Du Zhong
StarEucommia ulmoides Oliv.
Traditionally used for
- Pain & joints
- Blood pressure
- Energy & fatigue
Cautions & contraindications
- Kidney conditions
☯ TCM Properties
Nourishes Liver and Kidney Yin; Strengthens the Sinews and Bones; Calms the Fetus; Lowers Blood Pressure
Traditional Chinese Uses
Du Zhong (eucommia bark) is a warm, sweet herb primarily used to tonify the Liver and Kidney, strengthen the sinew and bones, and calm the fetus. It is one of the most important herbs for chronic lower back and knee pain, weakness, and stiffness arising from Liver-Kidney deficiency — conditions that commonly develop with aging. Du Zhong also lowers blood pressure and is frequently used in modern Chinese medicine for hypertension associated with rising Liver Yang over a deficient Kidney foundation.
Western Herbalism Properties
Pharmacological Effects
- Hypotensive: I.v. decoction lowered blood pressure in anesthetized dogs (longer with >1 g/kg); oral extracts lowered BP in hypertensive dogs; aqueous extract lowered BP and heart rate in rats via direct vasodilation; pinoresinol diglucoside considered the main active principle.
- Hypolipidemic: Leaf extract fed to high-fat-diet rats for 35 days suppressed rises in serum cholesterol, triacylglycerol, VLDL and LDL without affecting HDL.
- Sedative and analgesic: Decoction i.p. reduced spontaneous activity and prolonged barbiturate sleep in mice and inhibited writhing and hot-plate pain.
- Anti-inflammatory: Decoction and ethanolic extract inhibited egg white paw edema in rats; thymic atrophy in young mice suggested enhanced adrenocortical function.
- Reticuloendothelial phagocytosis: Oral decoction enhanced carbon clearance and macrophage phagocytosis in (hydrocortisone-treated) mice.
- Diuretic: Extracts were diuretic in anesthetized dogs, even in dogs tolerant to the hypotensive effect.
- Uterus: Decoction and ethanolic extract antagonized pituitrin- and acetylcholine-induced contraction of isolated rat and rabbit uteri; mild stimulation of cat uterus.
Source: Zhu YP. Chinese Materia Medica: Chemistry, Pharmacology and Applications. Harwood Academic, 1998, p. 602.
Used In Formulas (18)
Relationships
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Botanical Description
Eucommia ulmoides is a medium-sized deciduous tree in its own monotypic family Eucommiaceae, native to central China and now cultivated in many temperate regions. It typically grows 15-20 meters tall with a straight trunk, greyish-brown furrowed bark, and a spreading crown. The alternate leaves are elliptic to ovate, 8-16 cm long, with acuminate tips and serrate margins; uniquely, when a leaf is torn slowly, fine, white, elastic threads of latex (gutta-percha) stretch between the broken halves. The tree is dioecious, with small inconspicuous petalless flowers appearing before the leaves in spring, followed on female trees by flat, winged samaras. In TCM, the inner bark (Du Zhong) is harvested from trees about ten to fifteen years old and used as a sweet, warm herb that tonifies the liver and kidneys and strengthens sinews and bones.
Active Constituents
Pinoresinol di-O-beta-D-glucopyranoside (pinoresinol diglucoside)
Lignan diglucosideConcentration: about 0.5% of dried bark, markedly higher than in any other part of the tree; not detected at all in the leaf
The bark-specific marker lignan and the compound to which the antihypertensive activity of Eucommiae Cortex is most often attributed. The only controlled human trial of the bark used an aqueous extract standardised to 8% pinoresinol diglucoside. Because this lignan is undetectable in the leaf, it is the single clearest chemical line between Du Zhong and Du Zhong Ye.
Geniposidic acid
Iridoid glucosideConcentration: reported up to about 6.7% in the bark of branches, against roughly 1.5% in the leaf; a seven-cultivar survey found 9.6-230.2 mg/g in bark
A major iridoid of the bark that contributes to the drug's blood-pressure-lowering and bone-protective activity in animal models, with part of the antihypertensive effect in spontaneously hypertensive rats attributed to it alongside improved renal blood flow. Content varies several-fold between cultivars and with harvest timing, so bark potency is not uniform.
