Ginkgolic Acid: An Encyclopedic Reference
1. Identity and Chemical Characterization
1.1 Nomenclature and Classification
Ginkgolic acids (GAs) are alkylphenol constituents of the leaves and fruits of Ginkgo biloba. Chemically, ginkgolic acids are 2-hydroxy-6-alkylbenzoic acids related to anacardic acids; the C15:1 congener specifically is a 2-hydroxy-6-alkylbenzoic acid in which the alkyl chain contains 15 carbons and is unsaturated at the 8 position. The broader class of ginkgolic acids can also be described as 6-alkylsalicylic acids. More specifically, ginkgolic acid is a phenolic acid — a 6-alkyl or 6-alkenyl derivative of salicylic acid. It is a member of the urushiol family of compounds, sharing structural kinship with the allergenically active phenols found in poison ivy and cashew.
Ginkgolic acids are a mixture of several 2-hydroxy-6-alkylbenzoic acids in which the most common alkyl chains contain 13, 15, or 17 carbons; the 15- and 17-carbon chains are unsaturated at positions 8 and 10, respectively. The three primary GA structures are therefore designated C13:0, C15:1, and C17:1. Their structural diversity arises from variations in the length of side chains and their number of double bonds, resulting in six distinct forms within Ginkgo biloba extracts (GBE); of these, GA (C15:1) is the most prevalent.
Ginkgolic acids are distinctive secondary metabolites of Ginkgo biloba primarily found in its leaves and seeds, with the highest concentration located in the exotesta. They are classified as long-chain phenolic compounds and exhibit structural similarities to lignoceric acid. The molecular formula of the C15:1 congener (CAS 22910-60-7) is C22H34O3, with a molecular weight of approximately 346.5 g/mol.
1.2 Natural Sources and Plant Distribution
Ginkgo biloba L. (family Ginkgoaceae), commonly known as maidenhair tree, is the sole surviving species of the division Ginkgophyta and is considered a living fossil. It is a tree native to China and has been spread around the world as an ornamental tree. Ginkgolic acid is a phenolic acid extracted from ginkgo fruit, ginkgo exotesta, and ginkgo leaves. Ginkgolic acids are a group of 6-alkylsalicylic acids extracted from the sarcotesta and leaves of Ginkgo biloba.
Standardized Ginkgo biloba extracts contain approximately 24% flavone glycosides (quercetin, kaempferol, and isorhamnetin) and 6% terpene lactones (ginkgolides A, B, and C, and bilobalide). Other constituents include proanthocyanadins, glucose, rhamnose, organic acids, d-glucaric acid, and ginkgolic acid with related alkylphenols. The concentration of ginkgolic acids in raw, unprocessed plant material is substantially higher than in standardized pharmaceutical-grade extracts.
1.3 Forms and Preparations
Ginkgolic acids occur naturally across different fractions of the Ginkgo biloba plant. In commercial Ginkgo biloba extracts (GBE), their presence is tightly regulated. Numerous preclinical and clinical investigations have been performed with EGb 761, a standardized GBE introduced by Dr. Willmar Schwabe Pharmaceuticals in the early 1970s; EGb 761 contains 24% flavonoid glycosides and 6% terpene trilactones (TTLs), but less than 0.0005% ginkgolic acids. The Chinese, European, and United States pharmacopeias all mandate that the GA concentration in GBE be less than 5 μg g-1.
As an isolated research compound, ginkgolic acid C15:1 is available as a high-purity reference standard. Ginkgolic acid C15:1 may be used as a reference standard in the quantitative determination of alkylphenols like ginkgolic acids in Ginkgo extract using high performance liquid chromatography coupled with mass spectrometry (HPLC-MS). In research settings, it is also utilized as a cell-permeable biochemical probe for studying SUMOylation pathways. Various extraction methods — including ethanol, water, and oil-based preparations — have been employed in both traditional and modern contexts, as reflected in ethnobotanical and pharmacological literature.
2. Traditional and Historical Use
2.1 Traditional Chinese Medicine
Ginkgo biloba seeds have an extensive recorded history in Chinese medicine. In 2000-year-old traditional Chinese medicine, Ginkgo biloba seeds were used in the treatment of cough, asthma, tuberculosis, bladder infections, flatulence, and diarrhea. As reported in Ancient Chinese Medicinal Books, Ginkgo biloba L. fruit has been used as a traditional Chinese medicine for the treatment of asthma and cough or as a disinfectant.
