Artemisinin, related sesquiterpenes, and essential oil in artemisia-annua during a vegetation period in vietnam

The active principle of Artemisia annua L., artemisinin, is currently being developed to a registered antimalarial drug. For production purposes, plants with a high artemisinin content are required. We followed the development of the artemisinin content and of the biosynthetically related sesquiterpenes artemisinic acid, arteannuin B, and artemisitene in A. annua plants, during a vegetation period in Vietnam, where this species is indigenous. In addition, the essential oil content and composition were studied. Samples of leaves, buds, flowers, or post-bloom flowers and fruits were taken at different stages: vegetative (5, 6, and 8 months old), at mass formation of buds (9 months), at full bloom (10 months), and post-bloom (101/2 months). The highest artemisinin content (0.86% dry wt) was present in the leaves of 5 months-old plants. At this stage also the highest leaf yield was found. Subsequently, the artemisinin content gradually dropped. At the age of 5 months the highest artemisinic acid and arteannuin B contents, 0.16 and 0.08% dry wt, respectively, were found as well. Artemisitene was present at all stages of development, ranging from 0.002 to 0.09 % dry wt. With 1.9 % v/w, the essential oil content was maximal just before flowering and was composed of 55 % monoterpenes and 45 % sesquiterpenes. At all other stages (0.4-1.0 % v/w oil) this ratio was ca. 30 %/70 %. The main components of the oil were camphor and germacrene-D.