Tryptoline

Tryptoline is a natural organic amine. 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 monoamine oxidase type A (MAO-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 5-hydroxytryptamine and epinephrine; a significantly greater uptake inhibitory selectivity being shown for 5-hydroxytryptamine than epinephrine. The comparison of the inhibition kinetics of tetrahydro-β-carbolines for 5-hydroxytryptamine and epinephrine uptake (with that of the platelet aggregation response to these amines) have shown that 5-hydroxymethtryptoline, methtryptoline, and tryptoline are poor inhibitors of uptake. 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.