A pivotal 16th-century Chinese pharmacopoeia, the Ben Cao Gang Mu (Compendium of Materia Medica) compiled by Li Shi-Zhen, provides detailed records. Researchers have reviewed this 16th-century Chinese text to investigate the ancient prescription of ginkgo seeds for skin infections. In total, 17 traditional uses were reported in the book, including 8 for skin disorders such as chapped hands and feet, rosacea, patches and nodules on the face and scalp, genital ulcers, crab louse-induced itchiness, dog bite wound abscess, mastitis, and bullae or pustules. According to the Ben Cao Gang Mu, the topical usage of ginkgo seed involved a delivery media of water, alcohol, and oil; extractions were accordingly processed with water, 80% ethanol, and rapeseed oil.
The seeds have been used as snacks and medical materials in Traditional Chinese Medicine (TCM), while over the last century leaf extracts emerged as a source of rising pharmaceutical commerce related to brain health in Western medicine. A decoction extraction (boiling plant material in water to extract chemical substances) was performed for ginkgo leaves, since in Quan guo zhong cao yao hui bian (the Summary of Chinese Herbal Medicine), ginkgo leaf boiled in water was a treatment for enteritis in children.
Important distinction: In traditional use, the preparations employed were whole-plant extracts of seeds, leaves, or seed coats containing a mixture of many compounds; ginkgolic acid was not isolated or used as a single purified compound. The attribution of any specific historical therapeutic effect solely to ginkgolic acid is a retrospective scientific inference rather than an element of traditional practice itself.
2.2 Modern Pharmacological Interest and the Dual Role of GAs
Ginkgo biloba extracts (GBE) have been used as herbal supplements since at least the 16th century and remain widely in use. As GBE rose to pharmaceutical prominence in the 20th century — particularly in Europe for cognitive and circulatory applications — ginkgolic acids were progressively identified as toxicologically problematic components requiring removal or limitation, even as their independent pharmacological properties were recognized. Ginkgo biloba leaf extract (EGb) is high in bioactive components (over 170), which are used in food additives, medicine, cosmetics, health products, and other sectors; nonetheless, ginkgolic acids (GAs) in Ginkgo biloba have been identified as the primary source of EGb's adverse effects such as embryotoxicity, cytotoxicity, neurotoxicity, and inhibition of enzyme systems.
3. Key Constituents and Chemical Context Within Ginkgo biloba
Major constituents of GBE include terpene trilactones (ginkgolide A, B, C, J, and bilobalide), flavonoid glycosides (quercetin and rutin), as well as ginkgolic acids. While the flavonoids and TTLs are primarily responsible for the pharmacological actions of GBE, ginkgolic acids are associated with adverse effects, including allergenicity, genotoxicity, and neurotoxicity.
The members of the ginkgolic acid family contain the side chains C13H27 (C13:0), C15H31 (C15:0), C15H29 (C15:1), C17H33 (C17:1), and C17H31 (C17:2). Thus, the GA family includes GA (C13:0), GA (C15:0), GA (C15:1), GA (C17:1), and GA (C17:2). The activities of these compounds may be somewhat different, but most are mixed in extracts, and the isolation of a specific compound is difficult due to their similar polarity. The monomers C13:0, C15:0, and C17:1 have been shown to demonstrate antitumor activity.
The quality and safety of consumed ginkgo products is defined by the quantity of terpene trilactones, flavonoids, ginkgolic acid, and aglycones.
4. Mechanisms of Action
4.1 Inhibition of SUMOylation (Primary Molecular Target)
The most extensively characterized molecular mechanism of ginkgolic acid is its inhibition of the SUMOylation pathway. SUMOylation is an important post-translational modification owing to the wide range of pathways that it modulates. In several cancers, the E1, E2, or SENPs have been altered to produce a dysregulated SUMOylation pathway, which has emerged as a novel target for the development of new cancer treatments.
