Huang Yao Zi
StarDioscorea bulbifera L.
Traditionally used for
- Nose & throat
- Cough & breathing
- Skin
Cautions & contraindications
- Pregnancy
- Liver conditions
- Kidney conditions
☯ TCM Properties
Resolves Phlegm, dissipates nodules and reduces masses; Clears Heat and reduces toxicity; Cools the Blood and stops bleeding; Stops coughing and calms wheezing
Traditional Chinese Uses
Huang Yao Zi is the tuber of Dioscorea bulbifera (air-potato yam). Bitter and cold, entering the Liver, Lung and Heart channels, it resolves Phlegm and dissipates nodules to reduce masses, clears Heat and relieves toxicity, cools the Blood to stop bleeding, and calms cough and wheezing. Its signature use is stubborn goiter and thyroid/neck nodules (Phlegm binding), where it has long been considered notably effective; it also treats scrofula, sore swollen throat, toxic sores and carbuncles, cough with Phlegm-Heat, and various bleeding patterns.
It is usually decocted (about 3-9 g) or soaked in wine, and combined with Phlegm-softening, nodule-dissipating herbs. Critically, this tuber is hepatotoxic (diosbulbin constituents): it must be given only in limited courses of a few weeks with liver-function monitoring, avoided in liver disease and pregnancy, and stopped if nausea, jaundice or abdominal pain appear.
Western Herbalism Properties
Relationships
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Botanical Description
Huang Yao Zi is the tuberous rhizome (bulbil) of Dioscorea bulbifera L. (Dioscoreaceae), the air-potato yam, a perennial twining herbaceous vine 5-30 m long native to tropical Asia and Africa and widespread across southern China. The slender, smooth, left-twining stems arise from a large brown irregular subterranean tuber and bear conspicuous aerial bulbils 2-10 cm in diameter at the leaf axils. Alternate, long-petioled, broadly cordate leaves are 5-15 cm long with palmate venation. Small, fragrant, greenish-white flowers are borne in pendulous axillary spikes. The harvested tuber is sliced and dried, appearing as flat, brownish-yellow discs with a hard texture and bitter taste. In TCM the rhizome cools blood, resolves toxin, and softens hardness, used for goitre, lymphadenopathy, sore throat, and abscesses. The herb is hepatotoxic, especially with prolonged use or in raw form; modern guidance limits dosing duration and recommends processed material.
Active Constituents
Diosbulbin B
Clerodane furanoditerpenoid lactoneConcentration: Most abundant diterpene lactone of the tuber; content in commercial herb collected from 11 Chinese production areas varied by as much as 47-fold
The principal hepatotoxin of the drug. CYP3A4 oxidises its furan ring to a cis-enedial intermediate that binds covalently to hepatic protein and to DNA, and the hepatotoxic potency of tuber samples is proportional to how much diosbulbin B they contain.
8-Epidiosbulbin E acetate
Clerodane furanoditerpenoid lactoneConcentration: Second major furanoditerpenoid lactone of the tuber
Hepatotoxic by the same furan-ring bioactivation route as diosbulbin B, forming an epoxide and cis-enedial that adduct protein amines and generate reactive oxygen species with DNA damage. Metabolomic and transcriptomic profiling in rodents attributes a distinct component of the liver injury to this compound.
Diosbulbin C
Clerodane furanoditerpenoid lactoneConcentration: Minor diterpenoid lactone of the tuber
Inhibited proliferation of lung cancer cell lines in vitro by arresting the cell cycle in G0/G1. Cell-culture work only; no animal or human efficacy data.
Diosgenin
Steroidal sapogeninConcentration: Present as glycosides; Asian accessions of the species are described as comparatively rich in saponins and flavonoids, African accessions in clerodane diterpenoids
The saponin fraction accounts for much of the reported antioxidant, anti-inflammatory and antidiabetic activity of the plant in preclinical models. It is not the fraction responsible for the liver injury.
