Taraxacin

Taraxacin at a Glance

Taraxacin is the name attached to dandelion’s bitterness — and it is a name that has meant at least two different substances.

In herbal writing it is the bitter principle of common dandelion, a term inherited from nineteenth-century pharmacy. That usage never rested on a characterised molecule: the material Pollex and Kromayer extracted from dandelion root juice was reported with inconsistent properties and, by 1912, was being described as a mixture rather than a definite compound ^{2Reference 2Remington JP et al. · 1918ReviewTaraxacum — dispensatory monographView study →}.

In chemical databases it is something else entirely — a real, X-ray-characterised sesquiterpene lactone (C₁₅H₁₄O₃, PubChem CID 5241825), named in 2000 by Ahmad and co-workers for a new guaianolide they isolated from Taraxacum wallichii, a Himalayan dandelion ^{1Reference 1Ahmad VU et al. · 2000Taraxacin, a new guaianolide from Taraxacum wallichiiView study →}. That molecule was independently re-isolated from Taraxacum mongolicum eight years later ^{3Reference 3Shi SY et al. · 2008Shi SY, Zhou CX, Xu Y, Tao QF, Bai H, Lu FS, Lin WY, Chen HY, Zheng W, Wang LW, Wu YH, Zeng S, Huang KX, Zhao Y, Li XK, Qu J (2008). [Studies on chemical constituents from herbs of Taraxacum mongolicum]. Zhongguo Zhong Yao Za Zhi 33(10):1147–1157. https://pubmed.ncbi.nlm.nih.gov/18720865/View study →}.

The two are connected only by the word. And the connecting claim that would make it simple — that taraxacin is the bitter of dandelion (Taraxacum officinale) — is the one thing the primary record does not support. No isolation of taraxacin from T. officinale has been published. Modern work on that species assigns its bitterness to taraxinic acid β-D-glucopyranosyl ester and a handful of related lactones instead ^{5,6Reference 5Kisiel W · 2000Further sesquiterpenoids and phenolics from Taraxacum officinaleView study →Reference 6Esatbeyoglu T et al. · 2017In vitroSesquiterpene lactone composition and cellular Nrf2 induction of Taraxacum officinale leaves and roots and taraxinic acid β-D-glucopyranosyl ester — in vitroView study →}.

The Identity Question: Three Compounds, One Name

The single most useful thing to do is separate the things that “taraxacin” has been used to mean.

1. Taraxacin the historical bitter fraction (pre-1861 – ~1912). The nineteenth-century Dispensatory of the United States of America records that “a crystallizable principle has been extracted from the juice of the root by Pollex, who has named it taraxacin” — bitter and somewhat acrid, fusible but not volatile, sparingly soluble in cold water and freely soluble in hot water, alcohol and ether ^{2Reference 2Remington JP et al. · 1918ReviewTaraxacum — dispensatory monographView study →}. Kromayer (1861) reported obtaining taraxacin too, along with a second crystalline principle he called taraxacerin, assigned the formula C₈H₁₆O; a molecular formula of C₄₀H₈₀O₅ circulated for the taraxacerin fraction ^{2Reference 2Remington JP et al. · 1918ReviewTaraxacum — dispensatory monographView study →}. Those formulas are not compatible with one another, and F. B. Power’s 1912 assessment, as the Dispensatory relays it, was that both substances were mixtures rather than definite compounds ^{2Reference 2Remington JP et al. · 1918ReviewTaraxacum — dispensatory monographView study →}. This is the sense in which herbalists, and this database’s own dandelion monograph, use the word.

2. Taraxacin the defined guaianolide (2000 – present). Eighty-eight years later the name was applied to something specific. Ahmad, Yasmeen, Ali and colleagues isolated “a new guaianolide, taraxacin (1), and a known sesquiterpene ketolactone (2)” from the ethyl-acetate-soluble fraction of a methanolic extract of Taraxacum wallichii, establishing the structure “using NMR, MS, and X-ray crystallographic methods” ^{1Reference 1Ahmad VU et al. · 2000Taraxacin, a new guaianolide from Taraxacum wallichiiView study →}. X-ray crystallography is the strongest structural evidence available in natural-product chemistry, so this compound’s identity is not in doubt. It carries PubChem CID 5241825, molecular formula C₁₅H₁₄O₃, and CAS number 284666-72-4 ^{16Reference 16PubChem Compound Summary et al. · 2026National Center for Biotechnology Information — chemical database record, accessed July 2026View study →}. Whether the 2000 authors intended to resurrect the old name or simply reused an available one is not stated in the abstract.

