RESUMO
AIMS: Visceral leishmaniasis (VL), caused by Leishmania donovani in India, is fatal if untreated, having serious concern of limited chemotherapeutic options. In this study, we evaluated antileishmanial efficacy of purified chlorogenic acid (CGA) against promastigotes and intracellular amastigotes infected into RAW264.7 macrophages. METHODS AND RESULTS: Chlorogenic acid was effective both on promastigotes (IC50 = 78.394 µmol/L, i.e. 27.75 µg/mL) and intracellular amastigotes (ED50 = 26.752 µmol/L, i.e. 9.47 µg/mL). In promastigotes, significant retardation in mitotic growth was caused both by cell-death and reduction of metabolic activity, evidenced by propidium-iodide uptake and MTT assay, respectively. Flow cytometric analysis revealed that retardation of mitotic growth was due to cell-cycle arrest at G1/S checkpoint. Complete clearance of amastigotes from infected RAW264.7 cells, assessed by microscopic counting, was achieved with 60 µmol/L (21.24 µg/mL) CGA for 24 hours, with negligible toxicity to host macrophages. This parasite clearing efficacy was comparable to 1.0 µg/mL (1.082 µmol/L) Amphotericin B, and 20 µmol/L Miltefosine, two standard antileishmanial drugs. Cytokine-ELISA revealed that elevated IL-10 production by infected macrophages was reduced after parasite clearance. Consequently, IL-12, TNF and NO (assayed by Griess test) production by macrophages were significantly increased after successful resolution of infection. CONCLUSION: Chlorogenic acid might emerge as a potential antileishmanial drug.
