N-Acetyl-5-arylalkoxytryptamine analogs: probing the melatonin receptors for MT(1) -selectivity

A series of melatonin analogs obtained by the replacement of the ether methyl group with larger arylalkyl and aryloxyalkyl substituents was prepared in order to probe the melatonin receptors for MT(1) -selectivity. The most MT(1) -selective agents 11 and 15 were substituted with a Ph(CH(2) )(3) or a PhO(CH(2) )(3) group. Compounds 11 and 15 displayed 11.5-fold and 11-fold higher affinity for the MT(1) receptors than for the MT(2) subtype. Interestingly, in our binding assay 11 and 15 have shown considerably higher MT(1) -affinity and selectivity than the reference ligand, the dimeric agomelatine 1a.