We report the synthesis of twelve indole derivatives bearing nitro or amide groups via Fischer indole methodology followed by reduction/acetylation and amidation reactions. After thorough ...characterization, these indoles were subjected to a number of studies in order to evaluate their bioactive potential as photosynthesis and plant growth inhibitors. Firstly, these molecular hybrids were evaluated as photosystem II (PSII) inhibitors through chlorophyll a (Chl a) fluorescence measurement. In this study, 6‐chloro‐8‐nitro‐2,3,4,9‐tetrahydro‐1H‐carbazole (15a) and 5‐chloro‐2,3‐dimethyl‐7‐nitro‐1H‐indole (15b) showed the best results by reducing the phenomenological parameters of reaction centers ABS/RC, TR0/RC and ET0/RC of PSII. Electron chain blockage by these compounds may lead to diminished ATP synthesis and CO2 fixation which interrupt the plant development. The compounds 15a and 15b both act as postemergent herbicides, reducing the dry biomass of Ipomoea grandifolia and Senna alata weeds by an average of 40% and 37%, respectively, corroborating the fluorescence results. Additionally, the molecular docking study revealed that the presence of strong electron‐withdrawing groups at the indole phenyl ring is important for the ligand’s interaction with the binding pocket of protein D1 on PSII. The optimization of these molecular features is the goal of our research group in further understanding and development of new potent herbicides.
This work reports the synthesis of indole nitrogen hybrids and their bioactive potential as photosystem inhibitors. The molecular hybrids were evaluated as photosystem II inhibitors through chlorophyll a fluorescence measurements and plant growth inhibitors. Compounds 6‐Chloro‐8‐nitro‐2,3,4,9‐tetrahydro‐1H‐carbazole and 5‐chloro‐2,3‐dimethyl‐7‐nitro‐1H‐indole showed the best results by reducing the phenomenological parameters of the reaction center, diminishing ATP synthesis and CO2 fixation which interrupt the plant development. Additionally, the molecular docking study revealed that the presence of strong electron withdrawing groups at the indole phenyl ring are important for the ligands’ interaction with the binding pocked of protein D1.
PHOTOSYSTHEM II INHIBITORS: AN ALLELOCHEMICAL PERSPECTIVE. The process of photosynthesis involves the absorption of light energy by photosynthetic pigments found in the thylakoid membrane of ...chloroplasts in order to produce chemical energy. In the presence of photosynthetic inhibitors, plant development is affected mainly by the reduction of the electron chain, which leads to growth inhibition. In this context, chlorophyll a (Chl a) fluorescence is an important technique used to identify the effects of inhibitors on the photosynthetic apparatus employing the JIP-test, which correlates the Chl a fluorescence transient to biophysical parameters, providing valuable information about the efficiency of photosystems I and II. Natural products have been highlighted as photosynthesis inhibitors due to the continued use of synthetic herbicides, which leads to the development of invasive plants resistant to these pesticides, in addition to the toxicity caused to humans and the environment. Thus, this review describes the main applications of extracts and isolated secondary metabolites obtained from plants and microorganisms in the investigation of electron transport inhibition on photosystem II.
Este trabalho aborda o uso do experimento de enfloração para o ensino de Química empregando materiais acessíveis e disponíveis no comércio, como a gordura de soja hidrogenada (GSH) e pétalas de ...flores aromáticas. A abordagem pedagógica explorada no experimento pode ser trabalhada em fases distintas do método de enfloração, sendo possível a correlação de diversos conteúdos de química com atividades do cotidiano dos alunos. Dentre os conteúdos que podem ser estudados, destacam-se o ensino das estruturas químicas moleculares dos constituintes presentes nos óleos florais, com ênfase nos grupos funcionais e ligações covalentes polarizadas. É explorado o ensino das interações intermoleculares existentes nos processos de extração do óleo essencial com a GSH, assim como na extração líquido-líquido empregando álcool etílico como solvente orgânico. O produto obtido ao final do experimento pode ser oferecido aos alunos, os quais tem a oportunidade de usar o óleo essencial na elaboração de velas e aromatizantes de ambientes. Portanto, o método de enfloração, o qual muito utilizado na antiguidade e por vezes retratado em filmes na obtenção de perfumes de flores, pode auxiliar como uma interessante ferramenta pedagógica para desenvolver o interesse e favorecer a compreensão de conteúdos de química.
