Bilobalide

Bilobalide

Systematic (IUPAC) name
(5aR- (3aS*,5aα,8b,8aS*,9a,10aα))- 9-(1,1-dimethylethyl)- 10,10a-dihydro- 8,9-dihydroxy- 4H,5aH,9H-furo[2,3-b]furo[3',2':2,3]cyclopenta[1,2-c]furan- 2,4,7(3H,8H)-trione
Clinical data
Legal status	legal
Routes of administration	oral
Identifiers
CAS Number	33570-04-6 Y
PubChem	CID: 73581
IUPHAR/BPS	2366
ChemSpider	21106418 Y
ChEMBL	CHEMBL133266 N
Chemical data
Formula	C15H18O8
Molecular mass	326.299 g/mol
SMILES CC(C)(C)[C@@]1(C[C@H]2[C@@]3([C@]14[C@H](C(=O)O[C@H]4OC3=O)O)CC(=O)O2)O
InChI InChI=1S/C15H18O8/c1-12(2,3)14(20)4-6-13(5-7(16)21-6)10(19)23-11-15(13,14)8(17)9(18)22-11/h6,8,11,17,20H,4-5H2,1-3H3/t6-,8-,11-,13-,14+,15?/m0/s1 Y Key:MOLPUWBMSBJXER-ISSLQHLCSA-N Y
NY (what is this?)  (verify)

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

Chemistry

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.

Biosynthesis

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. However, due to the complexity of ginkgolide structures for rearrangement, ring cleavage, and formation of lactone rings, diterpene 8 is used to explain instead. Levopimaradiene 6 and abietatriene 7 are precursors for ginkgolide and bilobalide formation. The unusual tert-butyl substituent is formed from A ring cleavage in 9. Bilobalide 13 then formed in loss of carbons through degradation from ginkgolide 12, and lactones are formed from residual carboxyl and alcohol functions. The end product of bilobalide contains sesquiterpenes and three lactones units.

Pharmacology

Bilobalide is important for producing several of the effects of Gingko biloba extracts, and it has neuroprotective effects, as well as inducing the liver enzymes CYP3A1 and 1A2, which may be partially responsible for interactions between gingko and other herbal medicines or pharmaceutical drugs. Bilobalide has recently been found to be a negative allosteric modulator at the GABA_A and GABA_A-rho receptors. Of GABA_A, it may possibly be selective for the subunits predominantly implicated in cognitive and memory functioning such as α1.

See also

• Ginkgolide