In Vitro and In Vivo leishmanicidal activities of natural and synthetic quinoids

The activities of various compounds isolated from plants traditionally used against leishmaniasis in populations from the tablelands of the Guyanas have been examined. The leishmanicidal activity of plant extracts was evaluated by in vitro testing on promastigote and amastigote stages of Leishmania amazonensis and by in vivo tests on L. amazonensis in mice. The leaves of Jacaranda copaia (Aublet) D. Don yielded two compounds: ursolic acid and jaracanone. Ursolic acid showed an interesting activity in vitro with an ED₅₀ against amastigotes of 0.02 mM and no toxicity to macrophages at twice this dose. Jacaranone displayed a marked activity against promastigotes in vitro with an ED₅₀ of 0.02 mM. Both compounds have weak in vivo antileishmanial activity. Similar synthetic compounds such as quinol and quinone acetates were prepared and showed increased activity in experimental cutaneous leishmaniasis in mice.