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.

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ABSTRACT

The aim of this work was to identify and quantify the metabolites present in the roots of Combretum lanceolatum inoculated with its endophytic fungi. The metabolomics was accomplished using the 1H nuclear magnetic resonance (NMR) spectral data and evaluated via rNMR software and Madison Metabolomics Consortium Database (MMCD). The principal component analysis (PCA) and partial least squares-discriminant analysis (PLS-DA) showed that plants inoculated with Trichoderma spirale (Ts) present differentiation and discrimination over the time as compared to control. Seven days after Ts fungal inoculation, 15 metabolites were identified at different concentrations comparing to the control plants. The plants inoculated with Ts fungus present the metabolites spermidine and pantothenate in higher concentrations and 3-hydroxybutyric acid and β-alanine in lower concentrations as compared to control plants, indicating any response to biotic stress. These metabolites are involved in various plant processes, including secondary metabolites biosynthesis, energy metabolism and self-defense. Therefore, this work demonstrates the diversification of primary metabolites composition influenced by endophytes inoculation.

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