Triterpenes are a class of chemical compounds composed of three

terpene Terpenes () are a class of natural products consisting of compounds with the formula (C5H8)n for n > 1. Comprising more than 30,000 compounds, these unsaturated hydrocarbons are produced predominantly by plants, particularly conifers. Terpenes ...

units with the molecular formula C₃₀H₄₈; they may also be thought of as consisting of six isoprene units. Animals, plants and fungi all produce triterpenes, including squalene, the precursor to all steroids.

Structures

Triterpenes exist in a great variety of structures. Nearly 200 different skeletons have been identified. These skeletons may be broadly divided according to the number of rings present. In general pentacyclic structures (5 rings) tend to dominate. Squalene is biosynthesized through the head-to-head condensation of two farnesyl pyrophosphate units. This coupling converts a pair of C15 components into a C30 product. Squalene serves as precursor for the formation of many triterpenoids, including bacterial hopanoids and eukaryotic sterols.

Triterpenoids

By definition triterpenoids are triterpenes that possess heteroatoms, usually oxygen. The terms ''triterpene'' and ''triterpenoid'' often are used interchangeably. Triterpenoids possess a rich chemistry and pharmacology (e.g.

cholesterol Cholesterol is any of a class of certain organic molecules called lipids. It is a sterol (or modified steroid), a type of lipid. Cholesterol is biosynthesized by all animal cells and is an essential structural component of animal cell memb ...

) with several pentacyclic motifs. Lupane, oleanane and ursane show particular promise as anti-cancer agents.

Steroids

Steroids feature a

cucurbitane Cucurbitane is a class of chemical compounds with formula (CAS number 65441-59-0). It is a polycyclic hydrocarbon, specifically triterpene. It is also an isomer of lanostane (specifically 19(10→9β)-abeolanostane), from which it differs by ...

core, although in practice they are biosynthesised from either lanosterol (animals and fungi) or

cycloartenol Cycloartenol is an important triterpenoid of the sterol class which is found in plants. It is the starting point for the synthesis of almost all plant steroids, making them chemically distinct from the steroids of fungi and animals, which are, ...

(plants) via the cyclization of squalene. Steroids have two principal biological functions, being either key components of cell membranes or signaling molecules that activate steroid hormone receptors. Important sub-classes include sterols and cucurbitacins.

Triterpenoid saponins

Triterpenoid saponins are triterpenes which belong to the saponin group of compounds, making them triterpenoid

glycoside In chemistry, a glycoside is a molecule in which a sugar is bound to another functional group via a glycosidic bond. Glycosides play numerous important roles in living organisms. Many plants store chemicals in the form of inactive glycosides. ...

s. They are produced by plants as part of their self-defense mechanism with important sub-classes including ginsenosides and eleutherosides.

References

{{Terpenoids *