Chapter 2 The Chemistry of C20-Diterpenoid Alkaloids

Abstract

Publisher Summary The diterpenoid alkaloids, isolated mainly from Aconitum and Delphinium species (Ranunculaceae), have been of great interest since the early 1800s because of their pharmacological properties. Extracts of Aconitum species were used in ancient times for treatment of gout, hypertension, neuralgia, rheumatism, and even toothache. Extracts have also been used as arrow poisons. Some Delphinium species are extremely toxic and constitute a serious threat to livestock in the western United States and Canada. Delphinium extracts also manifest insecticidal properties. In the past 30 to 40 years, interest in the diterpenoid alkaloids has increased because of the complex structures and interesting chemistry involved. The diterpenoid alkaloids may be divided into two broad categories: those based on a hexacyclic C 19 -skeleton and those based on a C 20 -skeleton. The C 20 -diterpenoid alkaloids contain three basic skeletons: (1) Atisine-type, (2) Veatchine-type, and (3) Delnudine-type. This chapter includes a catalog of all known C 20 -diterpenoid alkaloids that shows the correct structures, physical properties, plant sources, and key references. Previously published books and recent reviews have reported incorrect structures for several well-known C 20 -diterpenoid alkaloids.