Investigación y desarrollo de nuevos fármacos anti-T. cruzi : inhibidores de cruzipaína derivados del sistema benzofuroxano y 1,3-dióxido de benzimidazol

La enzima cruzipaína, principal cisteín proteasa de Trypanosoma cruzi, está involucrada en diversas etapas relacionadas con el ciclo de vida del parásito lo cual la convierte en un interesante blanco terapéutico para el desarrollo de nuevos fármacos antichagásicos. En el presente trabajo de tesis doctoral se realizó el diseño, síntesis, evaluación biológica frente al parásito, estudios de inhibición enzimática y estudios de relación estructura-actividad inhibitoria de nuevos compuestos híbridos derivados del sistema benzofuroxano y 1,3-dióxido de benzimidazol conteniendo agrupamientos semicarbazona, tiosemicarbazona y amidinohidrazona (Serie I) o agrupamientos arilguanidina (Serie II) como potenciales inhibidores de cruzipaína. Los nuevos compuestos desarrollados se prepararon empleando procedimientos sintéticos eficientes. La caracterización estructural se realizó por técnicas espectroscópicas habituales. Los nuevos compuestos se evaluaron sobre la forma epimastigota de T. cruzi y se estudió su toxicidad frente a glóbulos rojos humanos y macrófagos murinos. Los derivados de la Serie II mostraron excelentes actividades frente al parásito, identificándose derivados, pertenecientes a ambas series, con índices de selectividad mayores que 50, siendo este valor para las referencias, anfotericina B y nifurtimox, de 10 y mayor que 13, respectivamente. Los nuevos compuestos presentaron una actividad variable frente a cruzipaína, no encontrándose relación entre ésta y la actividad anti-T. cruzi. En general, los derivados de la Serie I fueron mejores inhibidores de cruzipaina que los de la Serie II. A fin de racionalizar la actividad frente a cruzipaína se realizaron estudios de interacción inhibidorenzima empleando técnicas de docking y de resonancia magnética nuclear, experimentos de variación del tiempo de relajación longitudinal, experimentos DOSY y experimentos de diferencia en la transferencia de saturación, que permitieron analizar en forma detallada las interacciones de los distintos ligandos con residuos clave localizados en el sitio activo de la enzima

Cathepsin L inhibitors with activity against the liver fluke identified from a focus library of quinoxaline 1,4-di-N-Oxide derivatives

This article belongs to the Special Issue Recent Trends on Enzymes Inhibitors and Activators in Drug Research IIInfections caused by Fasciola species are widely distributed in cattle and sheep causing significant economic losses, and are emerging as human zoonosis with increasing reports of human cases, especially in children in endemic areas. The current treatment is chemotherapeutic, triclabendazole being the drug of preference since it is active against all parasite stages. Due to the emergence of resistance in several countries, the discovery of new chemical entities with fasciolicidal activity is urgently needed. In our continuous search for new fasciolicide compounds, we identified and characterized six quinoxaline 1,4-di-N-oxide derivatives from our in-house library. We selected them from a screening of novel inhibitors against FhCL1 and FhCL3 proteases, two essential enzymes secreted by juvenile and adult flukes. We report compounds C7, C17, C18, C19, C23, and C24 with an IC50 of less than 10 µM in at least one cathepsin. We studied their binding kinetics in vitro and their enzyme-ligand interactions in silico by molecular docking and molecular dynamic (MD) simulations. These compounds readily kill newly excysted juveniles in vitro and have low cytotoxicity in a Hep-G2 cell line and bovine spermatozoa. Our findings are valuable for the development of new chemotherapeutic approaches against fascioliasis, and other pathologies involving cysteine proteases

Compreendendo as formas sólidas de 5E-(feniletenil)benzofuroxano com diferente atividade anti-T. cruzi in vivo

5E-Phenylethenylbenzofuroxan (5PhEBfx) was reported as an excellent anti-Chagas drug candidate. However, its oral bioavailability was affected by the crystallization process. Two samples exhibiting variable in vivo activity was investigated: a thin yellow powder (5PhEBfx-Y) and orange needles (5PhEBfx-O). X-ray powder diffraction, differential scanning calorimetry, vibrational spectroscopy, optical and electron scanning microscopies were applied to investigate both solid forms in order to correlate the solid-state properties with the variable bioavailability of 5PhEBfx. It was observed that 5PhEBfx-Y have a better solubility and consequently higher bioavailability when compared with 5PhEBfx-O. This result suggests that the difference of activity between these two 5E-Phenylethenylbenzofuroxanes could be associated with the solid forms, which also cause the coloration variation.CAPESFINEPInstituto de Pesquisa e Desenvolvimento Institucional (IPDI)FUNCAPPrograma Sul-Americano de Apoio às Atividades de Cooperação em Ciência e Tecnologia (PROSUL) - CNPqDrugs for Neglected Diseases initiative (DNDi

