Novel conformationally constrained analogues of agomelatine as new melatoninergic ligands.

ABSTRACT

Novel conformationally restricted analogues of agomelatine were synthesized and pharmacologically evaluated at MT1 and MT2 melatoninergic receptors. Replacement of the N-acetyl side chain of agomelatine by oxathiadiazole-2-oxide (compound 3), oxadiazole-5(4H)-one (compound 4), tetrazole (compound 5), oxazolidinone (compound 7a), pyrrolidinone (compound 7b), imidazolidinedione (compound 12), thiazole (compounds 13 and 14) and isoxazole moieties (compound 15) led to a decrease of the melatoninergic binding affinities, particularly at MT1. Compounds 7a and 7b exhibiting nanomolar affinity towards the MT2 receptors subtypes have shown the most interesting pharmacological results of this series with the appearance of a weak MT2-selectivity.