Diterpenes are a class of

terpenes Terpenes () are a class of natural products consisting of compounds with the formula (C5H8)n for n ≥ 2. Terpenes are major biosynthetic building blocks. Comprising more than 30,000 compounds, these unsaturated hydrocarbons are produced predomi ...

composed of four

isoprene Isoprene, or 2-methyl-1,3-butadiene, is a common volatile organic compound with the formula CH2=C(CH3)−CH=CH2. In its pure form it is a colorless volatile liquid. It is produced by many plants and animals (including humans) and its polymers ar ...

units, often with the molecular formula C₂₀H₃₂. They are biosynthesized by plants, animals and fungi via the HMG-CoA reductase pathway, with

geranylgeranyl pyrophosphate Geranylgeranyl pyrophosphate is an intermediate in the biosynthesis of diterpenes and diterpenoids. It is also the precursor to carotenoids, gibberellins, tocopherols, and chlorophylls. It is also a precursor to geranylgeranylated proteins, whic ...

being a primary intermediate. Diterpenes form the basis for biologically important compounds such as

retinol Retinol, also called vitamin A1, is a fat-soluble vitamin in the vitamin A family that is found in food and used as a dietary supplement. Retinol or other forms of vitamin A are needed for vision, cellular development, maintenance of skin and ...

retinal Retinal (also known as retinaldehyde) is a polyene chromophore. Retinal, bound to proteins called opsins, is the chemical basis of visual phototransduction, the light-detection stage of visual perception (vision). Some microorganisms use ret ...

, and phytol. Some diterpenes are known to be

antimicrobial An antimicrobial is an agent that kills microorganisms (microbicide) or stops their growth (bacteriostatic agent). Antimicrobial medicines can be grouped according to the microorganisms they are used to treat. For example, antibiotics are used aga ...

and

anti-inflammatory Anti-inflammatory is the property of a substance or treatment that reduces inflammation, fever or swelling. Anti-inflammatory drugs, also called anti-inflammatories, make up about half of analgesics. These drugs reduce pain by inhibiting mechan ...

Structures

As with most terpenes a huge number of potential structures exists, which may be broadly divided according to the number of rings present.

Biosynthesis

Diterpenes are derived from the addition of one IPP unit to FPP to form

(GGPP). From GGPP, structural diversity is achieved mainly by two classes of enzymes; the diterpene synthases and cytochromes P450. Several diterpenes are produced by plants and

cyanobacteria Cyanobacteria ( ) are a group of autotrophic gram-negative bacteria that can obtain biological energy via oxygenic photosynthesis. The name "cyanobacteria" () refers to their bluish green (cyan) color, which forms the basis of cyanobacteri ...

. GGPP is also the precursor for the synthesis of the

phytane Phytane is the Diterpenoid, isoprenoid alkane formed when phytol, a chemical substituent of chlorophyll, loses its Hydroxy group, hydroxyl group. When phytol loses one carbon atom, it yields pristane. Other sources of phytane and pristane have al ...

by the action of the enzyme geranylgeranyl reductase. This compound is used for the biosynthesis of

tocopherol Tocopherols (; TCP) are a class of organic compounds comprising various methylated phenols, many of which have vitamin E activity. Because the vitamin activity was first identified in 1936 from a dietary fertility factor in rats, it was named ''t ...

s and the phytyl functional group is used in the formation of chlorophyll ''a'',

ubiquinone Coenzyme Q10 (CoQ10 ), also known as ubiquinone, is a naturally occurring Cofactor (biochemistry), biochemical cofactor (coenzyme) and an antioxidant produced by the human body. It can also be obtained from dietary sources, such as meat, fish, ...

plastoquinone Plastoquinone (PQ) is a terpenoid-quinone ( meroterpenoid) molecule involved in the electron transport chain in the light-dependent reactions of photosynthesis. The most common form of plastoquinone, known as PQ-A or PQ-9, is a 2,3-dimethyl-1,4- ...

and phylloquinone.

Diterpenoids

Diterpenes are formally defined as being

hydrocarbons In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons are examples of group 14 hydrides. Hydrocarbons are generally colourless and hydrophobic; their odor is usually faint, and may b ...

and thus contain no heteroatoms. Functionalized structures should instead be called diterpenoids, although in scientific literature the two terms are often used interchangeably. Although a wide range of terpene structures exist, few of them are biologically significant; by contrast, diterpenoids possess a rich pharmacology and include important compounds such as

, phytol or taxadiene.

Taxanes

Taxane Taxanes are a class of diterpenes. They were originally identified from plants of the genus ''Taxus'' (yews), and feature a taxadiene core. Paclitaxel (Taxol) and docetaxel (Taxotere) are widely used as chemotherapy agents. Cabazitaxel was FDA app ...

s are class of diterpenoids featuring a taxadiene core. They are produced by plants of the genus ''

Taxus ''Taxus'' is a genus of coniferous trees or shrubs known as yews in the family Taxaceae. Yews occur around the globe in temperate zones of the northern hemisphere, northernmost in Norway and southernmost in the South Celebes. Some populations ex ...

'' (yew trees) and are widely used as

chemotherapy Chemotherapy (often abbreviated chemo, sometimes CTX and CTx) is the type of cancer treatment that uses one or more anti-cancer drugs (list of chemotherapeutic agents, chemotherapeutic agents or alkylating agents) in a standard chemotherapy re ...

agents.

Other

* ''Dodonaea petiolaris'' yields the diterpene ''ent''-3β-acetoxy-15,16-epoxylabda-8(17),13(16),14-trien-18-oic acid (C₂₂H₂₈O₆) or its enantiomer. * '' Salvia divinorum'' yields Salvinorin A, a psychotropic drug

References