Antileishmanial activity of amides from Piper amalago and synthetic analogs

Two natural amides isolated from the chloroform extract of Piper amalago L., Piperaceae, leaves, a hydrogenated derivative and seven synthetic analogs were tested against the promastigote and intracellular amastigote forms of Leishmania amazonensis. The antileishmanial activity was evaluated in terms of growth inhibitory concentration for 50% of protozoa (IC50). The cytotoxicity toward the J774A1 macrophages was evaluated in terms of the cytotoxic concentrations for 50% of macrophages (CC50). The ability to induce nitric oxide production was also investigated for all compounds. The saturated amide 7-(1,3-benzodioxol-5-yl)-1-(1-pyrrolidinyl)- 1-heptanone was obtained by hydrogenation of the natural compound N-[7-(3’,4’- methylenedioxyphenyl)-2(Z),4(Z)-heptadienoyl]pyrrolidine. Synthetic amides were prepared by addition of the appropriate amine to the corresponding acyl chloride. The natural compound, N-[7-(3’,4’-methylenedioxyphenyl)-2(E),4(E)-heptadienoyl] pyrrolidine, was the most active of all tested compounds against the promastigote and intracellular amastigote forms with IC50 values of 15 μM and 14.5 μM, respectively. None of the compounds modulated the production of nitric oxide.