Flavanthrinin
PhenanthreneConcentration: Isolated from the aerial bulbils, not from the tuber that constitutes the drug
Antibacterial against Staphylococcus aureus, meticillin-resistant S. aureus and S. epidermidis with minimum inhibitory concentrations of 0.02-0.78 mg/mL, with low cytotoxicity to Vero cells. Relevant to the bulbil, and should not be read across to the rhizome drug.
⚠ Drug Interactions
Hepatotoxic drugs (paracetamol, methotrexate, isoniazid, azole antifungals)
Dioscorea bulbifera is an established cause of herb-induced liver injury in its own right: more than 100 cases of liver injury attributed to the herb have been reported in China over the past half-century, ranging from fatigue and raised transaminases through jaundice to severe hepatitis, hepatic failure, hepatic coma and death. The injury is intrinsic and dose-related, driven by cytochrome P450 oxidation of the furan rings of diosbulbin B and 8-epidiosbulbin E acetate to reactive cis-enedial intermediates that adduct hepatic protein and DNA, with oxidative stress, mitochondrial dysfunction and inhibition of hepatobiliary transporters. Any concurrent hepatotoxin adds to that burden on the same organ.
Clinical note: Do not combine with other hepatotoxic drugs. If the herb is used at all, check baseline liver function and repeat it during treatment, keep courses short, and stop immediately on nausea, anorexia, right upper quadrant discomfort, dark urine or jaundice.
CYP3A4 inducers (rifampicin, carbamazepine, phenytoin, St John's wort)
Bioactivation of diosbulbin B was mapped to CYP3A4/5, 2C9 and 2C19 using human recombinant P450s and selective inhibitors, with CYP3A4 the principal enzyme; a further study adds CYP2C19-mediated activation together with OAT3- and P-glycoprotein-associated transport. Because the toxicity depends on how much cis-enedial is made rather than on the parent compound, inducing CYP3A4 is expected to increase injury. Consistent with this, the sex difference in CYP3A expression tracks the sex difference in liver injury in rodents, and CYP3A4 inhibitors such as schisandrol B and glycyrrhizin reduce the injury in mice.
Clinical note: Treat concurrent enzyme-inducing drugs as a reason not to prescribe this herb. Note also that the herb is bioactivated by, and interacts with, the same enzyme that handles a large share of conventional drugs.
Shan Ci Gu (Pseudobulbus Cremastrae seu Pleiones)
Shan Ci Gu is officially the dried pseudobulb of the orchids Cremastra appendiculata, Pleione bulbocodioides or Pleione yunnanensis, but market material is drawn from several families and genera and substitution is well documented, driven by short supply and high price. Dioscorea bulbifera tuber shares the same traditional indication of dispersing nodules and goitre and is among the species that reach the Shan Ci Gu supply, so a patient dispensed Shan Ci Gu may receive a hepatotoxic furanoditerpenoid load that neither prescriber nor patient has accounted for. The reverse error - Iphigenia indica or Tulipa edulis, which carry colchicine - is documented in the same supply chain.
Clinical note: Authenticate Shan Ci Gu material to species before dispensing, and treat unexplained hepatitis in a patient taking Shan Ci Gu as possible Dioscorea bulbifera exposure.
Levothyroxine and antithyroid drugs (carbimazole, methimazole, propylthiouracil)
The herb is used in Chinese practice chiefly in compound formulas aimed at thyroid disorders and nodular disease, so co-prescription with thyroid drugs is common rather than hypothetical. Critical review of its toxicology lists thyroid dysfunction among its adverse effects alongside hepatotoxicity, nephrotoxicity, cardiotoxicity and gastrointestinal irritation, and the drug is not standardised, so its effect on thyroid function is not predictable batch to batch.
Clinical note: Monitor thyroid function if the herb is used alongside thyroid replacement or antithyroid therapy, and do not assume a stable dose remains stable.
P-glycoprotein and OAT3 substrates
Transport by organic anion transporter 3 and P-glycoprotein contributes to the disposition of the toxic constituents and to the resulting liver injury, and inhibition of hepatobiliary transporters is one of the mechanisms by which diosbulbin B damages the liver. Substrates of those transporters given at the same time may therefore accumulate. The evidence is preclinical.
