The Role of Alkaloids in Plants

TLDR: The proposed roles of alkaloids in plant metabolism, plant catabolism, or plant physiology are (1) end products of metabolism or waste products, (2) storage reservoirs of nitrogen, (3) protective agents for the plant against attack by predators, (4) growth regulators, or (5) substitutes for minerals in plants.

Abstract: The proposed roles of alkaloids in plant metabolism, plant catabolism, or plant physiology are (1) end products of metabolism or waste products, (2) storage reservoirs of nitrogen, (3) protective agents for the plant against attack by predators, (4) growth regulators (since structures of some of them resemble structures of known growth regulators), or (5) substitutes for minerals in plants, such as potassium and calcium (according to Justus von Liebig (1840, 1841). Of these items, (2) and (5) appear to be the least promising, and are not considered further here, but the other items, as well as new concepts, will be discussed in this chapter. There are several reviews of the raison d ’etre of secondary compounds (Errera, 1887; James, 1950; Mothes, 1953, 1966, 1969; Fraenkel, 1959, 1969; Bu’Lock, 1961, 1965; Mothes and Schuette, 1969; Geissman and Crout, 1969; Weinburg, 1971; Luckner, 1972; Robinson, 1974).