Terpenoids, like terpenes(named after the tree resin turpentine from which terpenes were originally extracted), are a large, heterogeneous group of naturally occurring chemical compounds that occur as secondary constituents in organisms. They are structurally derived from isoprene. Terpenoids differ from terpenes in that they contain functional groups, whereas terpenes are pure hydrocarbons. Currently, > 35,000 terpenoids are known. They represent the largest group of natural substances.
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Terpenoids
DefinitionThis section has been translated automatically.
ClassificationThis section has been translated automatically.
Like terpenes, terpenoids can also be divided into groups according to the number of isoprene units.
Terpenoids, especially mono-, sesqui- and diterpenoids, can be obtained from plant (parts) or essential oils by physical methods e.g. steam distillation, extraction or chromatography (methods used in the perfume industry).
In general, a distinction is made between acyclic, mono-, bi-, tri-, tetra- and pentacyclic terpenoids, i.e. molecules without, with one, with two, three, four or five rings. Furthermore, terpenes differ in the number of isoprene units (always 5 carbon atoms).
- Terpenoids with 5 carbon atoms are called hemiterpenoids (C5),
- with 1C5 unit: monoterpenoids (C10): citral, iridoids, camphor
- with 3 C5 units: sesquiterpenoids (C15) - "sesqui - greek = one and a half": proazulenes
- with 4 C5 units: diterpenoids (C20): resin acids
- with 5C5 units: ester terpenoids (C25): cochliobolin
- with 6 C5 units: triterpenoids(C30): steroids, sterols, squalene, cardiac glycosides like digitoxin
- with 8 C5 units: tetraterpenoids (C40): carotenoids
- with > 40 C5 units: Polyterpenoids (>C200): Rubbers
General informationThis section has been translated automatically.
In the case of terpenoids, one or more carbon atoms are more frequently removed or regrouped during biosynthesis, so that the relationship with isoprene is not so clear and there is also not necessarily an integral multiple of the five carbon atoms of isoprene. However, all terpenoids are biosynthetically derived from terpenes. Terpenoids form important features for the identification of plants(taxonomy), as a certain constituent pattern is characteristic for a certain plant(chemotaxonomy).
Note(s)This section has been translated automatically.
However, the terms terpene and terpenoid are rarely neatly separated in common usage and are very often used interchangeably.