Sesquiterpene lactone content in leaves of in vitro and field cultivated Arnica montana.

On the basis of GC and GC/MS analyses we report on the full qualitative and quantitative sesquiterpene lactone (STL) content of in vitro cultivated A. montana plantlets consisting of helenalin and 11alpha,13-dihydrohelenalin esters in approximately equal amounts. The accumulation of STL was shown to be correlated with tissue differentiation in the above-ground parts. The seasonal variation of STL content in leaves of A. montana cultivated in the proving field was investigated. Changes in the composition of the STL fraction were detected. While young plants accumulate mainly helenalin derivatives, the content of such compounds decreases to almost zero within about 6 weeks from the beginning of leaf formation while that of dihydrohelenalin type compounds increases at the same rate and remains constant for a longer period.