Volatile constituents of Artemisia annua L. (Asteraceae)

The volatile constituents of Artemisia annua L. plants, grown in the field in The Netherlands from seeds of Chinese and Vietnamese origin, were investigated using GC and GC–MS (EI, NICI) analysis. The plants grown from Chinese seeds contained 4.0% (v/w) essential oil on a dry weight (DW) basis, those from Vietnamese seeds, 1.4% (v/w). More than forty compounds were identified. The principal component of the Chinese oil was artemisia ketone (63.9%); other major constituents included artemisia alcohol (7.5%), myrcene (5.1%), α‐guaiene (4.7%) and camphor (3.3%). In the Vietnamese oil the main components were camphor (21.8%) and germacrene‐D (18.3%); other important constituents were β‐caryophyllene (5.6%), trans‐β‐farnesene (3.8%) and 1,8‐cineole (3.1%). In the Vietnamese variety the terpenoid biosynthesis proceeded further towards sesquiterpenes, whereas in the Chinese predominantly monoterpenes were formed. This was also reflected in the artemisinin contents, found in dichloromethane extracts of the herbaceous plant material: 0.17% (DW) in Chinese and 1.00% (DW) in Vietnamese plants. We suggest that the differences in the essential oil composition may be ascribed to the existence of different A. annua chemotypes. In a dichloromethane extract of the roots several non‐volatile sesquiterpenes were found. The main constituent was a new compound, which was identified tentatively as arteannuic alcohol.