Clinical note: Consider the possibility of altered exposure to narrow-therapeutic-index P-glycoprotein substrates, and prefer to avoid the combination rather than monitor it.
Gan Cao (Glycyrrhiza uralensis)
Processing the tuber with Glycyrrhiza uralensis juice reduced its toxicity in rodents while retaining the expectorant and antitussive effect, and co-administered Glycyrrhiza uralensis attenuated the liver injury by acting on FXR/Nrf2-bile acid signalling and the intestinal microbiota. Isolated licorice constituents work by the expected route: glycyrrhizin and glycyrrhetinic acid both reduced diosbulbin B hepatotoxicity in mice by suppressing its metabolic activation. All of this is animal and in vitro work.
Clinical note: The classical pairing with licorice has a plausible mechanism behind it, but it has never been shown to make the herb safe in people and must not be treated as protection.
Dosage
| Form | Amount | Frequency | Duration | Population | Notes |
|---|---|---|---|---|---|
| decoction | 5–15 g | Daily | — | — | Standard oral dose per Xi S, Gong Y. Essentials of Chinese Materia Medica and Medical Formulas. Academic Press/Elsevier, 2017, pp. 267–277. Exact wording: Normally, 5–15 g is decocted with water as an oral |
Evidence Tier
Strong evidence · 8 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
1
1 verified · 0 unverified
Randomized controlled trial
0
Other clinical trial
0
Observational / case report
0
In vitro / animal
7
6 verified · 1 unverified
Show 7 studies
- Diosbulbin B: An important component responsible for hepatotoxicity and protein covalent binding induced by Dioscorea bulbifera L.
- Metabolomic-transcriptomic landscape of 8-epidiosbulbin E acetate -a major diterpenoid lactone from Dioscorea bulbifera tuber induces hepatotoxicity
- In Vitro DNA Adduction Resulting from Metabolic Activation of Diosbulbin B and 8-Epidiosbulbin E Acetate
- Ameliorative effect of Schisandrol B against Diosbulbin B-induced hepatotoxicity via inhibiting CYP3A4-mediated bioactivation
- Discovery of Hepatotoxic Equivalent Combinatorial Markers from Dioscorea bulbifera tuber by Fingerprint-Toxicity Relationship Modeling
- Investigation of the principle of concoction by using the processing excipient Glycyrrhiza uralensis Fisch. juice to reduce the main toxicity of Dioscorea bulbifera L. and enhance its main efficacy as expectorant and cough suppressant
- Development of a mechanism-based biomarker for Dioscorea bulbifera L. exposure and hepatotoxicity in rats
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
Dioscorea bulbifera: Phytotherapeutic Potential and Toxicological Risks, A Critical Review
Systematic review of the phytochemistry, pharmacology and toxicology of the species. It attributes hepatotoxicity to the furanoid diterpenoids diosbulbin B and 8-epidiosbulbin E acetate, and adds nephrotoxicity, cardiotoxicity, gastrointestinal irritation and thyroid dysfunction to the risk profile. It records the complete absence of human trials, and notes that African accessions are rich in clerodane diterpenoids while Asian accessions are richer in saponins and flavonoids, so provenance changes the chemistry.
Diosbulbin B: An important component responsible for hepatotoxicity and protein covalent binding induced by Dioscorea bulbifera L.
Herb collected from 11 Chinese locations was fingerprinted by UPLC-MS/MS and tested in vitro and in mice. Diosbulbin B content varied as much as 47-fold between sources, hepatotoxic potency was proportional to that content, and mice given high-diosbulbin-B material showed intensified hepatic protein adduction. The practical consequence is that the toxicity of a given batch cannot be inferred from the dose in grams.
Metabolomic-transcriptomic landscape of 8-epidiosbulbin E acetate -a major diterpenoid lactone from Dioscorea bulbifera tuber induces hepatotoxicity
Integrated metabolomic and transcriptomic study in rodents of 8-epidiosbulbin E acetate, isolated from the tuber, establishing it as a hepatotoxin in its own right rather than only a marker compound.
