Synthesis, structure–affinity relationships, and modeling of AMDA analogs at 5-HT2A and H1 receptors: Structural factors contributing to selectivity Original Research Article

Histamine H1 and serotonin 5-HT2A receptors present in the CNS have been implicated in various neuropsychiatric disorders. 9-Aminomethyl-9,10-dihydroanthracene (AMDA), a conformationally constrained diarylalkyl amine derivative, has affinity for both of these receptors. A structure–affinity relationship (SAFIR) study was carried out studying the effects of N-methylation, varying the linker chain length and constraint of the aromatic rings on the binding affinities of the compounds with the 5-HT2A and H1 receptors. Homology modeling of the 5-HT2A and H1 receptors suggests that AMDA and its analogs, the parent of which is a 5-HT2A antagonist, can bind in a fashion analogous to that of classical H1 antagonists whose ring systems are oriented toward the fifth and sixth transmembrane helices. The modeled orientation of the ligands are consistent with the reported site-directed mutagenesis data for 5-HT2A and H1 receptors and provide a potential explanation for the selectivity of ligands acting at both receptors.