Synthesis and characterization of a pyridine-2-thiol N-oxide gold(I) complex with potent antiproliferative effect against Trypanosoma cruzi and Leishmania sp. insight into its mechanism of action.

In the search for new therapeutic tools against parasitic diseases caused by the Kinetoplastids Leishmania spp. and Trypanosoma cruzi, a novel gold(I) triphenylphosphine complex with the bioactive coligand pyridine-2-thiol N-oxide (mpo) was synthesized and characterized by using analytical and conductometric measurements, electrospray ionization-mass spectrometry (ESI) and electronic, FTIR and (1)H and (31)P NMR spectroscopies. A dinuclear structure is suggested for the complex. At a 1 microM concentration the complex induced in vitro after 30 min a potent leishmanicidal effect (LD(50)) against promastigotes of Leishmania (L.) mexicana while on Leishmania (V.) braziliensis with the same concentration only a leishmanistatic effect (IC(75)) was observed 48 h after treatment. Similar differential susceptibilities were also found when testing the ligand mpo, but at a higher dose (5 microM). In addition, the compound showed growth inhibitory effect on Dm28c T. cruzi epimastigotes in culture (IC(50) 0.09 microM), being even more active than the anti-trypanosomal reference drug Nifurtimox (IC(50) 6 microM). DNA interaction studies showed that this biomolecule does not constitute a main target for the mpo complex currently tested. Instead, the significant potentiation of the antiproliferative effect against both Leishmania species and T. cruzi could be associated to the inhibition of NADH fumarate reductase, a kinetoplastid parasite-specific enzyme absent in the host. Furthermore, due to its low unspecific cytotoxicity on mammalian cells (J774 macrophages), the new gold complex showed a selective anti-parasite activity. It constitutes a promising new potent chemotherapeutic alternative to be evaluated in vivo in experimental models of leishmaniasis and Chagas disease.

Synthesis and characterization of platinum-sterol hydrazone complexes with biological activity against Leishmania (L.) mexicana.

Leishmaniasis is a parasitic zoonosis caused by protozoans of the genus Leishmania transmitted by insects known as phlebotomines, which are found in wild or urban environments. The disease occurs in tropical and sub-tropical areas, mainly in Asia, Europe, Africa and the Americas. At present, there is no effective treatment for this disease. In the search for new rational chemotherapeutic alternatives, two novel trans [Pt(Hpy1)(2)(Cl)(2)] (1) and trans [Pt(Hpy2)(2) (Cl)(2)] (2) complexes were synthesized by the reaction of K(2)PtCl(4) with sterol hydrazone ligands 20-hydrazone-pyridin-2-yl-5alpha-pregnan-3beta-ol (Hpy1) and 22-hydrazone-pyridin-2-yl-chol-5-ene-3beta-ol (Hpy2). These organic compounds are specific inhibitors of sterol methyl transferase (SMT). The new platinum complexes were characterized by a combination of ESI-MS (electrospray ionization-mass spectroscopy), UV-vis, infrared and NMR spectroscopies; elemental analysis and molar conductivity. Promastigotes of Leishmania (L.) mexicana were treated for 48 h with 10 microM of the sterol hydrazones Hpy1 or Hpy2 alone or coordinated to Pt. Hpy1 produced higher leishmanistatic activity than Hpy2 (39% growth inhibition vs. 16%), which significatively increased (71%, p<0.001) when the complex trans-[Pt(Hpy1)(2)(Cl)(2)] was used. This complex represents a new chemotherapeutic alternative to be evaluated in depth in experimental models of leishmaniasis.

Synthesis and characterization of [Au(dppz)2]Cl3. DNA interaction studies and biological activity against Leishmania (L) mexicana.

[Au(dppz)(2)]Cl(3) was synthesized by the reaction of HAuCl(4) in excess of the dypirido[3,2-a: 2,3-c]phenazine (dppz) ligand. This complex was characterized by elemental analysis, fast atom bombardment (FAB) mass, NMR, UV-visible and IR spectroscopies. DNA-gold complex interactions were studied by spectroscopic titrations, viscosity measurements and electrophoretical assays. These studies showed that the gold complex interacts with DNA by intercalation mode. These observations, led us to carry out biological tests on cultures of promastigotes of Leishmania (L) mexicana. [Au(dppz)(2)]Cl(3) induced a dose dependent antiproliferative activity with minimal inhibitory concentration (MIC) of 3.4nM and lethal doses LD(26) of 17nM for 48h. These findings suggest that a very potent leishmanicidal activity could be associated to the cellular processes involving parasite DNA, constituting a new promising chemotherapeutic alternative in the search for definitive leishmaniasis cure.

