Antileishmanial activity of harmaline and other tryptamine derivatives

Tryptamine derivatives harmaline and α‐ethyltryptamine were found to possess a novel antiparasitic action against human pathogen Leishmania mexicana amazonensis both in vitro and in vivo. In vitro , harmaline was the most potent compound tested, with an ED 50 of 99μ, whilst α‐ethyltryptamine (ED 50 149 μ) had the best therapeutic index (2). In vivo , α‐ethyltryptamine was most effective when given orally (ED 50 47 mg/kg), but was also effective when given topically. We suggest that further investigation of traditional plant drugs containing derivatives of β‐carbolines and alkyltryptamines would provide a number of novel antiparasitic drugs.