What is "diterpene"

n. (label en chemistry) any terpene formed from four isoprene units, and having twenty carbon atoms; includes vitamin A, the gibberellins, and various biologically active lactones such as quassin

Diterpenes are a class of chemical compounds composed of two terpene units with the molecular formula CH; 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 are known to be antimicrobial and antiinflammatory.