In vitro and in vivo studies of the utility of dimethyl and diethyl carbaporphyrin ketals in treatment of cutaneous leishmaniasis.

Carbaporphyrin ketals are porphyrinoid compounds in which a pyrrole ring of a typical porphyrin macrocycle has been replaced by a ketal-substituted indene ring. It was recently demonstrated that these compounds are effective in vitro against Leishmania tarentolae. Their in vitro effectiveness is increased when they are exposed to visible light; they act as photosensitizers capable of mediating the production of reactive oxygen species (ROS). Following on this evidence, the effectiveness and cytotoxicity of the dimethyl and diethyl carbaporphyrin ketals (CKOMe and CKOEt, respectively) were determined in vitro using pathogenic Leishmania species with and without exposure to visible light (2 and 4 h). The effectiveness against various pathogenic Leishmania species was determined to be in a micromolar range. Additionally, the effect of encapsulating the carbaporphyrin ketals in liposome formulations was tested. Liposomal delivery diminished their toxicity, while the effectiveness was enhanced upon exposure to visible light (photodynamic effect). The cytotoxicity levels for human U937 cells and hamster peritoneal macrophages were in the ranges of 0.3 to 9 µM and 7 to 330 µM, respectively. When tested in vivo, using a hamster (Mesocricetus auratus) model of cutaneous leishmaniasis, CKOMe was active even in the dark, suggesting that the compound, once metabolized in the animal tissue, produces an active ingredient that does not seem to be photosensitive. Reduction in lesion size, histopathologic analyses, and smears confirmed the in vivo effectiveness of the compound, since the parasitic load was diminished without noticeable toxic effects.

Leishmania tarentolae: utility as an in vitro model for screening of antileishmanial agents.

Primary screens for antileishmanial compounds use Leishmania species pathogenic to humans that must be handled under biosafety conditions that cannot be adopted or guaranteed everywhere. Leishmania tarentolae, a parasite isolated from the gecko Tarentolae annularis, has not been considered pathogenic to humans. Promastigotes of L. tarentolae have been previously used as a eukaryotic expression system for the production of recombinant proteins and in the amplification of genes involved in resistance to antileishmanial drugs. To validate the use of this Leishmania species in the screening of antileishmanial drugs, the sensitivity of axenic and intracellular amastigotes of L. tarentolae was compared to the sensitivity showed by Leishmania species causative of human leishmaniasis. The ability of L. tarentolae to grow as axenic amastigotes is first described while its ability to infect several mammalian cells has been confirmed. L. tarentolae amastigotes offer a suitable model for the in vitro screening of compounds for antileishmanial activity.

New application for expanded porphyrins: sapphyrin and heterosapphyrins as inhibitors of Leishmania parasites.

Sapphyrins and a series of related porphyrinoid macrocycles have been investigated as potential agents for the treatment of leishmaniasis. The effectiveness of the compounds was evaluated in vitro upon incubation with Leishmania tarentolae or L. panamensis amastigotes and promastigotes. Their effectiveness was also assessed against intracellular L. panamensis. The cytotoxicity of the compounds was evaluated in vitro using the U937 human promonocyte cell line. Effectiveness and cytotoxicity were assessed in the presence and absence of visible light to assess the photodynamic activity of the compounds. Sapphyrin and two related heterosapphyrins were shown to be particularly effective as inhibitors of Leishmania. A photodynamic effect was observed, which may be attributed to the formation of reactive oxygen species. Yields of singlet oxygen ((1)O(2)) produced were determined in ethanol solutions by direct measurement of (1)O(2) phosphorescence. Confocal microscopy demonstrated that sapphyrin and related macrocycles were taken up by the Leishmania cells and that their presence induces the formation of mitochondrial superoxide. Sapphyrins have been widely investigated as anticancer agents and we here show activity against the Leishmania parasites.

Association of acenaphthoporphyrins with liposomes for the photodynamic treatment of leishmaniasis.

Acenaphthoporphyrins are potential photosensitizers for photodynamic therapy, but their hydrophobicity limits their potential. Liposomes have been widely investigated as delivery vehicles that can transport hydrophobic drugs in biological systems. Here we study the association of acenaphthoporphyrins with liposomes made up of dimyristoyl phosphatidylcholine (DMPC), and to liposomes made up of a mixture of DMPC, cholesterol (Chol) and distearoyl phosphatidylglycerol (DSPG) in a 2:1:0.8 molar ratio to evaluate how liposome composition affects association constants. In liposomes consisting only of DMPC, the smaller monoacenaphthoporphyrin had the largest association constant of 5.5 x 10(4) m(-1) while the larger adj-diacenaphthoporphyrin and opp-diacenaphthoporphyrin (ODP) had smaller association constants at 1.8 x 10(4) and 1.5 x 10(4) m(-1), respectively. The addition of liposomal Chol and DSPG has little effect on the magnitudes of the association constants. Polarization studies show that the acenaphthoporphyrins are driven far into the lipid bilayer to minimize polar-nonpolar interactions. Confocal microscopy confirms that the DMPC liposomes transport the porphyrins into promastigotes of Leishmania tarentolae. The compounds associated with DMPC:Chol:DSPG liposomes are effective in vitro against axenic and intracellular amastigotes of the pathogenic Leishmania panamensis. The effectiveness of the compounds is enhanced upon exposure of cultures to visible light.

Fototerapia para el tratamiento de la leishmaniasis cutánea / Phototherapy in treatment of cutaneous leishmaniasis

La leishmaniasis es una enfermedad endémica en 98 países, con más de 350 millones de personas en riesgo de adquirir la infección y 12 millones de casos. Los antimonios pentavalentes, la anfotericina B y la miltefosina han sido el tratamiento de elección para todas las formas de leishmaniasis. Sin embargo, desventajas como el alto costo, la duración del tratamiento y los efectos tóxicos asociados, promueven la falta de cumplimiento del tratamiento o su abandono y la aparición de cepas resistentes o poco sensibles al medicamento. Estos factores han estimulado la búsqueda de alternativas terapéuticas que sean económicas, sin efectos adversos y con resultados cosméticos favorables. La fototerapia es un procedimiento en el cual un agente fotosensibilizador, al ser activado por luz da lugar a la producción de especies reactivas del oxígeno. Este tratamiento utilizado en varias formas de cáncer, herpes y otras enfermedades e infecciones localizadas, surge como una prometedora estrategia para la leishmaniasis cutánea, con amplias ventajas como bajo costo, fácil manejo y resolución total de la lesión, haciéndola favorable frente a otras alternativas de manejo de la enfermedad.

Leishmaniasis is an endemic disease in 98 countries around the world, with 12 million cases and more than 350 million people at risk of acquiring infection. Available drugs such as pentavalent antimony, amphotericin B and miltefosine, have been the treatment of choice for all clinical forms of leishmaniasis. However, disadvantages such as high cost, duration of treatment and toxicity, promote non-adherence or neglect of treatment and the emergence of resistant or less sensitive to medicine. These problems have stimulated the search of new therapeutic alternatives that are affordable, without adverse effects and favorable cosmetic results. Phototherapy is a procedure in which an agent photosensitizer when activated by light leads to production reactive oxygen species. This therapy used in the treatment of various forms of cancer, herpes and other and localized infectious diseases, is emerging as a promising strategy for the treatment of cutaneous leishmaniasis with large advantages such as low cost, easy handling and total resolution injury, becoming a very promising alternative compared to the traditional treatment approaches.