Relationship between chemotypic and genetic diversity of natural populations of Artemisia herba-alba Asso growing wild in Tunisia.

A total of 80 individuals collected from eight populations growing wild in different geographic zones were considered to assess the intraspecific variability of essential oil composition, genetic diversity and population structure of Artemisia herba-alba. The essential oil composition varied significantly between populations. Essential oil profiles were classified into four chemotypes (trans-sabinyl acetate, α-thujone/trans-sabinyl acetate, camphor and α-thujone/camphor/ß-thujone). Despite significant correlation between the amount of some essential oil compounds and a set of climatic data, the global chemical divergence among populations was not related to their bioclimatic and geographic appurtenances. A high level of genetic diversity within populations was revealed either with RAPD and ISSR markers (Na = 1.67, PPL = 66.5%, H = 0.26, I = 0.38 and Na = 1.7, PPL = 69.8%, H = 0.26, I = 0.38, respectively). The level of genetic diversity varied across populations and chemotypes. Populations from the α-thujone/trans-sabinyl acetate chemotype exhibited the highest genetic diversity as revealed by the RAPD markers. However, populations from α-thujone/camphor/ß-thujone chemotype showed the important genetic variation determined by ISSR markers. A significant genetic differentiation among populations and among chemotypes was detected. The combined analysis showed a significant correlation (r = 0.484, p = .032) between the chemical and molecular markers. The PCA, performed on percentages of major oil compounds and the frequencies of polymorphic RAPD and ISSR bands, divided populations according to their chemotypic classification. Taking into consideration the current situation of A. herba-alba populations and their endangered habitats, these results are of value in order to ensure the in-situ and ex-situ conservation of this medicinal species.

Essential Oil Variability in Natural Populations of Artemisia campestris (L.) and Artemisia herba-alba (Asso) and Incidence on Antiacetylcholinesterase and Antioxidant Activities.

The intraspecific variability of Artemisia herba-alba and A. campestris essential oils and the evaluation of their antioxidant and antiacetylcholinesterase activities were determined. Artemisia herba-alba essential oil was found rich in camphor (19.61%), α-thujone (19.40%), ß-thujone (9.44%), chrysanthenone (9.26%), and trans-sabinyl acetate (8.43%). The major compounds of A. campestris essential oil were germacrene D (16.38%), ß-pinene (16.33%), and limonene (9.17%). Significant variation in the essential oil composition was observed among populations of each species. The divergence between populations was attributed to the variation of some climatic factors such as altitude, annual rainfall, winter cold stress, summer precipitation, summer drought stress, evapotranspiration, and humidity. Artemisia herba-alba and A. campestris essential oils exhibited promising antioxidant and antiacetylcholinesterase activities. The level of activity varied significantly according to the species and the essential oil. The highest scavenging activity (IC50 = 0.14 mg/ml) and the uppermost capacity to prevent ß-carotene bleaching (IC50 = 0.10 mg/ml) characterized A. campestris from population 6. A. campestris population 3 possessed the uppermost ability to reduce ferric ions (450.7 µmol Fe2+ /g EO). The population 2 of A. campestris showed the strongest antiacetylcholinesterase activity (IC50 = 0.02 mg/ml). The variation of these activities between the essential oils was explained by their composition differences.