CHAPTER 6 - Secondary Plant Products

Abstract

This chapter describes that secondary plant products are compounds, which have not so far been shown to be involved in primary metabolism. As far as their functions can be assessed at present, they are accessory rather than central to the physiology of the plants in which they occur. Secondary plant products are discontinuously distributed throughout the plant kingdom. Particular groups of secondary product are characteristic of single or related genera. Species with identical or closely related secondary products may have arisen from a common ancestor. The presence or absence of a characteristic secondary product can be a useful taxonomic character when other characteristics make the placing of the plant between two related families or genera difficult. The recent development of methods for the rapid elucidation of chemical structures and the associated rise of chemotaxomy have both stimulated the search for new secondary plant products; their number, already great, continues to rise rapidly. The chapter discusses the problems of biosynthesis and function posed by secondary plant products by a brief consideration of alkaloids, isoprenoids, nonprotein amino acids, flavonoids, and phenylpropanoids.