New silver polypyridyl complexes: synthesis, characterization and biological activity on Leishmania mexicana.

Leishmania parasites are the causal agents of leishmaniasis that currently threatens 350 million people in 88 different countries, in the absence of an effective drug. In order to continue the development of transition metal complexes with planar ligands that show interactions with DNA and activity against Leishmania parasites, the synthesis of the complexes [Ag(dpq)2]NO3 (1) and [Ag(dppz)2]NO3 (2), which were obtained by the reaction of silver nitrate with dpq and dppz, respectively, in a 1:2 molar ratio is reported. These complexes were characterized by elemental analysis and 1H-NMR, IR, and UV-vis spectroscopies. The most probable structure for these complexes is tetrahedral, with two molecules of ligand coordinated to the silver atom and a nitrate as a counter ion. Affinity studies of DNA vs. bovine albumin were carried out, and a strong interaction of the complexes with DNA was observed. Bioassays were undertaken in vitro on promastigotes of Leishmania (L.) mexicana exposed to the silver complexes for 48 h. At 10 micromol/L complex 2 induced a leishmanicidal effect (LD23), whilst complex 1 reduced the parasites growth rate by 55% (LD55). These findings suggest that biological activity could be associated with the interaction of the complexes with the parasitic DNA.

Relación entre la helmintiasis intestinal y el estado nutricional-hematológico en niños de una escuela rural en el estado Sucre Venezuela / Relantionship between intestinal helminthiasis and Nutritional-haematologic status on rural schoolchildren at Sucre state Venezuela

Se realizó una evaluación parasitológica, nutricional y hematológica en 103 niños de ambos sexos, entre 4-12 años de una escuela rural en Santa Fe, estado Sucre, Venezuela, durante el período enero-marzo 2003. Las muestras de heces se analizaron mediante un examen al fresco, Willis-Malloy y Kato-Katz cuantitativo. El estado nutricional se determinó utilizando la combinación de los índices antropométricos. Los parámetros hematológicos fueron evaluados por los métodos clásicos, y el grado de eosinofilia se expresó en valores absolutos de eosinófilos. 93,2 por ciento de los escolares estaban parasitados, presentando elevado poliparasitismo (83,3 por ciento). La prevalencia de helmintos intestinales fue de 82, por ciento, destacando la asociación de Trichuris trichiura y Ascaris lumbricoides (69,4 por ciento) y predominando una intensidad de infestación leve. De los individuos con desnutrición, el 91,2 por ciento (31/34) tenían helmintiasis. En 97,6 por ciento de los escolares infestados por helmintos se encontró eosinofilia (p<0,001). Del 23,3 por ciento de los niños con anemia, 83,3 por ciento (20/24) presentaron helmintiasis. El 88,8 por ciento de los niños con helmintiasis intestinal pertenecían al estrato socioeconómico V. Estos hallazgos sugieren que la población escolar evaluada habita en una zona hiperendémica de helmintos, consistente con el estrato socioeconómico encontrado. Adicionalmente, se estableció que la eosinofilia en estos escolares es un factor asociado a la helmintiasis intestinal

Synthesis, characterization, DNA binding study and biological activity against Leishmania mexicana of [Cu(dppz)2]BF4.

[Cu(dppz)(2)]BF(4) complex has been synthesized by the reaction of [Cu(CH(3)CN)(4)]BF(4) and dipyrido[3,2-A:2',3'-c]phenazine (dppz) in a molar ratio of 1:2. The compound was characterized by fast atom bombardment mass spectrometry, 1H nuclear magnetic resonance, UV-Vis and IR spectroscopies. Absorption and viscometric studies carried out on the interaction of [Cu(dppz)(2)]BF(4) complex with calf thymus DNA suggested that the complex binds by intercalation. No covalent binding was observed. Additionally, the results obtained from electrophoresis showed nuclease activity. The biological activity of the complex was tested in vitro on Leishmania mexicana promastigote cultures. A leishmanicidal effect (LD(30)) was observed in 48 h at concentration of 41 nM. Preliminary studies of the ultrastructure of L. mexicana treated with a sublethal dose of the complex (IC(7)=4.1 nM) for 48 h showed an induction of cytoplasm disorganization, vacuolization and binucleated cells. These findings suggest that the leishmanicidal activity of the title complex could be associated with its interaction with the parasitic DNA.

