compound 3 showed a significant DNA strand break effect through the in vitro CA and highly significant clastogenic and/or aneugenic effect in the CBMN. Compounds 5, 6, 8, 9 and 10 showed negative results in the CBMN and positive results in the in vitro CA, while the inverse effect was observed for 4 and 7. MAIN CONCLUSIONS Compound 10 was the most promising to proceed with the development as a drug candidate in the treatment of Chagas disease showing absence of chromosomal cytogenetic damage and high activity against T. cruzi, about two times higher than 3 and the clinical drug 1.

Naphthoquinones are of key importance in organic synthesis and medicinal chemistry. In the last few years, various synthetic routes have been developed to prepare bioactive compounds derived or based on lapachones. In this sense, this review is mainly focused on the synthetic aspects and strategies used for the design of these compounds on the basis of their biological activities for the development of drugs against the neglected diseases leishmaniases and Chagas disease and also cancer. Three strategies used to develop bioactive quinones are discussed and categorized: (i) C-ring modification, (ii) redox centre modification and (iii) A-ring modification. Framed within these strategies for the development of naphthoquinoidal compounds against T. cruzi. Leishmania and cancer, reactions including copper-catalyzed azide-alkyne cycloaddition (click chemistry), palladium-catalysed cross couplings, C-H activation reactions, Ullmann couplings and heterocyclisations reported up to July 2019 will be discussed. The aim of derivatisation is the generation of novel molecules that can potentially inhibit cellular organelles/processes, generate reactive oxygen species and increase lipophilicity to enhance penetration through the plasma membrane. Modified lapachones have emerged as promising prototypes for the development of drugs against leishmaniases, Chagas disease and cancer.

Background:: Although several research efforts have been made worldwide to discover novel drug candidates for the treatment of Chagas disease, the nitroimidazole drug benznidazol remains the only therapeutic alternative in the control of this disease. However, this drug presents reduced efficacy in the chronic form of the disease and limited safety after long periods of administration, making it necessary to search for new, more potent and safe prototypes. Objective:: We described herein the synthesis and the trypanocidalaction of new functionalized carbohydrazonamides (2-10) against trypomastigote forms of Trypanosoma cruzi. Methods: These compounds were designed through the application of molecular hybridization concept between two potent anti-T. cruzi prototypes, the nitroimidazole derivative megazol (1) and the cinnamyl N-acylhydrazone derivative (14) which have been shown to be twice as potent in vitro as benznidazole. Results:: The most active compounds were the (Z)-N'-((E)-3-(4-nitrophenyl)-acryloyl)-1-methyl-5- nitro-1H-imidazol-2-carbohydrazonamide (6) (IC50=9.50 μM) and the (Z)-N'-((E)-3-(4- hydroxyphe-nyl)-acryloyl)-1-methyl-5-nitro-1H-imidazol-2-carbohydrazonamide (8) (IC50=12.85 μM), which were almost equipotent to benznidazole (IC50=10.26 μM) used as standard drug. The removal of the amine group attached to the imine subunit in the corresponding N-acylhydrazone derivatives (11-13) resulted in less potent or inactive compounds. The para-hydroxyphenyl derivative (8) presented also a good selectivity index (SI = 32.94) when tested against mammalian cells from Swiss mice. Conclusion:: The promising trypanocidal profile of new carbohydrazonamide derivatives (6) and (8) was characterized. These compounds have proved to be a good starting point for the design of more effective trypanocidal drug candidates.

In this review, we intend to provide a general view of the evolution of experimental studies in the area of chemotherapy for Chagas disease. We can follow the process of drug development through three phases. The first phase began almost at the same time as the discovery made by Carlos Chagas and proceeds to 1970, during which time an extensive list of compounds was subjected to preclinical and clinical trials. The second phase began with the introduction of nifurtimox and benznidazole into the clinical setting, followed with the search for alternative drugs. In this phase, a dichotomy existed between rational and empirical approaches in preclinical studies. The third phase began with the unravelling of the T. cruzi genome. The development of transgenic parasites has allowed the development of solid HTS protocols, and the establishment of bioluminescent T. cruzi has allowed in vivo drug evaluations using a reduced number of animals. Among the wide variety of compounds subjected to preclinical studies, we have discovered azolic and non-azolic inhibitors of sterol C14α-demethylase (CYP51) and nitro compounds. Two compounds evaluated during the second phase, namely, MK-436 and allopurinol, could be revisited. Clinical studies of posaconazole and E1224 yielded disappointing results, and it is critical to understand the reason for their failure as a monotherapy. Currently, the combination and repositioning of drugs with different mechanisms of action are complementary approaches. The use of drug combinations, particularly those of nitro compounds with CYP51 inhibitors, is considered a real alternative for the treatment of Chagas disease.

Quinonoid compounds based on 5-iodo-1,4-disubstituted-, 1,4- and 1,5-disubstituted-1,2,3-triazoles were synthesized using simple methodologies and evaluated against T. cruzi, the etiological agent of Chagas disease, and cancer cell lines PC3, HCT-116, HL-60, MDA-MB-435 and SF-295. The cytotoxic potential of the lapachones was also assayed against peripheral blood mononuclear cells (PBMC). Two compounds 6 and 12 were identified as potential hits against T. cruzi. β-Lapachone-based 1,5-disubstituted-1,2,3-triazole (12) displayed an IC50/24 h = 125.1 μM, similar to benznidazole, the standard drug. Compound 12 was also more active than the precursor β-lapachone against the cancer cell lines. These compounds acting as multitarget quinoidal systems could provide promising new leads for the development of trypanocidal and/or anticancer drugs.

