Synthesis, trypanocidal and anti-leishmania activity of new triazole-lapachol and nor-lapachol hybrids.

A new library of twenty triazole-lapachol and nor-lapachol derivatives was synthesized. The compounds were evaluated against the epimastigotes form of Trypanosoma cruzi and promastigotes of Leishmania braziliensis and L. infantum. The cytotoxicity of the compounds was determined on murine fibroblasts and used to assess the selectivity index. The introduction of triazole rings in the naphthoquinone derivatives improved activity against the parasitic protozoa T. cruzi and Leishmania species. Some of the derivatives were three to six times more potent than benznidazole against T. cruzi, with similar or slightly better selectivity indexes. The results against L. braziliensis showed that the derivatives 5b and 5e were the most selective compounds. However, they were less selective than the reference compound, miltefosine. Among all products, the derivative 3a was the most selective compound against L. infantum. Nevertheless, it was less potent and less selective than miltefosine. Also, the minimum inhibitory concentration values of the derivatives against nine different bacteria were determined. Moderate antibacterial activity was observed for compound 5c against Staphylococcus aureus.

Antiprotozoal Activity of Triazole Derivatives of Dehydroabietic Acid and Oleanolic Acid.

Tropical parasitic diseases such as Chagas disease and leishmaniasis are considered a major public health problem affecting hundreds of millions of people worldwide. As the drugs currently used to treat these diseases have several disadvantages and side effects, there is an urgent need for new drugs with better selectivity and less toxicity. Structural modifications of naturally occurring and synthetic compounds using click chemistry have enabled access to derivatives with promising antiparasitic activity. The antiprotozoal activity of the terpenes dehydroabietic acid, dehydroabietinol, oleanolic acid, and 34 synthetic derivatives were evaluated against epimastigote forms of Trypanosoma cruzi and promastigotes of Leishmaniabraziliensis and Leishmania infantum. The cytotoxicity of the compounds was assessed on NCTC-Clone 929 cells. The activity of the compounds was moderate and the antiparasitic effect was associated with the linker length between the diterpene and the triazole in dehydroabietinol derivatives. For the oleanolic acid derivatives, a free carboxylic acid function led to better antiparasitic activity.

Multi-Anti-Parasitic Activity of Arylidene Ketones and Thiazolidene Hydrazines against Trypanosoma cruzi and Leishmania spp.

A series of fifty arylideneketones and thiazolidenehydrazines was evaluated against Leishmania infantum and Leishmania braziliensis. Furthermore, new simplified thiazolidenehydrazine derivatives were evaluated against Trypanosoma cruzi. The cytotoxicity of the active compounds on non-infected fibroblasts or macrophages was established in vitro to evaluate the selectivity of their anti-parasitic effects. Seven thiazolidenehydrazine derivatives and ten arylideneketones had good activity against the three parasites. The IC50 values for T. cruzi and Leishmania spp. ranged from 90 nM-25 µM. Eight compounds had multi-trypanocidal activity against T. cruzi and Leishmania spp. (the etiological agents of cutaneous and visceral forms). The selectivity of these active compounds was better than the three reference drugs: benznidazole, glucantime and miltefosine. They also had low toxicity when tested in vivo on zebrafish. Trying to understand the mechanism of action of these compounds, two possible molecular targets were investigated: triosephosphate isomerase and cruzipain. We also used a molecular stripping approach to elucidate the minimal structural requirements for their anti-T. cruzi activity.

Identification of biomedical journals in Spain and Latin America.

