Extending photocatalytic artemisin transformation from pure compound to plant extracts

Artemisinin, extracted from Artemisia annua, constitues a key treatment for malaria
worldwide. Because of the spread of artemisinin resistance, and to improve its efficacy, recent initiatives aim to create diverse chemical derivatives, such as Artemisinin G[1]. Photochemistry is a technique that, using only a light source and a catalyst, enables rapid complex structural modifications while reducing the consumption of reagents and energy. This study investigates the chemodiversification of Artemisinin into Artemisinin G through photochemical reactions, first on the compound itself and then applied to an A. annua extract. The initial phase concerns the photoreaction with pure Artemisinin, catalyzed by tetra-n butylammonium decatungstate (TBADT)[2]. After irradiation, the catalyst is removed from the reaction mixture through precipitation. The results were analysed by UPLC-qDa and NMR, assessing the transformation's efficiency. Then, the same method was applied to a crude A. annua acetone extract, containing Artemisinin and secondary metabolites. This comparative approach is crucial to assess the occurrence of the same photoreaction in a complex plant matrix. Notably, only trace amounts of Artemisinin G were detected, while another compound was predominantly formed. This suggests that the additional metabolites significantly affect the reaction’s outcome.