Diterpene

They are biosynthesized by plants, animals and fungi via the HMG-CoA reductase pathway, with geranylgeranyl pyrophosphate being a primary intermediate.

Diterpenes are derived from the addition of one IPP unit to FPP to form geranylgeranyl pyrophosphate (GGPP).

This compound is used for the biosynthesis of tocopherols and the phytyl functional group is used in the formation of chlorophyll a, ubiquinones, plastoquinone and phylloquinone.

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 retinol, phytol or taxadiene.

They are produced by plants of the genus Taxus (yew trees) and are widely used as chemotherapy agents.