Background: Approximately, 5-7 million people are infected with T. cruzi in the world, and approximately 10,000 people per year die of complications linked to this disease. Method: This work describes the construction of a new family of hidrazonoyl substituted derivatives, structurally designed exploring the molecular hybridization between megazol and nitrofurazone. Results and Discussion: The compounds were evaluated for their in vitro activity against bloodstream trypomastigotes of Trypanosoma cruzi, etiological agent of Chagas disease, and for their potential toxicity to mammalian cells. Conclusion: Among these hydrazonoyl derivatives, we identified the derivative (4) that showed trypanocidal activity (IC50/24 h = 15.0 µM) similar to Bz, the standard drug, and low toxicity to mammalian cells, reaching an SI value of 18.7.

We report herein a straightforward and efficient one-step reaction to prepare new nor-β-lapachone derivatives tethered with phenylthio groups at position 3 of the furan ring. We have screened the compounds on bloodstream trypomastigotes of Trypanosoma cruzi, the causative agent of Chagas disease, aimed at finding a new prototype with high trypanocidal activity. The new compounds possess a broad range of activity (IC50/24h from 9.2 to 182.7 μM), higher than the original quinone (391.5 μM) and four of them higher than standard drug benznidazole (103.6 μM). The most active was compound 13b (9.2 μM), being 11 times active than benznidazole and the less toxic derivative to heart muscle cells.

Nitroimidazoles exhibit high microbicidal activity, but mutagenic, genotoxic and cytotoxic properties have been attributed to the presence of the nitro group. However, we synthesised nitroimidazoles with activity against the trypomastigotes of Trypanosoma cruzi, but that were not genotoxic. Herein, nitroimidazoles (11-19) bearing different substituent groups were investigated for their potential induction of genotoxicity (comet assay) and mutagenicity (Salmonella/Microsome assay) and the correlations of these effects with their trypanocidal effect and with megazol were investigated. The compounds were designed to analyse the role played by the position of the nitro group in the imidazole nucleus (C-4 or C-5) and the presence of oxidisable groups at N-1 as an anion receptor group and the role of a methyl group at C-2. Nitroimidazoles bearing NO2 at C-4 and CH3 at C-2 were not genotoxic compared to those bearing NO 2 at C-5. However, when there was a CH3 at C-2, the position of the NO2 group had no influence on the genotoxic activity. Fluorinated compounds exhibited higher genotoxicity regardless of the presence of CH3 at C-2 or NO2 at C-4 or C-5. However, in compounds 11 (2-CH3; 4-NO2; N-CH2OHCH2Cl) and 12 (2-CH3; 4-NO2; N-CH2OHCH2F), the fluorine atom had no influence on genotoxicity. This study contributes to the future search for new and safer prototypes and provide.

In our continued search for novel trypanocidal compounds, arylamine, chalcone, triazolic, triazole– carbohydrate and chalcogenium derivatives containing a naphthoquinone scaffold were prepared; in addition to electrochemical studies, these compounds were evaluated against the infective bloodstream form of Trypanosoma cruzi, the etiological agent of Chagas disease. Among the thirty-eight compounds herein evaluated, six were found to be more potent against trypomastigotes than the standard drug benznidazole, with IC50/24 h values between 52.9 and 89.5 mM.

Thirty four halogen and selenium-containing quinones, synthesized by rhodium-catalyzed C-H bond activation and palladium-catalyzed cross-coupling reactions, were evaluated against bloodstream trypomastigotes of T. cruzi. We have identified fifteen compounds with IC50/24 h values of less than 2 μM. Electrochemical studies on A-ring functionalized naphthoquinones were also performed aiming to correlate redox properties with trypanocidal activity. For instance, (E)-5-styryl-1,4-naphthoquinone 59 and 5,8-diiodo-1,4-naphthoquinone 3, which are around fifty fold more active than the standard drug benznidazole, are potential derivatives for further investigation. These compounds represent powerful new agents useful in Chagas disease therapy.

The pathogenic trypanosomatidsTrypanosoma brucei,Trypanosoma cruzi, andLeishmaniaspp. are the causative agents of African trypanosomiasis, Chagas disease, and leishmaniasis, respectively. These diseases are considered to be neglected tropical illnesses that persist under conditions of poverty and are concentrated in impoverished populations in the developing world. Novel efficient and nontoxic drugs are urgently needed as substitutes for the currently limited chemotherapy. Trypanosomatids display a single mitochondrion with several peculiar features, such as the presence of different energetic and antioxidant enzymes and a specific arrangement of mitochondrial DNA (kinetoplast DNA). Due to mitochondrial differences between mammals and trypanosomatids, this organelle is an excellent candidate for drug intervention. Additionally, during trypanosomatids’ life cycle, the shape and functional plasticity of their single mitochondrion undergo profound alterations, reflecting adaptation to different environments. In an uncoupling situation, the organelle produces high amounts of reactive oxygen species. However, these species role in parasite biology is still controversial, involving parasite death, cell signalling, or even proliferation. Novel perspectives on trypanosomatid-targeting chemotherapy could be developed based on better comprehension of mitochondrial oxidative regulation processes.

