Synthesis and Evaluation of Thiochroman-4-One Derivatives as Potential Leishmanicidal Agents

ABSTARCT: The S-containing heterocyclic compounds benzothiopyrans or thiochromones stand out as having promising biological activities due to their structural relationship with chromones (benzopyrans), which are widely known as privileged scaffolds in medicinal chemistry. In this work, we report the synthesis of 35 thiochromone derivatives and the in vitro antileishmanial and cytotoxic activities. Compounds were tested against intracellular amastigotes of Leishmania panamensis and cytotoxic activity against human monocytes (U-937 ATCC CRL-1593.2). Compounds bearing a vinyl sulfone moiety, 4h, 4i, 4j, 4k, 4l and 4m, displayed the highest antileishmanial activity, with EC50 values lower than 10 μM and an index of selectivity over 100 for compounds 4j and 4l. When the double bond or the sulfone moiety was removed, the activity decreased. Our results show that thiochromones bearing a vinyl sulfone moiety are endowed with high antileishmanial activity and low cytotoxicity

Application of the Eco-Epidemiological Method in the Study of Leishmaniasis Transmission Foci

The study of transmission foci involves the clinical characterization of disease within a focus using active surveillance of human cases, characterization of the population group that is most frequently infected or at highest risk of becoming infected, diagnosis and treatment of infected people and identification of the conceptions, attitudes, beliefs and practices related to the disease. An entomological survey is necessary to determine the geographical distribution of species and incrimination of vector species, the ecological characteristics of the zone (macro-focus), times of the year and day of highest biting activity and places in homes in which the most frequent contact between the people and the vectors occurs. A survey of peri-domestic and wild mammals in the area is advisable to try to identify potential reservoir hosts. Using this information, it is feasible to design specific and accurate prevention and effective, rational and economic control measures and define the times of the year and locations in which these measures must be applied. In this chapter, a description of the application of the eco-epidemiological method to the study of leishmaniasis transmission foci is provided. A special emphasis is placed on the methodology, multidisciplinary work and analysis of findings

Leishmaniasis worldwide and global estimates of its incidence.

As part of a World Health Organization-led effort to update the empirical evidence base for the leishmaniases, national experts provided leishmaniasis case data for the last 5 years and information regarding treatment and control in their respective countries and a comprehensive literature review was conducted covering publications on leishmaniasis in 98 countries and three territories (see 'Leishmaniasis Country Profiles Text S1, S2, S3, S4, S5, S6, S7, S8, S9, S10, S11, S12, S13, S14, S15, S16, S17, S18, S19, S20, S21, S22, S23, S24, S25, S26, S27, S28, S29, S30, S31, S32, S33, S34, S35, S36, S37, S38, S39, S40, S41, S42, S43, S44, S45, S46, S47, S48, S49, S50, S51, S52, S53, S54, S55, S56, S57, S58, S59, S60, S61, S62, S63, S64, S65, S66, S67, S68, S69, S70, S71, S72, S73, S74, S75, S76, S77, S78, S79, S80, S81, S82, S83, S84, S85, S86, S87, S88, S89, S90, S91, S92, S93, S94, S95, S96, S97, S98, S99, S100, S101'). Additional information was collated during meetings conducted at WHO regional level between 2007 and 2011. Two questionnaires regarding epidemiology and drug access were completed by experts and national program managers. Visceral and cutaneous leishmaniasis incidence ranges were estimated by country and epidemiological region based on reported incidence, underreporting rates if available, and the judgment of national and international experts. Based on these estimates, approximately 0.2 to 0.4 cases and 0.7 to 1.2 million VL and CL cases, respectively, occur each year. More than 90% of global VL cases occur in six countries: India, Bangladesh, Sudan, South Sudan, Ethiopia and Brazil. Cutaneous leishmaniasis is more widely distributed, with about one-third of cases occurring in each of three epidemiological regions, the Americas, the Mediterranean basin, and western Asia from the Middle East to Central Asia. The ten countries with the highest estimated case counts, Afghanistan, Algeria, Colombia, Brazil, Iran, Syria, Ethiopia, North Sudan, Costa Rica and Peru, together account for 70 to 75% of global estimated CL incidence. Mortality data were extremely sparse and generally represent hospital-based deaths only. Using an overall case-fatality rate of 10%, we reach a tentative estimate of 20,000 to 40,000 leishmaniasis deaths per year. Although the information is very poor in a number of countries, this is the first in-depth exercise to better estimate the real impact of leishmaniasis. These data should help to define control strategies and reinforce leishmaniasis advocacy

