A novel nanoliposomal formulation of the FDA approved drug Halofantrine causes cell death of Leishmania donovani promastigotes in vitro

Leishmaniasis is a notorious disease affecting mainly poor people. Visceral Leishmaniasis (VL) is a clinical form of Leishmaniasis which mainly affects people living below poverty line. There are no available vaccines against VL and chemotherapy still remains the mainstay for treatment. However, the use of the current therapeutic agents are limited due to issues of toxicity, side effects and cost effectiveness. Thus, repositioning of FDA approved drugs for anti-leishmanial therapeutics and encapsulation of the same in nanoliposomes may pave the way of future anti-leishmanial therapeutics. In this work, liposome encapsulated Halofantrine (Halolipo) was prepared by extrusion of hydrated lipid film method. The Halolipo was characterized by Dynamic Light Scattering and Transmission Electron Microscopy. The effect of Halolipo on Leishmania donovani Ag83 promastigotes was assessed by MIT assay and qualitative analysis of ROS generation and mitochondrial membrane depolarization was performed. The cell death was visualized by dual staining with Acridine orange and Ethidium bromide followed by fluorescence microscopy. The encapsulation of Halofantrine drug in liposome was confirmed by characteristic peak at 260 nm by UV-vis spectrophotometer. The formulated halolipo was 20 nm in size and stable for > 4 weeks at 4 degrees C. Maximum encapsulation was observed at a ratio of 1:200 (Lipid:Halofantrine) Halofantrine is released from Halolipo at both pH 7.2 and 5.5. Halolipo causes decrease in cell viability of L. donovani Ag83 promastigotes and leading to cellular stress as evident from increased ROS generation and mitochondrial membrane depolarization. These events culminate into cell death as observed by dual staining of L. donovani promastigotes by Acridine orange and Ethidium bromide. The novel Halolipo is a promising anti-leishmanial agent and may be used for future anti-leishmanial therapeutics.