Synthetic compounds derived from cinnamic acid were tested in cultures containing the promastigote form of Leishmania amazonensis and the dimethylsulphoxide solution of B2 compound (2.0 mg/mL) led to a 92% decrease of leishmania in 96 h of treatment. Then, different liposomal systems (diameters similar to 200 nm) were prepared by the extrusion method in the presence and absence of compounds studied. DSC thermograms of the liposomes in the presence of these compounds caused changes in Delta H, T-m and Delta T-1/2, compared to controls, indicating that there was an interaction of the compounds with the lipid bilayer. Assays with negatively charged liposomal systems containing these drugs in L. amazonensis cultures led to a 50-80% decrease in the number of leishmanias with a concentration to 100 times lower when compared to the B2 initial test. These liposomal systems are promoting more interaction and delivery of the compounds and proved to be an efficient, stable and promising system.