OBJECTIVES: Journals in languages other than English that publish original clinical research are often not well covered in the main biomedical databases and therefore often not included in systematic reviews. This study aimed to identify Spanish language biomedical journals from Spain and Latin America and to describe their main features. METHODS: Journals were identified in electronic databases, publishers' catalogues and local registries. Eligibility was determined by assessing data from these sources or the journals' websites, when available. FINDINGS: A total of 2457 journals were initially identified; 1498 met inclusion criteria. Spain (27.3%), Mexico (16.0%), Argentina (15.1%) and Chile (11.9%) had the highest number of journals. Most (85.8%) are currently active; 87.8% have an ISSN. The median and mean length of publication were 22 and 29 years, respectively. A total of 66.0% were indexed in at least one database; 3.0% had an impact factor in 2012. A total of 845 journals had websites (56.4%), of which 700 (82.8%) were searchable and 681 (80.6%) free of charge. CONCLUSIONS: Most of the identified journals have no impact factor or are not indexed in any of the major databases. The list of identified biomedical journals can be a useful resource when conducting hand searching activities and identifying clinical trials that otherwise would not be retrieved.

Relationship between genetic diversity and morpho-functional characteristics of flight-related traits in Triatoma garciabesi (Hemiptera: Reduviidae).

BACKGROUND: Triatoma garciabesi, a potential vector of the parasitic protozoan Trypanosoma cruzi, which is the causative agent of Chagas disease, is common in peridomestic and wild environments and found throughout northwestern and central Argentina, western Paraguay and the Bolivian Chaco. Genetic differentiation of a species across its range can help to understand dispersal patterns and connectivity between habitats. Dispersal by flight is considered to be the main active dispersal strategy used by triatomines. In particular, the morphological structure of the hemelytra is associated with their function. The aim of this study was to understand how genetic diversity is structured, how morphological variation of dispersal-related traits varies with genetic diversity and how the morphological characteristics of dispersal-related traits may explain the current distribution of genetic lineages in this species. METHODS: Males from 24 populations of T. garciabesi across its distribution range were examined. The cytochrome c oxidase I gene (coI) was used for genetic diversity analyses. A geometric morphometric method based on landmarks was used for morpho-functional analysis of the hemelytra. Centroid size (CS) and shape of the forewing, and contour of both parts of the forewing, the head and the pronotum were characterised. Length and area of the forewing were measured to estimate the aspect ratio. RESULTS: The morphometric and phylogenetic analysis identified two distinct lineages, namely the Eastern and Western lineages, which coincide with different ecological regions. The Eastern lineage is found exclusively in the eastern region of Argentina (Chaco and Formosa provinces), whereas the Western lineage is prevalent in the rest of the geographical range of the species. CS, shape and aspect ratio of the hemelytra differed between lineages. The stiff portion of the forewing was more developed in the Eastern lineage. The shape of both portions of the hemelytra were significantly different between lineages, and the shape of the head and pronotum differed between lineages. CONCLUSIONS: The results provide preliminary insights into the evolution and diversification of T. garciabesi. Variation in the forewing, pronotum and head is congruent with genetic divergence. Consistent with genetic divergence, morphometry variation was clustered according to lineages, with congruent variation in the size and shape of the forewing, pronotum and head.

[First South american network of biomedical research. Education and biotechnology for health]. / Primera Red Sudamericana de Biomedicina. Investigación, educación y biotecnología aplicadas a la salud.

It is in our interest, in this brief manuscript, to report the creation of the first program of regional integration of a network of research institutes in Biomedicine belonging to members of the MERCOSUR countries. We discuss some of the foundations that gave sustenance to its creation and its objectives in the medium and long term. In addition, we consider the potential of the results of this program in the fields of applied medical research, education and biotechnology.

Luring Triatomines (Hemiptera: Reduviidae) into a Trap: Aliphatic and Aromatic Aldehydes as Attractants of Triatoma infestans.

