Variation of sesquiterpene lactone contents in different Arnica montana populations: influence of ecological parameters

Abstract

In ten grassland or heathland sites along a geog. (north to south) and climatic gradient in Germany, flowerheads of Arnica montana were collected, and the total content of sesquiterpene lactones (SLs) as well as the content of the detected single compds. were detd. The ratios of helenalin (H)- and corresponding 11alpha ,13-dihydrohelenalin(DH)-type compds. were calcd. All habitats were characterised concerning the climatic and soil conditions, and the values obtained were correlated with SL contents according to univariate statistical analyses. All populations showed very similar and const. ratios of helenalin (1)/11alpha ,13-dihydrohelenalin (2) at around 1,5-2/1 irresp. of different ecol. parameters. The ratio of helenalin/11alpha ,13-dihydrohelenalin esters was several fold higher in all samples, but it was nearly identical in every habitat among each other, except for the helenalin/11alpha ,13-dihydrohelenalin 2-methylbutyrate pair (5/11), which showed a constantly twofold higher H/DH ratio. However, the 6-O-isovalerylhelenalin content (6) showed highly significant correlations to climatic factors.