Diterpenes

Diterpenes are a class of terpenes consisting of four isoprene units, giving a carbon skeleton of 20 carbon atoms (C20). They are derived biosynthetically from geranylgeranyl pyrophosphate (GGPP) and occur as hydrocarbons and oxygenated derivatives, collectively referred to as diterpenoids.

In plants, fungi, and marine organisms, diterpene synthases sculpt GGPP into a variety of carbon skeletons, including labdane, clerodane, ent-kaurane, abietane, and taxane types. Further enzymatic oxidations, rearrangements, and glycosylations expand this diversity, producing compounds with a wide range of biological activities.

Diterpenes play several natural roles, such as participating in growth regulation, defense, and ecological interactions. A major biological function in plants is as precursors to gibberellins, a family of plant hormones derived from ent-kaurane-type skeletons that regulate growth and development.

Notable examples of diterpenes and diterpenoids include gibberellins, abietic acid and related resin acids from conifers, forskolin (a labdane-type diterpene used in research), steviol and related glycosides from Stevia (ent-kaurane derivatives used as sweeteners), and taxane-type diterpenes such as paclitaxel (Taxol), which is used as an anticancer drug. Diterpenes are also encountered in fragrances and resins.

Due to their structural diversity and wide range of bioactivities, diterpenes are of interest in pharmaceuticals, agriculture, and natural product chemistry, with ongoing research into their biosynthesis, functions, and potential applications.