Ginkgolic acid was one of the first natural products discovered to inhibit the SUMO E1 enzyme. By directly binding to E1, GA impairs SUMOylation by blocking the formation of an E1-SUMO thioester complex. Ginkgolic acid C15:1 inhibits SUMOylation in vitro (IC50 = 3 μM) and in cells without affecting protein ubiquitination; it directly binds the SUMO-activating enzyme E1, blocking the formation of the E1-SUMO intermediate. Importantly, this selectivity — inhibiting SUMOylation without affecting ubiquitination — distinguishes GA from non-specific proteasomal inhibitors.
Despite its use to mechanistically investigate the SUMOylation process, ginkgolic acid also modulates other pathways as well. Several mechanisms for GA's broader activity have been suggested, including: SUMOylation inhibition; blocking formation of the E1-SUMO intermediate; inhibition of fatty acid synthase; non-specific SIRT inhibition; and activation of protein phosphatase type-2C.
4.2 AMPK Activation and Lipogenesis Inhibition
GA inhibits the de novo lipogenesis of cancer cells through inducing activation of AMP-activated protein kinase (AMPK) signaling and downregulates the expression of key enzymes, including acetyl-CoA carboxylase (ACC) and fatty acid synthase (FASN), involved in lipogenesis. In vivo experiments showed that GA reduced the expression of key enzymes involved in lipogenesis and restrained tumor growth. This mechanism is relevant to the energy metabolism of malignant cells, which commonly depend on elevated de novo lipid synthesis.
4.3 NF-κB Pathway Modulation
The inhibitory effects of GA on NF-κB activity can be explained by the inhibition of SUMOylation of NEMO, leading to the failure of the IKK complex formation and IκB degradation. GA reduces oxidized-LDL-induced NF-κB activity; the mRNA and protein expression of TNF-α, IL-6, and VCAM-1 considerably increased in the oxidized-LDL treated group, and ginkgolic acid significantly reduced the mRNA and protein expression of these inflammatory markers.
4.4 Multi-Target Inhibition of Pro-Inflammatory Lipid Mediator Biosynthesis
Ginkgolic acid has been revealed as a potent multi-target inhibitor of key enzymes in the biosynthesis of pro-inflammatory lipid mediators (LMs). In search of microsomal prostaglandin E2 synthase-1 (mPGES-1) inhibitors from a Chinese Herbal Medicine database comprising 10,216 natural products, ginkgolic acid — a 6-alkenyl derivative of salicylic acid contained in Ginkgo biloba — was identified as an active molecule using established mPGES-1 pharmacophore models and virtual screening approaches. Many beneficial properties have been described for GA, including anti-tumoral and antibacterial effects, as well as suppression of inflammation along with reduced COX-2 expression and PGE2 levels in human umbilical vein endothelial cells.
4.5 Viral Fusion Inhibition
GA shows a broad spectrum of fusion inhibition of all three classes of viral fusion proteins, including HIV, Ebola virus (EBOV), influenza A virus (IAV), and Epstein-Barr virus (EBV); it also inhibits a non-enveloped adenovirus. These experiments suggest that GA inhibits virion entry by blocking the initial fusion event.
4.6 Protein Phosphatase Type-2C Activation and Neurotoxicity
GA specifically increases the activity of protein phosphatase type-2C (PP2C), which leads to neuronal cell death in chick embryos. This mechanism is relevant to GA's observed neurotoxicity at higher concentrations and underscores the dose-dependent and context-dependent nature of its biological activity, where the same target may produce different outcomes depending on concentration and cell type.
4.7 Heat Shock Protein 90 (Hsp90) Inhibition
In studies on human nasopharyngeal carcinoma cells, ginkgolic acids exhibited an inhibitory effect on the ATPase activity of heat shock protein 90 (Hsp90) and anti-proliferative activities against four human cancer cell lines, with IC50 values ranging from 14.91 to 23.81 μg·mL-1. Hsp90 is a molecular chaperone critical for the stability of numerous oncoproteins, making its inhibition a validated anticancer strategy.
4.8 Autophagy Induction
Inhibiting protein SUMOylation — a primary effect of GA — induces autophagic cell death through the upregulation of the pseudokinase TRIB3, and impairs cancer cell invasiveness by inhibiting activation of the small GTPase RAC1. Blocking the SUMO pathway reduces RAC1 SUMOylation, thereby diminishing the amount of active RAC1 available to drive cell migration and invasion. In neurological contexts, autophagy induction by GA has potential relevance to the clearance of aggregated proteins.