Herein, we report the design, synthesis and trypanocidal activity of some novel trisubstituted imidazole derivatives. These heterocyclic derivatives were structurally planned by exploring the concept of molecular hybridisation between two arylhydrazones derived from megazol, which has potent trypanocidal activity. The trypanocidal activity of these triarylimidazole derivatives was evaluated against infective trypomastigote forms of T. cruzi and the derivative 2'-(4-bromophenyl)-1-methyl-5'-phenyl-1H,3'H-2,4'-biimidazol-3'-ol showed moderate biological activity (IC50 = 23.9 µM) when compared to benznidazole, a standard trypanocidal drug. These compounds did not present cytotoxic effects at concentrations near the trypanocidal IC50, being considered a good starting point for the development of new anti-Chagas drug candidates.

Until now, there has been neither an agreed-upon experimental model nor descriptors of the clinical symptoms that occur over the course of acute murine infection. The aim of this work is to use noninvasive methods to evaluate clinical signs in Swiss Webster mice that were experimentally infected with the Y strain of Trypanosoma cruzi during acute phase (Inf group). Infected mice showed evident clinical changes beginning in the second week of infection (wpi) when compared to the noninfected group (NI): (1) animals in hunched postures, closed eyes, lowered ears, peeling skin, increased piloerection, prostration, and social isolation; (2) significant decrease in body weight (Inf: 26.2 ± 2.6 g vs. NI: 34.2 ± 2.5 g) and in chow (1.5 ± 0.3 vs. 6.3 ± 0.5 mg) and water (2.4 ± 0.5 vs. 5.8 ± 0.7 ml) intake; (3) significant decrease of spontaneous activity as locomotor parameters: distance (0.64 ± 0.06 vs. 1.8 ± 0.13 m), velocity (1.9 ± 0.3 vs. 6.7 ± 1.5 cm/sec), and exploratory behavior by frequency (1.0 ± 0.5 vs. 5.7 ± 1.0 events) and duration (1.4 ± 0.3 vs. 5.1 ± 0.5 sec in central arena region); (4) significant increase in the PR (41.7 ± 8.7 vs. 27.6 ± 1.9 msec) and QT intervals (39.7 ± 2.0 vs. 27.5 ± 4.0 msec), and a decreased cardiac frequency (505 ± 52.8 vs. 774 ± 17.8 msec), showing a marked sinus bradycardia and an atrioventricular block. At 3 and 4 wpi, the surviving animals showed a tendency of recovery in body weight, food intake, locomotor activity, and exploratory interest. Through the use of noninvasive parameters, we were able to monitor the severity of the infection in individuals prior to death. Our perspective is the application of noninvasive methods to describe clinical signs over the course of acute infection complementing the preclinical evaluation of new agents, alone or in combination with benznidazole.

Trypanosoma cruzi infection has a large public health impact in Latin American countries. Although the transmission rates via blood transfusions and insect vectors have declined sharply in the past 20 years due to policies of the Southern Cone countries, a large number of people are still at risk for infection. Currently, no accepted experimental model or descriptions of the clinical signs that occur during the course of acute murine infection are available. The aim of this work was to use non-invasive methods to evaluate the clinical signs of Balb/c mice infected with the Y strain of T. cruzi. The infected mice displayed evident clinical changes beginning in the third week of infection. The mice were evaluated based on physical characteristics, spontaneous activity, exploratory behaviour and physiological alterations. We hope that the results presented in this report provide parameters that complement the effective monitoring of trypanocidal treatment and other interventions used to treat experimental Chagas disease.

The biological activities of the naphthoquinones lapachol and its cyclization product beta-lapachone, extracted from trees of the genus Tabebuia, have been intensively studied. Given continuity to the studies about heterocyclic derivatives obtained from the reaction of these naphtoquinones with amino-containing reagents, 22 derivatives of beta-lapachone, nor-beta-lapachone and lapachol were synthesised and their activities against trypomastigote forms of T. cruzi were evaluated. The compounds were grouped as oxazolic, imidazolic, phenoxazinic, indolic, pyranic and cyclopentenic derivatives. The variability of the new structures is based on the great electrophilicity of 1,2-quinoidal carbonyls towards reagents containing nitrogen or carbon as nucleophilic centres. In relation to the trypanocidal activity of the synthesised compounds, in view of their structural diversity, tendencies only could be verified. Among the cyclofunctionalised products the oxazolic and imidazolic derivatives showed +/- 1.5 to 34.8 times higher activity than crystal violet, the standard drug for the sterilization of stored blood. These results corroborate the tendency of trypanocidal activity in imidazolic skeletons, and indicate that this moiety could be used as a guide for architectural delineation of molecules with potential value for the chemotherapy of Chagas disease.

Chagas disease (CD), caused by the intracellular protozoan Trypanosoma cruzi, is a parasitic illness endemic in Latin America. In the centennial after CD discovery by Carlos Chagas (1909), although it still represents an important public health problem in these affected areas, the existing chemotherapy, based on benznidazole and nifurtimox (both introduced more than four decades ago), is far from being considered ideal due to substantial toxicity, variable effect on different parasite stocks and well-known poor activity on the chronic phase. CD is considered one of the major “neglected” diseases of the world, as commercial incentives are very limited to guarantee investments for developing and discovering novel drugs. In this context, our group has been pursuing, over the last years, the efficacy, selectivity, toxicity, cellular targets and mechanisms of action of new potential anti-T. cruzi candidates screened from an in-house compound library of different research groups in the area of medicinal chemistry. A brief review regarding these studies will be discussed, mainly related to the effect on T. cruzi of (i) diamidines and related compounds, (ii) natural naphthoquinone derivatives, and (iii) megazol derivatives.

