The enantiomers of MDA, PMA, and MDMA, along with their alpha,alpha-dimethylated derivatives, were tested for their ability to release serotonin from rat whole brain synaptosomes. At bath concentrations of 1 and 10 micrometers, the amphetamine isomers potently induced serotonin release, but were inactive at 0.1 micrometers. At 1 micrometer, the (+) isomer of MDMA was more effective than the (-) isomer, and because the (+) isomer is the clinically active form, this suggests that transmitter release may contribute to MDMA's biological activity. The alpha,alpha-dimethyl compounds did not release serotonin even at the highest concentration.
The hallucinogen analogue DMCPA was separated into its two mirror-image forms using a crystallization technique. By comparing the optical properties of these forms to a related compound of known structure, the absolute configuration of the (-) isomer was determined to be (1R,2S) and the (+) isomer (1S,2R). Earlier work showed the (-) isomer causes selective behavioral effects in cats and mice; this study found it also selectively raises body temperature in rabbits compared to the (+) isomer. This stereoselective activity supports a model linking the active binding conformation of phenethylamine hallucinogens to that of serotonin and tryptamines.
The S-(-) enantiomer of 2-amino-1,2,3,4-tetrahydronaphthalene (2-AT) produces selective central effects in mice and rabbits that resemble those of hallucinogens such as mescaline. A stereochemical analysis of these findings suggests that the structural relationship between mescaline and other phenethylamine-type hallucinogens may involve a correspondence between the aromatic ring of the phenethylamines and the pyrrole portion of the indole nucleus in LSD.