Bilobalide (Ginkgo Sesquiterpene Trilactone · Neuroprotective · GABA-A Modulator · Anti-ischaemic)
| Compound | Bilobalide |
| Chemical class | Terpenoid — Sesquiterpene Trilactone (Unique Ginkgo sesquiterpene; structurally related to ginkgolides) |
| CAS | 33570-04-6 |
| Primary source | Ginkgo biloba (leaves; approximately 2.6% of total terpene trilactone fraction in EGb 761) |
| Key applications | Neuroprotective; GABA-A modulation; mitochondrial protection; stroke protection; cognitive support |
| Claim strength | Moderate |
| Typical form | Ginkgo biloba extract (co-delivered with ginkgolides in 6% terpene trilactone fraction) |
| Buy from Herbuno |
Ginkgo Biloba Extract Powder → Ginkgo Biloba Leaf Liquid Extract (Water Soluble) → |
Name origin: Named after the bilobed (two-lobed) leaf of Ginkgo biloba from which it was isolated. Bilobalide is a sesquiterpene trilactone — despite being smaller than the ginkgolides (sesquiterpene vs diterpene), it shares structural features (multiple lactone rings, cage-like character) and biological origins within the ginkgolide biosynthetic pathway. It is unique to Ginkgo biloba, like the ginkgolides. Pharmacological importance: Bilobalide is considered the most neuroprotectively active constituent of standardised Ginkgo extract. Its mechanisms include: (1) negative allosteric modulation of GABA-A receptors (reducing excessive inhibitory tone and potentially improving cognition); (2) inhibition of ischaemia-induced glutamate release (neuroprotection in hypoxia); (3) mitochondrial membrane potential stabilisation (anti-apoptotic); (4) anti-excitotoxic activity. The multiple complementary neuroprotective mechanisms make bilobalide particularly relevant for ischaemic stroke and cognitive impairment research. Research context: Most bilobalide clinical data are embedded within EGb 761 extract trials — there are few isolated bilobalide human studies. However, mechanistic research strongly implicates bilobalide as the primary neuroprotective driver within EGb 761, complementing ginkgolide B’s cardiovascular/PAF-antagonism contribution. Commercial source: Ginkgo Biloba extract in multiple forms, all co-delivering bilobalide alongside ginkgolides is available from Herbuno.
Evidence for Bilobalide Applications
Neuroprotection — anti-ischaemic: Bilobalide reduces infarct volume and neurological deficit in multiple rodent models of cerebral ischaemia (MCAO, global ischaemia). Mechanisms include reduction of ischaemia-induced glutamate release from presynaptic terminals (reducing excitotoxicity), inhibition of NMDA receptor overactivation, and preservation of mitochondrial ATP synthesis during hypoxic stress. Claim strength: Moderate (animal models; clinical via EGb 761).
GABA-A receptor modulation: Bilobalide is a negative allosteric modulator at GABA-A receptors — it reduces the efficacy of GABA at Cl- channels without affecting basal channel function. This mild reduction in GABAergic inhibitory tone may paradoxically improve alertness and cognitive processing in states where excessive inhibition is present (as in ageing brains or post-stroke). This mechanism also contributes to bilobalide’s anti-seizure effects in some animal models. Claim strength: Moderate (well-characterised mechanism; clinical significance debated).
Mitochondrial protection: Bilobalide preserves mitochondrial membrane potential and inhibits cytochrome c release (a key early apoptosis trigger) in neuronal cells under oxidative stress. This mitochondria-centric neuroprotection is complementary to its GABA-A and glutamate mechanisms. Claim strength: Moderate (in vitro and animal).
Ginkgo Biloba Extract Powder →
Ginkgo Biloba Leaf Liquid Extract (Water Soluble) →
Browse Standardised Extract Powders →
Dosage & Formulator Specification
Bilobalide is not commercially available as an isolated ingredient — it is delivered within standardised Ginkgo extract. In EGb 761 at 120 mg/day, bilobalide content is approximately 2.4 mg (2% of the 6% terpene trilactone fraction at 120 mg = ~7.2 mg total terpene trilactones, with bilobalide ~33% = ~2.4 mg). For higher bilobalide delivery, specify ginkgo extract with verified terpene trilactone composition and bilobalide % by HPLC. Same quality specifications apply as ginkgolide B: ginkgolic acid <5 ppm, standardised total terpene trilactones 6%, flavonol glycosides 24%.
Frequently Asked Questions — Bilobalide
Is bilobalide a GABA inhibitor — does it cause seizures?
Bilobalide’s GABA-A negative allosteric modulation (reducing GABA efficacy) could theoretically increase seizure risk by reducing inhibitory tone. However, in practice at concentrations achieved by standard Ginkgo doses, bilobalide does not cause seizures in humans. Paradoxically, bilobalide has shown anti-convulsant properties in some animal seizure models — possibly because its anti-excitotoxic and neuroprotective mechanisms offset the mild GABA-A inhibition. There is a theoretical concern about Ginkgo extract in patients with epilepsy on GABA-potentiating medications; most epilepsy guidelines advise caution with Ginkgo in this population.
How does bilobalide compare to ginkgolide B for cognitive support?
The two terpene trilactone components of Ginkgo extract work through complementary mechanisms. Bilobalide is primarily neuroprotective (reducing neuronal death and preserving function) via anti-excitotoxic and mitochondrial mechanisms. Ginkgolide B primarily provides cardiovascular/cerebrovascular protection via PAF antagonism (reducing thrombosis and platelet activation in cerebral vessels). For cognitive support, both contribute — bilobalide from the neuronal preservation angle, ginkgolide B from the cerebrovascular protection angle. This complementarity is the pharmacological rationale for standardising Ginkgo extract to include both.
Is Ginkgo extract safe long-term?
EGb 761 standardised extract has been used by millions of patients for decades with a generally favourable safety profile. The most significant safety concerns are: (1) anticoagulant interactions (see Ginkgolide B); (2) rare hypersensitivity reactions; (3) theoretical seizure risk in susceptible populations; (4) ginkgolic acid content in poorly manufactured products. The GuidAge trial (5 years, n=2,854 elderly patients) found no significant increase in serious adverse events compared to placebo — the longest and largest safety dataset for EGb 761. Long-term Ginkgo use appears safe in healthy adults at standard doses.
What does the GABA-A modulation mean for sleep and anxiety?
Bilobalide’s GABA-A negative allosteric modulation is distinct from GABA enhancers (benzodiazepines, alcohol, valerian) which sedate. Bilobalide’s partial inhibition of GABA efficacy may produce mild alerting effects — consistent with clinical observations that Ginkgo extract improves alertness and concentration rather than causing sedation. This distinguishes Ginkgo from GABA-enhancing adaptogens and supports its use for daytime cognitive support rather than sleep formulations.
Related compounds: Ginkgolide B, Huperzine-A, Vinpocetine, Galantamine
Claim-strength scale – High = multiple human RCTs; Moderate = limited trials or strong preclinical convergence; Emerging = early-stage lab or animal data.
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