To assess the attracting capacity of aliphatic and aromatic aldehydes to Triatoma infestans, the Chagas disease vector, laboratory tests were conducted using individual compounds and mixtures to evaluate their potential use in baited traps for intradomicile population dynamics analysis. Commercial samples of hexanal, nonanal, and benzaldehyde were used at 95% purity. The experiments were performed at 25°C and 65% relative humidity using two procedures: a glass arena with filter papers impregnated with 1, 5, and 10 µL of the tested compounds and a double-choice olfactometer. Attraction was scored positively if the insect remained more than 30 seconds on one of the surfaces. The results of the study showed that hexanal was attractive to females at higher concentrations (5-10 µL; P < 0.0001), and IV instar nymphs were only attracted at the highest concentration (10 µL; P < 0.01). Nonanal was attractive to IV instar nymphs at 1 and 5 µL (P < 0.0001), whereas males and females were more attracted at 1 µL (P < 0.01 and P < 0.05, respectively). Benzaldehyde showed significant differences with respect to controls, attracting females at low concentrations (1 µL; P < 0.0001) and IV instar nymphs at 5 and 10 µL (P < 0.0001 and P < 0.001, respectively). In the olfactometer, the 60:40 hexanal/nonanal mixture was the most effective. In conclusion, this study demonstrated that the aliphatic and aromatic aldehydes studied here, both individually and in mixtures, could be used as effective attractants for T. infestans in intradomicile-baited traps. These results suggest that mixtures of these compounds could be implemented in field trials for Chagas disease surveillance.

Phenotypic variability in traits related to flight dispersal in the wing dimorphic species Triatoma guasayana.

BACKGROUND: Triatoma guasayana is considered an emerging vector of Chagas disease in the Southern Cone of South America. The presence of a triatomine population with brachypterous individuals, in which both wings are reduced, has recently been reported for this species. The aim of the present study was to determine if flight-related traits varied across populations, if these traits could explain differences in flight capacity across populations and if flight-related traits are associated with geographic and/or climatic variation. METHODS: The study involved 66 male T. guasayana specimens from 10 triatomine populations. Digital images of wing, head and pronotum were used to estimate linear and geometric morphometric variables. Variations in size and shape were analysed using one-way analysis of variance and canonical variate analysis (CVA), respectively. Mantel tests were applied to analyse the relationship between morphometric and geographic distances, and the association between size measurements was analysed using Pearson's correlation. We explored covariation between size and shape variables using partial least square analyses (PLS). The association of geographic and climatic variables with size measurements was tested using linear regression analyses. We performed PLS analyses for shape measurements. RESULTS: Wing size differed significantly across triatomine populations. The CVA showed that wing shape of the brachypterous population is well discriminated from that of the other populations. The Mantel test showed a positive and significant association between wing shape and geographic distances. The heads of the brachypterous population were significantly larger than those of the other populations. Similar to wing shape, the head shape of the brachypterous population was well discriminated from those of the other populations. Pronotum width did not show significant differences across populations. Geographic and climatic factors were associated with size and shape of both the wing and head, but not with pronotum width. CONCLUSIONS: Most of the traits related to flight dispersal varied across populations. Wing shape and head shape were found to be better markers for differentiated morphological variation across populations. Head measurements also varied in accordance with this condition. Geographic and climatic variables were associated with most of the flight-related traits.

Antiproliferative activity of trans-avicennol from Zanthoxylum chiloperone var. angustifolium against human cancer stem cells.

Zanthoxylum chiloperone var. angustifolium root bark was studied with the aim of finding novel molecules able to overcome cancer stem cell chemoresistance. Purification of a methanol-soluble extract resulted in the isolation of a known pyranocoumarin, trans-avicennol (1). Compound 1 demonstrated antiproliferative activity on glioma-initiating cells, whereas it was inactive on human neural stem cells. trans-Avicennol (1) activated the MAPK/ERK pathway and was also evaluated for its ability to inhibit the enzyme indoleamine-2,3-dioxygenase.

Phenotypic Variations of Aedes aegypti Populations and Egg Abundance According to Environmental Parameters in Two Dengue-Endemic Ecoregions in Paraguay.

