Design and synthesis of heterocyclic derivatives for the study and characterization of receptorial system

The 18 kDa Translocator Protein (TSPO) is a mitochondrial protein whose basal density is altered in several diseases, with the result that the evaluation of its expression levels by means of molecular imaging techniques represents a promising diagnostic approach. A wide number of N,N-dialkyl-(2-phenylindol-3-yl)glyoxylamides have been study as potent and selective TSPO ligands exhibiting Ki values in the nanomolar/subnanomolar range, and stimulating steroid biosynthesis in rat C6 glioma cells to an extent similar to, or higher than, that of classical TSPO ligands, such as PK 11195, Ro 5-4864 and alpidem. Starting from these derivatives, in this PhD work have been designed novel TSPO irreversible ligands bearing an electrophilic isothiocyanato group, together with an irreversible NBD-fluorescent probe . The TSPO affinity of the new irreversible ligands was measured on rat tissue homogenates by [3H]Ro 5-4864 radiobinding kinetic assays, all compounds showing high affinities for the target protein. With the aim to further refine the TSPO pharmacophore/topological model and to investigate the role of the 1-NH indole in the binding of these ligands to the TSPO, a novel series of N1-methylindole derivatives were synthesized.