The Sunlight Experiment

Compound Monograph

Fraxetin

Fraxetin (7,8-dihydroxy-6-methoxycoumarin) is the aglycone of fraxin — a catechol-type coumarin of ash (Fraxinus) bark and Cortex Fraxini, released from fraxin by gut β-glucosidase. Distinctively, it is an iron-chelating, redox-active coumarin whose preclinical research centres on antioxidant/ferroptosis modulation, NF-κB anti-inflammatory action and hepatoprotection, with no human trials of the isolate. It is not a warfarin-type anticoagulant, and not horse chestnut's toxic principle (that is esculin).

Work in progress

Where Does It Come From? (5)

Fraxetin is a naturally occurring coumarin, found in Ash bark, Manna ash, Horse Chestnut — bark and seed and 2 other sources. It is well tolerated orally (low toxicity).

Ash barkFraxinus and Aesculus barksHorse Chestnut — bark and seedManna ashVarious plants as an iron-mobilizing root coumarin

Pharmacology & Research

Fraxetin (7,8-dihydroxy-6-methoxycoumarin) is the aglycone of fraxin — fraxin is fraxetin 8-O-glucoside, and gut β-glucosidase releases fraxetin as the better-absorbed, active moiety, so much of fraxin’s reported in-vivo activity is really fraxetin’s. Its distinctive feature among the horse-chestnut/ash coumarins is that its 7,8-catechol makes it both a strong scavenger and an iron chelator/reductant — and that iron chemistry cuts both ways by context. Two discipline points hold (as for scopoletin and esculetin): it is a 7,8-dihydroxy-6-methoxycoumarin, not a 4-hydroxycoumarin/warfarin-type anticoagulant, and it is not horse chestnut’s named toxic principle — that is esculin. All evidence is preclinical.

What the evidence supports
  • A redox-active, iron-binding coumarin: strong antioxidant/lipid-peroxidation data plus a distinctive iron-chelation profile that restrains ferroptotic lipid peroxidation in mammalian injury models 2,5,6Reference 22001Antioxidant activity of fraxetin: in-vivo and ex-vivo parameters in normal versus induced stressView study →Reference 52021Fraxetin attenuates ferroptosis in myocardial infarction via AKT/Nrf2/HO-1 signallingView study →Reference 62023Fraxetin alleviates bleomycin-induced pulmonary fibrosis by inhibiting NCOA4-mediated epithelial-cell ferroptosisView study →.
  • The honest headline: no human trials of the isolate; the anti-inflammatory, hepatoprotective, neuro and anticancer signals are single-lab rodent or scattered cell-line work, and the iron chemistry is context-dependent (Fe-mobilizing in plant roots, anti-ferroptotic in disease models) 4,5Reference 42018Scopoletin 8-hydroxylase-mediated fraxetin production is crucial for iron mobilisationView study →Reference 52021Fraxetin attenuates ferroptosis in myocardial infarction via AKT/Nrf2/HO-1 signallingView study →.
Evidence by indicationStrength of support
Antioxidant / Iron-Redox & FerroptosisShaky
42%
Anti-Inflammatory (NF-kB / NLRP3)Shaky
32%
Hepatoprotective / AntifibroticShaky
28%
NeuroprotectiveShaky
24%
AnticancerShaky
20%
1. Antioxidant / iron-redox & ferroptosis

Fraxetin’s distinctive hook. Its 7,8-catechol makes it a strong radical scavenger with in-vivo/ex-vivo antioxidant and lipid-peroxidation-lowering activity 2,3Reference 22001Antioxidant activity of fraxetin: in-vivo and ex-vivo parameters in normal versus induced stressView study →Reference 31997AnimalModifications of antioxidant capacity and lipid peroxidation in mice under fraxetin treatmentView study →, and an iron chelator/reductant whose direction is context-dependent: in plant roots it reduces and mobilises Fe(III) (a siderophore-like, pro-redox role) 4Reference 42018Scopoletin 8-hydroxylase-mediated fraxetin production is crucial for iron mobilisationView study →, while in disease models it restrains iron-dependent ferroptotic lipid peroxidation via Nrf2/HO-1/GPX4 5Reference 52021Fraxetin attenuates ferroptosis in myocardial infarction via AKT/Nrf2/HO-1 signallingView study → and by blocking NCOA4-mediated ferritinophagy 6Reference 62023Fraxetin alleviates bleomycin-induced pulmonary fibrosis by inhibiting NCOA4-mediated epithelial-cell ferroptosisView study →.

