DNA damage induced by an extract of Mangifera indica stem bark using in vitro Comet assay / Daño inducido al ADN por un extracto de la corteza de Mangifera indica mediante un ensayo Cometa in vitro

The aqueous standard extract of Mangifera indica L stem bark (MSBE) is used as a food supplement in Cuba. In this study, the genotoxic effect of MSBE was measured using different variants of the in vitro Comet assay in human lymphocytes and rat hepatocytes incubated with MSBE at 37C for 1 hour. Lymphocytes were incubated with MSBE for the subcellular (at two different pH conditions) and the standard Comet assays, in presence of catalase or S9 microsomal fraction. Hydrogen peroxide, benzo(a)pirene and UV radiation were used as positive controls. Results from standard and subcellular Comet assays clearly showed that MSBE (50 ug/mL) induced primary DNA damage to lymphocytes. This genotoxic effect was slightly reduced when lymphocytes were incubated with MSBE plus catalase, which suggests that hydrogen peroxide is involved in this DNA injury. S9 fraction also decreased MSBE-induced damage to DNA in human lymphocytes. Not genotoxic effect was observed when rat hepatocytes were exposed at MSBE, suggesting that the metabolic activity can be involved in the elimination of the DNA damage generated by the MSBE. In conclusion, MSBE causes primary DNA injury of human lymphocytes in vitro Comet assay, but not in rat hepatocytes in similar conditions.

El extracto acuoso de la corteza de Mangifera indica L. (MSBE) es usado como suplemento alimenticio en Cuba. En este estudio se determinaron los efectos genotóxicos de MSBE mediante diferentes variantes del ensayo Cometa in vitro en linfocitos humanos y hepatocitos de rata incubados con MSBE a 37C por 1 hora. Los linfocitos fueron incubados con MSBE para la realización de los ensayos Cometa subcelular (a dos condiciones de pH diferentes) y estándar, en presencia de catalasa o fracción microsomal S9. Peróxido de hidrógeno, benzo(a)pireno y radiación UV fueron usados como controles positivos. Los resultados de los ensayos Cometa, tanto subcelular como estándar, mostraron que MSBE (50 ug/mL) indujo daño primario al ADN de los linfocitos. Este efecto genotóxico fue ligeramente reducido cuando las células fueron incubadas con MSBE más catalasa, lo que sugiere que el peróxido de hidrógeno está involucrado en este daño al ADN. La fracción S9 también decreció el daño inducido por MSBE al ADN en linfocitos humanos. No fueron observados efectos genotóxicos cuando los hepatocitos de rata fueron expuestos a MSBE, sugiriendo que la actividad metabólica pudiera estar involucrada en la eliminación del daño al ADN generado por MSBE. En conclusión, MSBE causa daño primario al ADN de linfocitos humanos en el ensayo Cometa in vitro, pero no en hepatocitos de rata bajo condiciones similares.

Antimutagenic properties of Mangifera indica L. stem bark extract and evaluation of its effects on hepatic CYP1A1.

Mangifera indica stem bark extract (MSBE) is a Cuban natural product which has shown strong antioxidant properties. In this work, the antimutagenic effect of MSBE was tested against 10 well-known mutagens/carcinogens in the Ames test in the absence or presence of metabolic fraction (S9). The chemical mutagens tested included: cyclophosphamide, mitomycin C, bleomycin, cisplatin, dimethylnitrosamine (DMNA), benzo[a]pyrene (BP), 2-acetylaminofluorene (2-AAF), sodium azide, 1-nitropyrene (1-NP) and picrolonic acid. Protective effects of the extract were also evaluated by comparing the efficiency of S9 fraction obtained from rats treated during 28 days with oral doses of MSBE (50-500 mg/kg) with that obtained from rats treated with vehicle (control) to activate bleomycin and cyclophosphamide in the Ames test. MSBE concentrations between 50 and 500 µg/plate significantly reduced the mutagenicity mediated by all the chemicals tested with the exception of sodium azide. Higher mutagenicity was found when bleomycin and cyclophosphamide (CP) were activated by control S9 than by MSBE S9. In addition, inhibition of CYP1A1 microsomal activity was observed in the presence of MSBE (10-20 µg/ml). We can conclude that besides its potent antioxidant activity previously reported, MSBE may also exert a chemoprotective effect due to its capacity to inhibit CYP activity.