Secondary metabolites are
organic compounds that are not directly involved in the normal
growth,
development, or
reproduction of an organism. Unlike
primary metabolites, absence of secondary metabolites does not result in immediate death, but rather 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. Secondary metabolites often play an important role in
plant defense against herbivory and other interspecies defenses. Humans use secondary metabolites as medicines, flavorings, and recreational drugs.