Chlorogenic acid acts upon Leishmania donovani arresting cell cycle and modulating cytokines and nitric oxide in vitro

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 anti-leishmanial efficacy of purified chlorogenic acid (CGA) against promastigotes and intracellular amastigotes infected into RAW264.7 macrophages.

METHODS AND RESULTS: CGA was effective both on promastigotes (IC50 =78.394 µM i.e. 27.75 µg/mL) and intracellular amastigotes (ED50 =26.752 µM 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. Flowcytometric 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 µM (21.24 µg/mL) CGA for 24 h, with negligible toxicity to host macrophages. This parasite clearing efficacy was comparable to 1.0 µg/mL (1.082 µM) Amphotericin B, and 20 µM Miltefosine, two standard anti-leishmanial 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: CGA might emerge as a potential anti-leishmanial drug.