The in vitro Effects of Tryptamine, Harmine, and Harmaline on Leishmania tarentolae and the Possible Implications for Leishmaniasis

Leishmaniasis is a disease caused by Leishmania parasitic protozoans affecting people in both the Eastern and Western Hemispheres. The secreted acid phosphatase enzymes (SAPs) are reported to play a critical role in infection by Leishmania. Thus, these enzymes are potential targets for Leishmania therapy. Tryptamines have various physiological effects and thus serve different purposes socially. Tryptamines are used in ritualistic ceremonies in countries where Leishmania cases are reported. In this work, tryptamine and two other indole derivatives, harmine and harmaline, were investigated. Harmine and harmaline were selected because of their presence in the biological materials used in some South American ritualistic ceremonies. We investigated the effects on axenic Leishmania tarentolae cell shape, motility, clumping, and viability as well as on the activity of secreted acid phosphatase (SAP) from L. tarentolae. An overall decrease in cell viability over a seven-day period and a small recovery in cell viability, only at lower concentrations of test compounds, were observed. These compounds were, in general, activators of L. tarentolae SAP activity. This is the first report of effects of these compounds on Leishmania secreted acid phosphatase activity in vitro. We speculate that those with Leishmania infections may be worsening their condition with the exposure to these compounds. *Correspondence to: Marjorie A Jones, Department of Chemistry, Illinois State University, Normal, IL 61790-4160, USA, E-mail: majone3@ilstu.edu