Dengue in Paraguay is an endemic disease of public health importance. Several studies suggest that an increased density of Aedes aegypti and the presence of dengue cases may be associated with climatic conditions. This study aimed to establish the phenotypic variations of Ae. aegypti from four cities (Asunción, Itauguá, Minga Guazú, and Ciudad del Este) and the potential association of environmental variables with the number of eggs in capture sites. Eleven morphometric phenotypic characters were evaluated, and environmental data were obtained from Earth Engine and local meteorological stations. An analysis was carried out using principal component analysis and linear discriminant analysis, and we estimated the correlation using [relative humidity, Normalized Difference Vegetation Index (NDVI) and Normalized Difference Water Index (NDWI)] between variables and the number of eggs in each site. Differences in mean NDVI and NDWI between cities and their relationship with the morphometric performance of individuals were also assessed. The study demonstrated morphometric variations between the populations of Ae. aegypti from two ecoregions, with the Litoral ecoregion populations presented a greater phenotypic variation than those observed in the Alto Paraná ecoregion. Significant statistical associations were registered between the number of eggs with relative humidity (r = -0.45) and the NDVI at 100 meters from the capture points (r = -0.61) for Minga Guazú, and with the NDWI at 100 meters (r = 0.54) for Ciudad del Este. Future studies on these Ae. aegypti populations, and its dispersion could contribute to improve vector control measures and foster future genetic studies.

Dynamics of Triatoma infestans populations in the Paraguayan Chaco: Population genetic analysis of household reinfestation following vector control.

BACKGROUND: Although domestic infestations by Triatoma infestans have been successfully controlled across Latin America, in areas of the Gran Chaco region, recurrent post-spraying house colonization continues to be a significant challenge, jeopardizing Chagas disease vector control and maintaining active Trypanosoma cruzi transmission. METHODOLOGY/PRINCIPAL FINDINGS: To investigate the dynamics of triatomine reinfestation in a rural area of the Paraguayan Chaco, genetic characterization (based on 10 microsatellite loci and cytochrome B sequence polymorphisms) was performed on baseline and reinfestant T. infestans (n = 138) from four indigenous communities and adjacent sylvatic sites. House quality and basic economic activities were assessed across the four communities. Significant genetic differentiation was detected among all baseline triatomine populations. Faster reinfestation was observed in the communities with higher infestation rates pre-spraying. Baseline and reinfestant populations from the same communities were not genetically different, but two potentially distinct processes of reinfestation were evident. In Campo Largo, the reinfestant population was likely founded by domestic survivor foci, with reduced genetic diversity relative to the baseline population. However, in 12 de Junio, reinfestant bugs were likely derived from different sources, including survivors from the pre-spraying population and sympatric sylvatic bugs, indicative of gene-flow between these habitats, likely driven by high human mobility and economic activities in adjacent sylvatic areas. CONCLUSIONS/SIGNIFICANCE: Our results demonstrate that sylvatic T. infestans threatens vector control strategies, either as a reinfestation source or by providing a temporary refuge during insecticide spraying. Passive anthropogenic importation of T. infestans and active human interactions with neighboring forested areas also played a role in recolonization. Optimization of spraying, integrated community development and close monitoring of sylvatic areas should be considered when implementing vector control activities in the Gran Chaco.

A paraguayan toad Rhinella schneideri preparation based on Mbya tradition increases mitochondrial bioenergetics with migrastatic effects dependent on AMPK in breast cancer cells.

ETHNOPHARMACOLOGICAL RELEVANCE: In Paraguay, healers from the Mbya culture treat cancer with a recipe prepared with the native toad Rhinella schneideri. However, the chemical composition and biological effects of the recipe remain unknown. AIM OF THE STUDY: The aim is to determine the composition of the traditional preparation made using the toad R. schneideri and to evaluate its effect on human breast cancer (BC) cells. MATERIALS AND METHODS: The metabolites contained in the preparation were concentrated using XAD-7 resin, and the concentrate was analyzed by HPLC-MS/MS. The effect of the preparation was assessed in normal (MCF10F) and BC cells (MDA-MB-231 and MCF7). The mitochondrial membrane potential (Δψm), reactive oxygen species (ROS) levels, and cell cycle progression were determined by flow cytometry. The oxygen consumption rate (OCR) was measured by Clark electrode, and fibronectin-dependent migration in normoxia and hypoxia-like conditions were evaluated by transwell assay. RESULTS: From the Amberlite-retained extract from the preparation, 24 compounds were identified, including alkaloids, amino acids, bufadienolides, and flavonoids, among others. The crude extract (CE) did not affect cell cycle progression and viability of BC cell lines. Moreover, it did not make cancer cells more sensitive to the cytotoxic effect of the chemotherapeutics doxorubicin and teniposide. On the other hand, the CE reduced the menadione-induced ROS production and increased NADH, Δψm, and the OCR. Respiratory complexes I and III as well as ATP synthase levels were increased in an AMPK-dependent manner. Moreover, the CE inhibited the migration of BC cells in normoxia and a hypoxia-like condition using CoCl2 as a HIF1α-stabilizing agent. This latter effect involved an AMPK-dependent reduction of HIF1α levels. CONCLUSIONS: The Paraguayan toad recipe contains metabolites from the toad ingredient, including alkaloids and bufadienolide derivatives. The CE lacks cytotoxic effects alone or in combination with chemotherapeutics. However, it increases mitochondrial bioenergetics and inhibits the cancer cell migration in an AMPK-dependent manner in BC cells. This is the first report of the in vitro anticancer effect of a traditional Rhinella sp. toad preparation based on Mbya tradition.