3. Taraxacine A and B — a third, unrelated collision. PubChem lists “Taraxacine” among the synonyms for taraxacin ^{16Reference 16PubChem Compound Summary et al. · 2026National Center for Biotechnology Information — chemical database record, accessed July 2026View study →}, which is an outright hazard, because taraxacine A and taraxacine B are different molecules of a different chemical class: β-carboline alkaloids isolated from Taraxacum formosanum in 2003 ^{8Reference 8Leu YL et al. · 2003Chemical constituents of Taraxacum formosanumView study →}, with taraxacine A the subject of a 2025 total synthesis via silver(I)-catalysed imidate–alkyne cyclization ^{9Reference 9Zalte RR et al. · 2025Total synthesis of the taraxacine A natural product via Ag(I)-catalysed imidate-alkyne cyclizationView study →}. A sesquiterpene lactone and a β-carboline alkaloid have nothing in common beyond four shared letters. Any search that folds these together will return nonsense.

The verdict. Taraxacin is a real molecule — this is not a mitraversine-style case of a name with no structure behind it. But the real molecule and the herbal bitter principle are not demonstrably the same thing, and the real molecule has never been reported from the plant the herbal literature is talking about.

What Dandelion’s Bitterness Is Actually Assigned To

If taraxacin is not the answer for T. officinale, something has to be, and the modern literature is fairly clear about what.

Kisiel and Barszcz isolated five germacrane- and guaiane-type sesquiterpene lactones from T. officinale roots — two taraxinic acid derivatives plus 11β,13-dihydrolactucin, ixerin D and ainslioside — and assigned the stereochemistry at C-11 in dihydrotaraxinic acid ^{5Reference 5Kisiel W · 2000Further sesquiterpenoids and phenolics from Taraxacum officinaleView study →}. Taraxacin is not among them. Esatbeyoglu and colleagues later profiled the sesquiterpene lactone composition of both leaves and roots and identified taraxinic acid β-D-glucopyranosyl ester as the main compound of the leaf extract, showing that both the leaf extract and that isolated ester induced Nrf2 in human hepatocytes more strongly than the root extract ^{6Reference 6Esatbeyoglu T et al. · 2017In vitroSesquiterpene lactone composition and cellular Nrf2 induction of Taraxacum officinale leaves and roots and taraxinic acid β-D-glucopyranosyl ester — in vitroView study →}. Again, no taraxacin.

So the honest mapping is: the function the herbal literature attributes to “taraxacin” — dandelion’s bitterness, and the bitter-tonic and choleretic reputation built on it — is real and belongs to the sesquiterpene lactone fraction. The specific attribution to a compound called taraxacin does not survive contact with the primary phytochemistry.

It is worth being precise about the taste mechanism too, because it is a class property, not a taraxacin property. The broadly-tuned human bitter receptor hTAS2R46 responds to a wide range of sesquiterpene lactones as well as clerodane and labdane diterpenoids ^{12Reference 12Brockhoff A et al. · 2007In vitroBroad tuning of the human bitter taste receptor hTAS2R46 to various sesquiterpene lactones, clerodane and labdane diterpenoids, strychnine, and denatonium — in vitroView study →}, and receptor-level work on lactones from edible Asteraceae has quantified that response — 11β,13-dihydrolactucopicrin activating TAS2R46 with an EC₅₀ of 2.0 ± 0.6 μM, with bitterness suppressible by shifting pH toward weakly acidic ^{13Reference 13Yanagisawa T · 2021In vitroCharacterization of the human bitter taste receptor response to sesquiterpene lactones from edible Asteraceae species and suppression of bitterness through pH control — in vitroView study →}. Taraxacin has never been tested at any bitter taste receptor. Its bitterness is assumed from its class, not measured.

The Structure — and the Missing Michael Acceptor

The structure of the defined taraxacin is worth reading carefully, because it cuts against the default assumption people bring to sesquiterpene lactones.

Taraxacin is 1,5,8-trimethyl-3a,4-dihydroazuleno[6,5-b]furan-2,6-dione ^{16Reference 16PubChem Compound Summary et al. · 2026National Center for Biotechnology Information — chemical database record, accessed July 2026View study →} — a heavily unsaturated, near-aromatic azulenic guaianolide. Its lactone is an α-methyl butenolide: the carbon α to the carbonyl carries a ring methyl and sits inside the conjugated azulene system. There is no exocyclic α-methylene group.

