RESUMEN
Tinidazole (TNZ), a second-generation 5-nitroimidazole compound chemically related to metronidazole (MTZ), has been widely used throughout Europe and developing countries for the treatment of amoebic and parasitic infections. Despite TNZ's increasing use in therapeutics, scarce experimental reports are available in literature on its potential genotoxicity in human cells. Therefore, the aim of the present study was to achieve a precise characterization of the cytotoxic and genotoxic activities of this nitroimidazole in cultured human lymphocytes at therapeutic concentrations (0.1, 1, 10 and 50 microg/ml of culture) and evaluate the possible cell death mechanism associated with it. The endpoints analyzed included: mitotic index (MI), replication index (RI), sister chromatid exchange (SCE) and chromosomal aberrations (CA). A significant decrease (p<0.0001) in MI as well as an increase in SCE (p<0.0001) and CA (p<0.0001) frequencies were observed. No modifications in RI were found. The results suggest a genotoxic and cytotoxic effect of TNZ related with cell death process. Therefore, we evaluated this mechanism by DNA fragmentation (laddering), fluorescence microscopy using acridine orange/ethidium bromide (AO/EB) staining and flow cytometry propidium iodide (PI). DNA extracts of TNZ-treated cells resulted in nucleosomal DNA ladder pattern after 48 h of cell treatment; meanwhile no differences were detected in untreated cells. This pattern correlated with the observed decrease in cellular viability (p<0.05), morphological evidence of apoptosis and increase in the percentage of nuclei with hypodiploid DNA content of TNZ exposed cultures compared with control (p<0.05). We concluded that TNZ is genotoxic, cytotoxic and is able to modulate cell death through apoptotic mechanisms in the experimental design employed.
Asunto(s)
Alquilantes/toxicidad , Linfocitos/efectos de los fármacos , Mutágenos/toxicidad , Tinidazol/toxicidad , Adulto , Apoptosis/efectos de los fármacos , División Celular/efectos de los fármacos , Supervivencia Celular/efectos de los fármacos , Células Cultivadas , Aberraciones Cromosómicas/inducido químicamente , ADN/efectos de los fármacos , Fragmentación del ADN , Relación Dosis-Respuesta a Droga , Femenino , Humanos , Linfocitos/patología , Masculino , Microscopía Fluorescente , Índice Mitótico , Intercambio de Cromátides Hermanas/efectos de los fármacosRESUMEN
5-Nitroimidazoles are a well-established group of antiprotozoal and antibacterial agents. Thanks to their antimicrobial activity these chemotherapeutic agents inhibit the growth of both anaerobic bacteria and certain anaerobic protozoa such as Trichomonas vaginalis, Entamoeba histolytica and Giardia lamblia. The aim of the present study is to achieve a precise characterization of the genotoxic activity of these compounds and to establish the value of cytogenetic assays in order to determine the effect of these drugs, at therapeutic doses, to settle an improved risk assessment. Two nitroimidazole were studied, metronidazole and ornidazole, at four different concentrations (0.1, 1, 10 and 50 microg/ml of peripheral blood lymphocyte culture). Endpoints analyzed included: mitotic index (MI), replication index (RI), sister chromatid exchange (SCE) and chromosomal aberrations (CA). An analysis of variance test (ANOVA) was performed to evaluate the results. A significant decrease (P<0.0001) in MI as well as an increase in SCE (P<0.0001) and CA (0.0001) frequencies for both drugs was observed. No modifications in RI were found. The results suggest a genotoxic and cytotoxic effect of MTZ and ONZ in human peripheral blood cultures in vitro.
Asunto(s)
Antitricomonas/toxicidad , Aberraciones Cromosómicas/inducido químicamente , Daño del ADN , Metronidazol/toxicidad , Ornidazol/toxicidad , Adulto , Técnicas de Cultivo de Célula , División Celular/efectos de los fármacos , Relación Dosis-Respuesta a Droga , Femenino , Humanos , Linfocitos , Masculino , Mitosis/efectos de los fármacos , Pruebas de Mutagenicidad , Medición de Riesgo , Intercambio de Cromátides HermanasRESUMEN
One of the useful drugs in the treatment against infestations caused by Trichomonas vaginalis, Entamoeba histolytica and Giardia lamblia is Tinidazole (TNZ) 1-[2-(ethylsulfonyl) ethyl]-2-methyl-5-nitroimidazole) (Gilman R.H., Marquis G.S., Miranda E., Vestegui M., Martinez H., 1988. Rapid reinfection by Giardia lamblia after treatment in a hyperendemic third world community. Lancet i, 343-345). We decided to evaluate the potential genetic damage induced by TNZ using different biological biomarkers such as the mitotic index (MI), sister chromatid exchange (SCE) and cell proliferation kinetics (CPK). We observed a significant decrease (P<0.0005) in the MI as well as an increase (P<0.0005) in SCE frequency and no modifications in the replication index (RI). The results obtained suggest a potential genotoxic and cytotoxic effect of TNZ in human peripheral blood cultures in vitro.