5. Scientific Evidence by Area of Use
5.1 Oncology / Anticancer Activity
Evidence base: Predominantly preclinical (in vitro and in vivo animal). No completed human clinical trials specifically attributing anticancer effects to isolated ginkgolic acid have been identified in the peer-reviewed literature. Some clinical trials have studied whole Ginkgo biloba extract (GBE) in oncology settings, but these cannot be attributed specifically to the ginkgolic acid fraction.
Pancreatic Cancer
In cell-based studies, GA suppressed the viability of pancreatic cancer cells but showed little toxicity on normal cells, such as HUVEC cells; treatment with GA resulted in impaired colony formation, migration, and invasion ability and increased apoptosis of cancer cells. GA inhibited the de novo lipogenesis of cancer cells through inducing activation of AMPK signaling and downregulation of key enzymes including acetyl-CoA carboxylase (ACC) and fatty acid synthase (FASN). Moreover, in an in vivo experiment, GA reduced the expression of these key lipogenic enzymes and restrained tumor growth in a xenograft mouse model.
Breast Cancer
All seven GA congeners and their mixture inhibited wound healing in MCF-7 and MDA-MB 231 breast cancer cells. None of the compounds nor the mixture showed cytotoxicity towards the two cell lines when tested by the resazurin assay — indicating the anti-migratory effects were separable from cytotoxicity at tested concentrations. C13:0 inhibited NF-κB activity in a reporter cell line and inhibited degradation of IκBα. SUMOylation assay revealed that GA inhibited SUMOylation of NF-κB essential modulator (NEMO). These findings are confined to cell culture models.
Colon Cancer
In cell studies, ginkgolic acid inhibited the growth of SW480 colon cancer cells in a concentration-dependent manner and reduced cell proliferation and migration. Several previous studies have indicated that ginkgolic acid inhibits tumor growth and invasion in a number of cancer types, including pancreatic, liver, laryngeal, and breast cancer.
Oral Squamous Cell Carcinoma
GA can significantly reduce cell vitality in a dose- and time-dependent manner and can also accelerate cyto-apoptosis in both Tca8113 and Cal-27 oral squamous cell carcinoma cells. Migration and wound-healing assays confirmed the anti-migration effect of GA. GA treatment significantly attenuated TGF-β1-induced SMAD4 SUMOylation in these cell lines, identifying a specific molecular event in the anti-migratory action.
Nasopharyngeal Carcinoma
The anti-cancer properties of ginkgolic acids isolated from G. biloba were investigated in human nasopharyngeal carcinoma cells; GAs exhibited an inhibitory effect on the ATPase activity of Hsp90 and anti-proliferative activities against four human cancer cell lines, with IC50 values ranging from 14.91 to 23.81 μg·mL-1.
Clinical Studies with Whole GBE in Oncology
Two single-arm phase 2 trials that treated patients with pancreatic or colorectal cancer with ginkgo extract in combination with 5-fluorouracil (5-FU) demonstrated an overall response rate of 9.4% and 6.3%, respectively. A single-arm trial treated 32 patients with advanced hepatocellular carcinoma with increasing doses of ginkgo extract (60 mg, 120 mg, or 240 mg once daily) plus sorafenib (400 mg twice daily); partial response occurred in 3 patients, stable disease in 21, and progressive disease in 8, with an overall survival of 11.6 months and a median time to progression of 2.5 months. These trials used whole standardized GBE, in which ginkgolic acid content is deliberately minimized to less than 5 μg/g per pharmacopeial requirements; therefore, these outcomes cannot be attributed specifically to ginkgolic acid.
Evidence strength summary (oncology): Preliminary. All anticancer evidence for isolated ginkgolic acid derives from in vitro cell culture and, in some cases, xenograft animal models. No human clinical trials have evaluated purified ginkgolic acid as an anticancer agent. The mechanistic basis (SUMOylation inhibition, AMPK activation, Hsp90 inhibition) is scientifically coherent, but translation to clinical efficacy in humans remains unestablished.
