Interaction of beta-carbolines with the benzodiazepine receptor. Structure-activity relationships of amide derivatives of beta-carboline and tetrahydro-beta-carboline.

1. The inhibition of specific 3H-flunitrazepam binding to rat cortical membrane preparations (benzodiazepine receptors) by a series of amide derivatives of beta-carboline and tetrahydro-beta-carboline related to the ethyl ester of beta-carboline 3-carboxylate (beta-CCE) was measured. 2. beta-Carboline amides which are unsaturated in the C ring of the beta-carboline nucleus were the most potent inhibitors of benzodiazepine receptor binding. 3. Increasing the length of the hydrocarbon moiety in the aliphatic amide side chain beyond two carbon atoms decreased potency.