Avaliação in vivo e in vitro da citotoxicidade, genotoxicidade e dos efeitos protetores de extratos de plantas do cerrado brasileiro

AUTOR(ES)
DATA DE PUBLICAÇÃO

2008

RESUMO

The use of plants for healing purposes is becoming increasingly popular, as soon as they are believed to be beneficial and free of side effects. However, most of information available on several medicinal herbs does not have any scientific supporting data and their use as medicaments is based simply on traditional folk. Among the plants used by the humanity as a source of medicine are those that belong to Miconia genus. Studies have shown that Miconia extracts have analgesic effects, they were active against blood trypomastigote forms of Trypanosoma and Primin, an antibiotic extracted from Miconia sp., presented strong antineoplastic action. Although several biological activities of Miconia species had been reported, no study concerning their effects on DNA (induction, reduction or prevention of mutations) has been available until the present time. The aim of the present study was to assess the cytotoxic, genotoxic and mutagenic potential of extracts from four Miconia species and also the possible protective effects of these species against the damage induced on DNA by chemotherapeutics cyclophosphamide and doxorubicin using, respectively, in acute in vivo and in vitro tests. The tests employed in vivo were comet assay and micronucleus test in mice cells. For the genotoxic evaluation, three concentrations were tested, 200, 400 and 540 mg/kg b.w., based on the solubility limit of the extract in distilled water, and for the protective effects, only the higher dose was evaluated against 40 mg/kg b.w. of cyclophosphamide. For the in vitro analysis of cytotoxicity, the clonogenic assay was used in cultures of Chinese hamster lung fibroblasts (V79). From the obtained results, the three lowest no citotoxic concentrations were chosen to be used for the evaluations of the extracts mutagenicity and antimutagenicity. The cultures were treated with different concentrations of the extracts (mutagenicity test) or with the extract associated with doxorubicin at 1 µg/mL (antimutagenicity test) in protocols of pre, post and simultaneous treatment. All the extracts induced alterations in DNA migration (comet assay) in vivo. Both in vivo as in vitro, negative results for mutagenicity and positive results about the protective effects were observed for all of the treatment groups. These effects can be explained due to the chemical constituents present in the extracts. The main constituents isolated were flavonoids, tannins and phenolic compounds, all of them with antioxidant activity described in the literature. The additive and synergistic effects of these phytochemicals in fruit and vegetables also have been proposed as being the responsible for their potent antioxidant and anticancer activities. Although mutagenic effects were not seen, further investigations should be made to guarantee the security of these results, since a moderate genotoxic effect was found in the in vivo studies. Also the protective effect detected has encouraged new studies regarding these extracts.

ASSUNTO(S)

genética molecular miconia - testes de mutagenicidade plantas medicinais plant genetics mutagenicity testing medicinal plants

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