Qin Pi
StarFraxinus rhynchophylla Hance
Traditionally used for
- Eye health
- Bowel health
- Urinary & fluids
- Menstrual & women's health
Cautions & contraindications
- Bleeding disorders
☯ TCM Properties
Clears Heat and dries Dampness; Astringes the Intestines and Stops Diarrhea; Astringes to Stop Vaginal Discharge; Clears Liver Heat and Brightens the Eyes
Traditional Chinese Uses
Qin Pi (秦皮) is the branch or stem bark of Fraxinus rhynchophylla Hance and related ashes (Oleaceae), Cortex Fraxini. It is bitter and astringent and cold, entering the Liver, Gallbladder and Large Intestine channels. It clears Heat and dries Dampness, astringes the Intestines to stop diarrhoea, checks abnormal vaginal discharge, and clears Liver Heat to brighten the eyes.
Its combination of cooling and astringing makes it well suited to Damp-Heat dysenteric disorders and chronic diarrhoea, and it is one of the four herbs of Bai Tou Weng Tang. It is used for Damp-Heat vaginal discharge, and — reflecting its entry into the Liver channel — for red, swollen, painful eyes and for superficial visual obstruction, where it is also applied as an eyewash.
A decoction of the bark shows a characteristic blue fluorescence, long used as a simple identity check on the drug.
Western Herbalism Properties
Pharmacological Effects
- Antibacterial: Decoction inhibited S. aureus, E. coli, Shigella flexneri and Sh. sonnei in vitro; esculin 10–20 mg/ml and esculetin (MIC 1:1000–1:2500) inhibited several bacteria.
- Antiinflammatory: Esculin and fraxin blocked histamine capillary permeability; i.p. esculetin, esculin and fraxin reduced various induced paw edemas in rats; effect linked to adrenocortical stimulation (lowered adrenal vitamin C); esculetin/esculin reduced UV erythema in guinea pigs.
- Sedative, anticonvulsive and analgesic: Esculin/esculetin prolonged cyclobarbital sleep in mice; esculetin antagonized electroshock and delayed strychnine/cardiazol convulsions and was analgesic (70% at 100 mg/kg i.p.).
- Antitussive, expectorant and antiasthmatic: i.p. esculetin or esculin was antitussive in ammonia-cough mice and expectorant (phenol red); esculetin was antiasthmatic in histamine guinea pigs and relaxed isolated bronchi.
- Lipoxygenase and cyclooxygenase inhibition: Esculetin potently inhibited platelet lipoxygenase (IC50 0.65 µM) and 5-lipoxygenase incl. in human PMNs, reducing leukotriene synthesis; also inhibited platelet cyclooxygenase (IC50 0.45 mM).
Source: Zhu YP. Chinese Materia Medica: Chemistry, Pharmacology and Applications. Harwood Academic, 1998, p. 206.
Relationships
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Botanical Description
Fraxinus rhynchophylla (Chinese ash) is a deciduous tree in the Oleaceae family, growing 10-15 m tall with a broad rounded crown and grey-brown, longitudinally fissured bark on mature trunks; young branches are smooth and lenticellate. The opposite, pinnately compound leaves are 15-25 cm long with 5-7 broadly ovate to elliptic, sharply serrate leaflets, the terminal one largest, dark green above and paler beneath. The small, inconspicuous, apetalous, polygamous flowers appear in dense terminal panicles with the unfolding leaves in spring. The fruit is a slender, oblong-spatulate, single-winged samara 3-4 cm long containing one flattened seed. The medicinal Qin Pi is the dried bark of the trunk and branches, cut into curved strips or quill-like rolls with a yellow-brown outer surface (POWO; Wikipedia).
Active Constituents
Esculin (aesculin)
Coumarin glucoside (esculetin 6-O-glucoside)Concentration: 0.26-2.80% of the dried bark across 10 commercial batches of Fraxini Cortex assayed by HPLC-UV
One of the two official quality-control markers for Fraxini Cortex in the Chinese Pharmacopoeia. Oral bioavailability is very low (reported near 0.6%); it is hydrolysed at the 8-glucose linkage to the aglycone esculetin, which is the species most likely to reach tissues. Reported activities are antioxidant, anti-inflammatory and antibacterial, and in rodent hyperuricaemia models esculin increases urinary urate and creatinine excretion.
Esculetin (aesculetin, 6,7-dihydroxycoumarin)
Simple dihydroxycoumarin aglyconeConcentration: 0.11-1.47% of the dried bark across the same 10 batches of Fraxini Cortex
The aglycone of esculin and the second official marker compound; average oral bioavailability is reported around 19%, far higher than esculin. In oxonate-induced hyperuricaemic mice it lowers serum urate, and it is a lipoxygenase inhibitor with antioxidant and anti-inflammatory activity in vitro. It is a simple 6,7-dihydroxycoumarin, structurally unrelated to the 4-hydroxycoumarin anticoagulants.
Fraxin
Coumarin glucoside (fraxetin 8-O-glucoside)Identified by bioaffinity ultrafiltration mass spectrometry as the Cortex Fraxini component that binds the urate efflux transporter ABCG2. It activated ABCG2-mediated uric acid transport in vitro with an EC50 of 7.55 micromolar and lowered serum uric acid in rats after oral dosing.
Fraxetin
Simple coumarin aglycone (7,8-dihydroxy-6-methoxycoumarin)The aglycone of fraxin, formed by hydrolysis of the glucoside. Reported in reviews of Fraxini Cortex as contributing to the antioxidant and anti-inflammatory activity attributed to the coumarin fraction.
