Raman and infrared characterization of the vibrational properties of the antimalarial drug Artemisinin

Artemisinin is one of the most powerful antimalarial drugs of new generation. The active center is the peroxide group of the caged trioxane heterocycle, which either blocks the free heme released by the Plasmodium falciparum parasite or acts on key proteins causing the parasite death. Both processes involve the activation of the 1,2,4-trioxanic ring through interaction with the Fe(II)-heme complex. Since considerable effort was made to synthesize antimalarial drugs containing the endoperoxide group, it becomes fundamental to know the structural and dynamical properties of artemisinin. For this reason Raman and FT infrared studies have been here undertaken on the vibrational properties of artemisinin, its derivative artemether and d-valerolactone, the latter being the molecule mimicking the lactonic ring of artemisinin. The vibrational data of the three molecules have been analyzed through the comparison with ab initio calculations based on DFT/B3-LYP/cc-pVDZ procedures. Modes of artemisinin have been correlated with those of component units.