Cycloalkanoindoles. 2. 1-Alkyl-1,2,3,4-tetrahydrocarbazole-1-ethanamines and related compounds. Potential antidepressants.

The synthesis is described of a series of cycloalkanoindoles, comprising tetrahydrocarbazoles, a cyclopentindole, and a cycloheptindole, all bearing an ethanamine side chain at position 1. The acute toxicities of these compounds were evaluated, as well as their potential antidepressant properties, using tests based on the prevention of ptosis induced by reserpine and tetrabenazine. 9-Ethyl-N,N1-trimethyl-1,2,3,4-tetrahydrocarbazole-1-ethanamine (AY-24 614) was found to be the most potent analogue, having an ED50 of 0.12 mg/kg ip in preventing reserpine-induced ptosis in mice and an ED50 at 3.3 mg/kg ip in preventing tetrabenazine-induced ptosis in rats.