Can the iron content of culture media impact on the leishmanicidal effect of artemisinin?

Abstract

Endoperoxides (EPs) like artemisinin following cleavage of their EP bridge can kill parasites via generation of carbon-centered radicals. As the presence of low molecular mass iron and/or heme is crucial, this study aimed to establish the influence of iron on the leishmanicidal action of artemisinin when present in differing amounts in culture media. In promastigotes cultured in Schneiders insect medium (SIM), that had a 8.0-fold higher amount of iron as compared to Medium 199 (M199), the impact of artemisinin on cell viability, redox status, labile iron pool (LIP), and Annexin-V positivity was evaluated. In SIM, the IC50 of artemisinin was 25.50-fold lower than M199, and in both media its cytotoxicity was decreased by the addition of hemin or following chelation of Fe2+ by Deferoxamine (DFO). In SIM vis-a-vis M199, artemisinin caused a greater redox imbalance which translated into a higher degree of externalization of phosphatidylserine and depletion of the LIP. The presence of a higher proportion of iron in SIM as compared to M199 significantly enhanced the cytotoxicity of artemisinin in Leishmania promastigotes, and was attributed to a higher degree of iron-mediated cleavage of its EP bridge that led to a higher generation of free radicals.

Keywords:

• Artemisinin
• iron
• Leishmania
• Schneider’s insect medium
• Medium 199
• redox imbalance

Disclosure statement

The authors declare that they have no competing interests.

Additional information

Funding

The study was supported financially by the International Bilateral Cooperation Division, Dept of Science & Technology (DST), Govt. of India INT/AUSTRIA/BMWF/P-06/2017, and Austrian Exchange Office (OEAD) in the Scientific & Technological Cooperation project with India IN 04/2017, Austrian Science Fund (FWF), grant P 27814-B22, Fund for Improvement of S and T infrastructure in Universities and Higher Educational Institutions Program, Dept. of Science and Technology, Government of India [Grant number: SR/FST/LS1-663/2016]; Department of Science and Technology, Government of West Bengal [Grant number: 969 [Sanc.]/ST/P/S&T/9G-22/2016], Multidisciplinary Research Unit (MRU), Department of Health Research (DHR), Govt. of India [Grant number: V.25011/611/2016-HR]. MC is a recipient of a JC Bose Fellowship, Science Engineering and Research Board, Dept. of Science and Technology, Government of India, and AD a Senior Research Fellowship from University Grants Commission (UGC), Government of India.