Targeting Leishmania amazonensis amastigotes through macrophage internalisation of a hydroxymethylnitrofurazone nanostructured polymeric system.

Dextran-coated poly (n-butyl cyanoacrylate) nanoparticles (PBCA-NPs) were prepared and were evaluated for enhanced delivery of a promising anti-Leishmania drug candidate, hydroxymethylnitrofurazone (NFOH), to phagocytic cells. Currently available chemotherapy for leishmaniasis, such as pentavalent antimonials, presents low safety and efficacy. Furthermore, widespread drug resistance in leishmaniasis is rapidly emerging. To overcome these drawbacks, the use of nanosized delivery systems can reduce systemic drug toxicity and increase the drug concentration in infected macrophages, therefore improving treatment of leishmaniasis. PBCA-NPs containing NFOH (PBCA-NFOH-NPs) were prepared by an anionic emulsion polymerisation method. The z-average and polydispersity index (PDI) were determined by photon correlation spectroscopy, the zeta potential by microelectrophoresis and the entrapment efficiency by HPLC. Cytotoxicity was determined using macrophages from BALB/c mice. Efficacy tests were performed using Leishmania amazonensis promastigotes and amastigotes. The z-average of PBCA-NFOH-NPs was 151.5 ± 61.97 nm, with a PDI of 0.104 ± 0.01, a zeta potential of -10.1 ± 6.49 mV and an entrapment efficiency of 64.47 ± 0.43%. Efficacy in amastigotes revealed IC50 values of 0.33 µM and 31.2 µM for the nanostructured and free NFOH, respectively (95-fold increase). The cytotoxicity study indicated low toxicity of the PBCA-NFOH-NPs to macrophages. The selectivity index was 370.6, which is 49-fold higher than free NFOH (7.6). Such findings indicated that improved efficacy could be due to NP internalisation following site-specific drug delivery and reactivation of immune protective reactions by the NP components. Thus, PBCA-NFOH-NPs have the potential to significantly improve the treatment of leishmaniasis, with reduced systemic side effects.

A prodrug approach to improve the physico-chemical properties and decrease the genotoxicity of nitro compounds.

In therapeutics research, the nitro compounds are part of an important group of drugs with multiple pharmacological activities. However, in drug design, the inclusion of a nitro group in a molecule changes the physico-chemical and electronic properties and is associated with increased mutagenicity and carcinogenicity. In addition, several studies have related the relationship between the antimicrobial and/or anti-protozoal activity and the mutagenic effect to reduction of the nitro group. This work reviews the toxicity of nitro compounds and shows how the use of prodrugs can increase the biological activity and decrease the genotoxicity of nitro compounds, without any modification in nitro reduction behavior, but rather by physico-chemical improvement. Examples are given of metronidazole and nitrofurazone prodrugs.

Interaction between nitroheterocyclic compounds with beta-cyclodextrins: phase solubility and HPLC studies.

Chagas disease is a serious health problem for Latin America. Nitrofurazone (NF) and Hidroxymethylnitrofurazone (NFOH) are active against Trypanosoma cruzi. The effect of beta-cyclodextrin (beta-CD) and dimethyl-beta-cyclodextrin (DM-beta-CD) complexation on the UV absorption and retention time of nitrofurazone (NF) and its hydroxymethylated analog (NFOH) were studied in solution. The retention behavior was analyzed on a reversed phase C18 column and the mobile phase used was acetonitrile-water (20/80 v/v), in which cyclodextrins (beta-CD or DM-beta-CD) were incorporated as a mobile phase additive. The decrease in the retention times of NF (or NFOH) with increasing concentration of HP-beta-CD enables the determination of the complex stability constants by HPLC. A phase-solubility study was performed, according to the method reported by Higuchi and Connors, to evaluate the changes of NF/NFOH in the complexation state, and the diagrams obtained suggested that it forms complexes with a stoichiometry of 1:1. This is an important study for the characterization of potential formulations to be used as therapeutic options for the treatment of Chagas disease.

Implications of the use of semicarbazide as a metabolic target of nitrofurazone contamination in coated products.

Data from the Brazilian Agricultural Ministry show that before the implementation of the Brazilian programme of nitrofuran control in February 2003, the cases of contamination of Brazilian chicken by nitrofurans were almost exclusively due to furaltadone. After May 2003, such cases decreased until no more reports of Brazilian chicken contamination with this nitrofuran were reported. Curiously, after April 2003, an increase was observed in the numbers of contaminated samples by semicarbazide, the target metabolite of nitrofurazone. Most Brazilian chicken found to be contaminated with semicarbazide has been covered with flour, salt and spices. For this reason, the authors' laboratory initialized a programme for tracing possible sources of food contamination by semicarbazide. After several semicarbazide positives in flour of controlled origin (results varying between 2.2 and 5.2 microg kg(-1)), the different additives used in the cereal industry as flour improvement agents were studied. The results indicate that the compound azodicarbonamide was responsible for the source of the contaminant semicarbazide.

Synthesis and in vitro evaluation of potential antichagasic hydroxymethylnitrofurazone (NFOH-121): a new nitrofurazone prodrug.

The synthesis of mutual prodrugs of nitrofurazone with primaquine, using specific and nonspecific spacer groups, has been previously attempted seeking selective antichagasic agents. The intermediate reaction product, hydroxymethylnitrofurazone (NFOH-121), was isolated and tested in LLC-MK(2) culture cells infected with trypomastigotes forms of Trypanosoma cruzi showing higher trypanocidal activity than nitrofurazone and benznidazol in all stages. The mutagenicity tests showed that the prodrug was less toxic than the parent drug. Degradation assays were carried out in pH 1.2 and 7.4.

Niveles de nitrofurazona y furazolidona en alimento comercial para pollo de engorda determinados por espectrofotometría visible / Nitrofurazone and furazolidone concentrations in commercial broilers fedd measured by light spectroscopy

Se tomaron 3 muestras de tres tipos de alimentos para pollo de engorda (iniciador, desarrollo y finalizador) de 4 marcas disponibles en el valle de México (Purina, La Hacienda, Malta y Flagasa) para cuantificar fuerazolidona y nitrofurazona mediante una técnica colorimétrica. Las concentraciones se graficaron, asimismo se sujetaron a un análisis estadístico considerando: marca comercial, tipo de alimento y compuesto. Los resultados del análisis mostraron que los nitrofuranos son usados por diferentes fabricantes de alimento comercial para pollo de engorda, pero no lo indican en las etiquetas de sus productos, ni mencionan las concentraciones que manejan, aunque ninguno de los alimentos analizados superó las dosis terapéuticas recomendadas. El contenido promedio más alto de furazolidona fue de 249.84 ppm (marca Purina tipo indicador) superando el nivel máximo permitido por la Food and Drug Administration de Estados Unidos de América que de 200 ppm en alimento para pollo de engorda. Los niveles de nitrofurazona detectados no superaron la dosis terapéutica pero sí el máximo permitido 50 ppm (Purina iniciador, La Hacienda iniciador y Malta finalizador). De acuerdo al tipo de alimento, se encontró que la concentración más elevada corresponde al alimento de iniciación. Los resultados mostraron que Purina es la marca que utiliza mayores concentraciones de nitrofuranos en sus formulaciones. La sobredosis que puede causar el efecto nocivo de los nitrofuranos es factible cuando los niveles añadidos a los del granjero se le suman los del fabricante. Se encontró diferencia estadística del contenido de nitrofurano por marca, tipo de alimento y compuesto (P<0.05)