Design and synthesis of N-alkyl-N′-substituted 2,4-dioxo-3,4-dihydropyrimidin-1-diacylhydrazine derivatives as ecdysone receptor agonist

Based on the discovery of thymine as an ecdysteroid agonist, a series of 1,4-disubstituted diacylhydrazine derivatives with a thymine moiety were designed and synthesized. The activities of these compounds against Spodoptera litura (Fabricius) were evaluated by the insect immersion method. Results showed that compound 2h with an N-cyclohexylmethyl substituent exhibits the most potent agonist activity with a median lethal concentration of 23.21 μg/mL. This compound also caused malformation of molting larvae and adults. Compound 2h was further demonstrated as an ecdysteroid agonist by reporter gene assay on the Spodoptera frugiperda cell line (Sf9 cells). A molecular docking study indicated that hydrophobic interactions and the formation of hydrogen bonds between the compounds and the ecdysone receptor play critical roles in promoting the binding affinity of the compound. The structure of compound 2h may serve as a favorable template for the development of new ecdysteroid agonists with a pyrimidinedione moiety.