Chemical composition and chemosystematic evaluation of the fruit and root headspace fractions of selected Heracleum taxa from Southeastern Europe

This work is focused on nine Heracleum taxa (Apiaceae): H. sphondylium, H. sibiricum, H. montanum, H. ternatum, H. pyrenaicum subsp. pollinianum, H. pyrenaicum subsp. orsinii and H. verticillatum, belonging to the H. sphondylium group, and H. orphanidis, all from sect. Heracleum, as well as H. austriacum subsp. siifolium from sect. Wendia. The aim was to isolate the headspace (HS) fractions from 17 fruit samples (collected from all nine Heracleum taxa) and 13 root samples (collected from all eight taxa belonging to sect. Heracleum), to investigate their composition and chemosystematic significance, as well as to compare these results with those previously obtained for the essential oils isolated by hydrodistillation from the same fruit and root samples. The HS fractions were isolated using an automatic static HS sampler and analysed by GC-FID and GC-MS. The fruit HS fractions were dominated by octyl acetate and/or α-pinene (the taxa from the sect. Heracleum), or n-octanol (H. austriacum), whereas the root HS fractions mainly contained β-pinene and/or (Z)-β-ocimene (the taxa from the H. sphondylium group), or n-nonane (H. orphanidis). The chemosystematic significance was evaluated using multivariate statistical methods: principal component analysis (PCA), non-metric multidimensional scaling (nMDS) and agglomerative hierarchical clustering based on the unweighted pair-group arithmetic average (UPGMA) algorithm. As in the case of previously investigated essential oils, the statistical analysis of the fruit and root HS fractions generally resulted in the grouping of the investigated H. sphondylium group representatives, and within this group, the grouping of morphologically related H. sphondylium and H. montanum and the isolated position of H. verticillatum. The statistical analysis of the root HS fractions resulted in better separation of the taxa (even compared to previous analysis of the essential oils), i.e. isolated positions of H. ternatum and H. pyrenaicum were observed.