Binding Properties of Photosynthetic Herbicides: Photosynthetic Activity and Molecular Docking Approach towards 1,4-Dihydropyridines Derivatives.

In the current work, we describe the synthesis of 1,4-dihydropyridine (1,4-DHP) derivatives via Hantzsch multicomponent reaction and their evaluation as photosystem II (PSII) inhibitors through chlorophyll a fluorescence bioassay. Among all the compounds tested, 1,1'-(2,4,6-trimethyl-1,4-dihydropyridine-3,5-diyl)bis(ethan-1-one) (4b) showed best results, reducing the parameters performance index on absorption basis (PIabs ) and electron transport per reaction center by 61 % and 49 %, respectively, as compared to the control. These results indicate the inhibitory activity of PSII over the electron transport chain. Additionally, a molecular docking approach using the protein D1 (PDB code 4V82) was performed in order to assess the structure-activity relationship among the 1,4-DHP derivatives over the PSII, which revealed that both, size of the group at position 4 and the carbonyl groups at the dihydropyridine ring are important for the ligand's interaction, particularly for the hydrogen-bonding interaction with the residues His215, Ser264, and Phe265. Thus, the optimization of these molecular features is the aim of our research group to extend the knowledge of PSII electron chain inhibitors and the establishment of new potent bioactive molecular scaffolds.