Francis Yoshimoto and co-workers at the University of Texas at San Antonio (UTSA) have reported in the Journal of Natural Products on the synthesis of a dihydroartemisinic acid isotopologue, which was regioselectively deuterated at C-3, and in turn was used to measure the rate of nonenzymatic conversion to artemisinin. Artemisinin was the topic of the 2015 Nobel Prize in Medicine and the biosynthesis of the endoperoxide, which is responsible for its antimalarial activity, has been controversial. This paper is related to the spontaneous oxidation of dihydroartemisinic acid to artemisinin when a dried down sample of dihydroartemisinic acid was exposed to air. Funny enough, there is another article on the spontaneous oxidation of avermectin, which was the topic of the 2015 Nobel Prize in Medicine as well.
Naturalproductman's Blog 