Aucubin
Iridoid glucosideConcentration: present in bark, but highly variable between cultivars; a seven-cultivar survey reported 6.6-368.6 mg/g of dried bark
An iridoid shared with the leaf that carries most of the anti-inflammatory and osteoblast-stimulating activity reported for Eucommia extracts. Aucubin is chemically labile and readily hydrolysed, so the content of a stored or badly dried bark is not that of fresh material.
Chlorogenic acid
Phenylpropanoid (caffeoylquinic acid)Concentration: 2.7-37.5 mg/g of dried bark in a seven-cultivar survey, against 11.4-120.0 mg/g in the leaf of the same trees
Present in the bark but at a small fraction of the leaf level, so chlorogenic-acid-based rationales belong properly to Du Zhong Ye rather than to the bark. It contributes antioxidant and mild vasorelaxant activity.
Eucommia gum (gutta-percha, trans-1,4-polyisoprene)
PolyterpeneConcentration: about 10-12% of the bark, against 2-3% of the leaf
The elastic polymer responsible for the silvery threads that stretch across the break when good Du Zhong bark is snapped, which is the classical quality criterion for the drug and the practical way to tell bark from leaf material. It is not water-soluble and is pharmacologically inert, so it does not enter a decoction, but its abundance is why the bark is dense and hard to powder.
⚠ Drug Interactions
Antihypertensive drugs, particularly beta-blockers
In the only controlled human trial of the bark, an aqueous extract standardised to 8% pinoresinol diglucoside at 1 g three times daily for two weeks reduced 24-hour ambulatory blood pressure by an average of 7.5/3.9 mmHg. The same study showed the extract reduced isoproterenol-stimulated lipolysis in a human fat cell assay from 2.67 to 1.4 times the buffer control, which the authors interpreted as beta-adrenergic blocking activity. Animal work adds nitric-oxide-mediated vasorelaxation and renin-angiotensin system effects. So the bark is not merely an incidental hypotensive, it appears to share a mechanism with prescribed beta-blockers.
Clinical note: Check blood pressure and pulse before and two weeks after adding Du Zhong to a patient on antihypertensives, and be alert for symptomatic hypotension or bradycardia in a patient already on a beta-blocker. It is not a substitute for antihypertensive medication and should not be used to justify reducing one.
Beta-agonist bronchodilators (e.g. salbutamol, formoterol)
The beta-adrenergic blocking activity demonstrated for the standardised bark extract in a human adipocyte assay is the same pharmacology that makes beta-blockers a caution in asthma. No study has tested Eucommia bark against a beta-agonist in the airway, and the potency in adipocytes says nothing quantitative about bronchial beta-2 receptors, so this is an inference from mechanism only.
Clinical note: There is no evidence of harm, but in a patient with brittle asthma who needs reliable reliever response, prefer another Kidney-and-sinew tonic or monitor peak flow when starting the bark.
Nephrotoxic drugs (e.g. NSAIDs, aminoglycosides, calcineurin inhibitors)
A 13-week rodent toxicology study of Eucommia ulmoides extract found a dose-dependent rise in nephrotoxicity indices with histological change in renal tissue, which resolved five weeks after stopping the lower dose (11.2 g/kg raw-plant equivalent) but persisted at the higher dose (56 g/kg). The same study found no genotoxicity and a maximum tolerated dose of at least 168 g/kg, roughly 1260 times the human clinical dose, so acute risk at ordinary doses is very low; the concern is confined to long-term high-dose exposure. The study reports the extract without specifying which plant part it was made from.
Clinical note: At Pharmacopoeial decoction doses over normal treatment courses this is not a practical concern. For patients taking concentrated Eucommia extracts for months, particularly alongside NSAIDs, check renal function periodically and avoid open-ended high-dose use.
Dosage
| Form | Amount | Frequency | Duration | Population | Notes |
|---|---|---|---|---|---|
| decoction | 6–10 g | Daily | — | — | 中国药典 2020 【用法与用量】6～10g。 【性味与归经】甘，温。归肝、肾经。 — 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.