⚠ Drug Interactions
Urate-lowering drugs (allopurinol, febuxostat, benzbromarone)
In hyperuricaemic rat and mouse models, Fraxini Cortex extracts and their coumarins lower serum urate by more than one route: esculin and esculetin raise renal urate and creatinine excretion and up-regulate OAT1 and the OCT/OCTN transporters without changing URAT1 or GLUT9 expression, while fraxin activates ABCG2-mediated urate efflux. These are the same excretory pathways that uricosuric drugs act on. No human interaction study has been published, so the concern rests entirely on animal pharmacology.
Clinical note: If a patient on urate-lowering therapy is also taking Qin Pi, check serum urate before and after adding or stopping the herb rather than assuming the change reflects the drug dose.
Warfarin and other vitamin K antagonists
The coumarins of Fraxini Cortex are simple 6,7- and 7,8-dihydroxycoumarins and their glucosides. They lack the 4-hydroxycoumarin substitution that is required for vitamin K epoxide reductase antagonism, and they are not 4-hydroxycoumarin dimers of the dicoumarol type, so a warfarin-like effect is not expected. Esculetin does inhibit lipoxygenase in vitro, which is the only plausible route to an effect on platelet function, and this has not been shown to translate into clinical bleeding. There are no human pharmacokinetic or pharmacodynamic interaction data for this herb with warfarin.
Clinical note: Do not adjust warfarin on the assumption of a coumarin interaction, and equally do not assume safety: if Qin Pi is started or stopped in an anticoagulated patient, check the INR as you would for any new herbal product.
Dosage
| Form | Amount | Frequency | Duration | Population | Notes |
|---|---|---|---|---|---|
| decoction | 6–12 g | Daily | — | — | 中国药典 2020 【用法与用量】6～12g。外用适量，煎洗患处。 【性味与归经】苦、涩，寒。归肝、胆、大肠经。 — Chinese Pharmacopoeia 2020, quoted verbatim; route and cautions preserved. Replaces a cleared category-filler value. |
Dui Yao — Herb Pairs
The classical two-herb combinations this herb appears in, each with an action neither herb has alone.
Together they clear heat, dry damp, cool the blood and stop dysentery, targeting heat-toxin dysentery with blood and pus.
Core pair of a classical formula — Bai Tou Weng Tang, Shang Han Lun (Zhang Zhongjing)
Evidence Tier
Limited evidence · 2 studiesRecorded studies by study design, strongest design at the top. This is a study-design tier only, not a GRADE rating: it does not weigh risk of bias, consistency or precision.
Systematic review / meta-analysis
0
Randomized controlled trial
0
Other clinical trial
0
Observational / case report
0
In vitro / animal
2
2 verified · 0 unverified
Other / unclassified
0
Verified: design read from PubMed for a DOI that resolves to the cited paper Unverified: taken from the study's recorded description
Clinical Studies
Research on the pharmacodynamics and mechanism of Fraxini Cortex on hyperuricemia based on the regulation of URAT1 and GLUT9
Fraxini Cortex extracts sourced from three Chinese provinces were given to rats made hyperuricaemic with hypoxanthine plus potassium oxonate. The extracts lowered serum uric acid, blood urea nitrogen and creatinine and raised urinary urate, with the size of the effect differing by geographic source, which the authors attribute to differing proportions of the coumarin constituents. The work is on the multi-species official drug Fraxini Cortex rather than on authenticated Fraxinus rhynchophylla alone.
Target Screen of Anti-Hyperuricemia Compounds from Cortex Fraxini In Vivo Based on ABCG2 and Bioaffinity Ultrafiltration Mass Spectrometry
Bioaffinity ultrafiltration mass spectrometry applied to plasma from rats dosed with Cortex Fraxini identified fraxin as the constituent binding ABCG2, a urate efflux transporter. Fraxin activated ABCG2-mediated uric acid transport with an EC50 of 7.55 micromolar, surface plasmon resonance gave a dissociation constant of 141.2 micromolar, and oral fraxin significantly lowered serum uric acid in rats. As above, the starting material is the official multi-species Cortex Fraxini.
⚠ Safety & Contraindications
- Bleeding disorders
Contraindications
Its use is prohibited in patients with deficiency-cold of the spleen and stomach.
Source: Xi S, Gong Y. Essentials of Chinese Materia Medica and Medical Formulas. Academic Press/Elsevier, 2017, pp. 46–50.
Side Effects
- Decoction caused no side effects other than vomiting
Source: Zhu YP. Chinese Materia Medica: Chemistry, Pharmacology and Applications. Harwood Academic, 1998, p. 206.
Historical Texts
Shen Nong Ben Cao Jing
Han dynastyBen Cao Gang Mu
Ming dynastyReferences
- Zheng Z, Sun C, Zhong Y, Shi Y, Zhuang L, Liu B, Liu Z. Fraxini cortex: Progresses in phytochemistry, pharmacology and ethnomedicinal uses . Journal of Ethnopharmacology (2024) [DOI]
- Cai T, Cai B. Pharmacological activities of esculin and esculetin: A review . Medicine (2023) [DOI]
- Qian ZM, Wu MQ, Tan GY, Jin LL, Li N, Xie JY. Rapid determination of aesculin and aesculetin in Fraxini Cortex by high performance liquid chromatography-ultraviolet at equal absorption wavelength . Chinese Journal of Chromatography (Se Pu) (2023) [DOI]
- Xin P, Fan YH, Xu JY, Mao SJ, Zhang JW, Luo ZL, Zhou X. Fraxini cortex (Qinpi): reframing a traditional heat-clearing botanical drug as a systemic immune-metabolic regulator . Frontiers in Pharmacology (2026) [DOI]
This information is for educational purposes only and is not intended to replace professional medical advice. Always consult a qualified healthcare provider before using any herbal remedy, especially if you are pregnant, nursing, or taking medications.
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