The Leishmanicidal Effect of (3S)-16,17Didehydrofalcarinol, an Oxylipin Isolated from Tridax procumbens, is Independent of NO Production

The in vitro leishmanicidal effect of (3S)-16,17-didehydrofalcarinol (1) isolated from Tridax procumbens whole plant against Leishmania mexicana, the causative agent of cutaneous leishmaniasis (chiclero’s ulcer) in the New World, was investigated. This oxylipin showed signifi cant in vitro activity against promastigotes and intracellular amastigotes of L. mexicana. Its inhibitory effect on amastigotes was not due to activation of NO in recombinant γ-interferon-stimulated macrophages, since the production of NO was decreased in presence of the oxylipin. This is the fi rst report on the leishmanicidal activity against the intracellular stage (amastigote) of the oxylipin (3S)-16,17-didehydrofalcarinol.