Genetic and toxinological divergence among populations of Tityus trivittatus Kraepelin, 1898 (Scorpiones: Buthidae) inhabiting Paraguay and Argentina.

Envenoming by scorpions in genus Tityus is a public health problem in Tropical America. One of the most medically significant species is Tityus trivittatus, which is known to occur from southwest Brazil to central-northern and eastern Argentina. In this work, we studied the lethality, composition, antigenicity, and enzymatic activity of venom from a T. trivittatus population found further north in urban areas of eastern Paraguay, where it has caused serious envenomation of children. Our results indicate that the population is of medical importance as it produces a potently toxic venom with an LD50 around 1.19 mg/kg. Venom neutralization in preliminary mouse bioassays was complete when using Brazilian anti-T. serrulatus antivenom but only partial when using Argentinean anti-T. trivittatus antivenom. Venom competitive solid-phase enzyme immunoassays and immunoblotting from Argentinean and Paraguayan T. trivittatus populations indicated that antigenic differences exist across the species range. SDS-PAGE showed variations in type and relative amounts of venom proteins between T. trivitattus samples from Argentina and Paraguay. MALDI-TOF mass spectrometry indicated that while some sodium channel toxins are shared, including ß-toxin Tt1g, others are population-specific. Proteolytic activity by zymography and peptide identification through nESI-MS/MS also point out that population-specific proteases may exist in T. trivitattus, which are postulated to be involved in the envenoming process. A time-calibrated molecular phylogeny of mitochondrial COI sequences revealed a significant (8.14%) genetic differentiation between the Argentinean and Paraguayan populations, which appeared to have diverged between the mid Miocene and early Pliocene. Altogether, toxinological and genetic evidence indicate that T. trivitattus populations from Paraguay and Argentina correspond to distinct, unique cryptic species, and suggest that further venom and taxonomic diversity exists in synanthropic southern South American Tityus than previously thought.

First Molecular Report of Leishmania (Leishmania) amazonensis and Leishmania (Viannia) guyanensis in Paraguayan Inhabitants Using High-Resolution Melt-PCR.

American tegumentary leishmaniasis is an endemic anthropozoonosis undergoing expansion on the American continent. The disease is caused by several Leishmania species and it is manifested as cutaneous and mucocutaneous leishmaniasis. In this study, we evaluate the viability of high-resolution melt polymerase chain reaction (HRM-PCR) analysis to differentiate four closely related Leishmania species as a routine tool for the diagnosis of leishmaniasis. For this purpose, biopsy specimens from cutaneous and mucocutaneous lesions were taken from 132 individuals from endemic and non-endemic areas for leishmaniasis. Each sample was processed for parasitological, histopathological, and molecular analysis. Positive biopsy samples were analyzed by HRM-PCR of a 144-bp heat-shock protein (hsp70) gene fragment, and new cases were confirmed by sequencing. Of the 132 samples analyzed, 36 (27%) were positive for Leishmania spp., of which 86% were from cutaneous lesions and 14% from mucocutaneous lesions. We identified Leishmania (Viannia) braziliensis (84%), Leishmania (Leishmania) infantum (13%), and Leishmania (Leishmania) amazonensis (3%) in cutaneous lesions, and L. (V.) braziliensis (40%), L. (L.) infantum (20%), L. (L.) amazonensis (20%), and Leishmania (Viannia) guyanensis (20%) in mucocutaneous lesions. The main purpose of this research was to report for the first time in Paraguay the presence of L. (L.) amazonensis and L. (V.) guyanensis in patients with cutaneous and mucocutaneous lesions, using the HRM-PCR technique. In addition, we report the presence of additional new cases of L. (L.) infantum in cutaneous lesions.

