Evaluation of Antiparasitc Activity of Mentha crispa Essential Oil, Its Major Constituent Rotundifolone and Analogues against Trypanosoma brucei.

Considering the pressing need for new drugs to treat sleeping sickness and Nagana disease, essential oil, its principal constituent rotundifolone, and four related -menthane-type monoterpenes (two stereoisomers of limonene epoxide, perillyl alcohol, and perillyl aldehyde) were investigated for their activity against bloodstream forms of . The general cytotoxicity of the compounds was determined with human myeloid HL-60 cells. The effect of the essential oil and the monoterpenes on the growth of parasite and human cells was evaluated in cell cultures with the resazurin viability assay. Of all of the compounds tested, essential oil, rotundifolone, and perillyl aldehyde showed the highest trypanocidal activities with 50 % growth inhibition (GI) and minimum inhibitory concentration values of 0.3 µg/mL and 1 µg/mL, respectively. In contrast, HL-60 cells were considerably less sensitive to the compounds with minimum inhibitory concentration values of 100 µg/mL and GI values ranging between 3.4 to 13.8 µg/mL. As a consequence of this, GI and minimum inhibitory concentration ratios of cytotoxic to trypanocidal activity (selectivity index) of these three compounds were promising with values of 11-45 and 100, respectively. These results indicate that the -menthane-type monoterpenes rotundifolone and perillyl aldehyde are interesting lead candidates for further rational antitrypanosomal drug development.