32 páginas, 11 figuras, 1 tabla.-- et al., Autophagy is the degradative process by which eukaryotic cells digest their own components using acid hydrolases within the lysosome. Originally thought to function almost exclusively in providing starving cells with nutrients taken from their own cellular constituents, autophagy is in fact involved in numerous cellular events including differentiation, turnover of macromolecules and organelles, and defense against parasitic invaders. During the last 10-20 years, molecular components of the autophagic machinery have been discovered, revealing a complex interactome of proteins and lipids, which, in a concerted way, induce membrane formation to engulf cellular material and target it for lysosomal degradation. Here, our emphasis is autophagy in protists. We discuss experimental and genomic data indicating that the canonical autophagy machinery characterized in animals and fungi appeared prior to the radiation of major eukaryotic lineages. Moreover, we describe how comparative bioinformatics revealed that this canonical machinery has been subject to moderation, outright loss or elaboration on multiple occasions in protist lineages, most probably as a consequence of diverse lifestyle adaptations. We also review experimental studies illustrating how several pathogenic protists either utilize autophagy mechanisms or manipulate host-cell autophagy in order to establish or maintain infection within a host. The essentiality of autophagy for the pathogenicity of many parasites, and the unique features of some of the autophagy-related proteins involved, suggest possible new targets for drug discovery. Further studies of the molecular details of autophagy in protists will undoubtedly enhance our understanding of the diversity and complexity of this cellular phenomenon and the opportunities it offers as a drug target., The authors gratefully acknowledge the following organizations: A.B., M.G.L. and P.A.M.M. the ‘Fonds de la Recherche Scientifique’ (FRS-FNRS) and associated foundations (FRSM and FRIA) and the Belgian Interuniversity Attraction Poles- Federal Office for Scientific, Technical and Cultural Affairs for support of their research on autophagy in trypanosomes; M.L.G. the Royal Society for an University Research Fellowship; G.L. the Wellcome Trust for a Special Initiative grant (075820/A/04/Z) for support for ‘An integrated approach for the development of sustainable methods to control tropical theileriosis’; J.C.M. and G.H.C. the Medical Research Council for support (G0700127); M.N. the MICINN for support (SAF2009-07587); B.T. and V.S. the Slovenian Research Agency for research grants (P1-0140, J1-9520, J3-2258); S.L.d.C. and R.M.B. the Brazilian agencies CNPq and Faperj; M.I.C. and P.R. the ANPCYT (PICT 2005 # 38420) and Comisión Nacional Salud Investiga in Argentina for research grants; B.T. and V.S. would like to thank Vito Turk for valuable discussions.

The composition of a Brazilian green propolis ethanolic extract (Et-Bra) and its effect onTrypanosoma cruzitrypomastigotes and other pathogenic microorganisms have already been reported. Here, we further investigated Et-Bra targets inT. cruziand its effect on experimental infection of mice. The IC50/4 days for inhibition of amastigote proliferation was 8.5 ± 1.8 μg mL−1, with no damage to the host cells. In epimastigotes Et-Bra induced alterations in reservosomes, Golgi complex and mitochondrion. These effects were confirmed by flow cytometry analysis. In trypomastigotes, Et-Bra led to the loss of plasma membrane integrity. Thein vitrostudies indicate that Et-Bra interferes in the functionality of the plasma membrane in trypomastigotes and of reservosomes and mitochondrion in epimastigotes. Acutely infected mice were treated orally with Et-Bra and the parasitemia, mortality and GPT, GOT, CK and urea levels were monitored. The extract (25–300 mg kg−1body weight/day for 10 days) reduced the parasitemia, although not at significant levels; increased the survival of the animals and did not induce any hepatic, muscular lesion or renal toxicity. Since Et-Bra was not toxic to the animals, it could be assayed in combination with other drugs. Et-Bra could be a potential metacyclogenesis blocker, considering its effect on reservosomes, which are an important energy source during parasite differentiation.

Croton cajucara is a plant found in the Amazon region and is known for its medicinal properties. The effects of the methanolic extract of the stem bark of C. cajucara (MCC) and of the isolated terpenes, trans-dehydrocrotonin (t-DCTN) and acetyl aleuritolic acid (AAA), were investigated using four isolates of Trypanosoma cruzi. In assays with trypomastigotes, the extract was more active than the isolated compounds, presenting IC(50) in the range of 10 to 50 μg/mL. The trypanocidal effect of MCC, AAA and benznidazole was significantly higher in the GLT291 and C45 strains, which were recently isolated from wild animals. MCC and AAA caused a dose-dependent inhibition of epimastigote proliferation. In assays using intracellular amastigotes, AAA and MCC reduced the percent of infection and the endocytic index after 96 h of treatment, at concentrations that were non-toxic to the host cells. MCC inhibited the trypanothione reductase pathway in both epimastigotes and trypomastigotes of all the subpopulations. The absence of AAA activity on the trypanothione reductase pathway in epimastigotes of Dm28c suggests heterogeneity of the biochemical profile between this clone and the three strains. Epimastigotes and trypomastigotes (GLT291) were treated for 24 h with MCC or AAA, and both induced alterations of the plasma membrane, while AAA-treated epimastigotes also displayed mitochondrial damage.

