New Organotin (IV) Compounds Derived from Dehydroacetic Acid and Thiosemicarbazides: Synthesis, Rational Design, Cytotoxic Evaluation, and Molecular Docking Simulation.

Organotin complexes were prepared through a one-pot reaction with three components by reacting thiosemicarbazide or 4-methyl-3-thiosemicarbazide or 4-phenylthiosemicarbazide, dehydroacetic acid (DHA) and dibutyl, diphenyl, dicyclohexyl, and bis[(trimethylsilyl)methyl]tin(IV) oxides; all complexes were characterized by infrared (IR), ultraviolet-visible (UV-vis), mass spectrometry (MS), and nuclear magnetic resonance (NMR) spectroscopy. The 119Sn NMR revealed chemical shifts corresponding to a pentacoordinated environment in solution. The X-ray crystallography of the two complexes evidenced the formation of monomeric complexes with a pentacoordinated geometry around tin via three donor atoms from the ligand, the sulfur of the thiol, the nitrogen of the imine group, and the oxygen of the pyran ring. The geometries of the five-coordinated complexes 3a (Bu2SnL3), 3c (Ph2SnL3), and 3d (Cy2SnL3) acid were intermediate between square pyramidal and trigonal bipyramidal, and complex 1a (Bu2SnL1) adopted a bipyramidal trigonal geometry (BPT). The sulforhodamine B assay assessed the cytotoxicity of organotin(IV) complexes against the MDA-MB-231 and MCF-7 (human mammary adenocarcinoma) cell lines and one normal COS-7 (African green monkey kidney fibroblast). The IC50 values evidenced a significant antiproliferative effect on cancer cells; the complexes were more potent than the positive cisplatin control and the corresponding ligands, dehydroacetic acid thiosemicarbazone (L1), dehydroacetic acid-N(4)-methylthiosemicarbazone (L2), and dehydroacetic acid-N(4)-phenylthiosemicarbazone (L3). The IC50 values also indicated that the organotin(IV) complexes were more cytotoxic against the triple-negative breast cell line MDA-MB-231 than MCF-7, inducing significant morphological alterations. The interactions of organotin(IV) 1c (Ph2SnL1), 1d (Cy2SnL1), and 1e (((CH3)3SiCH2)2SnL1) were evaluated with ss-DNA by fluorescence; intensity changes of the fluorescence were indicative of the displacement of ethidium bromide (EB), confirming the interaction of the organotin(IV) complexes with ss-DNA; the results showed a DNA binding affinity. The thermodynamic parameters obtained through isothermal titration calorimetry showed that the interaction of 1c (Ph2SnL1), with ss-ADN, was exothermic. Molecular docking studies also demonstrated that the organotin(IV) complexes were intercalated in DNA by conventional hydrogen bonds, carbon-hydrogen bonds, and π-alkyl interactions. These complexes furthermore showed a greater affinity towards DNA than cisplatin.

Differential activity on trypanosomatid parasites of a novel recombinant defensin type 1 from the insect Triatoma (Meccus) pallidipennis.

Defensins are one of the major families of antimicrobial peptides (AMPs) that are widely distributed in insects. In Triatomines (Hemiptera: Reduviidae) vectors of Trypanosoma cruzi the causative agent of Chagas disease, two large groups of defensin isoforms have been described: type 1 and type 4. The aim of this study was to analyze the trypanocidal activity of a type 1 recombinant defensin (rDef1.3) identified in Triatoma (Meccus) pallidipennis, an endemic specie from México. The trypanocidal activity of this defensin was evaluated in vitro, against the parasites T. cruzi, T. rangeli, and two species of Leishmania (L. mexicana and L. major) both causative agents of cutaneous leishmaniasis. Our data demonstrated that the defensin was active against all the parasites although in different degrees. The defensin altered the morphology, reduced the viability and inhibited the growth of T.cruzi. When tested against T. rangeli (a parasite that infects a variety of mammalian species), stronger morphological effects where observed. Surprisingly the greatest effects were observed against the two Leishmania species, of which L. major was the parasite most affected with 50% of dead cells or with damaged membranes, in addition of a reduction in its proliferative capacity in culture. These results suggest that rDef1.3 has an important antimicrobial effect against trypanosomatids which cause some of the more important neglected tropical diseases transmitted by insect vectors.

Haemosporidian prevalence, parasitaemia and aggregation in relation to avian assemblage life history traits at different elevations.

