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International Journal of Chemistry


Leishmania, secreted acid phosphatase, enzyme inhibition, vanadium complexes, orthovanadate, decavanadate


Leishmaniasis is a parasitic disease caused by the protozoa Leishmania. These organisms secrete acid phosphatases during their growth cycle as an important part of cell targeting to host macrophage cells thus allowing for a successful infection. Secreted acid phosphatases (SAP) are reported to play a significant role in the survival of Leishmania cells, thus evaluation of these enzymes is of interest. The inhibition of SAP can be the focus of a new drug therapy. We tested for SAP activity from Leishmania tarentolae following the addition of a series of vanadium complexes including decavanadate. Cell cultures at different stages in their growth curve were harvested by centrifugation and supernatant was collected. The SAP activity in the supernatant was assayed with the artificial substrate p-nitrophenylphosphate (pNPP). Incubation with orthovanadate resulted in a decrease in activity of 18% ± 1 relative to the control, in comparison to decavanadate, which resulted in a 35% ± 4 decrease in activity. Other vanadium complexes showed smaller inhibitory effects than orthovanadate. Some vanadium complexes appeared to have an effect on reducing cell clumping when compared to control cells. The SAP was partially isolated through anion exchange chromatography and results indicate that SAP isozyme forms are present in the supernatant from cells. Future work is focused on obtaining recombinant enzyme which can be more completely characterized for inhibition by vanadium complexes.

Funding Source

The authors thank the National Science Foundation (US) (CHE0645081) for financial support.




First published in International Journal of Chemistry 6, no. 1 (2014).

Presented in part at the 8th International Vanadium Symposium: Chemistry, Biological Chemistry, & Toxicology, Washington, DC, August 2012.

This is an open-access article distributed under the terms and conditions of the Creative Commons Attribution license (

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