The antileishmanial activity of lapachol, isolapachol, and dihydrolapachol, along

Summary In a previous work, the in vitro and in vivo activity of a series of diarylheptanoid derivatives against Leishmania amazonensis has been described. Based on the promising results, ten new compounds belonging to the same chemical class were synthesized and have been investigated in relation to their leishmanicidal activity. The compounds were obtained through several chemical modifications on the basic structure of curcumin (1,7-bis-(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dione) in an attempt to increase its effectiveness and decrease the potential toxic effects. The drugs were assayed in vitro against L. amazonensis promastigotes and using pentamidine isethionate as reference drug. The results showed that the most effective compound is 1,7-bis-(4-propargyl-3-methoxyphenyl)-1,6-heptadiene-3,5-dione, which is about ten times more efficient than the original curcumin. Nevertheless, these results did not allow us to make any correlation between the leishmanicidal activity and the chemical structure of the compounds.