RESUMEN
Megazol (7) is a 5-nitroimidazole that is highly active against Trypanosoma cruzi and Trypanosoma brucei, as well as drug-resistant forms of trypanosomiasis. Compound 7 is not used clinically due to its mutagenic and genotoxic properties, but has been largely used as a lead compound. Here, we compared the activity of 7 with its 4H-1,2,4-triazole bioisostere (8) in bloodstream forms of T. brucei and T. cruzi and evaluated their activation by T. brucei type I nitroreductase (TbNTR) enzyme. We also analysed the cytotoxic and genotoxic effects of these compounds in whole human blood using Comet and fluorescein diacetate/ethidium bromide assays. Although the only difference between 7 and 8 is the substitution of sulphur (in the thiadiazole in 7) for nitrogen (in the triazole in 8), the results indicated that 8 had poorer antiparasitic activity than 7 and was not genotoxic, whereas 7 presented this effect. The determination of Vmax indicated that although 8 was metabolised more rapidly than 7, it bounds to the TbNTR with better affinity, resulting in equivalent kcat/KM values. Docking assays of 7 and 8 performed within the active site of a homology model of the TbNTR indicating that 8 had greater affinity than 7.
Asunto(s)
Animales , Humanos , Masculino , Ratones , Nitrorreductasas/efectos de los fármacos , Tiadiazoles , Triazoles , Tripanocidas , Trypanosoma brucei brucei/efectos de los fármacos , Trypanosoma brucei brucei/enzimología , Ensayo Cometa , Daño del ADN/efectos de los fármacos , Activación Enzimática/efectos de los fármacos , Nitrorreductasas/metabolismo , Pruebas de Sensibilidad Parasitaria , Relación Estructura-Actividad , Tiadiazoles/química , Tiadiazoles/metabolismo , Tiadiazoles/farmacología , Tiadiazoles/toxicidad , Triazoles/química , Triazoles/metabolismo , Triazoles/farmacología , Triazoles/toxicidad , Tripanocidas/química , Tripanocidas/farmacología , Tripanocidas/toxicidad , Trypanosoma cruzi/efectos de los fármacosRESUMEN
Megazol (7) is a 5-nitroimidazole that is highly active against Trypanosoma cruzi and Trypanosoma brucei, as well as drug-resistant forms of trypanosomiasis. Compound 7 is not used clinically due to its mutagenic and genotoxic properties, but has been largely used as a lead compound. Here, we compared the activity of 7 with its 4H-1,2,4-triazole bioisostere (8) in bloodstream forms of T. brucei and T. cruzi and evaluated their activation by T. brucei type I nitroreductase (TbNTR) enzyme. We also analysed the cytotoxic and genotoxic effects of these compounds in whole human blood using Comet and fluorescein diacetate/ethidium bromide assays. Although the only difference between 7 and 8 is the substitution of sulphur (in the thiadiazole in 7) for nitrogen (in the triazole in 8), the results indicated that 8 had poorer antiparasitic activity than 7 and was not genotoxic, whereas 7 presented this effect. The determination of Vmax indicated that although 8 was metabolised more rapidly than 7, it bounds to the TbNTR with better affinity, resulting in equivalent kcat/KM values. Docking assays of 7 and 8 performed within the active site of a homology model of the TbNTR indicating that 8 had greater affinity than 7.
Asunto(s)
Nitrorreductasas/efectos de los fármacos , Tiadiazoles , Triazoles , Tripanocidas , Trypanosoma brucei brucei/efectos de los fármacos , Trypanosoma brucei brucei/enzimología , Animales , Ensayo Cometa , Daño del ADN/efectos de los fármacos , Activación Enzimática/efectos de los fármacos , Humanos , Masculino , Ratones , Nitrorreductasas/metabolismo , Pruebas de Sensibilidad Parasitaria , Relación Estructura-Actividad , Tiadiazoles/química , Tiadiazoles/metabolismo , Tiadiazoles/farmacología , Tiadiazoles/toxicidad , Triazoles/química , Triazoles/metabolismo , Triazoles/farmacología , Triazoles/toxicidad , Tripanocidas/química , Tripanocidas/farmacología , Tripanocidas/toxicidad , Trypanosoma cruzi/efectos de los fármacosRESUMEN
The feasibility of ablating differentiated adipocytes and the mechanism of cell ablation with a suitable prodrug activating system is described. The system is based on the use of E. coli nitroreductase (NTR) enzyme that activates certain nitro compounds, such as the antitumor drug CB1954, into cytotoxic DNA interstrand cross-linking agents. Differentiated preadipocyte cells (3T3L1) transfected with an aP2 driven nitroreductase construct were efficiently killed after incubation with medium containing the prodrug CB1954, while untransfected cells were not affected. It was demonstrated that the mechanism of cell ablation is apoptosis and that the system has a bystander effect mediated by a toxic metabolite of the prodrug. The described system should provide a good alternative approach for gene therapy studies and a new inducible approach to manipulating the number of cells in tissues of transgenic animals and the ability to study the recovery of the tissue from cell damage or loss.