In continuing our screening program of naphthoquinone activity against Trypanosoma cruzi, the aetiological agent of Chagas' disease, new beta-lapachone-based 1,2,3-triazoles, 3-arylamino-nor-beta-lapachones, 3-alkoxy-nor-beta-lapachones and imidazole anthraquinones were synthesised and evaluated against bloodstream trypomastigote forms of the parasite. Compounds 2,2-dimethyl-3-(2,4-dibromophenylamino)-2,3-dihydro-naphtho[1,2-b]furan-4,5-dione, IC(50)/24h 24.9+/-7.4 and 4-azido-3-bromo-2,2-dimethyl-3,4-dihydro-2H-benzo[h]chromene-5,6-dione with 23.4+/-3.8 microM showed a trypanosomicidal activity higher than benznidazole. These results demonstrate the potential of naphthoquinone derivatives as novel structures for the development of alternative drugs for Chagas' disease.

Chagas disease, a neglected illness, affects nearly 12-14 million people in endemic areas of Latin America. Al¬though the occurrence of acute cases sharply has declined due to Southern Cone Initiative efforts to control vector transmission, there still remain serious challenges, including the maintenance of sustainable public policies for Chagas disease control and the urgent need for better drugs to treat chagasic patients. Since the introduction of benznidazole and nifurtimox approximately 40 years ago, many natural and synthetic compounds have been as¬sayed against Trypanosoma cruzi, yet only a few compounds have advanced to clinical trials. This reflects, at least in part, the lack of consensus regarding appropriate in vitro and in vivo screening protocols as well as the lack of biomarkers for treating parasitaemia. The development of more effective drugs requires (i) the identification and validation of parasite targets, (ii) compounds to be screened against the targets or the whole parasite and (iii) a panel of minimum standardised procedures to advance leading compounds to clinical trials. This third aim was the topic of the workshop entitled Experimental Models in Drug Screening and Development for Chagas Disease, held in Rio de Janeiro, Brazil, on the 25th and 26th of November 2008 by the Fiocruz Program for Research and Technological Development on Chagas Disease and Drugs for Neglected Diseases Initiative. During the meeting, the minimum steps, requirements and decision gates for the determination of the efficacy of novel drugs for T. cruzi control were evaluated by interdisciplinary experts and an in vitro and in vivo flowchart was designed to serve as a general and standardised protocol for screening potential drugs for the treatment of Chagas disease.

Despite ongoing efforts, the current treatment for Chagas disease is still unsatisfactory, mainly because of the severe side effects and variable efficacy of the available nitroheterocycles. Our group has been assaying natural quinones isolated from Brazilian flora, and their derivatives, as alternative chemotherapeutic agents against Trypanosoma cruzi. From C-allyl lawsone three naphthofuranquinones were synthesized, which were active against trypomastigotes and epimastigotes. Here, we further investigated the activity and the mechanisms of action of these quinones. They exhibited powerful effects on intracellular amastigotes, presenting low toxicity to the host cells. Ultrastructural analyses of treated epimastigotes and trypomastigotes indicated a potent effect of the three naphthofuranquinones on the parasite mitochondrion, which appeared drastically swollen and with a washed-out matrix profile. Fluorescence-activated cell sorting analysis of rhodamine 123-stained T. cruzi showed that the three naphthofuranquinones caused a potent dose-dependent collapse of the mitochondrial membrane potential, especially in the epimastigote form. Naphthofuranquinones also decreased specifically mitochondrial complex I–III activity in both epimastigotes and trypomastigotes, parallel to a reduction in succinate-induced oxygen consumption. Mitochondrial hydrogen peroxide formation was also increased in epimastigotes after treatment with the naphthofuranquinones. Our results indicate that the trypanocidal action of the naphthofuranquinones is associated with mitochondrial dysfunction, leading to increased reactive oxygen species generation and parasite death.

Aromatic diamidines (ADs) have been recognized as promising antiparasitic agents. Therefore, in the present work, the in vitro trypanocidal effect of 11 ADs upon the relevant clinical forms of Trypanosoma cruzi was evaluated, as well as determining their toxicity to mammalian cells and their subcellular localization.The trypanocidal effect upon trypomastigotes and amastigotes was evaluated by light microscopy through the determination of the IC(50) values. The cytotoxicity was determined by the MTT colorimetric assay against mouse cardiomyocytes. For the subcellular localization, transmission electron microscopy and fluorescence approaches were used. The fluorescence intensity within the kinetoplast DNA (kDNA) and nuclear DNA (nDNA) of treated parasites was determined using the Image J program.Compounds 2, 5 and 7 showed the lowest IC(50) values (micromolar range) against intracellular amastigotes and trypomastigotes. In the presence of blood, all the tested ADs exhibited a reduction of their activity. The compounds did not exhibit toxicity to cardiac cells and the highest selectivity index (SI) was achieved by compound 5 with an SI of137 for trypomastigotes and compound 7 with an SI of107 for intracellular parasites. The subcellular effects upon bloodstream forms treated with compounds 5 and 7 were mainly on kDNA, leading to its disorganization. The higher accumulation in the kDNA observed for all tested ADs was not directly related to their efficacy.Our results show the high activity of this new series of ADs against both trypomastigote and amastigote forms, with excellent SIs, especially compound 7, which merits further in vivo evaluation.