The transmission of vector-borne protozoa such as parasites of the Order Haemosporida is dependent on both biotic and abiotic factors such as host life history traits and environmental conditions. This study aimed to identify the variables that determine haemosporidian prevalence, parasitaemia and aggregation within the context of elevation and avian life history traits in Central Veracruz, Mexico. We sampled 607 birds from 88 species; we used microscopy and the mtDNA cytochrome b gene to detect parasites. We found an overall prevalence of 32.3%. Haemosporidian prevalence was 21.6% in tropical sub-deciduous forest (at sea level), 38% in tropical deciduous forest (265 m above sea level (asl)), 19.4% in montane cloud forest (1630 m asl), and 51.7% in pine-oak forest (2790 m asl). The prevalence of each parasite genus was strongly influenced by elevation (a proxy of habitat type). Plasmodium showed the highest prevalence at low elevation. Haemoproteus increased in prevalence with elevation. Leucocytozoon displayed the highest prevalence at the highest elevation (pine-oak forest). Haemoproteus spp. and Leucocytozoon spp. prevalences were higher in open cup than in closed nests. Haemoproteus prevalence and haemosporidian parasitaemia were lower in solitary birds than birds with pairing and gregarious behavior. Haemosporidian aggregation decreased with elevation, yielding the significantly lowest values at the pine-oak forest. Elevation distribution patterns of prevalence for each genus were similar to those previously reported in other geographical areas (e.g., South America, Europe).

Mammea type coumarins isolated from Calophyllum brasiliense induced apoptotic cell death of Trypanosoma cruzi through mitochondrial dysfunction, ROS production and cell cycle alterations.

Chagas Disease is a neglected tropical disease caused by the protozoan parasite Trypanosoma cruzi which affects 6-8 million people, mostly in Latin America. The medical treatment is based on two nitroimidazole compounds, which have limited effectiveness in the chronic phase of the disease and produce several adverse effects; consequently, there is an urgent need to develop new, safe, and effective drugs. Previous reports had shown that natural coumarins, especially mammea A/BA isolated from the tropical tree Calophyllum brasiliense, is a promissory molecule for developing new drugs, due to its potent activity, higher than benznidazole, selectivity, and its low toxicity in mice. However, its mode of action is still unknown. In the present work, we evaluated the mechanism of action of the coumarin mammea A/BA (93.6%), isolated from the tropical tree C. brasiliense on Querétaro strain (Tc1) of T. cruzi. This compound was tested in vitro on epimastigotes and trypomastigotes of T. cruzi for intracellular esterase activity, plasma membrane integrity, phosphatidylserine exposure, ROS production, mitochondrial membrane potential, caspase-like activity, DNA integrity, cell cycle and autophagy. Mammea A/BA showed a 50% lethal concentration (LC50) of 85.8 and 36.9 µM for epimastigotes and trypomastigotes respectively. It affected intracellular esterase activity, produced important plasma membrane damage and induced phosphatidylserine exposure. An increase in reactive oxygen species (ROS) and decrease in mitochondrial membrane potential were detected. Caspase-like activity was present in both parasite forms producing DNA integrity damage. This compound also induced a cell cycle arrest in the G1 phase and the presence of autophagy vacuoles. The above data suggest that mammea A/BA induce cell death of T. cruzi by autophagy and apoptosis-like phenomena and support our suggestion that mammea A/BA could be a promising molecule for the development of new drugs to treat Chagas Disease.

Coumarins isolated from Calophyllum brasiliense produce ultrastructural alterations and affect in vitro infectivity of Trypanosoma cruzi.

BACKGROUND: The current drugs for Chagas Disease caused by the protozoan Trypanosoma cruzi have limited therapeutic potential and are associated with serious side effects. Natural products can aid to develop new chemotherapeutic agents. Several natural coumarins, especially Mammea A/BA, have shown significant activity against T. cruzi and low toxicity on human lymphocytes, but its effectivity on a wide range of strains need to be tested, as well as to deepen in their mode of action and safety. HYPOTHESIS/PURPOSE: To discern the effects and explore the action mechanisms of mammea A/BA and a mixture of mammea coumarins isolated from Calophyllum brasiliense on Mexican strains of T. cruzi belonging to different genotypes and compare its effectivity with the drug benznidazole. STUDY DESIGN: We evaluated the trypanocidal activity in vitro of mammea A/BA (93.6%), and a mixture of coumarins, mammea A/BA + A/BB + A/BD (86:10:1%) on Mexican T. cruzi strains belonging to different genotypes Ninoa, Querétaro (TcI) and Ver6 (TcVI). MATERIAL AND METHODS: Mammea A/BA and the mixture of coumarins, were isolated from Calophyllum brasiliense, identified by proton NMR and purity determined by HPLC. The in vitro trypanocidal activity was evaluated on mobility, growth recovery, morphology and infectivity of T. cruzi. The cytotoxicity on mammalian cells was compared with benznidazole. The ultrastructure of the treated epimastigotes was analyzed by transmission electron microscopy (TEM). RESULTS: Mammea A/BA and the mixture of coumarins showed high trypanocidal activity, affecting the mobility, growth recovery, morphology, ultrastructure of epimastigotes, and drastically reduce trypomastigotes infectivity on Vero cells. These substances were four times more potent than benznidazole and showed low cytotoxicity and high selectivity index. The TEM showed severe alterations on the plasmatic membrane, nuclear envelope, as well as, mitochondrial swelling, that leads to the death of parasites. CONCLUSION: Mammea A/BA (93.6%) and a mixture of mammea A/BA + A/BB and A/BD (86: 10: 1%) isolated from the tropical tree C. brasiliense showed higher trypanocidal activity than the current drug benznidazole on three Mexican strains of T. cruzi. These compounds induced severe physiological and morphological alterations. These results suggest their possible use in preclinical studies.