Gap: the two iron literatures barely reference each other, there is no human antioxidant readout, and “iron chelator” is a chemical property, not a demonstrated therapeutic in people 4,5Reference 42018Scopoletin 8-hydroxylase-mediated fraxetin production is crucial for iron mobilisationView study →Reference 52021Fraxetin attenuates ferroptosis in myocardial infarction via AKT/Nrf2/HO-1 signallingView study →.

2. Anti-inflammatory (NF-kB / NLRP3)

A reproducible NF-κB-restraint signal shared with the sibling coumarins: fraxetin inhibits IKKβ to block NF-κB and the NLRP3 inflammasome in septic spleen injury 7Reference 72025Fraxetin inhibits IKKβ, blocks NF-κB and NLRP3 inflammasome activation, and alleviates spleen injury in sepsisView study →, acts anti-inflammatory/antifibrotic in chronic pancreatitis 8Reference 82021AnimalFraxetin prevented sodium-fluoride-induced chronic pancreatitis in ratsView study →, and protects IL-1β-driven chondrocytes 9Reference 92020Fraxetin inhibits IL-1β-induced apoptosis, inflammation and matrix degradation in chondrocytesView study →.

Gap: all acute rodent/cell models, in single-lab clusters, with no human data 7,8Reference 72025Fraxetin inhibits IKKβ, blocks NF-κB and NLRP3 inflammasome activation, and alleviates spleen injury in sepsisView study →Reference 82021AnimalFraxetin prevented sodium-fluoride-induced chronic pancreatitis in ratsView study →.

3. Hepatoprotective / antifibrotic

The most internally consistent organ-protection theme: fraxetin reduces CCl₄-induced liver fibrosis via NF-κB/IκBα, MAPK and Bcl-2/Bax 10Reference 102019Antifibrotic effects of fraxetin on CCl₄-induced liver fibrosis via NF-κB/IκBα, MAPKs and Bcl-2/BaxView study → and mitigates ethanol-induced hepatic fibrosis by enhancing ethanol metabolism and lowering oxidative stress 11Reference 112018Therapeutic effect of fraxetin on ethanol-induced hepatic fibrosisView study →.

Gap: the classic “reduce oxidative stress in a toxin model” design, rodent only 10,11Reference 102019Antifibrotic effects of fraxetin on CCl₄-induced liver fibrosis via NF-κB/IκBα, MAPKs and Bcl-2/BaxView study →Reference 112018Therapeutic effect of fraxetin on ethanol-induced hepatic fibrosisView study →.

4. Neuroprotective

Fraxetin reduced microglia-mediated neuroinflammation after ischemic stroke 12Reference 122022Fraxetin alleviates microglia-mediated neuroinflammation after ischemic strokeView study → and produced antidepressant-like effects in a chronic-unpredictable-stress model 13Reference 132023Fraxetin attenuates disrupted behavioural and central neurochemical activity in chronic unpredictable stressView study →.

Gap: heterogeneous acute models with no convergent mechanism and no clinical work 12,13Reference 122022Fraxetin alleviates microglia-mediated neuroinflammation after ischemic strokeView study →Reference 132023Fraxetin attenuates disrupted behavioural and central neurochemical activity in chronic unpredictable stressView study →.

5. Anticancer

Fraxetin induces apoptosis/mitochondrial dysfunction in hepatocellular-carcinoma cells 14Reference 142021Fraxetin suppresses cell proliferation and induces apoptosis via mitochondrial dysfunction in hepatocellular-carcinoma cellsView study → and, as the traditionally “anti-dysenteric” coumarin, sensitises pancreatic cancer to gemcitabine 15Reference 152021The anti-dysenteric drug fraxetin enhances gemcitabine efficacy and suppresses pancreatic-cancer developmentView study →.

