Bilobalide is a biologically active terpenic trilactone present in Ginkgo biloba.

To transform from GGPP to abietenyl cation 5, a single bifunctional enzyme abietadiene synthase E1 is required.

Bilobalide is important for producing several of the effects of Ginkgo biloba extracts, and it has neuroprotective effects,[3][4] as well as inducing the liver enzymes CYP3A1 and CYP1A2,[5] which may be partially responsible for interactions between ginkgo and other herbal medicines or pharmaceutical drugs.

Bilobalide has recently been found to be a negative allosteric modulator at the GABAA and GABAA-rho receptors.

[6] Of GABAA, it may possibly be selective for the subunits predominantly implicated in cognitive and memory functioning such as α1[citation needed].