Secondary metabolites

Secondary Metabolites a.k.a. Natural Products: Those products (chemical compounds) of metabolism that are not essential for normal growth, development or reproduction of the plant or organism. In this sense they are “secondary”. The function or importance of these compounds to the organism's development is usually of ecological nature as they are used as defence against predators (herbivores[?], pathogens etc…) for interspecific competition and to facilitate the reproductive processes. Contrary to primary metabolites[?] these compounds are not ubiquitous in the living organisms who produce them nor are they expressed continuously. Although plants are better known as a source of Secondary Metabolites also Bacteria, Fungi and many Marine Organisms (sponges, tunicates, corals, snails) are very interesting sources too. The main classes of secondary metabolites are: Alkaloids, Terpenoids[?], Aliphatic[?], Aromatic and Heteroaromatic[?] organic acids, Phenols, Irridoids[?], Steroids[?], Volatile oils[?], Resins[?] and Balsams[?], Saponins[?].