Gallic and ellagic acids: two natural immunomodulator compounds solve infection of macrophages by Leishmania major

Leishmaniasis is a complex of parasitic protozoan diseases caused by more than 20 different species of parasites from Leishmania genus. Conventional treatments are high costly, and promote a sort of side effects. Besides, protozoan resistance to treatments has been reported. Natural products have been investigated as a source of new therapeutic alternatives, not only acting directly against the parasite but also being able to synergistically act on the host immune system in order to control parasitemia. Gallic acid (GA) and ellagic acid (EA) are plant-derived phenolic compounds which are able to induce antiinflammatory, gastroprotective, and anticarcinogenic activities. Therefore, the antileishmania, cytotoxic, and immunomodulatory activities of GA and EA were evaluated in this study. Both GA and EA were able to inhibit the growth of Leishmania major promastigotes (effective concentration (EC50) values 16.4 and 9.8 μg/mL, respectively). The cytotoxicity against BALB/c murine macrophages for GA and EA was also assessed (CC50 values 126.6 and 23.8 μg/mL, respectively). Interestingly, GA and EA also significantly reduced the infection and infectivity of macrophages infected by L. major (EC50 values 5.0 and 0.9 μg/mL, respectively), with selectivity index higher than 20. Furthermore, both GA and EA induced high immunomodulatory activity evidenced by the increase of phagocytic capability, lysosomal volume, nitrite release, and intracellular calcium [Ca2+ i] in macrophages. Further investigations are reinforced in order to evaluate the therapeutic effects of GA and EA in in vivo experimental infection model of leishmaniasis.