secondary metabolite

Secondary metabolites are organic compounds that are not directly involved in the normal growth, development or reproduction of organisms.

Unlike primary metabolites, absence of secondary metabolities results not in immediate death, but in long-term impairment of the organism’s survivability/fecundity or aesthetics, or perhaps in no significant change at all.

Secondary metabolites are often restricted to a narrow set of species within a phylogenetic group.

Functions

The function or importance of these compounds to the organism is usually of an ecological nature as they are used as defenses against predators, parasites and diseases, for interspecies competition, and to facilitate the reproductive processes (coloring agents, attractive smells, etc).

Since these compounds are usually restricted to a much more limited group of organisms, they have long been of prime importance in taxonomic research.

Secondary metabolites may be likely candidates for drug or other technological development directly, or as an inspiration for unnatural products.

This will concern secondary metabolites in plants, bacteria, fungi and many marine organisms (sponges, tunicates, corals, snails).

In some cases, higher organisms will host a microorganism which is the actual producer of the product in question, as part of a symbiotic relationship.

Categories

Most of the secondary metabolites of interest to humankind fit into categories which classify secondary metabolites based on their biosynthetic origin.

Since secondary metabolites are often created by modified primary metabolite synthases, or "borrow" substrates of primary metabolite origin, these categories should not be interpreted as saying that all molecules in the category are secondary metabolites (for example the steroid category), but rather that there are secondary metabolites in these categories.

Biosynthesis of secondary metabolites

 terpenoid biosynthesis
 diterpenoid biosynthesis
 monoterpenoid biosynthesis
 limonene and pinene degradation
 indole and ipecac alkaloid biosynthesis
 zeatin biosynthesis
 carotenoid biosynthesis
 brassinosteroid biosynthesis
 phenylpropanoid biosynthesis
 flavonoid biosynthesis
 flavone and flavonol biosynthesis
 anthocyanin biosynthesis
 isoflavonoid biosynthesis
 alkaloid biosynthesis I
 alkaloid biosynthesis II
 acridone alkaloid biosynthesis
 caffeine metabolism
 benzoxazinone biosynthesis
 penicillin and cephalosporin biosynthesis
 beta-Lactam resistance
 streptomycin biosynthesis
 tetracycline biosynthesis
 clavulanic acid biosynthesis
 puromycin biosynthesis
 novobiocin biosynthesis
 insect hormone biosynthesis

See also

 metabolisms