Variations in key artemisinic and other metabolites throughout plant development in Artemisia annua L. for potential therapeutic use.

Dried leaves of Artemisia annua show promise as an inexpensive and sustainable antimalarial therapeutic, especially for use in developing countries. Along with the potent terpene, artemisinin, many other small molecules produced by the plant seem to aid in the therapeutic response. However, little is known about the ontogenic and phenological production of artemisinin in the plant, and its plethora of other important secondary metabolites. From a consistently high artemisinin-producing A. annua clone (SAM) we extracted and analyzed by GC/MS 22 different metabolites including terpenes, flavonoids, a coumarin, and two phenolic acids as they varied during leaf development and growth of the plant from the vegetative stage through the reproductive, full flower stage. As leaves developed, the maximum amount of most metabolites was in the shoot apical meristem. Artemisinin, on the other hand, maximized once leaves matured. Leaf and apical tissues (e.g. buds, flowers) varied in their metabolite content with growth stage with maximum artemisinin and other important secondary metabolites determined to be at floral bud emergence. These results indicated that plants at the floral bud stage have the highest level of artemisinin and other therapeutic compounds for the treatment of malaria.