(including retinoids and steroids)

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Hydrocarbon carotenoids (a subclass of tetraterpenes). See also terpenes. See under carotenoids.


Tetraterpenoids (C40), formally derived from the acyclic parent [psi],[psi]-carotene (I) by hydrogenation, dehydrogenation, cyclization, oxidation, or combination of these processes. This class includes carotenes, xanthophylls and certain compounds that arise from rearrangement of the skeleton of (I) or by loss of part of this structure. Retinoids are excluded. BNRD Rule Carotenoid-1 (p. 226, 237). See also retro. E.g.

diterpenoids: Terpenoids having a C20 skeleton.


Cyclic monoterpenoids having the iridane skeleton (1-isopropyl-2,3-dimethylcyclopentane according to NOC Rule C-15.11), the traditional, but not undisputed, numbering of which is as shown.


Compounds formally derived from isoprene (2-methylbuta-1,3-diene), the skeleton of which can generally be discerned in repeated occurrence in the molecule. The skeleton of isoprenoids may differ from strict additivity of isoprene units by loss or shift of a fragment, commonly a methyl group. The class includes both Hydrocarbon and oxygenated derivatives. See also carotenoids , steroids, terpenes, terpenoids. BNRD, Pr-10 (p. 255).

monoterpenes: See terpenes.

monoterpenoids: Terpenoids having a C10 skeleton.


Alcohols of general formula H-[CH2C(Me)=CHCH2]nOH in which the carbon skeleton is composed of one or more isoprene units (biogenetic precursors of the isoprenoids ). BNRD, Prenol Nomenclature, Rule Pr-1 (p. 252).


Oxygenated derivatives of 3,7-dimethyl-1-(2,6,6-trimethylcyclohex-1-enyl)nona-1,3,5,7- tetraene as shown and derivatives thereof. BNRD, Nomenclature of Retinoids, Rule Ret-1 (p. 247). See also carotenoids, retro.

R = -CH2OR', -C(=O)H, -CH2OH, -C(=O)OH


Terpenoids having a C15 skeleton.


Terpenoids having a C25 skeleton. Sometimes erroneously referred to as sesterpenoids.


Naturally occurring compounds and synthetic analogues, based on the cyclopenta[a]phenanthrene carbon skeleton, partially or completely hydrogenated; there are usually methyl groups at C-10 and C-13, and often an alkyl group at C-17. By extension, one or more bond scissions, ring expansions and/or ring contractions of the skeleton may have occurred. BNRD, Rule 3S-1.0 (p. 193). Natural steroids are derived biogenetically from triterpenoids.


Natural products derived from the steroid skeleton and containing a hydroxy group in the 3 position, closely related to cholestan-3-ol. BNRD, Rule 3S-1.0 (p. 193).


Hydrocarbons of biological origin having carbon skeletons formally derived from isoprene [CH2=C(CH3)CH=CH2]. This class is subdivided into the C5 hemiterpenes, C10 monoterpenes, C15 sesquiterpenes, C20 diterpenes, C25 sesterterpenes, C30 triterpenes, C40 tetraterpenes (carotenoids), and C5n polyterpenes. See also carotenes, carotenoids, isoprenoids, prenols, retinoids, steroids , terpenoids.


Natural products and related compounds formally derived from isoprene units (see isoprenoids). They contain oxygen in various functional groups. This class is subdivided according to the number of carbon atoms in the same manner as are terpenes. The skeleton of terpenoids may differ from strict additivity of isoprene units by the loss or shift of a fragment, generally a methyl group. BNRD, Prenol Nomenclature, Rule Pr-10 (p. 255)


Terpenoids having a C40 skeleton. See also carotenes, carotenoids, xanthophylls.


Terpenoids having a C30 skeleton.


A subclass of carotenoids consisting of the oxygenated carotenes. BNRD Rule Carotenoid 1 (p. 226).

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