Synthesis, antiprotozoal activity and cytotoxicity in U-937 macrophages of triclosan–hydrazone hybrids

The synthesis and biological activities (cytotoxicity, leishmanicidal, and trypanocidal) of 11 triclosan–hydrazone hybrids are described herein. The structure of the products was elucidated by spectral data (NMR, IR) and mass spectrometric analyses. The synthesized compounds were evaluated against amastigotes forms of L. (V) panamensis, which is the most prevalent Leishmania species in Colombia, and against Trypanosoma cruzi, which is the major pathogenic species to Chagas disease in humans. In addition, the cytotoxic activity of the synthesized compounds was evaluated against human U-937 macrophages. Hydrazone hybrids were obtained as E-synperiplanar and E-antiperiplanar conformers. Nine of them were active against L. (V) panamensis (5a–5d, 5f–5j) and eight of them against T. cruzi (5a, 5c, 5d, 5f–5j), with EC50 values lower than 40 µM. The compounds 5c, 5e, and 5h exhibit the best selectivity index against both L. (V) panamensis and T. cruzi, with values ranging from 5.90 to 16.55, thus showing potential as starting compounds for the eventual development of drugs against these parasites. The presence of hydroxy or methoxy groups in positions 2 and 4 of the aromatic ring of the benzylidene moiety increases both activity and cytotoxicity. There is no clear relationship between the antiprotozoal activity and the methylation pattern of the hydroxy groups, since in some cases methylation decreases the activity (5d vs. 5g) while in other cases the activity is increased (5c vs. 5f and 5i vs. 5j

Synthesis, Leishmanicidal and Cytotoxic Activity of Triclosan-Chalcone, Triclosan-Chromone and Triclosan-Coumarin Hybrids

Twelve hybrids derived from triclosan were obtained via Williamson etherification of O-triclosan alkyl bromide plus chalcone and O-coumarin or O-chromone alkyl bromide plus triclosan, respectively. Structures of the products were elucidated by spectroscopic analysis. The synthesized compounds were evaluated for antileishmanial activity against L. (V) panamensis amastigotes. Cytotoxic activity was also evaluated against mammalian U-937 cells. Compounds 7–9 and 17, were active against Leishmania parasites (EC50 = 9.4; 10.2; 13.5 and 27.5 µg/mL, respectively) and showed no toxicity toward mammalian cells (>200 µg/mL). They are potential candidates for antileishmanial drug development. Compounds 25–27, were active and cytotoxic. Further studies using other cell types are needed in order to discriminate whether the toxicity shown by these compounds is against tumor or non-tumor cells. The results indicate that compounds containing small alkyl chains show better selectivity indices. Moreover, Michael acceptor moieties may modify both the leishmanicidal activity and cytotoxicity. Further studies are required to evaluate if the in vitro activity against Leishmania panamensis demonstrated here is also observed in vivo.The authors thank COLCIENCIAS (contract No. 0333-2013, code: 111556933423) and the Universidad de Antioquia (Estrategia de Sostenibilidad 2013–2014 and CIDEPRO) for financial support

Synthesis and leishmanicidal activity of cinnamic acid esters: structure–activity relationship

