A chemotaxonomic investigation of Thapsia villosa L., Apiaceae (Umbelliferae)

Chemotaxonomic investigations of Thapsia villosa L., Apiaceae, have resulted in a division of the species into five different types, representing two distinctly different groups. Thapsigargins, the guaianolide sesquiterpene lactones with unique bioactivity, are present only in one of these groups, which includes two morphologically identical types, with different chromosome numbers, 2n = 44 [4×] and 2n = 66 [6×]. Besides thapsigargins, 6-methoxy-7-geranyloxycoumarin and phenylpropanoids are characteristic constituents of the roots, and limonene and methyl eugenol are the two major constituents of the fruit essential oil. The other group with clearly different morphological characters includes three types with the chromosome numbers 2n = 22 [x], 2n = 22 [2×] and 2n = 44 [4×]. Different sesquiterpenes are the characteristic constituents of their roots, tovarol and hydroindene derivatives being present in all three types, whereas guaiane esters have been detected in only one of the diploid types. Geranyl acetate is the major constituent of the fruit essential oil of all three types within this group.