Activity of Fluorinated Curcuminoids against Leishmania major and Toxoplasma gondii Parasites

A new 3,4-difluorobenzylidene analog of curcumin, CDF, was recently reported, which demonstrated significantly enhanced bioavailability and in vivo anticancer activity compared with curcumin. For highlighting the antiparasitic behavior of CDF, we tested this compound together with its new O-methylated analog MeCDF against Leishmania major and Toxoplasma gondii parasites. Both CDF and MeCDF were tested in vitro against L. major and T. gondii. In addition, the in vitro cytotoxicity against Vero cells and macrophages was determined and selectivity indices were calculated. The DPPH radical scavenging activity assay was carried out in order to determine the antioxidant activity of the test compounds. Both compounds showed high activities against both parasite forms with EC₅₀ values in the (sub-)micromolar range (0.35 to 0.8 μM for CDF, 0.31 to 1.2 μM for MeCDF). The higher activity of CDF against L. major amastigotes when compared with MeCDF can in parts be attributed to the antioxidant activity of CDF while MeCDF lacking any antioxidant activity was more active than CDF against T. gondii parasites. In conclusion, CDF and MeCDF are promising antiparasitic drug candidates due to their high activities against L. major and T. gondii parasites.