Tryptoline


Tryptoline, also known as tetrahydro-β-carboline and tetrahydronorharmane, is a natural organic derivative of beta-carboline. It is an alkaloid chemically related to tryptamines. Derivatives of tryptoline have a variety of pharmacological properties and are known collectively as tryptolines.

Pharmacology

Many tryptolines are competitive selective inhibitors of the enzyme monoamine oxidase type A. 5-Hydroxytryptoline and 5-methoxytryptoline are the most active monoamine oxidase inhibitors with IC50s of 0.5 μM and 1.5 μM respectively, using 5-hydroxytryptamine as substrate.
Tryptolines are also potent reuptake inhibitors of serotonin and epinephrine, with a significantly greater selectivity for serotonin. Comparison of the inhibition kinetics of tetrahydro-β-carbolines for serotonin and epinephrine reuptake to that of the platelet aggregation response to these amines has shown that 5-hydroxymethtryptoline, methtryptoline, and tryptoline are poor inhibitors of reuptake. In all respects 5-hydroxytryptoline and 5-methoxytryptoline showed greater pharmacological activity than the tryptoline and methtryptoline.
Although the in vivo formation of tryptolines has been a matter of controversy, they have profound pharmacological activity.