Chagas disease, which is caused by the intracellular parasite Trypanosoma cruzi, is a neglected illness with 12-14 million reported cases in endemic geographic regions of Latin America. While the disease still represents an important public health problem in these affected areas, the available therapy, which was introduced more than four decades ago, is far from ideal due to its substantial toxicity, its limited effects on different parasite stocks, and its poor activity during the chronic phase of the disease. For the past 15 years, our group, in collaboration with research groups focused on medicinal chemistry, has been working on experimental chemotherapies for Chagas disease, investigating the biological activity, toxicity, selectivity and cellular targets of different classes of compounds on T. cruzi. In this report, we present an overview of these in vitro and in vivo studies, focusing on the most promising classes of compounds with the aim of contributing to the current knowledge of the treatment of Chagas disease and aiding in the development of a new arsenal of candidates with anti-T. cruzi efficacy.

Electron microscopy has proven to be a reliable and essential tool to determine morphological alterations and target organelles in the investigation of new drugs for Chagas disease. In this review, we focused on evaluating different agents that induce death of Trypanosoma cruzi, i.e. lysophospholipids analogues, naphthoquinones and derivatives, cytoskeletal inhibitors and natural products. Apoptosis-like presents as morphological characteristics DNA fragmentation, membrane blebbing and apoptotic body formation. Autophagy involves autophagosome formation, with the appearance of membranes surrounding organelles and cytosolic structures. Necrosis causes the loss of osmotic balance, an increase of cytoplasmic vacuolization and plasma membrane disruption. Mitochondrion appears as a central checkpoint in both apoptosis and necrosis. Our evidences of ultrastructural changes to T. cruzi treated with the different classes of compounds point to dramatic mitochondrial alterations and similar autophagic phenotypes. Lysophospholipid analogues interfere in the lipid biosynthesis in epimastigotes, altering the amount of both phospholipids and sterols, and consequently the physical properties of the membrane. Naphthoquinone derivatives led to a strong DNA fragmentation in trypomastigotes and to the release of cysteine proteases from reservosomes to cytosol in epimastigotes, starting a proteolytic process which results in parasite death. The susceptibility of reservosomes was also observed in parasites treated with propolis, suggesting impairment of lipid metabolism, compromising membrane fluidity and leading to lysis. The cytoskeletal agents blocked mitosis of epimastigotes, arresting cell cycle and impairing the parasite proliferation. The variety of drug stimuli converge to the same pathway of death suggests an intense cross-talking between the three types of PCD in the protozoa.

Megazol is a highly active compound against Trypanosoma cruzi, and has become a core structure for the design of new trypanocidal agents. Recently, we have identified the new potent trypanocide agent Brazilizone A, which presents an IC(50) twofold more potent than the prototype megazol. This result has encouraged us to further explore structurally-related 1,3,4-thiadiazole-2-arylhydrazone derivatives, in order to get a better understanding of their structural and antiprotozoal activity relationships. Herein we report the synthesis and trypanocidal profile of thirteen new Brazilizone A analogues, which supported the construction of 3D-QSAR models used for its structural optimization.

The chemical composition of ethanol extracts from samples of Brazilian propolis (EEPs) determined by HPLC and their activity againstTrypanosoma cruzi,Staphylococcus aureus,Streptococcus pneumoniae,Klebisiella pneumoniae,Candida albicans,Sporothrix schenckiiandParacoccidioides brasiliensiswere determined. Based on the predominant botanical origin in the region of samples' collection, the 10 extracts were separated into three groups: A (B. dracunculifolia+Auraucariaspp), B (B. dracunculifolia) and C (Araucariaspp). Analysis by the multiple regression of all the extracts together showed a positive correlation, higher concentrations leading to higher biological effect, ofS. aureuswithp-coumaric acid (PCUM) and 3-(4-hydroxy-3-(oxo-butenyl)-phenylacrylic acid (DHCA1) and of trypomastigotes ofT. cruziwith 3,5-diprenyl-4-hydroxycinnamic acid derivative 4 (DHCA4) and 2,2-dimethyl-6-carboxyethenyl-2H-1-benzopyran (DCBEN). When the same approach was employed for each group, due to the small number of observations, the statistical test gave unreliable results. However, an overall analysis revealed for group A an association ofS. aureuswith caffeic acid (CAF) and dicaffeoylquinic acid 3 (CAFQ3), ofS. pneumoniaewith CAFQ3 and monocaffeoylquinic acid 2 (CAFQ2) and ofT. cruzialso with CAFQ3. For group B, a higher activity againstS. pneumoniaewas associated DCBEN and forT. cruziwith CAF. For group C no association was observed between the anitmicrobial effect and any component of the extracts. The present study reinforces the relevance of PCUM and derivatives, especially prenylated ones and also of caffeolyquinic acids, on the biological activity of Brazilian propolis.

Extracts of propolis samples collected in Brazil and Bulgaria were assayed against four Leishmania species--Leishmania amazonensis, L. braziliensis, L. chagasi from the New World, and L. major from the Old World--associated to different clinical forms of leishmaniasis. The composition of the extracts has been previously characterized by high temperature high resolution gas chromatography coupled to mass spectrometry. Considering the chemical differences among the extracts and the behavior of the parasites, it was observed significant differences in the leishmanicidal activities with IC50/1 day values in the range of 2.8 to 229.3 microg/ml . An overall analysis showed that for all the species evaluated, Bulgarian extracts were more active than the ethanol Brazilian extract. As the assayed propolis extracts have their chemical composition determined it merits further investigation the effect of individual components or their combinations on each Leishmania species.