5.2 Antiviral Activity
Evidence base: Preclinical in vitro studies and limited in vivo animal models. No human clinical trials.
GA shows antiviral activity against Herpes simplex virus 1 (HSV-1), human cytomegalovirus (HCMV), and Zika virus (ZIKV) primarily through viral fusion inhibition. GA demonstrated broad-spectrum fusion inhibition of all three classes of viral fusion proteins, including HIV, EBOV, IAV, and EBV, and also inhibited a non-enveloped adenovirus; GA was found to inhibit virion entry by blocking the initial fusion event, and data showing inhibition of HSV-1 and CMV replication when GA was administered post-infection suggest a possible secondary mechanism targeting protein and DNA synthesis.
Ginkgolic acid is described as a pan-antiviral molecule with proven effective in vitro and in vivo activity; it inhibits HSV-1 by disrupting viral structure, blocking fusion, and inhibiting viral protein synthesis; additionally, GA displays broad-spectrum fusion inhibition encompassing all three classes of fusion proteins, including those of HIV, Ebola, influenza A, and Epstein-Barr virus.
Regarding arboviruses, a study assessed the possible antiviral activity of ginkgolic acid against CHIKV (Chikungunya), MAYV (Mayaro), UNAV (Una), and ZIKV (Zika); results indicate that GA is capable of reducing replication in a dose-dependent manner in all tested arboviruses.
Other studies have demonstrated that this molecule can inhibit HIV protease in a cell-free system and HIV infection in human peripheral blood mononuclear cells.
With respect to coronaviruses, effective antiviral compounds are an essential component in addressing the family of coronaviruses, and ginkgolic acid is a pan-antiviral molecule with proven effective in vitro and in vivo activity against coronavirus strain 229E, as demonstrated in human epithelial lung cell models.
Evidence strength summary (antiviral): Compelling preclinical evidence across multiple virus families. Activity is demonstrated in cell culture models and, in some studies, animal models. No human antiviral clinical trials of isolated ginkgolic acid exist.
5.3 Antibacterial Activity
Evidence base: Preclinical in vitro; one study scientifically validated a traditional TCM claim.
Antibacterial assays were performed on various ginkgo seed extracts against pathogens (Staphylococcus aureus, Cutibacterium acnes, Klebsiella pneumoniae, Acinetobacter baumannii, Streptococcus pyogenes) relevant to skin and soft tissue infections; ginkgo seed coats and immature seeds exhibit antibacterial activity against Gram-positive skin pathogens (C. acnes, S. aureus, and S. pyogenes), thus validating its use in TCM; one compound tied to the antibacterial activity, ginkgolic acid C15:1, was identified.
Regarding the mechanism against Gram-positive bacteria, the function of the ferric uptake regulator (Fur) was found to be highly correlated with the antimicrobial activity of GA (15:1) against E. faecalis, and the antibacterial activity of GA (15:1) could be strengthened by the disruption of iron homeostasis. GA was also reported to have activity against Escherichia coli and Staphylococcus aureus.
Ginkgolic acid is active against the tubercle bacillus. This has historical relevance given the traditional TCM use of ginkgo seeds in conditions associated with pulmonary disease.
Evidence strength summary (antibacterial): Moderate preclinical. The antimicrobial activity, particularly against Gram-positive organisms, has been consistently reproduced across independent in vitro studies. The mechanistic validation of a historical TCM use (Emory University study, 2019) represents a rigorous scientific bridge between ethnobotany and modern microbiology. However, no human clinical trials exist.
5.4 Anti-Inflammatory Activity
Evidence base: Preclinical in vitro (cell models) and mechanistic studies. No human clinical trials on isolated GA.
GA has been revealed as a potent multi-target inhibitor of key enzymes in the biosynthesis of pro-inflammatory lipid mediators (LMs). These include mPGES-1 (microsomal prostaglandin E2 synthase-1), cyclooxygenases (COX), and 5-lipoxygenase (5-LO). One hallmark of unresolved inflammation is constantly elevated levels of prostaglandins (PGs) and leukotrienes (LTs), leading to chronic diseases like asthma, cardiovascular diseases, Alzheimer's disease, type 2 diabetes, and cancer. GA's multi-target suppression of this pathway may offer a pharmacological advantage over NSAIDs, which target only COX enzymes and can lead to compensatory LT production.
