Wang Gua Gen

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Trichosanthes cucumeroides (Ser.) Maxim.

Not yet clinically reviewed

Pinyin: Wang Gua Gen
Japanese Snakegourd Root

Traditionally used for

  • Cough & breathing
  • Colds & fever
  • Digestion
  • Bowel health
  • Urinary & fluids
  • Menstrual & women's health
  • Skin
  • Liver & jaundice

Cautions & contraindications

  • Pregnancy
  • Allergy risk
Moderate evidence · 3 studies

☯ TCM Properties

Category: clearing heat
Temperature: cold
Taste: bitter
Meridians: bladder, lung, heart
Functions:

Clears Heat, generates Fluids, invigorates the Blood and breaks up Blood Stasis

Traditional Chinese Uses

Wang Gua Gen (Radix Trichosanthis Cucumeroidis) is the root of Trichosanthes cucumeroides, the Japanese snake gourd. Bitter and cold, entering the Bladder, Lung and Heart channels, it clears Heat and generates Fluids while also invigorating the Blood and breaking up Blood Stasis. On the Heat-clearing side it is used for febrile thirst and wasting-thirst (polydipsia), heat in the Lungs, jaundice, and heat-type constipation, and topically for hot sores and skin lesions.

Through its Blood-moving action it treats amenorrhea, palpable abdominal masses (Zheng Jia) and Stasis-type swellings. It is generally decocted in modest doses or pounded for juice, and applied externally as a poultice for boils and abscesses. As a cold, Blood-breaking herb it is used cautiously in pregnancy and in patterns of cold or deficiency.

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Botanical Description

Trichosanthes cucumeroides, the Japanese snake gourd, is a herbaceous perennial climbing vine of the Cucurbitaceae family native to East Asia, including central and southern China, Korea, and Japan. The plant produces slender angled stems that ascend by branched tendrils, with broadly cordate to three- or five-lobed leaves arranged alternately and bearing a roughened surface. Solitary white flowers open at dusk and display the characteristic finely fringed lace-like petal margins typical of the genus, attracting nocturnal pollinators. The fruit is an ovoid berry, green and white striped when young, ripening to bright orange or red, hanging conspicuously from the climbing stems. Beneath ground the plant develops elongated, tuberous, starchy roots which constitute the medicinal portion harvested in autumn and dried for use.

Active Constituents

beta-Trichosanthin

Type 1 ribosome-inactivating protein

A 28 kDa single-chain protein purified from the root tuber of this species (the drug Wangua). It is immunochemically identical to trichosanthin from Trichosanthes kirilowii but differs in molecular weight, carbohydrate content, charge and amino acid composition, and was about twice as potent as trichosanthin at inducing mid-term abortion in mice. Its presence is the reason this root must not be given in pregnancy.

Dihydrocucurbitacin B

Cucurbitane-type triterpenoid

One of the bitter principles of the root. In HepG2 cells it promoted LDL uptake by upregulating LDL receptor protein in a PCSK9-dependent manner. Cucurbitacins as a class are potently cytotoxic and are the constituents responsible for the root's bitterness and its toxicity in overdose.

Isocucurbitacin D

Cucurbitane-type triterpenoid

One of 27 cucurbitacins characterised from Trichosanthes cucumeroides root. Together with hexanorisocucurbitacin D it gave the highest LDL uptake rates in HepG2 cells of the series tested, dose-dependently raising LDLR and lowering PCSK9 protein. This is in vitro work only.

11-Oxocucurbit-5-ene-3-beta,24(R),25-triol 3-O-triglycoside

Cucurbitane triterpenoid glycoside

One of three bitter triterpenoid glycosides obtained from the fresh root, bearing a rhamnosyl-glucosyl-glucosyl chain at C-3. These glycosides carry the characteristic bitter taste of the fresh drug.

alpha-Spinasterol

Phytosterol

Present in the fresh root together with its 3-O-beta-D-glucopyranoside, stigmast-7-en-3-beta-ol and the corresponding glucoside. These sterols are common Cucurbitaceae root constituents and are not the pharmacologically distinctive part of the drug.

7-Oxodihydrokarounidiol

Multiflorane-type (26-norolean-8-ene) triterpene

Isolated from the unsaponifiable matter of the seeds, alongside two triterpenes described as new in the same work. This is a seed constituent (Wang Gua Zi) and should not be attributed to the root drug.

⚠ Drug Interactions

Tian Hua Fen (Trichosanthes kirilowii root) and trichosanthin-containing preparations

Major Evidence: Probable

Both drugs are Trichosanthes root tubers and both carry type 1 ribosome-inactivating proteins. beta-Trichosanthin from Trichosanthes cucumeroides is immunochemically identical to trichosanthin from Trichosanthes kirilowii and was roughly twice as potent an abortifacient in mice. Because the two are immunochemically identical, prior sensitisation to one predicts reactivity to the other. The pinyin names compound the hazard: Wang Gua Gen has long circulated under the alternative name Tu Gua Gen and is confused in commerce with Gua Lou Gen and Tian Hua Fen, so a decoction may contain both proteins when the prescriber intended one.

Clinical note: Absolutely contraindicated in pregnancy or when pregnancy is possible. Verify the botanical origin of any Trichosanthes root on the label before dispensing, and do not stack two Trichosanthes root drugs in one formula.

