ABSTRACT
Leishmania is the etiological agent of a group of parasitic disease Leishmaniases. Recent reports show that the disease is on the rise in Pakistan. As no vaccine is yet available for any type of leishmaniasis, chemotherapy is the only means of controlling the disease. As a part of our project to find out new antileishmanial compounds, we have studied the antileishmanial activity of nystatin [mycostatin], a polyene compound, on the promastigote forms of L. tropica and L. infantum isolates of Pakistan. In in vitro cultivation, the EC50 values [the concentration of drug necessary to inhibit the growth rate of cells to 50% of the control value] obtained for Nystatin against the promastigote of L. tropica and L. infantum were 19.5-19.8 iu/ml. The mode of action proposed for this drug is same as for famous leishmanicidal drug Amphotericin B as both of these polyene drugs strongly and selectively binds to the sterols present on the surface of the parasite result in the formation of unusual pores / gaps on the surface that result in the leakage of the ions. This leakage finally leads to the destruction of the cell