In cardiovascular inflammation, ginkgolic acid considerably reduced pro-inflammatory cytokines in oxidized-LDL-treated HMEC-1 cells in a study using concentrations of 5 μg/mL and 20 μg/mL. The mRNA and protein expression of TNF-α, IL-6, and VCAM-1 considerably increased in the ox-LDL treated group and ginkgolic acid significantly reduced their mRNA and protein expression.
Evidence strength summary (anti-inflammatory): Preliminary. Multiple in vitro models demonstrate anti-inflammatory activity via distinct molecular targets. The identification of mPGES-1, 5-LO, and COX as multi-target sites provides mechanistic depth. No human clinical trials exist for isolated ginkgolic acid.
5.5 Neuroprotection and Neurodegeneration
Evidence base: In vitro cell models and animal studies for isolated GA; extensive clinical evidence exists for the whole GBE preparation EGb 761, but this cannot be solely attributed to ginkgolic acid.
Alzheimer's Disease / Amyloid-β Pathology
Ginkgolic acid is a component of the EGb 761 extract that shows pleiotropic effects including antitumoral and anti-HIV action; electrophysiological analysis was carried out to investigate the effects of GA on long-term potentiation and synaptic transmission at CA1 hippocampal synapses, and the potential rescuing effect of GA on the synaptic dysfunction following in vitro application of amyloid-β (Aβ) was evaluated. Data obtained indicate that GA exerts neuroprotective effects against Aβ-induced impairment of neurotransmitter release and synaptic plasticity. This study used rat hippocampal slice preparations.
Parkinson's Disease / Alpha-Synuclein Clearance
The accumulation of intracytoplasmic inclusion bodies (Lewy bodies) composed of aggregates of the alpha-synuclein (α-syn) protein is the principal pathological characteristic of Parkinson's disease and may lead to degeneration of dopaminergic neurons; to date there is no medication that can promote the efficient clearance of these pathological aggregates. The effect on α-syn aggregate clearance of ginkgolic acid, a natural compound extracted from Ginkgo biloba leaves that inhibits SUMOylation among other pathways, was assessed in SH-SY5Y neuroblastoma cells and rat primary cortical neurons. Ginkgolic acid reduced intracytoplasmic α-synuclein clumps and increased autophagosome quantity in these models. The study suggested that GA or analogues could be useful therapeutics against Parkinson's disease.
Pulmonary Fibrosis and SMAD4 SUMOylation
Data indicated that GA may participate in lung fibrogenesis by regulating TGF-β1-induced SUMOylation of SMAD4 in a mouse model of pulmonary fibrosis. This mechanism mirrors the anti-fibrotic effect of GA also reported in cardiac contexts.
Evidence strength summary (neuroprotection): Preliminary. In vitro electrophysiology and cell culture models provide mechanistic plausibility for neuroprotective effects in both Alzheimer's and Parkinson's disease contexts. Animal-level studies support biological feasibility. No human clinical trials of isolated ginkgolic acid for neurodegenerative diseases have been reported.
5.6 Molluscicidal Activity (Schistosomiasis Vector Control)
Molluscicidal activities of ginkgolic acids, a group of 6-alkylsalicylic acids extracted from the sarcotesta and leaves of Ginkgo biloba, have been described; five GA monomers were identified, all differing in their chain lengths (13 to 17 carbon atoms). This activity is relevant to global schistosomiasis control as Oncomelania hupensis snails are the intermediate host for the parasite.
6. Body Systems and Health Areas
Based on the available preclinical literature, ginkgolic acid has documented biological activity across the following body systems:
- Oncology: As inhibitors of SUMOylation, GAs demonstrate significant antitumor activity, and can exert antineoplastic effects through multiple pathways, which positions them as potentially promising therapeutic agents for cancer treatment.
- Immune and Inflammatory Systems: GAs exhibit notable anti-inflammatory, antibacterial, and antiviral properties, highlighting their multifaceted medicinal potential.
- Central Nervous System: The biological activities of GA include antitumor, anti-inflammatory, neuroprotective, and antianxiety activities, as well as antimicrobial activities in vitro and broad antiviral activities.