Kidney yang is warmed while the lower back and knees are strengthened.
Kidney-deficiency low back pain.
Core pair of a classical formula — Qing E Wan, Tai Ping Hui Min He Ji Ju Fang
Liver and kidney are tonified and sinews and bones strengthened while the blood vessels are unblocked, securing the Chong and Ren.
Low back pain from kidney deficiency, uterine bleeding and threatened miscarriage.
Named pairing — Lü Jingshan, Shi Jinmo Dui Yao
Evidence Tier
Moderate 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
1
0 verified · 1 unverified
Other clinical trial
0
Observational / case report
0
In vitro / animal
1
0 verified · 1 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
A clinical trial testing the safety and efficacy of a standardized Eucommia ulmoides Oliver bark extract to treat hypertension
Three linked studies of an aqueous bark extract standardised to 8% pinoresinol di-beta-D-glucoside. Study 1 randomised 24 adults with blood pressure of 120-160/80-100 mmHg to 500 mg three times daily for eight weeks and found no toxicity and no difference in blood pressure between groups. Study 3 randomised 30 similar adults to 1 g three times daily for two weeks and found a reduction of 7.5/3.9 mmHg on 24-hour ambulatory monitoring (P less than 0.008). Study 2, a human fat cell assay, showed the extract at 0.5% w/v reduced isoproterenol-stimulated lipolysis from 2.67 to 1.4 times the buffer control (P less than 0.001), indicating beta-adrenergic blocking activity. The lower dose was therefore ineffective and only the doubled dose lowered blood pressure; both were well tolerated. Predates DOI registration for this journal, so cited by PubMed record.
Metabolite Profiles, Bioactivity, and HPLC Fingerprint of Different Varieties of Eucommia ulmoides Oliv.: Towards the Utilization of Medicinal and Commercial Chinese Endemic Tree
HPLC profiling of leaf and bark from seven Eucommia ulmoides varieties. Pinoresinol diglucoside was detected only in bark (23.0-53.6 mg/g) while rutin, hyperoside and astragalin were detected only in leaf, establishing the two drugs as chemically distinct rather than interchangeable. Chlorogenic acid was far higher in leaf (11.4-120.0 mg/g) than bark (2.7-37.5 mg/g); aucubin and geniposidic acid occurred in both with wide between-cultivar variation. The authors concluded that different varieties suit bark versus leaf use.
⚠ Safety & Contraindications
- Kidney conditions
Side Effects
- Low toxicity in animals; long-term i.p. decoction in dogs produced only mild renal tubular epithelial degeneration; no blood or liver/kidney abnormalities in rats given oral decoction or alcoholic extract.
Source: Zhu YP. Chinese Materia Medica: Chemistry, Pharmacology and Applications. Harwood Academic, 1998, p. 602.
Historical Texts
Shen Nong Ben Cao Jing
Han dynastyMing Yi Bie Lu
Southern dynasties (Tao Hongjing, c. 500 CE)Ben Cao Gang Mu
Ming dynasty (Li Shizhen, 1596)References
- Lichuang Huang, Qiang Lyu, Wanying Zheng, Qiao Yang, Gang Cao. Traditional application and modern pharmacological research of Eucommia ulmoides Oliv. . Chinese Medicine (2021) [DOI]
- Yun Li, Xiangyang Kang. Advances in research on the bioactive compounds and genetic improvement of Eucommia ulmoides . Medicinal Plant Biology (2024) [DOI]
- Ying Yan, Hui Zhao, Cuihua Chen, Lisi Zou, Xunhong Liu, Chuan Chai, Chengcheng Wang, Jingjing Shi, Shuyu Chen. Comparison of Multiple Bioactive Constituents in Different Parts of Eucommia ulmoides Based on UFLC-QTRAP-MS/MS Combined with PCA . Molecules (2018) [DOI]
- Xiaomei Luo, Jiashuo Wu, Zhuangzhuang Li, Weiyi Jin, Fangqing Zhang, Hong Sun, Yue Shi. Safety evaluation of Eucommia ulmoides extract . Regulatory Toxicology and Pharmacology (2020) [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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