L-Amino acid methyl esters, such as L-leucine methyl ester (Leu-OMe), have been identified as agents targeting the lysosomal system of Leishmania amazonensis amastigotes, by a mechanism that involves ester hydrolysis by parasite enzymes located inside megasomes. We have here analyzed the effect of Leu-OMe on all three evolutive forms of Trypanosoma cruzi, in a search for potential targets of the compound in this protozoan. Treatment of epimastigote forms resulted in dose-dependent growth inhibition, with IC50/1 day = 0.55 +/- 0.21 mM. Incubation with 4-8mM/1 day led to 100% cell death. Treatment of bloodstream trypomastigotes resulted in cell lysis, with an IC50/1 day = 1.46 +/- 0.16 mM. Furthermore, infected macrophages treated with 0.125-1mM Leu-OMe showed a dose- and time-dependent decrease in the percent of amastigote infection. Morphological changes in macrophages were observed only at concentrations above 8mM, at the third day of treatment. Analysis of treated parasites by transmission electron microscopy demonstrated severe morphological alterations in cell shape, mitochondrion and nucleus, while kinetoplast and reservosomes (pre-lysosomal compartments) appeared to be not affected. Lysis of bloodstream trypomastigotes and intracellular amastigotes indicated that lysosomes of T. cruzi are the main target for the drug, since reservosomes occur only in epimastigote forms. The presence of lysosomes in T. cruzi epimastigotes was demonstrated by using ultrastructural cytochemistry.

Disability and mortality as consequence of Chagas disease is enormous in South America. Recently, the success of the trypanocidal treatment with benznidazole, the only available drug, has been associated with the host immune response. In the current study, the impact of benznidazole administration immediately after the experimental infection with Trypanosoma cruzi was evaluated in the main lymphocyte populations in lymphoid organs. Untreated mice displayed enlargement of spleen and lymph node related to the increased frequency of T and B lymphocytes, respectively. An intense thymus involution with the depletion of CD4(+)CD8(+) double-positive thymocytes also occurred. Benznidazole treatment led to a partial reversion of the spleen and lymph node enlargement related to changes in the frequency of lymphocyte subsets due to infection. Prevention of thymus involution was achieved, with the profile of thymocyte subsets similar to that of non-infected mice. The parasitic load at the onset of T. cruzi infection seems critical to trigger immune system activation.

Phamacological activities of a standard ethanol extract G1 from Brazilian green propolis, typified as BRP1, was evaluated in mouse models of pain and inflammation. Intraperitoneal injection ( I. P.) of G1 inhibited acetic acid-induced abdominal constrictions with an ID (50) = 0.75 +/- 0.05 mg/kg, and in the formalin test the ID (50) values were 0.85 +/- 0.07 mg/kg and 13.88 +/- 1.12 mg/kg, respectively, for the neurogenic and inflammatory phases. The extract was ineffective when assessed in the hot-plate assay. In serotonin-induced paw edema, G1 led to a maximal inhibition (MI) of 51.6 % after 120 min when administered I. P. and of 36 % after 15 min by the oral route ( O. R.). When the inflammatory agent was complete Freund's adjuvant, inhibition of paw edema was also observed after administration of the extract by both routes. In the capsaicin-induced ear edema the ID (50) values were 1.09 +/- 0.08 mg/kg ( I. P.) and 10.00 +/- 0.90 mg/kg ( O. R.). In the acute carrageenan-induced inflammatory reaction induced by carrageenan, G1 reduced the number of neutrophils in the peritoneal cavity with IC (50) values of 0.72 +/- 0.08 mg/kg and 4.17 +/- 0.50 mg/kg, by I. P. or O. R. administration, with a preferential migration of polymorphonuclear neutrophils. IN VITRO, G1 decreased nitric oxide production in LPS-stimulated RAW 264.7 cells (IC (50) = 41.60 microg/mL), and also the luciferase activity in TNF-alpha-stimulated HEK 293 cells transfected with NF-kappaB-luciferase reporter gene driven by the nuclear factor kappaB (NF-kappaB) (IC (50) = 200 microg/mL). This extract, which at low concentrations induces anti-inflammatory and analgesic effects in mouse models, presents a high content of flavonoids, known to inhibit inducible NOS (iNOS) activity. These data taken together led us to reinforce the hypothesis in the literature that the anti-inflammatory effect of propolis may be a due to inhibition of iNOS gene expression, through interference with NF-kappaB sites in the iNOS promoter.

Propolis has shown activity against pathogenic microorganisms that cause diseases in humans and animals. The ethanol (Et-Blg) and acetone (Ket-Blg) extracts from a Bulgarian propolis, with known chemical compositions, presented similar activity against tissue culture-derived amastigotes. The treatment of Trypanosoma cruzi-infected skeletal muscle cells with Et-Blg led to a decrease of infection and of the intracellular proliferation of amastigotes, while damage to the host cell was observed only at concentration 12.5 times higher than those affecting the parasite. Ultrastructural analysis of the effect of both extracts in epimastigotes revealed that the main targets were the mitochondrion and reservosomes. Et-Blg also affected the mitochondrion-kinetoplast complex in trypomastigotes, offering a potential target for chemotherapeutic agents.