Computational Methods to Discover Compounds for the Treatment of Chagas Disease.

Infectious diseases continue to be a major public health. Among these diseases, American trypanosomiasis or Chagas disease (CD) is a major cause of morbidity and death for millions of people in Latin America. The two drugs currently available for the treatment of CD have poor efficacy and major side effects. Thus, there is a pressing need to develop safe and effective drugs against this disease. Herein we review the diversity and coverage of chemical space of compounds tested as inhibitors of Trypanosoma cruzi, a parasite causing CD. We also review major molecular targets currently pursued to kill the parasite and recent computational approaches to identify inhibitors for such targets.

Evaluación económica de dos variaciones de un tratamiento lactoinductor en vaquillas de reemplazo en un sistema de doble propósito tropical / Economic evaluation of two variations of a hormonal induction treatment in replacement heifers in a tropical dual purpose system

The aim of this study was to evaluate the productivity and profitability of two commercial sources of progesterone therapy as part of a hormonal induction treatment in a heifer dual purpose herd. A second objective was to determine the productivity and profitability of a recombinant bovine somatotropin (ST) application during induced lactation. Forty four Holstein heifers x Zebu crosses were used. Four treatments and two control groups were evaluated. For economic analysis all components of total cost (TC) of the companies were considered, further there was a simulation which was designed for three natural lactations after the hormonal induction, based on two scenarios in which different body weights were considered as different periods. Artificial induction of lactation yielded a 100% success rate in the four groups of animals with no statistical differences between them (P > 0.05). The best cost-benefit ratio (CBR) was recorded by CIDR treatment without ST. Although the four treatments showed economic viability, those without ST had a better ratio (B / C) than those supplemented with ST. As for the net present value (NPV), the benefits updated showed that the profits were higher when ST was not applied and, mainly, in the CIDR treatment. The internal rate of return (IRR) reveals that most of the treatments have a yield above 20%.

Los objetivos del presente trabajo fueron: 1) evaluar la productividad y rentabilidad de dos fuentes comerciales de progesterona como integrantes de un tratamiento lactoinductor en vaquillas de reemplazo de un hato de doble propósito y 2) determinar la productividad y rentabilidad de la aplicación de somatotropina bovina recombinante (ST) durante la lactación inducida. Se usaron 44 novillonas producto de cruzas Holstein x Cebú. Se evaluaron cuatro tratamientos y se manejaron dos grupos testigo. Para el análisis económico se consideraron todos los componentes del costo total (CT) de las empresas, adicionalmente se realizó una simulación en la que se proyectó para tres lactaciones naturales posteriores a la lactoinducción, basadas en dos escenarios en los que se consideraron diferentes pesos corporales como diferentes periodos. En los cuatro grupos de animales lactoinducidos, el 100% de las vaquillas respondió al tratamiento sin diferencias estadísticas entre ellas (P > 0.05). La mejor relación beneficio-costos (RBC) la registró el tratamiento CIDR sin ST. Si bien los cuatro tratamientos presentaron viabilidad económica, los tratamientos sin ST presentaron mejor relación (beneficio/costo) que aquellos tratamientos que sí fueron complementados con ST. En cuanto al valor actual neto (VAN), los beneficios actualizados de todos los años muestran que las utilidades que generaron los tratamientos fueron superiores cuando no se aplicó ST y, principalmente, en el tratamiento con CIDR. La tasa interna de rentabilidad (TIR) revela que la mayoría de los tratamientos tienen una rentabilidad arriba del 20%.