Potencial fitotóxico com enfoque alelopático de Bauhinia ungulata L. sobre sementes e plântulas de alface e cebola / Phytotoxic potential with allelopathic focus of Bauhinia ungulata L. on seeds and seedlings of lettuce and onion

O presente trabalho avaliou o efeito do extrato etanólico e diferentes frações das folhas de Bauhinia ungulata L. sobre a germinação, crescimento, respiração e conteúdo de clorofila de plântulas de Lactuca sativa (alface) e Allium cepa (cebola). Sementes de alface e cebola foram mantidas em contato com solução das amostras e colocadas em câmara de germinação. Realizaram-se contagens diárias para avaliar a interferência sobre a germinação e crescimento, e verificou-se possíveis interferências sobre a respiração radicular e o conteúdo de clorofila total das folhas das plântulas. Não foi observada nenhuma interferência das amostras sobre a porcentagem de germinação e massa seca das duas espécies. Com relação ao IVG, houve um atraso da germinação das sementes de alface quando em contato com o EB. O crescimento radicular das duas espécies foi inibido principalmente pelas frações EB e FR, sem nenhuma interferência sobre o crescimento do hipocótilo da alface e estímulo do crescimento do coleóptilo da cebola. Redução nos teores de clorofila total da alface e aumento na cebola, assim como estímulo da respiração das raízes. Conclui-se que o extrato e as frações de Bauhinia ungulata L. apresentam compostos químicos com atividade fitotóxica sobre o desenvolvimento de plântulas de alface interferindo principalmente no crescimento radicular, teor de clorofila e respiração radicular das espécies avaliadas.

This study evaluated the effect of ethanol extract and different fractions of leaves of Bauhinia ungulata L. on germination, growth, respiration and chlorophyll content of seedlings of Lactuca sativa (lettuce) and Allium cepa (onion). Seeds of lettuce and onions were put in contact with the sample solution and placed in a germination chamber. Daily counts were carried out to assess the interference on the germination and growth, and it was possible interference on the root respiration and the total chlorophyll content of the leaves of the seedlings. No interference of the samples on the percentage of germination and dry mass of the two species was not observed. With respect to GVI, there was a delay of germination of lettuce seeds when in contact with the CE. Root growth of the two species was inhibited mainly by fractions CE and RF, without any interference on the growth of hypocotyl of lettuce and stimulating onion coleoptile growth. Reduction in total chlorophyll content of lettuce and onion increased, as well as stimulating the respiration of roots. It is concluded that the extract and the Bauhinia ungulata L. fractions have chemical compounds with phytotoxic activity on the development of lettuce seedlings interfering mainly on root growth, chlorophyll content and root respiration of species assessed.

Antioxidant capacity and in vitro prevention of dental plaque formation by extracts and condensed tannins of Paullinia cupana.

Chemical evaluation of the semi-purified fraction from the seeds of guaraná, Paullinia cupana H.B.K. var. sorbilis (Mart.) Ducke, yielded the following compounds: caffeine, catechin, epicatechin, ent-epicatechin, and procyanidins B1, B2, B3, B4, A2, and C1. Measurement of the antioxidant activity by reduction of the DPPH radical confirmed the anti-radical properties of the aqueous (AqE) and crude (EBPC) extracts and semi-purified (EPA and EPB) fractions. The EPA fraction showed radical-scavenging activity (RSA) and protected DPPH from discoloration at 5.23 +/- 0.08 (RSD% = 1.49) microg/mL, and for the phosphomolybdenum complex showed a higher Relative Antioxidant Capacity (RAC) at 0.75 +/- 0.01 (1.75). The EPA fraction had a total polyphenolics content of 65.80% +/- 0.62 (RSD% = 0.93). The plant drug showed 5.47% +/- 0.19 (RSD% = 3.51) and 6.19% +/- 0.08 (RSD% = 1.29) for total polyphenolics and methylxanthines, respectively. In vitro assessment of the antibacterial potential of the Paullinia cupana extracts against Streptococcus mutans showed that these could be used in the prevention of bacterial dental plaque.