Systematic Implications of the Distribution of Iridoids and Other Chemical Compounds in the Loganiaceae and Other Families of the Asteridae

The distribution of the chemical compounds iridoids, anthraquinones, and verbascosides is demonstrated in Dahlgrenograms. An analysis of iridoid biosynthesis and structure allows distinction of two main groups of compounds. Thus, the biosynthetic route I gives rise to the seco-iridoids and their derivatives, and another (route II) to aucubin and similar decarboxylated iridoid glucosides. Seco-iridoids from route I are widely distributed in Cornanae, Loasanae, and Gentiananae but never in Lamianae. Aucubinlike compounds derived by route II are commonly found in Lamianae and in three small families in Cornanae, but are not found in Gentiananae (...)