Chiroptical properties of artemisinin and artemether investigated using time-dependent density functional theory

Chiroptical properties including electronic circular dichroism (ECD) and optical rotatory dispersion (ORD) of artemisinin and artemether have been fully studied using quantum-chemical calculation based on time-dependent density functional theory. Both theoretical ECD and ORD of these two compounds were in good match with the experimental data. ECD spectrum of artemether could be totally attributed to the peroxide group, and that of artemisinin was an overlay of contribution from δ-lactone and peroxide moieties, which leading to a positive maximum at 260 nm. Our results showed that peroxide group could produce a broad ECD band in the far-UV region originated from electron transitions of HOMO → LUMO, HOMO−1 → LUMO and HOMO−2 → LUMO in the case of artemether. This work provided a theoretical interpretation of the ECD behavior of peroxide bond.

Graphical abstractChiroptical properties of antimalaria drugs artemisinin and artemether have been calculated theoretically using quantum-chemical method and showed high coincidence with the experimental data. The n → σ* transitions with lone pair electrons of all oxygen atoms in a carbon–oxygen chain contributed to the ECD profile of the peroxide bridge.Figure optionsDownload full-size imageDownload as PowerPoint slide