Diterpene

Diterpenes are a class of chemical compounds composed of two terpene units with the molecular formula C20H32; they may also be thought of as consisting of four isoprene units. They are biosynthesized by plants, animals and fungi via the HMG-CoA reductase pathway, with geranylgeranyl pyrophosphate being a primary intermediate. Diterpenes form the basis for biologically important compounds such as retinol, retinal, and phytol. They also form the basis for a class of steroids known as diterpenoids.

Biosynthesis

Diterpenes are synthesized in plants via the mevalonate pathway or the non-mevalonate pathway, also known as the DOXP/MEP pathway. The former involves the condensation of two molecules of geranylgeranyl pyrophosphate (GGPP), a 20-carbon terpenoid, to form a variety of diterpenes. The latter pathway involves the condensation of dimethylallyl pyrophosphate (DMAPP) and isopentenyl pyrophosphate (IPP) to form geranyl pyrophosphate (GPP), which is then converted to GGPP by the enzyme geranylgeranyl pyrophosphate synthase.

Types of Diterpenes

There are several types of diterpenes, including:

• Clerodane diterpenes
• Labdane diterpenes
• Kaurane diterpenes
• Abietane diterpenes
• Pimarane diterpenes
• Podocarpane diterpenes
• Cassane diterpenes
• Rosane diterpenes

Each of these types of diterpenes has unique structures and biological activities.

Biological Importance

Diterpenes have a wide range of biological activities, including anti-inflammatory, antimicrobial, antiviral, and anticancer properties. They are also involved in the biosynthesis of important biological compounds such as vitamin A and vitamin K.

See Also

• Terpenes
• Terpenoids
• Steroids
• Vitamin A
• Vitamin K

• 
  Geranylgeranyl pyrophosphate
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  Taxadiene
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  All-trans Retinol
• 
  Phytol