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.

[1] Tryptolines are competitive selective inhibitors of the enzyme monoamine oxidase type A (MAO-A).

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

[2] In vivo formation of tryptolines has been a matter of controversy.