Bilobalide is a main constituent of the terpenoids found in Ginkgo leaves. It also exists in minor amounts in the roots. It is a sesquiterpenoid, i.e. it has a 15-carbon skeleton. Its exact synthesis pathway from farnesyl pyrophosphate is still unknown. Bilobalide and ginkgolide both have very similar biosynthesis pathway. Bilobalide is formed by partially degraded from ginkgoglide. Bilibalide is derived from geranylgeranyl pyrophosphate (GGPP), which is formed by addition of farnesyl pyrophosphate (FPP) to isopentenyl pyrophosphate (IPP) unit, to form a C15 sesquiterpene. Such formation went through the mevalonate pathway (MVA) and methylerythritol phosphate MEP pathway. In order to generate bilobalide, C20 ginkgolide 13 must form first. To transform from GGPP to abietenyl cation 5, a single bifunctional enzyme abietadiene synthase E1 is required.
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