(R)-(−)-Aloesaponol III 8-Methyl Ether from Eremurus persicus: A Novel Compound against Leishmaniosis

Leishmaniosis is a neglected tropical disease which affects several millions of people worldwide. The current drug therapies are expensive and often lack efficacy, mainly due to the development of parasite resistance. Hence, there is an urgent need for new drugs effective against Leishmania infections. As a part of our ongoing study on the phytochemical characterization and biological investigation of plants used in the traditional medicine of western and central Asia, in the present study, we focused on Eremurus persicus root extract in order to evaluate its potential in the treatment of leishmaniosis. As a result of our study, aloesaponol III 8-methyl ether (ASME) was isolated for the first time from Eremurus persicus root extract, its chemical structure elucidated by means of IR and NMR experiments and the (R) configuration assigned by optical activity measurements: chiroptical aspects were investigated with vibrational circular dichroism (VCD) and electronic circular dichroism (ECD) spectroscopies and DFT (density functional theory) quantum mechanical calculations. Concerning biological investigations, our results clearly proved that (R)-ASME inhibits Leishmania infantum promastigotes viability (IC(50) 73 µg/mL), inducing morphological alterations and mitochondrial potential deregulation. Moreover, it is not toxic on macrophages at the concentration tested, thus representing a promising molecule against Leishmania infections.