Ação genotóxica e antiproliferativa de Polygonum punctatum Elliott (Polygonaceae) sobre o ciclo celular de Allium cepa L / Genotoxic and antiproliferative action of Polygonum punctatum Elliott (Polygonaceae) on the cell cycle of Allium cepa L

RESUMO: A espécie Polygonum punctatum Elliott (Polygonaceae) é amplamente utilizada pela população como planta medicinal. O objetivo deste trabalho é o de avaliar o potencial genotóxico e mutagênico de P. punctatum utilizando raízes de bulbos e radículas em sementes germinadas de Allium cepa através do teste in vivo, e realizar comparações da extração do material vegetal por calor (infusões) e extração a frio (extrato). Para isso, foram preparadas dois tipos de soluções, infusões e extratos foliares de P. punctatum, em duas concentrações 0,4 g mL-1 e 2,4 g mL-1. A infusão foi preparada pela adição das folhas secas em água destilada fervente (100ºC), permanecendo por 10 minutos enquanto o extrato foi preparado através da maceração das folhas secas em água destilada fria. Para o teste em A. cepa foram utilizados, para cada tratamento, seis grupos de quatro bulbos e seis caixas gerbox com 50 sementes em cada caixa. Duas lâminas para cada tratamento foram obtidas através da técnica de esmagamento das raízes e coradas com orceína acética 2%. Foram contadas 2000 células por grupo de bulbos e 3000 células por grupo de sementes, observando-se a ocorrência de interrupções em metáfases, alterações cromossômicas estruturais, bem como a inibição ou aumento da divisão celular. Os valores do índice mitótico foram calculados e analisados estatisticamente pelo Teste χ2 (p≤0,05). Os resultados demonstraram que as infusões e os extratos de folhas apresentaram redução nos valores de índices mitóticos nas concentrações utilizadas em relação ao controle em água destilada. Foram identificadas alterações cromossômicas na divisão celular, tais como pontes anafásicas, em todas as concentrações de infusões e extratos indicando assim que P. punctatum possui atividade antiproliferativa e genotóxica.

ABSTRACT: The species Polygonum punctatum Elliott (Polygonaceae) is widely used by the Brazilian population as a medicinal plant. The aims of this study are to evaluate the genotoxic and mutagenic potential of P. punctatum, using its root bulbs and rootlets in germinated seeds of Allium cepa by in vivo testing, and to compare the extraction of plant material by heat (infusions) and cold (extract). Thus, two types of solutions - infusions and leaf extracts - of P. punctatum were prepared at the two concentrations of 0.4 g ml -1 and 2.4 g mL- 1. The infusion was prepared by addition of dry leaves in boiling distilled water (100ºC), remaining for 10 minutes, while the extract was prepared by maceration of dried leaves in cold distilled water. For the A. cepa, we used for each treatment six groups of six bulbs and six seedling boxes with 50 seeds each. Two slides for each treatment were obtained by the technique of crushing the roots, and they were stained with 2 % acetic orcein. For the analysis, 2000 cells per group of bulbs and 3000 cells per group of seeds were counted, and we noted the occurrence of interruptions in the metaphase, chromosomal aberrations, as well as inhibited or increased cell division. The values of the mitotic index were calculated and statistically analyzed by the χ2 test (p ≤ 0.05). The results showed that the infusions and extracts of leaves showed reduced values of mitotic indices in the concentrations used compared to the control in distilled water. Chromosomal alterations were identified in the cell division, in all concentrations of infusions and extracts, thus indicating that P. punctatum has an antiproliferative and genotoxic activity.

Post-treatment with plant extracts used in Brazilian folk medicine caused a partial reversal of the antiproliferative effect of glyphosate in the Allium cepa test

Species of the genus Psychotria are used for multiple purposes in Brazilian folk medicine, either as water infusions, baths or poultices. This study was aimed to evaluate the genotoxic and antiproliferative effects of infusions of Psychotria brachypoda and P. birotula on the Allium cepa test. Exposure to distilled water was used as a negative control, while exposure to glyphosate was used as a positive control. The interaction of extracts (as a post-treatment) with the effects of glyphosate was also studied. Results showed that glyphosate and the extracts of both P. brachypoda and P. birotula reduced the mitotic index as compared with the negative control (distilled water). Surprisingly, however, both extracts from P. brachypoda and P. birotula caused a partial reversal of the antiproliferative effect of glyphosat e when used as a post-treatment. Glyphosate also induced the highest number of cells with chromosomal alterations, which was followed by that of P. birotula extracts. However, the extracts from P. brachypoda did not show any significant genotoxic effect. Post-treatment of glyphosate-treated samples with distilled water allowed a partial recovery of the genotoxic effect of glyphosate, and some of the Psychotria extracts also did so. Notably, post-treatment of glyphosate-treated samples with P. brachypoda extracts induced a statistically significant apoptotic effect. It is concluded that P. brachypoda extracts show antiproliferative effects and are not genotoxic, while extracts of P. birotula show a less potent antiproliferative effect and may induce chromosomal abnormalities. The finding of a partial reversion of the effects of glyphosate by a post-treatment with extracts from both plants should be followed up.

Post-treatment with plant extracts used in Brazilian folk medicine caused a partial reversal of the antiproliferative effect of glyphosate in the Allium cepa test

Species of the genus Psychotria are used for multiple purposes in Brazilian folk medicine, either as water infusions, baths or poultices. This study was aimed to evaluate the genotoxic and antiproliferative effects of infusions of Psychotria brachypoda and P. birotula on the Allium cepa test. Exposure to distilled water was used as a negative control, while exposure to glyphosate was used as a positive control. The interaction of extracts (as a post-treatment) with the effects of glyphosate was also studied. Results showed that glyphosate and the extracts of both P. brachypoda and P. birotula reduced the mitotic index as compared with the negative control (distilled water). Surprisingly, however, both extracts from P. brachypoda and P. birotula caused a partial reversal of the antiproliferative effect of glyphosat e when used as a post-treatment. Glyphosate also induced the highest number of cells with chromosomal alterations, which was followed by that of P. birotula extracts. However, the extracts from P. brachypoda did not show any significant genotoxic effect. Post-treatment of glyphosate-treated samples with distilled water allowed a partial recovery of the genotoxic effect of glyphosate, and some of the Psychotria extracts also did so. Notably, post-treatment of glyphosate-treated samples with P. brachypoda extracts induced a statistically significant apoptotic effect. It is concluded that P. brachypoda extracts show antiproliferative effects and are not genotoxic, while extracts of P. birotula show a less potent antiproliferative effect and may induce chromosomal abnormalities. The finding of a partial reversion of the effects of glyphosate by a post-treatment with extracts from both plants should be followed up.(AU)