- Cardiovascular System: GA has an inhibitory effect on the myocardial fibrosis caused by cardiac infarction in experimental models.
- Pulmonary System: GA has been studied in the context of bleomycin-induced pulmonary fibrosis in animal models, showing attenuation of fibrogenesis through SMAD4 SUMOylation modulation.
- Microbiology / Infectious Disease: GA exhibits activity against multiple Gram-positive bacteria, including MRSA-relevant organisms, as well as a broad range of viruses encompassing DNA viruses (HSV, CMV), RNA viruses (HIV, Ebola, influenza, Zika, CHIKV), and coronaviruses.
- Parasitology: GA demonstrates molluscicidal activity relevant to schistosomiasis vector control.
7. Dosage Forms and Dosages Reported in Studies
Ginkgolic acid as an isolated compound has not been approved or formulated as a consumer dietary supplement in a standardized dose. All dosage information below derives directly from reported research studies and must be understood in that context.
- SUMOylation inhibition (in vitro): GA C15:1 inhibits SUMOylation in vitro at an IC50 of 3 μM.
- HIV protease inhibition: GA functions as a potent, cell-permeable protease and SUMO inhibitor with an IC60 of 90 nM against HIV-1 protease.
- Antiviral (HCMV, in vitro): Ginkgolic acids (C13:0, C15:1, C17:1) inhibit HCMV in a dose-dependent manner and prevent plaque formation; IC50 was determined using monolayers of human foreskin fibroblasts inoculated with HCMV clinical isolates, with GA concentrations ranging from 0 to 10 μM.
- Anti-inflammatory (cell culture): Cells were incubated with different concentrations of ginkgolic acid for 24 hours; groups included GA at 5 μg/mL and 20 μg/mL alongside oxidized-LDL treatment.
- Anti-migratory (breast cancer cell lines, in vitro): A reduction of sumoylated NEMO levels was observed at concentrations of 10 and 100 μM in sumoylation assays.
- Nasopharyngeal carcinoma (in vitro): Anti-proliferative activities against four human cancer cell lines showed IC50 values ranging from 14.91 to 23.81 μg·mL-1.
- Arbovirus inhibition (in vitro): Vero and HeLa cells were pre-treated with ginkgolic acid at 10 μM or 0.1% DMSO as a control for 1 hour before viral infection.
- Clinical studies (whole GBE, not isolated GA): In a single-arm trial of advanced hepatocellular carcinoma, increasing doses of ginkgo extract were used: 60 mg, 120 mg, or 240 mg once daily, plus sorafenib 400 mg twice daily.
It is critical to note that the pharmacopeial standard for pharmaceutical-grade GBE limits ginkgolic acid to below 5 μg/g (5 ppm). Due to their recognized toxicity, the concentration of GAs is typically regulated to within 5 ppm in the standardized G. biloba leaf extract EGb 761. No established therapeutic human dose of purified ginkgolic acid exists.
8. Safety Considerations, Toxicology, and Regulatory Limits
8.1 Allergenicity
Ginkgolic acid was identified as the main allergen in Ginkgo biloba-derived ingredients. Direct skin contact with ginkgo leaves can cause contact dermatitis in some people due to GA. The allergenic potential is structurally consistent with GA's classification as a urushiol-type compound, the same chemical class responsible for contact dermatitis from poison ivy and related plants.
The ginkgolic acid contained in GBE is proved to be highly allergenic and cytotoxic; even minimal residual amounts could also cause severe adverse effects in sensitized individuals, according to earlier pharmacological reviews.
8.2 Cytotoxicity and Hepatotoxicity
Previous studies have shown that GA may cause immunotoxicity, neurotoxicity, cytotoxicity, and hepatotoxicity. GAs can induce significant hepatic damage by promoting cellular apoptosis, oxidative stress, and the disruption of various metabolic processes.
In studies on hepatic metabolism, the drug-metabolizing enzymes involved in GA (17:1) metabolism were identified as human CYP1A2, CYP3A4, UGT1A6, UGT1A9, and UGT2B15; MTT assays indicated that the cytotoxicity of GA (17:1) in HepG2 cells occurred in a time- and dose-dependent manner; further investigation showed that GA (17:1) had less cytotoxicity in primary rat hepatocytes than in HepG2 cells, and that toxicity was enhanced through CYP1A- and CYP3A-mediated metabolism.