In Vitro DNA Adduction Resulting from Metabolic Activation of Diosbulbin B and 8-Epidiosbulbin E Acetate
Both furanoditerpenoids were shown to form DNA adducts after P450-mediated metabolic activation, meaning the reactive intermediate reaches genetic material and not only protein. This is the genotoxic limb of the concern about the herb.
Ameliorative effect of Schisandrol B against Diosbulbin B-induced hepatotoxicity via inhibiting CYP3A4-mediated bioactivation
Schisandrol B reduced diosbulbin B liver injury in mice by inhibiting CYP3A4-mediated bioactivation, confirming from the protective side that CYP3A4 activity is the determinant of how much injury the compound causes.
Discovery of Hepatotoxic Equivalent Combinatorial Markers from Dioscorea bulbifera tuber by Fingerprint-Toxicity Relationship Modeling
Chemical fingerprints of tuber batches were modelled against measured hepatotoxicity to identify the combination of markers that accounts for the toxic effect, supporting toxicity-linked rather than purely chemical quality control of the drug.
Investigation of the principle of concoction by using the processing excipient Glycyrrhiza uralensis Fisch. juice to reduce the main toxicity of Dioscorea bulbifera L. and enhance its main efficacy as expectorant and cough suppressant
Rodent study of the classical processing method: tuber processed with Glycyrrhiza uralensis juice showed reduced hepatotoxicity while its expectorant and antitussive effect was preserved or improved. It describes the processed drug, not the raw one, and offers no human safety data.
Development of a mechanism-based biomarker for Dioscorea bulbifera L. exposure and hepatotoxicity in rats
Derived a mechanism-based biomarker of exposure and liver injury in rats from the reactive metabolite pathway, so that exposure to the herb can in principle be identified biochemically rather than only from a drug history.
⚠ Safety & Contraindications
- Pregnancy
- Liver conditions
- Kidney conditions
Contraindications
Don’t take too much or for a long time. Its use is cautious in patients with weakness of the spleen and stomach and functional lesion of the liver and kidney.
Source: Xi S, Gong Y. Essentials of Chinese Materia Medica and Medical Formulas. Academic Press/Elsevier, 2017, pp. 267–277.
Historical Texts
Kai Bao Ben Cao
Northern Song dynasty, 973-974 CERi Hua Zi Ben Cao
Five Dynasties to early Song, c. 10th centuryBen Cao Gang Mu
Ming dynasty, 1596References
- Li H, Peng Y, Zheng J. Dioscorea bulbifera L.-induced hepatotoxicity and involvement of metabolic activation of furanoterpenoids . Drug Metabolism Reviews (2020) [DOI]
- Zhang Y, Miao J, Zhou D, Xu D, Fu P, Ou Y, Pan D, Li C, Zheng D, Qiu J. The double-edged sword of Dioscorea bulbifera L.: Recent advances in its pharmacological benefits and hepatotoxicity, and the quest for detoxification strategies . Journal of Ethnopharmacology (2026) [DOI]
- Guan XR, Zhu L, Xiao ZG, Zhang YL, Chen HB, Yi T. Bioactivity, toxicity and detoxification assessment of Dioscorea bulbifera L.: a comprehensive review . Phytochemistry Reviews (2017) [DOI]
- Sanguansermsri D, Sanguansermsri P, Buaban K, Choommongkol V, Akekawatchai C, Charoensri N, Fraser I, Wongkattiya N. Antibacterial activity of Dioscorea bulbifera Linn. extract and its active component flavanthrinin against skin-associated bacteria . BMC Complementary Medicine and Therapies (2024) [DOI]
- Zhu Z, Liu Y, Zeng J, Ren S, Wei L, Wang F, Sun X, Huang Y, Jiang H, Sui X, Jin W, Jin L, Sun X. Diosbulbin C, a novel active ingredient in Dioscorea bulbifera L. extract, inhibits lung cancer cell proliferation by inducing G0/G1 phase cell cycle arrest . BMC Complementary Medicine and Therapies (2023) [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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