In vitro leishmanicidal activity of aurones.

A series of aurones with drug-potential for Leishmania infections was identified in vitro using both a direct cytotoxicity assay against extracellular promastigotes of Leishmania donovani, L. infantum, L. enriettii, and L. major, and a test against intracellular amastigote forms of L. donovani residing within murine macrophages. The most active aurone (6-hydroxy-2-[phenylmethylene]-3(2H)-benzofuranone) had an EC50 of 0.45 microgram/ml in the extra-, and an EC50 of 1.40 micrograms/ml in the intracellular assay. Other aurones were active between 0.06-12.50 micrograms/ml and 0.04-7.81 micrograms/ml, respectively. When tested against murine bone marrow-derived macrophages as a mammalian host cell control, the compounds showed only moderate cytotoxicity (EC50 2.32 to > 25.0 micrograms/ml). This is the first report on aurones as a new class of natural products with leishmanicidal activity.