The involvement of CYP1A2 and CYP3A4 in GA metabolism carries implications for drug interactions, as these are among the most clinically important cytochrome P450 isoforms. Drugs that inhibit or induce these enzymes could theoretically alter GA metabolism, although direct interaction studies in humans are lacking.
8.3 Nephrotoxicity and Other Systemic Effects
GAs can induce significant hepatic damage by promoting cellular apoptosis, oxidative stress, and the disruption of various metabolic processes; furthermore, a limited number of studies have indicated that GAs may exhibit nephrotoxicity, as well as adverse effects on the skin and nervous system.
8.4 Neurotoxicity
GA specifically increases the activity of protein phosphatase type-2C, which leads to neuronal cell death in chick embryos. Ginkgolic acids are associated with adverse effects, including allergenicity, genotoxicity, and neurotoxicity. This neurotoxic potential is paradoxical relative to the neuroprotective effects described at lower concentrations in other model systems, and reflects the dose-dependent and context-dependent nature of GA's biological actions.
8.5 Embryotoxicity
Ginkgolic acids have been identified as the primary source of EGb's adverse effects, including embryotoxicity, cytotoxicity, neurotoxicity, and inhibition of enzyme systems. Embryotoxic potential has been documented in preclinical models, contributing to pharmacopeial restrictions on GA content in products intended for general use.
8.6 Mutagenicity
Currently, there is no definitive evidence supporting the mutagenic toxicity of GAs. Earlier chemical literature described potential mutagenic activity, but the review literature as of 2025 notes this remains unestablished by definitive evidence.
8.7 Pharmacopeial and Regulatory Limits
The Chinese, European, and United States pharmacopeias all mandate that the GA concentration in EGb be less than 5 μg g-1. The content of ginkgolic acids in GBE is low and commercial products are generally well tolerated; available G. biloba products, including EGb 761, conform to monographs of the European Pharmacopoeia 6.1 and the United States Pharmacopeia 32 (USP 32).
8.8 Processing Methods to Reduce GA Content
Thermal technologies (steaming, roasting, microwaving, drying, and boiling), fermentation, membrane separation, and non-thermal technologies (ultrasound, osmo-sonication, high hydrostatic pressure, and osmo-vacuum) treatment of ginkgo seeds can reduce toxicity while retaining active ingredients; the severity of toxicity depends on the processing method, and understanding ginkgotoxins (MPN), ginkgotoxin-5-glucoside (MPNG), and ginkgolic acid as distinct toxicants is important; current works have shown that processing methods can reduce these toxicants to levels unlikely to cause toxicity.
This review examined technologies such as adsorption/desorption, enzymatic degradation, counter-current chromatography, liquid-liquid microextraction, dual-frequency ultrasonic-solvent extraction, and deep eutectic solvent methods to lower GA to desired concentrations.
9. Overall Evidence Assessment and Research Status
Ginkgolic acid occupies a scientifically unusual position: it is simultaneously a well-characterized molecular biology tool (as a SUMOylation inhibitor), a phytochemical with a growing body of preclinical pharmacological data across multiple therapeutic areas, and a recognized safety concern that has driven pharmacopeial limits in standardized herbal preparations worldwide. Ginkgolic acid exhibits anticancer activity and inhibits the migration of several different cancer cell lines; while several natural products have been shown to inhibit enzymes involved in the SUMOylation process, there has been little progress toward the development of more selective and potent SUMOylation inhibitors.
GA has shown pleiotropic effects in vitro, including antitumor effects through inhibition of lipogenesis, decreased expression of invasion-associated proteins through AMPK activation, and potential rescue of amyloid-β-induced synaptic impairment. Despite this, the entirety of direct evidence for isolated ginkgolic acid remains preclinical. High hopes are associated with the possible medical use of ginkgolic acid, yet transition to clinical application requires human trials that have not yet been conducted. The principal barrier to therapeutic development of GA as a standalone agent is its toxicity profile — particularly hepatotoxicity, allergenicity, and neurotoxicity at concentrations overlapping with its pharmacologically active range.
References
Go back