PLANT NATURAL PRODUCTS
A. LESLIE GUNATILAKA
Southwest Center for Natural Products Research, University of Arizona, Tucson, Arizona
Plants contain numerous natural products (secondary metabolites) that may not participate directly in their growth and development but play an important role in ecological interactions with other organisms. Despite immense chemical diversity, which originates from simple carbohydrates produced because of photosynthesis, plant natural products are formed from only a few biosynthetic building blocks that consist of acetate, mevalonate, and shikimate. These basic building blocks undergo a variety of biosynthetic transformations and combinations that lead to numerous classes of plant natural products including, but not limited to, carbohydrates, fatty acids and their esters, aromatic polyketides (phenols and quinones), terpenoids and steroids, phenyl propanoids (lignans and lignin, coumarins, flavonoids, and isoflavonoids), and alkaloids. Summarized in this chapter are representative members of these important classes of plant natural products with special emphasis on their chemical diversity. The chapter concludes with a brief discussion on recent methods for the maximization of chemical diversity and the production of natural products from plants.
The number of different plant species on the surface of the earth has been estimated to be over 250,000 (1, 2), and only a fraction of these have been investigated for their constituent natural products ...