Cytotoxic chemotherapy agents

Theoretical Evidence: Theoretical

The root is rich in cucurbitacins, which are among the more potent plant cytotoxins. In the most recent phytochemical study of this species, cucurbitacins from the root gave IC50 values as low as 0.051 micromolar against MDA-MB-231, SKOV3 and T24 cell lines, and comparably low values against non-malignant HUVEC endothelial cells, so the cytotoxicity is not tumour-selective. No human pharmacokinetic or interaction data exist.

Clinical note: Do not co-prescribe with cytotoxic chemotherapy. There is no dosing evidence in humans for this root.

Statins and PCSK9 inhibitors

Theoretical Evidence: Theoretical

Cucurbitacins isolated from this root raise LDL receptor protein and lower PCSK9 protein in HepG2 cells, the same axis targeted by statins and by PCSK9 monoclonal antibodies. The observation is confined to a cell line; there is no animal or human evidence of a lipid-lowering effect of the whole drug, and no reason to expect a clinically useful one at traditional doses.

Clinical note: Not a reason to use the herb for lipids, and not a documented clinical interaction. Recorded so the in vitro finding is not mistaken for a therapeutic indication.

Evidence Tier

Moderate evidence · 3 studies

Recorded 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.

Verified: design read from PubMed for a DOI that resolves to the cited paper Unverified: taken from the study's recorded description

Clinical Studies

β-Trichosanthin: a new abortifacient protein from the Chinese drug, Wangua, Trichosanthes cucumeroides

Yeung HW, Li WW (1987) International Journal of Peptide and Protein Research animal Verified: In vitro / animal

A 28 kDa protein without cysteine was purified from the root tubers of Trichosanthes cucumeroides. It was immunochemically identical to trichosanthin from Trichosanthes kirilowii but differed in molecular weight, carbohydrate content, charge and amino acid composition, and was roughly twice as potent as trichosanthin at inducing mid-term abortion in mice. This is the primary evidence for the pregnancy contraindication attached to this specific root.

Lipid-Lowering Activities of Cucurbitacins Isolated from Trichosanthes cucumeroides and Their Synthetic Derivatives

Zhang X, Li H, Wang W, Chen T, Xuan L (2020) Journal of Natural Products in vitro

Twenty-seven cucurbitacins, seven of them new, were isolated from Trichosanthes cucumeroides roots and tested in an LDL uptake assay in HepG2 cells alongside synthetic derivatives. Hexanorisocucurbitacin D and isocucurbitacin D gave the highest LDL uptake rates (2.53 and 2.47), comparable to the positive control nagilactone B, and dose-dependently raised LDLR while reducing PCSK9 protein on Western blot. Cell-based work only, with no in vivo confirmation.

Undescribed cucurbitacin-type triterpenoids from the roots of Trichosanthes cucumeroides with antitumor effects, and their molecular docking studies

Aamer M, Huang F, Xiao D, Tariq M, Zhou X, Mao Y, Yang Y, Wang Y, Choudhary MI, Li B, Wang W (2026) Bioorganic Chemistry in vitro

Twenty-five compounds, eleven of them previously undescribed, were isolated from the roots of Trichosanthes cucumeroides and tested by MTT against MDA-MB-231, SKOV3, T24 and HUVEC cells. IC50 values ranged from 0.051 micromolar to above 20 micromolar, with three compounds in the 0.05 to 0.10 micromolar range. Cytotoxicity of this order against a normal endothelial line as well as tumour lines is a toxicity signal for the crude drug, not a therapeutic result.

Historical Texts

Shen Nong Ben Cao Jing

Han dynasty
Wang Gua is entered in the Han-dynasty classic; the root, seed and fruit were later separated as Wang Gua Gen, Wang Gua Zi and Wang Gua. The entry is for the plant now identified as Trichosanthes cucumeroides, a different species from the Gua Lou and Tian Hua Fen of the Pharmacopoeia, which are Trichosanthes kirilowii and Trichosanthes rosthornii.

Jin Gui Yao Lue

Han dynasty
Records Tu Gua Gen San, a powder of Tu Gua Gen with Zhe Chong, Gui Zhi and Shao Yao taken in wine three times daily for menstrual irregularity with abdominal fullness and pain. Later commentators identify the Tu Gua Gen of this formula with the root of this species. The identification is commentarial rather than certain, and is one reason Wang Gua Gen and Tu Gua Gen circulate as names for the same drug.

Ben Cao Gang Mu

Ming dynasty
Li Shizhen discusses Wang Gua alongside Gua Lou and notes the resemblance between the two vines, which is the origin of the persistent commercial confusion between this root and Trichosanthes kirilowii root.

References

  1. Kitajima J, Tanaka Y. Studies on the Constituents of Trichosanthes Root. II. Constituents of Roots of Trichosanthes cucumeroides MAXIM. . Yakugaku Zasshi (1989) [DOI]
  2. Chao Z, Shibusawa Y, Yanagida A, Shimotakahara S, Shindo H. Two new triterpenes from the seeds of Trichosanthes cucumeroides . Natural Product Research (2005) [DOI]
  3. Ng TB, Chan WY, Yeung HW. Proteins with abortifacient, ribosome inactivating, immunomodulatory, antitumor and anti-AIDS activities from Cucurbitaceae plants . General Pharmacology: The Vascular System (1992) [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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