Synthesis and Phytocytogenotoxic Activity of N-Phenyl-2-phenoxyacetamides Derived from Thymol.

The excessive use of herbicides has caused a series of problems related to human health, environmental pollution, and an increase in the resistance of plants to commercial herbicides. As an alternative, natural compounds and their semisynthetic derivatives have been widely studied to obtain environmentally friendly and more effective herbicides than the usual ones. In view of these factors, the aim of this work was to synthesize new molecules with herbicidal potential using thymol as a starting material, a natural phenol that has a pronounced phytotoxic effect. Novel N-phenyl-2-thymoxyacetamides were synthesized and characterized by MS and by 1H and 13C NMR. All prepared molecules were subjected to phytotoxic and cytotoxic activity assays using Lactuca sativa L. and Sorghum bicolor L. as model plants. Molecules containing chlorine in the para position of the thymoxy group exhibited phytotoxic and cytogenotoxic effects superior to those of the commercial herbicides 2,4-D and glyphosate.

Synthesis and Phytotoxic Evaluation of Isatin Derivatives Supported by 3D-QSAR Study.

Concerned about weed infestation, a major threat to food production and herbicide resistance that interferes in the mechanism of action of the main herbicides, we have synthesized eight isatin derivatives using the "Click Chemistry" approach through copper-catalyzed azide-alkyne cycloadditions (CuAAC). Sixteen isatin derivatives were evaluated for their phytotoxic activity against the seed culture of the model plants, Lactuca sativa and Allium cepa. Six of them showed phytotoxic activity similar to the positive control, trifluralin. Hypocotyl length measurement analysis in L. sativa revealed that triazole derivative 8 is more active than trifluralin. For A. cepa, root length measurement analyses revealed that 3, 10, 14, 16, and 17 were similar to the positive control trifluralin. Three-dimensional quantitative structure-activity relationship (3D-QSAR) comparative molecular field analysis (CoMFA) model construction using the acetolactate synthase (ALS) crystallographic structure displayed pki values of predicted inhibitory activity and contour maps revealing sterically bulky groups for 11, the CF3 group in ortho, and for 17, Br in ortho, favoring the inhibitory ALS activity.

Induction of in vitro shoots of Billbergia euphemiae E. Morren (Bromeliaceae) from leaf explants / Indução in vitro de brotos de Billbergia euphemiae E. Morren (Bromeliaceae) a partir de explantes foliares

Bromeliads are an important group for the maintenance of the Atlantic Forest, with many threatened species due to exacerbated extraction and destruction of their natural habitats. Considering the need of developing protocols for the conservation of these species, the aim of this work was to evaluate the effect of different growth regulators in the in vitro induction of shoots of Billbergia euphemiae. Leaf explants were excised from seedlings derived from in vitro germination and grown on MS medium supplemented with NAA (0, 1 or 2 µM) and BA (0, 2, 4 or 6 µ M) combinations. The evaluation of the number of shoots per explant, shoot length, number of leaves per shoot and longest leaf length average was carried out after 30 and 60 days of culture. The best in vitro responses were observed in the presence of 1 µM NAA after 60 days of culture, which induced the best production of shoots per explant (16.39), as well as the highest rates of shoot length (1.08 cm), number of leaves per shoot (5.00) and the longest leaf length (0.56 cm). This work determined the best conditions for shoot production from leaf explants of B. euphemiae, being the first report on micropropagation of this species.

As bromélias constituem um importante grupo para a manutenção da Floresta Atlântica, com várias espécies ameaçadas de extinção pelo extrativismo exacerbado e a destruição dos habitats naturais. Considerando a necessidade do desenvolvimento de protocolos para a conservação destas espécies, este trabalho teve como objetivo avaliar o efeito de diferentes reguladores de crescimento na indução de brotos de Billbergia euphemiae. Explantes foliares foram excisados de plântulas derivadas da germinação in vitro e inoculados em meio MS suplementado com combinações de ANA (0, 1 ou 2 µM) e BA (0, 2, 4 ou 6 µM). O número de brotos por explantes, comprimento dos brotos, número médio de folhas por broto e comprimento médio da maior folha foram avaliados após 30 e 60 dias de cultura. As melhores respostas foram observadas na presença de ANA a 1 µM, após 60 dias de cultura, que induziu a maior produção de brotos por explante (16,39), assim como as maiores taxas de comprimento dos brotos (1,08 cm), número médio de folhas por broto (5,00) e comprimento da maior folha (0,56 cm). Este trabalho determinou as melhores condições para produção de brotos de B. euphemiae a partir de explantes foliares, representando o primeiro relato de micropropagação desta espécie.