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
Tryptolines are competitive selective inhibitors of the enzyme monoamine oxidase type A (MAO-A). 5-Hydroxytryptoline and 5-methoxytryptoline (pinoline) are the most active monoamine oxidase inhibitors (MAOIs) with IC50s of 0.5 μM and 1.5 μM respectively.

Tryptolines are also potent reuptake inhibitors of serotonin and epinephrine, with a significantly greater selectivity for serotonin.

In vivo formation of tryptolines has been a matter of controversy.