Artemisinin, Related Sesquiterpenes, and Essential Oil inArtemisia annuaDuring a Vegetation Period in Vietnam

Abstract

In Vietnam, Artemisia annua (Asteraceae) is a popular medicinal plant, indicated to relieve fever and to stop malarial attacks (1). The plant's active principle, artemisinin, is currently being developed to a registrated antimalarial drug, requiring plants with a high artemisinin content (2). We followed the development of the artemisinin content (HPLC) in A. annua plants and of the biosynthetically related sesquiterpenes arteannuic acid, arteannuin B, and artemisitene (GC), during a vegetation period in Vietnam. In addition, the essential oil content (hydrodistillation) and composition (GC, GC-MS) were studied.Seeds of A. annua were sown near Hanoi, mid-January 1992. Samples of leaves, buds, flowers, or ceased flowers and seeds were taken at different stages: vegetative (5, 6, and 8 months old), at mass formation of buds (9 months), at full blooming (10 months), and at cease of blooming (10'/, months). They were air-dried and analysed (3, 4).The highest artemisinin content in the leaves (0.86% dry wt) was found in 5-months-old plants. At this stage they had almost reached their full size and possessed the highest leaf yield (21.1 g dry wt per plant). Then, the artemisinin content gradualiy dropped, through 0.42% when bnds had formed, to 0.16% postflowering. At the age of 5 months also the highest arteannuinic acid and arteannuin B contents, 0.16 and 0.08 % dry wt, respectively, were found. Artemisitene was present at all stages of development, ranging from 0.002 to 0.09%drywt.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 30 %170 %. The main components of the oil were camphor and germacrene-D, as found previously (5). Just before flowering, especially the monoterpenes myrcene and 1,8-cineole were abundant, with 8.5 and 7.3%, respectively. At the end of the vegetation period, the trans-flfarnesene content was significantly increased to ca. 13 % of the oil.We conclude that the highest artemisinin content as well as the highest possible yield in Vietnamese plants are foi.md at an early vegetative stage (5 months old), and not just prior to flowering, as found in all other studies performed on this subject so far. Acknowledgements

Plant Metabolomics

“…The terpenoid metabolite profiles showed that synthesis and accumulation of terpenoids changed dynamically from VGS to FBS in the two A. annua genotypes. The content of terpenoids compounds reached the highest levels at VGS, decreased at PFBS; however, the content of artemisinin reached the highest level at PFBS, and decreased at FBS, which was consistent with the report of Woerdenbag et al (Woerdenbag et al 1994). Interestingly, the content changes of artemisinic acid and dihydroartemisinic acid exhibited similar dynamics, and their contents decreased rapidly at PFBS.…”

The GenusArtemisia: A Comprehensive Review

“…Volatile oil containing cineole, α-pinene, camphene, borneol, camphor, germacrene-D, hydroxyl amino isoartemisia ketone (Woerdenbag et al, 1994), sesquiterpene lactones artemisinin, artemisinic acid, arteanniun B, artemisinin derivatives artesunate, trioxanes, artemether artemisinin G and arteether (He et al, 2009;Bhakuni et al, 1990;Wei et al, 1992); phenolic compounds, flavones (Han et al, 2008;Han et al, 2007)…”

Artemisia (Asteraceae) essential oils: compositional variation and mechanisms of its origin, biosynthesis of constituents, correspondence between biological activities and ethnomedicinal usage and repurposement prospects

“…Artemisia individual plants can produce many thousand (~ 10 5 ) of wind dispersed seeds in a flowering season (Goel et al, 2011). The reproductive stage Artemisia plants are a richer resource of essential oil than vegetative stage plants because of higher density of glandular trichomes, which produce and store essential oil, on inflorescence and leaves of plants on which flowering has set in (Woerdenbag et al, 1994;Ferreira and Janick 1995;Tellez et al, 1999;Soetaert et al, 2013). Whereas several Artemisia species, including Artemisia annua, are commercial resource of essential oils, presently A. annua is the only commercial Artemisia resource of the antimalarial terpenoid drug artemisinin.…”