Design of copper DNA intercalators with leishmanicidal activity.

The complexes [Cu(dppz)(NO(3))]NO(3) (1), [Cu(dppz)(2)(NO(3))]NO(3) (2), [Cu(dpq)(NO(3))]NO(3) (3), and [Cu(dpq)(2)(NO(3))]NO(3) (4) were synthesized and characterized by elemental analysis, FAB-mass spectrometry, EPR, UV, and IR spectroscopies, and molar conductivity. DNA interaction studies showed that intercalation is an important way of interacting with DNA for these complexes. The biological activity of these copper complexes was evaluated on Leishmania braziliensis promastigotes, and the results showed leishmanicidal activity. Preliminary ultrastructural studies with the most active complex (2) at 1 h revealed parasite swelling and binucleated cells. This finding suggests that the leishmanicidal activity of the copper complexes could be associated with their interaction with the parasitic DNA.

Inhibition of Paracoccidioides brasiliensis by ajoene is associated with blockade of phosphatidylcholine biosynthesis.

In Paracoccidioides brasiliensis, a dimorphic fungus pathogenic for humans, no significant differences were observed in the phospholipid species of both morphological phases. The species observed were phosphatidylcholine (PC, 30-40%), phosphatidylethanolamine (PE, 27-28%), phosphatidylserine (16-19%), phosphatidylinositol (13-17%) and sphingomyelin (3-5%). The main fatty acids found in the yeast (Y) phase were palmitate (56%), linoleate (18%) and oleate (15%), while linoleate predominated (61%) in the mycelial (M) phase, followed by palmitate (27%) and oleate (7%). In the Y phase the main free sterol was ergosta-5,22-dien-3 beta-ol (82%) plus some lanosterol (12%) and ergosterol (6%), while in the M phase, the latter predominated (88%), followed by low levels of ergosta-5,22-dien-3 beta-ol (12%). Ajoene [(E,Z)-4,5,9-trithiadodeca-1,6,11-triene 9-oxide], a platelet aggregation inhibitor derived from garlic, induced alterations in phospholipid and fatty acid proportions such that PC was reduced to about 18% in both phases and PE increased to 38% (Y phase) or 44% (M phase), suggesting inhibition of PC synthesis. Ajoene also reduced saturated fatty acids (16:0 and 18:0) from 67 to 35% in the Y phase, with a corresponding increase in the unsaturated components. This effect was not seen in the M phase.

Sinergismo en la acción antiproliferativa de inhibidores de la sintesis de esteroles sobre el trypanosoma cruzi in vitro e in vivo implicaciones terapéuticas / Sinergistic in the antiproliferative action of sterol synthesis inhibitors on in vitro and in vivo thypanosoma cruzi: therapeutic aspects

Los estudios realizados desde el punto de vista molecular, celular y organismico revelan que el Trypanosoma cruzi en su proliferación depende de la producción de esteroles endógenos. Cualquier intervención farmacológica que modifique esta ruta biosintética previene la proliferación del parásito, in vivo e in vitro. Además cuando se combinan estos agentes, ellos pueden tener acción sinergética sobre la proliferación del parásito, lo que permite pensar, que podría ser útil en el tratamiento de la Enfermedad de Chagas, sin efectos secundarios. Las combinaciones hasta ahora conocidas son el ketoconazol (Janssen) Lamisil (Sandoz) y el ketoconazol-Mevacor (Merk Sharp & Dohme). Otras combinaciones han sido evaluadas por nuestro grupo y la OMS, como el itraconazol (Janssen) que posee mayor actividad y menor toxicidad que el anterior, usándolo en combinación con la sinvastatina (Merk Sharp & Dohne) y la fluvastatina (Sandoz). Finalmente, las terapéuticas propuestas pueden ser útiles en el tratamiento de otras enfermedades parasitarias y algunas micosis sistémicas