Gap: a broad but shallow cell-line literature — almost entirely in-vitro, across scattered targets, with no in-vivo efficacy standard 14,15Reference 142021Fraxetin suppresses cell proliferation and induces apoptosis via mitochondrial dysfunction in hepatocellular-carcinoma cellsView study →Reference 152021The anti-dysenteric drug fraxetin enhances gemcitabine efficacy and suppresses pancreatic-cancer developmentView study →.

Mechanisms

Target / pathwayEffectRelevant to
Iron (Fe³⁺) via 7,8-catecholchelation + redox (mobilises Fe in plants; restrains labile-iron ferroptosis in mammalian models)antioxidant, ferroptosis, organ protection
Nrf2 / HO-1 / GPX4activated; suppresses ferroptotic lipid peroxidationantioxidant, cardioprotection
NCOA4 (ferritinophagy)suppressedanti-fibrotic / anti-ferroptosis
ROS / lipid peroxidationdirect scavenging + loweredantioxidant, hepato/neuroprotection
IKKβ → NF-κB / IκBα; NLRP3inhibited; suppressedanti-inflammatory, hepatoprotective
MAPK; Bcl-2/Bax; JAK2/STAT3modulated; pro-apoptotic balanceliver fibrosis, anticancer

All mechanisms are preclinical (rodent / cell / plant).

Pharmacokinetics

Fraxetin is the aglycone and is better absorbed than its glucoside fraxin, which must first be hydrolysed by gut/microbial β-glucosidase to release it (the fraxin→fraxetin gut loop — a UPLC-MS/MS study in dogs detected the two interconverting in plasma after oral dosing) 16Reference 162018Simultaneous determination of aesculin, aesculetin, fraxetin, fraxin and polydatin in beagle-dog plasma by UPLC-ESI-MS/MSView study →. Once absorbed, fraxetin undergoes rapid phase-II glucuronidation by human UGT enzymes (chiefly the UGT1A family) 17Reference 172014Identification and characterisation of the human UGTs responsible for the glucuronidation of fraxetinView study →, and the resulting glucuronides are actively effluxed, giving high first-pass clearance and short systemic exposure of the free aglycone. No dedicated single-isolate human pharmacokinetics exists — the net picture is that fraxetin is the pharmacologically relevant moiety of the fraxin/fraxetin pair but is itself short-lived in circulation.

Clinical trials

There are no human clinical trials of isolated fraxetin. All human exposure is as an untargeted minor coumarin of Cortex Fraxini/horse-chestnut/ash-bark preparations (including the traditional astringent/anti-dysenteric use of ash bark), where any activity belongs to the whole extract, not to fraxetin.

CompletedPlannedTerminatedPreclinical
—(none, isolate)——Moderate(multi-lab cell + single-lab rodent)

Last checked: July 2026.

Toxicity & Safety

Fraxetin is a minor medicinal coumarin with low apparent toxicity — no isolated-toxicity signal appears in the reviewed literature 1Reference 12024ReviewHealth benefits of fraxetin: from chemistry to medicine (review)View study →, and across the injury models it is uniformly protective rather than harmful. The [low] flag rests on several points: it is not a warfarin-type anticoagulant (a 7,8-dihydroxy-6-methoxycoumarin, not a 4-hydroxycoumarin, so the “coumarins thin the blood” caution does not apply and any bleeding concern is purely theoretical, as for scopoletin and esculetin); it is not horse chestnut’s named toxic principle (that is esculin, which alone carries the [moderate] framing — fraxetin, like fraxin, is a benign co-coumarin and should not inherit it); and rapid glucuronidation and efflux limit systemic accumulation 17Reference 172014Identification and characterisation of the human UGTs responsible for the glucuronidation of fraxetinView study →. One honest caveat: as a redox-active iron-binding catechol, very high experimental exposures could in principle be pro-oxidant (the plant iron-reduction role 4Reference 42018Scopoletin 8-hydroxylase-mediated fraxetin production is crucial for iron mobilisationView study →), but this is a chemical property at non-physiological levels, not a reported clinical harm.

Pregnancy & lactation

Avoid. There are no reproductive-safety data on isolated fraxetin, and the standard caution for an unstudied coumarin applies. It is not an anticoagulant, so there is no warfarin-class fetal concern, but the absence of data governs.