Several cinnamic acid esters were obtained via Fischer esterification of cinnamic acids derivatives with aliphatic alcohols. Structures of the products were elucidated by spectroscopic analysis. The synthesized compounds were evaluated for antileishmanial activity against L. (V) panamensis amastigotes and cytotoxic activity was evaluated against mammalian U-937 cells. The compounds 11, 15–17, and 23, were active against Leishmania parasite and although toxic for mammalian cells, they still are potential candidates for antileishmanial drug development. A SAR analysis indicates that first, while smaller alkyl chains lead to higher selectivity indices (10, 11 vs. 12–17); second, the degree of oxygenation is essential for activity, primarily in positions 3 and 4 (17 vs. 18–20 and 22); and third, hydroxyl groups increase both activity and cytotoxicity (14 vs. 23). On the other hand, the presence of a double bond in the side chain is crucial for cytotoxicity and leishmanicidal activity (12 vs. 21). However, further studies are required to optimize the structure of the promising molecules and to validate the in vitro activity against Leishmania demonstrated here with in vivo studies.The authors thank Dr. Javier Garcés for his help in this study. We acknowledge the support by the Universidad de Antioquia (Estrategia de Sostenibilidad 2013–2014 and CIDEPRO) and Colciencias (contract No. 357-2011)

Triclosan-caffeic acid hybrids: Synthesis, leishmanicidal, trypanocidal and cytotoxic activities

The synthesis, cytotoxicity, anti-leishmanial and anti-trypanosomal activities of twelve triclosan-caffeic acid hybrids are described herein. The structure of the synthesized products was elucidated by a com- bination of spectrometric analyses. The synthesized compounds were evaluated against amastigotes forms of L. (V) panamensis , which is the most prevalent Leishmania species in Colombia, and against Trypanosoma cruzi, which is the pathogenic species to humans. Cytotoxicity was evaluated against hu- man U-937 macrophages. Eight compounds were active against L. (V) panamensis ( 18 e 23, 26 and 30 ) and eight of them against T. cruzi ( 19 e 22 , 24 and 28 e 30 ) with EC 50 values lower than 40 m M. Compounds 19 e 22 , 24 and 28 e 30 showed higher activities than benznidazole (BNZ). Esters 19 and 21 were the most active compounds for both L. (V) panamensis and T. cruzi with 3.82 and 11.65 m M and 8.25 and 8.69 m M, respectively. Compounds 19 e 22 , 24 and 28 e 30 showed higher activities than benznidazole (BNZ). Most of the compounds showed antiprotozoal activity and with exception of 18 , 26 and 28 , the remaining compounds were toxic for mammalian cells, yet they have potential to be considered as candidates for anti-trypanosomal and anti-leishmanial drug development. The activity is dependent on the length of the alkyl linker with compound 19 , bearing a four-carbon alkyl chain, the most performing hybrid. In general, hydroxyl groups increase both activity and cytotoxicity and the presence of the double bond in the side chain is not decisive for cytotoxicity and anti-protozoal activity

Synthesis, leishmanicidal, trypanocidal and cytotoxic activities of quinoline-chalcone and quinoline-chromone hybrids

We report herein the synthesis and biological activities (cytotoxicity, leishmanicidal and trypanocidal) of six quinoline-chalcone and five quinoline-chromone hybrids. The synthesized compounds were evaluated against amastigotes forms of Leishmania (V) panamensis, which is the most prevalent Leishmania species in Colombia and Trypanosoma cruzi, which is the major pathogenic species to humans. Cytotoxicity was evaluated against human U-937 macrophages. Compounds 8–12, 20, 23 and 24 showed activity against Leishmania (V) panamensis, while compounds 9, 10, 12, 20 and 23 had activity against Trypanosoma cruzi with EC50 values lower than 18 mg mL−1. 20 was the most active compound for both Leishmania (V) panamensis and Trypanosoma cruzi with EC50 of 6.11 ± 0.26 μg mL−1 (16.91 μM) and 4.09 ± 0.24 (11.32 μM), respectively. All hybrids compounds showed better activity than the anti-leishmanial drug meglumine antimoniate. Compounds 20 and 23 showed higher activity than benznidazole, the current anti-trypanosomal drug. Although these compounds showed toxicity for mammalian U-937 cells,they still have the potential to be considered as candidates to antileishmanial or trypanocydal drug development

Especies de flebotomíneos (Diptera: Psychodidae) recolectados en reservas naturales de las regiones del Darién y del Pacífico en Colombia