The efficacy of new 2,5-dihydroxybenzyl derivatives against Trypanosoma cruzi, Leishmania infantum and Leishmania braziliensis.

INTRODUCTION: Chagas disease and Leishmaniasis are among the most important parasitic diseases. They are considered to be within the most relevant group of neglected tropical diseases and have been included as priorities for searching new drugs due to their several treatment limitations. These parasitic diseases caused by flagellated protozoans affect more than 20 million people predominantly in developing countries. METHODOLOGY: In this study, we prepared a series of 2-substituted 1,4-benzenediols by an efficient, green, and lithium salt-free synthesis in water/ethanol as solvent to test their anti-parasitic activity. All 36 phenolic derivatives were evaluated in vitro for their activity against T. cruzi epimastigotes, L. infantum, and L. braziliensis promastigotes, as well as their cytotoxicity on macrophage and fibroblast cell lines. RESULTS: Based on the results obtained, the compounds that presented a methyl, trifluoromethyl or bromo group at the para-position of the second benzene ring were found the most active analogs, with higher selective index values on the three parasites assayed. CONCLUSION: This evidence suggests that the anti-parasitic activity observed in these analogs is affected by the size of the group at the 4-position of the second ring, but not related with electronic factors.This study identified hit compounds with the potential to target several kinetoplastid parasites.

Helietta apiculata: a tropical weapon against Chagas disease.

The present study pretends to evaluate the in vivo efficacy of the crude chloroform bark extract of Helietta apiculata, then the activity will be compared with the reference drug, benznidazole, in acute Trypanosoma cruzi infected mice when administered by oral route. The chloroformic extract of Helieta apiculata was administered by oral route at 5, 10 and 50 mg/kg daily for two weeks. This study has shown a moderate efficacy of the H. apiculata bark extract in reducing T. cruzi parasitaemia in 42 to 54% after a monitoring of 60 days post-infection and when compared with control groups. Concerning mice mortality, only two only two mice died, one from the control group and the other one from the group threated with 10 mg of the chlorofom extract of H. apiculata, suggesting the potential of H. apiculta extracts as a safe and inexpensive treatment of Chagas disease.

Activity of a hydroxybibenzyl bryophyte constituent against Leishmania spp. and Trypanosoma cruzi: in silico, in vitro and in vivo activity studies.

The synthesis and potent antiprotozoal activity of 14-hydroxylunularin, a natural hydroxybibenzyl bryophyte constituent is reported. 14-hydroxylunularin was highly active in vitro assays against culture and intracellular forms of Leishmania spp. and Trypanosoma. cruzi, in absence of cytotoxicity against mammalian cells. Preliminary structure-activity relationship studies showed that the reported bioactivity depends on hybridization at the carbon-carbon bridge, position and number of free hydroxy group on the aromatic rings. The reported results were also in agreement with the in silico prediction using Non-Stochastic Quadratic Fingerprints-based algorithms. The same compound also showed antiprotozoal activity in Leishmania spp. infected mice by oral and subcutaneous administration routes, with an optimal treatment of a daily subcutaneous administration of 10 mg/kg of body weight for 15 days. This study suggested that 14-hydroxylunularin may be chosen as a new candidate in the development of leishmanicidal therapy.

Phytochemical and antiprotozoal activity of Ocotea lancifolia.