Aromatic amine N-oxide organometallic compounds: Searching for prospective agents against infectious diseases

In search of prospective agents against infectious diseases, 1,1′-bis(diphenylphosphino)ferrocene pyridine-2-thiolato-1-oxide M(II) hexafluorophosphate compounds [M(mpo)(dppf)](PF6), where M = palladium or platinum, were synthesized and fully characterized in the solid state and in solution using experimental and DFT computational techniques. The compounds are isomorphous and the M(II) transition metal ions are in a nearly planar trapezoidal cis-coordination bound to the pyridine-2-thiolato-1-oxide (mpo) and to the 1,1′-bis(diphenylphosphino)ferrocene molecules, both acting as bidentate ligands. Both compounds showed high cytotoxic activity on Trypanosoma cruzi and Mycobacterium tuberculosis (MTB) and acceptable selectivities towards MTB, but good to excellent selectivity index values as anti-T. cruzi compounds. The inclusion of the ferrocene moiety (dppf ligand) improved the selectivity towards the parasite when compared to the previously reported [M(mpo)2] complexes. Related to the probable mechanism of action of the complexes, molecular docking studies on modelled T. cruzi NADH-fumarate reductase (TcFR) predicted that both be very good inhibitors of the enzyme. The effect of the compounds on the enzyme activity was experimentally confirmed using T. cruzi protein extracts. According to all obtained results, both [M(mpo)(dppf)](PF6) compounds could be considered prospective anti-trypanosomal agents that deserve further research.Fil: Rodríguez Arce, Esteban. Universidad de la República; UruguayFil: Mosquillo, M. Florencia. Universidad de la República; UruguayFil: Pérez Díaz, Leticia. Universidad de la República; UruguayFil: Echeverría, Gustavo Alberto. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Departamento de Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; ArgentinaFil: Piro, Oscar Enrique. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Departamento de Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; ArgentinaFil: Merlino, Alicia. Universidad de la República; UruguayFil: Coitiño, E. Laura. Universidad de la República; UruguayFil: Maríngolo Ribeiro, Camila. Universidade Estadual Paulista Julio de Mesquita Filho; BrasilFil: Leite, Clarice Q. F.. Universidade Estadual Paulista Julio de Mesquita Filho; BrasilFil: Pavan, Fernando R.. Universidade Estadual Paulista Julio de Mesquita Filho; BrasilFil: Otero, Lucía. Universidad de la República; UruguayFil: Gambino, Dinorah. Universidad de la República; Urugua

Novel and selective Rhipicephalus microplus triosephosphate isomerase inhibitors with acaricidal activity

The cattle tick Rhipicephalus microplus is one of the most important ectoparasites causing significant economic losses for the cattle industry. The major tool of control is reducing the number of ticks, applying acaricides in cattle. However, overuse has led to selection of resistant populations of R. microplus to most of these products, some even to more than one active principle. Thus, exploration for new molecules with acaricidal activity in R. microplus has become necessary. Triosephosphate isomerase (TIM) is an essential enzyme in R. microplus metabolism and could be an interesting target for the development of new methods for tick control. In this work, we screened 227 compounds, from our in-house chemo-library, against TIM from R. microplus. Four compounds (50, 98, 14, and 161) selectively inhibited this enzyme with IC50 values between 25 and 50 M. They were also able to diminish cellular viability of BME26 embryonic cells by more than 50% at 50 M. A molecular docking study showed that the compounds bind in different regions of the protein; compound 14 interacts with the dimer interface. Furthermore, compound 14 affected the survival of partially engorged females, fed artificially, using the capillary technique. This molecule is simple, easy to produce, and important biological data—including toxicological information—are available for it. Our results imply a promising role for compound 14 as a prototype for development of a new acaricidal involving selective TIM inhibition

Development of second generation amidinohydrazones, thio- and semicarbazones as Trypanosoma cruzi-inhibitors bearing benzofuroxan and benzimidazole 1,3-dioxide core scaffolds

Peer Reviewe