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Quantitative structure-activity relationships in the 2,4,5-ring substituted phenylisopropylamines.
NIDA Research Monograph
|January 1, 1978
Summary
Rabbit hyperthermia assays accurately predict human psychotomimetic potency for phenylisopropylamines. Substituent position significantly impacts drug potency, with 4- and 5-substituted isomers being more potent than 2-substituted ones.
Area of Science:
- Pharmacology
- Medicinal Chemistry
- Computational Chemistry
Background:
- Phenylisopropylamines are a class of psychoactive compounds.
- Understanding structure-activity relationships is crucial for drug design.
- Predictive models for psychotomimetic potency are valuable.
Purpose of the Study:
- To investigate the potency of 2,4,5-ring substituted phenylisopropylamines.
- To establish a correlation between rabbit hyperthermia and human psychotomimetic activity.
- To explore the influence of substituent position and electronic/conformational factors on biological activity.
Main Methods:
- Rabbit hyperthermia assay for potency determination.
- PCILO and ab initio molecular orbital methods for conformational analysis.
- CNDO/2 method for electronic structure calculations.
- Partition coefficient measurements (octanol/water) for lipophilicity.
Main Results:
- Excellent correlation (r=0.99) between rabbit hyperthermia and human psychotomimetic potencies.
- 4-X-substituted-2,5-dimethoxyphenylisopropylamines were 10-100 times more potent than positional isomers.
- HOMO energies correlated with photoelectron spectroscopy but not strongly with biological activity.
- 2-X-substituted isomers exhibited unusual hydrophilicity.
Conclusions:
- Rabbit hyperthermia assay is a reliable predictor of psychotomimetic potency.
- Substituent position at the 4- and 5-positions enhances phenylisopropylamine potency.
- Lipophilicity and electronic factors play a role, but do not fully explain potency variations.