Serotonin receptor binding affinities of tryptamine analogues

Using a rat fundus model, the serotonin (5-HT) receptor binding affinities of 27 tryptamine analogues were determined. Factors which might affect affinity were examined, e.g., lipids solubility, as reflected by partition coefficient, and pKa. Structure-activity relationships were developed and are discussed in terms of substituents on the terminal amine, the side chain, and the indole 1 position, the 5 position, and at other positions on the indolic nucleus. If lipid solubility and metabolism can be accounted for, there appears to be a parallelism between 5-HT receptor binding affinities and the hallucinogenic (psychotomimetic) potencies of several of these compounds.