Thirteen known isoquinoline alkaloids were isolated from Ocotea lancifolia, popularly known as << canela pilosa >> in Brasil and << laurel né >> by the Guarani people which means smell laurel. Their activities against the promastigote forms of three Leishmania strains and the bloodstream form of Trypanosoma cruzi were evaluated, as well as their hepatocytotoxicity. Among them, the noraporphine alkaloid (-) caaverine has shown the most interesting antiprotozoal activity against Leishmania and T. cruzi parasites.

The Paraguayan Rhinella toad venom: Implications in the traditional medicine and proliferation of breast cancer cells.

ETHNOPHARMACOLOGICAL RELEVANCE: Toads belonging to genus Rhinella are used in Paraguayan traditional medicine to treat cancer and skin infections. AIM OF THE STUDY: The objective of the study was to determine the composition of venoms obtained from three different Paraguayan Rhinella species, to establish the constituents of a preparation sold in the capital city of Paraguay to treat cancer as containing the toad as ingredient, to establish the effect of the most active Rhinella schneideri venom on the cell cycle using human breast cancer cells and to assess the antiprotozoal activity of the venoms. METHODS: The venom obtained from the toads parotid glands was analyzed by HPLC-MS-MS. The preparation sold in the capital city of Paraguay to treat cancer that is advertised as made using the toad was analyzed by HPLC-MS-MS. The effect of the R. schneideri venom and the preparation was investigated on human breast cancer cells. The antiprotozoal activity was evaluated on Leishmania braziliensis, L. infantum and murine macrophages. RESULTS: From the venoms of R. ornata, R. schneideri and R. scitula, some 40 compounds were identified by spectroscopic and spectrometric means. Several minor constituents are reported for the first time. The preparation sold as made from the toad did not contained bufadienolides or compounds that can be associated with the toad but plant compounds, mainly phenolics and flavonoids. The venom showed activity on human breast cancer cells and modified the cell cycle proliferation. The antiprotozoal effect was higher for the R. schneideri venom and can be related to the composition and relative ratio of constituents compared with R. ornata and R. scitula. CONCLUSIONS: The preparation sold in the capital city of Paraguay as containing the toad venom, used popularly to treat cancer did not contain the toad venom constituents. Consistent with this, this preparation was inactive on proliferation of human breast cancer cells. In contrast, the toad venoms of Rhinella species altered the cell cycle progression, affecting the proliferation of malignant cells. The findings suggest that care should be taken with the providers of the preparation and that the crude drug present a strong activity towards human breast cancer cell lines. The antiprotozoal effect of the R. schneideri venom was moderate while the venom of R. ornata was devoid of activity and that of R. scitula was active at very high concentration.

2H-benzimidazole 1,3-dioxide derivatives: a new family of water-soluble anti-trypanosomatid agents.

Three series of benzimidazole N-oxide derivatives were developed and were examined for their activity against trypanosomatid parasites (Trypanosoma cruzi and Leishmania spp.). 2H-benzimidazole 1,3-dioxides displayed remarkable in vitro activities against both parasites, with derivatives 28, 29, and 32 being the most potent (IC50 < 5 microM) against the epimastigote form of T. cruzi and 28, 33, and 35 the most potent against the promastigote form of Leishmania spp. Unspecific cytotoxicity was evaluated using murine macrophages, and derivative 33 was not toxic at a concentration 30 times that of its IC50 against T. cruzi that was completely toxic for Leishmania spp., implying that the series of 2H-benzimidazole 1,3-dioxides is selective toward both trypanosomatid parasites. Derivatives 33 and 35 were submitted to an in vivo assay using an acute model of Chagas' disease and a short-term treatment (30 mg/kg/day orally administrated as aqueous solution, during 10 days). While in the control (untreated) and Benznidazole (50 mg/kg/day) groups survival fraction was 60.0% and 87.5%, respectively, none of the animals treated with derivatives 33 and 35 died. From the preliminary structure-activity relationship studies reduction potential and electrophilicity were found relevant to anti-T. cruzi activity. Active compounds are better electrophiles and more easily reduced than inactive ones.