Introduction: The departments of Chocó and Antioquia in Colombia show climatic and vegetation conditions favoring the establishment of vector species of the genus Lutzomyia and the transmission of Leishmania spp. to human populations entering conserved forest environments.Objective: To report the species of Phlebotomine sandflies present in three natural reserves in the Darien and Pacific regions of Colombia.Materials and methods: Sand flies were collected specifically in the natural reserves El Aguacate (Acandí, Chocó), Nabugá (Bahía Solano, Chocó) and Tulenapa (Carepa, Antioquia). Sand flies were collected with CDC light traps, active search in resting places and Shannon traps. The taxonomic determination of species was based on taxonomic keys. For some species of taxonomic interest, we evaluated the partial sequences of the 5’ region of COI gene.Results: A total of 611 adult sand flies were collected: 531 in Acandí, 45 in Carepa and 35 in Bahía Solano. Seventeen species of the genus Lutzomyia, three of the genus Brumptomyia and one of the genus Warileya were identified. The genetic distances (K2P) and grouping supported (>99%) in the neighbor joining dendrogram were consistent for most established molecular operational taxonomic units (MOTU) of the Aragaoi group and clearly confirmed the identity of Lu. coutinhoi.Conclusion: Species that have importance in the transmission of leishmaniasis in Acandí, Bahía Solano and Carepa were identified. The presence of Lu. coutinhoi was confirmed and consolidated in Colombia.Introducción. Los departamentos de Chocó y Antioquia en Colombia presentan condiciones climáticas y de vegetación que favorecen el establecimiento de especies de vectores del género Lutzomyia y la transmisión de Leishmania spp. a poblaciones humanas que ingresan a ambientes selváticos conservados.Objetivo. Reportar las especies de flebotomíneos presentes en tres reservas naturales de las regiones del Darién y del Pacífico en Colombia.Materiales y métodos. Los flebotomíneos se recolectaron en las reservas naturales El Aguacate (Acandí, Chocó), Nabugá (Bahía Solano, Chocó) y Tulenapa (Carepa, Antioquia). La recolección se hizo con trampas de luz CDC, mediante búsqueda activa en sitios de reposo y con trampas Shannon. La determinación taxonómica de especies se basó en las claves taxonómicas. En algunas especies de interés taxonómico, se evaluó el uso de secuencias parciales de la región 5’ del gen COI. Resultados. Se recolectaron 611 flebotomíneos adultos: 531 en Acandí, 45 en Carepa y 35 en Bahía Solano. Se identificaron 17 especies del género Lutzomyia, tres del género Brumptomyia y una del género Warileya. Las distancias genéticas (K2P) y los soportes de agrupación (>99 %) en el dendrograma de neighbor joining correspondieron a la mayoría de unidades taxonómicas operacionales moleculares (Molecular Operational Taxonomic Units, MOTU) establecidas para el grupo Aragaoi y confirmaron claramente la identidad de Lu. coutinhoi.Conclusión. Se identificaron especies que tienen importancia en la transmisión de la leishmaniasis en Acandí, Bahía Solano y Carepa. Se confirmó la presencia de Lu. coutinhoi en Colombia

Furanchalcone–biphenyl hybrids: synthesis, in silico studies, antitrypanosomal and cytotoxic activities

The synthesis, antitrypanosomal, and cytotoxic activities of 17 furanchalcone derivatives are described herein. The structure of the synthesized products was elucidated by a combination of spectrometric analyses. The synthesized compounds were evaluated against Trypanosoma cruzi, which is the pathogenic species to humans. Cytotoxicity was evaluated against human U-937 macrophages. Eleven compounds were active against amastigotes of T. cruzi with EC50 values lower than 40 µM. Hybrids 7b–7d and 8a–8g showed better activity than benznidazole. Structure activity relationship (SAR) showed that the presence of electron withdrawing groups, such as nitro or fluorine, increased the activity and that the degree of oxygenation is essential for activity. In addition, molecular docking was used to identify a possible protein target for the designed compounds. A spearman correlation of 0.608 between the predicted scores and the experimental data profile the enzyme cruzipain as a potential candidate. Finally, in silico ADMET studies of the arylfuranchalcones showed that these novel compounds have suitable drug-like properties, making them potentially promising agents for antichagasic therapy