Sources of variability of wormwood (Artemisia absinthium L.) essential oil

Artemisia absinthium L. is a medicinal and aromatic bitter herb frequently used in traditional medicine as antimicrobial agent since ancient times. The important active constituents, essential oil and bitter substances have attracted the interest of several researchers and producers throughout the world. The use of this herb as a source of natural products and the alcoholic beverage absinthe has recently experienced a revival after a period of prohibition. The composition of the essential oil exhibits a large intraspecific variability. Besides the most well known β-thujone, at least 17 other major compounds were described in the oil, among others myrcene, sabinene, sabinyl acetate, epoxyocimene, chrysanthenol, chrysanthenyl acetate, etc. Until now, both “pure” chemotypes and “mixed” chemotypes have been defined. Drugs originating from different regions often show great variability in quality. Nevertheless, most references do not characterize correctly the source of the plant material, therefore it is difficult to divide the roles of the genotype and other influencing factors.The essential oil composition might change also during the ontogenesis, nevertheless there are only a few samples investigated in different chemotypes. The thujones seem to be varying during the vegetation period, as well. Although the organic differences have only scarcely been investigated, it seems that monoterpenes predominate in aerial parts, while the essential oil of the roots shows characteristically high ratios of monoterpenic and aliphatic esters. The role of environmental effects on the composition of wormwood oil needs further confirming data. Compared to hydrodistillation, other extraction methods resulted in significantly different compositions. According to some references, even the presence of thujones could be influenced by the extraction method.