Ethanol extract of Bulgarian propolis (Et-Blg) was administered by oral route in doses ranging from 25 to 100mg/kg body weight in experimental Trypanosoma cruzi-infected Swiss mice. Treatment with 50mg Et-Blg/kg body weight/day led to a decrease in parasitemia and showed no hepatic or renal toxic effect. Treatment with Et-Blg led to a decrease in the spleen mass and modulated the initial inflammatory reaction as demonstrated by analysis of the leukocyte profile in peripheral blood, quantification of T cells subsets, and phenotypic markers in the spleen. Preferential expansion of CD8(+) and partial inhibition in the increase of CD4(+)CD69(+) and CD8(+)CD69(+) in CD4(+)CD44(+) and CD8(+)CD44(+) and in the decrease of CD8(+)CD62L in Trypanosoma cruzi-infected mice were also observed. Taken together, our data indicate that treatment of Trypanosoma cruzi-infected mice with Et-Blg interferes with the basic properties of immune cells.

Received 14 January 2005; returned 15 May 2005; revised 24 May 2005; accepted 7 October 2005Objectives: Investigation of the mode of action of the naphthoimidazole N1, obtained from the reaction ofb-lapachonewithbenzaldehyde,whichamong45semi-syntheticderivativesofnaphthoquinonesisolatedfrom Tabebuia sp. was one of the most active compounds against Trypanosoma cruzi trypomastigotes.Methods: Quantification of the effect of N1 against the proliferative forms of T. cruzi, and investigation ofpotential targets in the parasite using electron microscopy and flow cytometry techniques.Results:N1presentedthefollowingorderofactivity:amastigotes>trypomastigotes>epimastigotes.Theeffectonintracellularformswas 25timeshigherthanonmacrophagesandheartmusclecells.N1-treatedparasites presented an abnormal chromatin condensation and mitochondrial damage. In epimastigotes,alterations of reservosomes were observed, and in trypomastigotes, a decrease in the electron density ofacidocalcisomeswasobserved.Inepimastigotes,thenaphthoimidazoleinhibitedtheactivityofsuccinatecytochrome c reductase. Labelling with rhodamine 123 or Acridine Orange was decreased in both formstreated with N1.Conclusions:Theresultssuggestthatepimastigotes,reservosomes,mitochondrion,andnucleuscontainN1 targets. In trypomastigotes, in which reservosomes are absent, the organelles affected by thecompound were also the mitochondrion and nucleus, as well as acidocalcisomes, in which the decreasein electron density could be due to the use of polyphosphate as an alternative energy supply.Keywords: T. cruzi, chemotherapy, naphthoquinones, parasites

Objectives Investigation of the antiproliferative synergy of the lysophospholipid analogues (LPAs) edelfosine, ilmofosine and miltefosine with the ergosterol biosynthesis inhibitor ketoconazole against Trypanosoma cruzi. Methods The effect of LPAs, ketoconazole and their combination was evaluated against epimastigotes and intracellular amastigotes by the parameter IC50 leading to construction of isobolograms, for determination of a synergic effect. For epimastigotes, ultrastructural damage induced by these treatments was evaluated by transmission and scanning electron microscopy. Results Synergy was confirmed against both epimastigotes and amastigotes of the parasite. Edelfosine or ketoconazole alone induced morphological alterations in the plasma membrane and reservosomes of the parasites, while in combination, they also led to severe mitochondrial damage, formation of autophagic structures and multinucleation. Scanning electron microscopy confirmed the effect at the plasma membrane and also revealed alterations in the shape of the parasites. Conclusions Our results describe the synergic anti-proliferative effect of LPAs and ketoconazole against epimastigotes and intracellular amastigotes and suggest that in epimastigotes, plasma membrane, reservosomes and mitochondria are targets of these drugs, possibly by interference with lipid metabolism.

In this work we reported the synthesis and the trypanocidal profile of new 1,3,4-thiadiazole-2-arylhydrazone derivatives of nitroimidazole series (4) or phenyl series (5), designed by exploring the molecular hybridization approach between megazol (2) and guanyl hydrazone derivative (3). The evaluation of the activity against bloodstream trypomastigote forms of Trypanosoma cruzi forms lead us to identify a new potent trypamomicide prototype, that is, brazilizone A (4k), which present an IC50/24 h=5.3 microM.

Objectives: Analysis of the effect of edelfosine, ilmofosine and miltefosine on Leishmania amazonensis and of potential targets of these lysophospholipid analogues. Methods: Quantification and ultrastructural analysis of the effect of lysophospholipid analogues on promastigote forms and on infected peritoneal macrophages, and flow cytometry analysis of treated promastigotes labelled with propidium iodide and rhodamine 123 (Rh123). Results: The lysophospholipid analogues presented potent antiproliferative activity with IC50/3 days of 1.9‐3.4mM for promastigotes and 4.2‐9.0mM for intracellular amastigotes. Treatment with these analogues in Schneider medium for 1 day led to a dose-dependent decrease in Rh123 fluorescence, an effect more accentuated in edelfosine-treated parasites, suggesting interference with the potential of the mitochondrial membrane. In both forms of L. amazonensis, edelfosine induced extensive mitochondrial damage, multinucleation and, in promastigotes, also led to plasma membrane alterations, formation of autophagic structures and membranous arrangements inside the flagellar pocket. Conclusions: The alkylglycerophosphocholines edelfosine and ilmofosine were more active than the alkylphosphocholine miltefosine against promastigotes and intracellular amastigotes of L. amazonensis, and ultrastructural and flow cytometry data indicate the mitochondrion as a target of edelfosine.