Infraspecific variation in the chemistry of glandular trichomes of two Brazilian Viguiera species (Heliantheae; Asteraceae)

A chemical survey on the glandular trichome chemistry of different populati ons of two Brazilian Viguiera species has been performed by the glandular t richome microsampling technique and isocratic HPLC analyses. In all six ana lysed samples of V. robusta, the furanoheliangolide budlein A and its tigla te and methacrylate isomers were detected as the major compounds. They were accompanied by various constituents in mostly minor or trace amounts. The chemical pattern of all samples was qualitatively very similar, thus featur ing V. robusta as a taxon of high "chemoconsistency". In contrast, V. quinq ueremis represented an example of "chemodiversity". Although budlein A and its derivatives were present in five of the six analysed populations, other heliangolides and germacrolides co-occurred and partly dominated in quanti ty. Distinct compound patterns divided the samples of V. quinqueremis into three chemical subgroups.