Structure-activity studies on amphetamine analogs using drug discrimination methodology.

Area of Science:

• Pharmacology
• Neuroscience
• Medicinal Chemistry

Background:

• Amphetamine and its analogs are psychoactive compounds with significant effects on the central nervous system.
• Understanding the structure-activity relationships (SAR) of amphetamine is crucial for developing new therapeutic agents and understanding its mechanism of action.

Purpose of the Study:

• To investigate the structure-activity relationships (SAR) of various amphetamine analogs.
• To determine how specific structural modifications to the amphetamine molecule affect its pharmacological activity.

Main Methods:

• Rats were trained using an operant conditioning procedure to discriminate between S(+)-amphetamine sulfate and saline.
• Various amphetamine analogs with modifications including benz-fusion, alpha-demethylation, carbonylation, and conformational restriction were synthesized and administered.
• Stimulus generalization tests were conducted to assess the behavioral effects of these analogs.

Main Results:

• Benz-fusion and alpha-demethylation of the amphetamine molecule significantly reduced or abolished its activity.
• The carbonylated analog, cathinone, was found to be equipotent with amphetamine.
• The S-isomer of cathinone was more potent than its R-enantiomer, similar to amphetamine.
• Among conformationally restricted analogs, 2-aminotetralin exhibited approximately half the potency of racemic amphetamine.

Conclusions:

• Specific structural features of the amphetamine molecule are critical for its pharmacological activity.
• Carbonylation of the benzylic position (forming cathinone) retains significant activity, with stereoselectivity observed.
• Conformational restriction can alter potency, with 2-aminotetralin showing notable, albeit reduced, activity compared to amphetamine.