Dosage

There is no established human dose — fraxetin has never been administered to humans as an isolate. Every figure in the literature is a preclinical research dose (rodent, mg/kg) and is not a recommendation; human intake occurs only incidentally, as a trace coumarin within whole Cortex Fraxini/horse-chestnut/ash-bark preparations.

References

  1. (2024). Health benefits of fraxetin: from chemistry to medicine (review). Archiv der Pharmazie (Weinheim). https://pubmed.ncbi.nlm.nih.gov/38501886/
  2. (2001). Antioxidant activity of fraxetin: in-vivo and ex-vivo parameters in normal versus induced stress. Biological & Pharmaceutical Bulletin. https://pubmed.ncbi.nlm.nih.gov/11456117/
  3. (1997). Modifications of antioxidant capacity and lipid peroxidation in mice under fraxetin treatment. Journal of Pharmacy and Pharmacology. https://pubmed.ncbi.nlm.nih.gov/9120770/
  4. (2018). Scopoletin 8-hydroxylase-mediated fraxetin production is crucial for iron mobilisation. Plant Physiology. https://pubmed.ncbi.nlm.nih.gov/29559590/
  5. (2021). Fraxetin attenuates ferroptosis in myocardial infarction via AKT/Nrf2/HO-1 signalling. American Journal of Translational Research. https://pubmed.ncbi.nlm.nih.gov/34650699/
  6. (2023). Fraxetin alleviates bleomycin-induced pulmonary fibrosis by inhibiting NCOA4-mediated epithelial-cell ferroptosis. Inflammation Research. https://pubmed.ncbi.nlm.nih.gov/37798541/
  7. (2025). Fraxetin inhibits IKKβ, blocks NF-κB and NLRP3 inflammasome activation, and alleviates spleen injury in sepsis. Chemico-Biological Interactions. https://pubmed.ncbi.nlm.nih.gov/39921189/
  8. (2021). Fraxetin prevented sodium-fluoride-induced chronic pancreatitis in rats. International Immunopharmacology. https://pubmed.ncbi.nlm.nih.gov/33524802/
  9. (2020). Fraxetin inhibits IL-1β-induced apoptosis, inflammation and matrix degradation in chondrocytes. Saudi Pharmaceutical Journal. https://pubmed.ncbi.nlm.nih.gov/33424243/
  10. (2019). Antifibrotic effects of fraxetin on CCl₄-induced liver fibrosis via NF-κB/IκBα, MAPKs and Bcl-2/Bax. Pharmacological Reports. https://pubmed.ncbi.nlm.nih.gov/31003150/
  11. (2018). Therapeutic effect of fraxetin on ethanol-induced hepatic fibrosis. International Immunopharmacology. https://pubmed.ncbi.nlm.nih.gov/29414667/
  12. (2022). Fraxetin alleviates microglia-mediated neuroinflammation after ischemic stroke. Annals of Translational Medicine. https://pubmed.ncbi.nlm.nih.gov/35571418/
  13. (2023). Fraxetin attenuates disrupted behavioural and central neurochemical activity in chronic unpredictable stress. Frontiers in Pharmacology. https://pubmed.ncbi.nlm.nih.gov/37033640/
  14. (2021). Fraxetin suppresses cell proliferation and induces apoptosis via mitochondrial dysfunction in hepatocellular-carcinoma cells. Pharmaceutics. https://pubmed.ncbi.nlm.nih.gov/33477262/
  15. (2021). The anti-dysenteric drug fraxetin enhances gemcitabine efficacy and suppresses pancreatic-cancer development. Aging (Albany NY). https://pubmed.ncbi.nlm.nih.gov/34320467/
  16. (2018). Simultaneous determination of aesculin, aesculetin, fraxetin, fraxin and polydatin in beagle-dog plasma by UPLC-ESI-MS/MS. Molecules. https://pubmed.ncbi.nlm.nih.gov/30205426/
  17. (2014). Identification and characterisation of the human UGTs responsible for the glucuronidation of fraxetin. Drug Metabolism and Pharmacokinetics. https://pubmed.ncbi.nlm.nih.gov/24025985/