That matters, and it is the specific structural claim that matters most. Most bioactive Asteraceae sesquiterpene lactones carry an α-methylene-γ-lactone, an exocyclic C=CH₂ conjugated to the lactone carbonyl that acts as a Michael acceptor and alkylates cysteine thiols. Because that warhead is shared across the class, the familiar readouts attributed to it — NF-κB inhibition, glutathione depletion, broad cytotoxicity — are close to uninformative about any individual lactone. The contrast within dandelion’s own chemistry is direct:

Compound	Skeleton	Formula	α-Methylene-γ-lactone?
Taraxinic acid (and its β-glucosyl ester)	Germacranolide	C₁₅H₁₈O₄	Yes — exocyclic C=CH₂ on the lactone ring
Taraxacin (as defined 2000)	Azulenic guaianolide	C₁₅H₁₄O₃	No — α-methyl butenolide, methylene absent

So the thiol-alkylating chemistry that drives the sibling compound taraxinic acid β-glucoside, and relatives such as lactucin, parthenolide and costunolide, is not available to taraxacin. Its α,β-unsaturated butenolide is a far weaker electrophile, and conjugation into the azulene system deactivates it further.

This is a structural inference, not an experimental result — nobody has run a thiol-trapping or glutathione-adduct assay on taraxacin. But it means the usual shortcut of assuming an Asteraceae lactone will behave like parthenolide is not available here, and any future work should be designed accordingly.

What It's Used For

There is essentially no pharmacology for taraxacin. It has never been assayed for a receptor, an enzyme, a cell line, an animal model, or a taste response. The two records that attach any activity to the name are not isolate experiments, and neither used the compound.

No toxicological dataset was found to assess, so nothing here should be read as a clearance. Pregnancy and lactation decisions belong to the dandelion herb page, where intake is actually decided.

Dosage

There is no dose, and no basis for one. Taraxacin has never been administered to a cell line, an animal or a person; no study reports a quantity of it; and it is not available as a product or a reference standard.

Dandelion’s traditional use as a bitter tonic and choleretic is dosed as the whole herb — root, leaf or extract — and that dosing belongs on the dandelion monograph, not here. Attaching it to this molecule would compound the original error, since the molecule has not been shown to occur in that plant. Nothing here is dosing guidance.

References

1. Ahmad VU, Yasmeen S, Ali Z, Khan MA, Choudhary MI, Akhtar F, Miana GA, Zahid M (2000). Taraxacin, a new guaianolide from Taraxacum wallichii. Journal of Natural Products 63(7):1010–1011. https://pubmed.ncbi.nlm.nih.gov/10924189/
2. Remington JP, Wood HC, et al., eds. (1918). Taraxacum — dispensatory monograph. The Dispensatory of the United States of America, 20th edition. https://www.henriettes-herb.com/eclectic/usdisp/taraxacum.html
3. Shi SY, Zhou CX, Xu Y, Tao QF, Bai H, Lu FS, Lin WY, Chen HY, Zheng W, Wang LW, Wu YH, Zeng S, Huang KX, Zhao Y, Li XK, Qu J (2008). [Studies on chemical constituents from herbs of Taraxacum mongolicum]. Zhongguo Zhong Yao Za Zhi 33(10):1147–1157. https://pubmed.ncbi.nlm.nih.gov/18720865/
4. Ali S, Yasmeen S, Afza N, Malik A, Iqbal L, Lateef M, Riaz N, Ashraf M (2009). Mutiniside, new antioxidant phenolic glucoside from Abutilon muticum. Journal of Asian Natural Products Research 11(5):457–464. https://pubmed.ncbi.nlm.nih.gov/19504389/
5. Kisiel W, Barszcz B (2000). Further sesquiterpenoids and phenolics from Taraxacum officinale. Fitoterapia 71(3):269–273. https://pubmed.ncbi.nlm.nih.gov/10844166/
6. Esatbeyoglu T, Obermair B, Dorn T, Siems K, Rimbach G, Birringer M (2017). Sesquiterpene lactone composition and cellular Nrf2 induction of Taraxacum officinale leaves and roots and taraxinic acid β-D-glucopyranosyl ester — in vitro. Journal of Medicinal Food 20(1):71–78. https://pubmed.ncbi.nlm.nih.gov/28026992/
7. Sharifi-Rad M, Roberts TH, Matthews KR, Bezerra CF, Morais-Braga MFB, Coutinho HDM, Sharopov F, Salehi B, Yousaf Z, Contreras MDM, Varoni EM, Verma DR, Iriti M, Sharifi-Rad J (2018). Ethnobotany of the genus Taraxacum — phytochemicals and antimicrobial activity — review. Phytotherapy Research 32(11):2131–2145. https://pubmed.ncbi.nlm.nih.gov/30039597/
8. Leu YL, Shi LS, Damu AG (2003). Chemical constituents of Taraxacum formosanum. Chemical & Pharmaceutical Bulletin (Tokyo) 51(5):599–601. https://pubmed.ncbi.nlm.nih.gov/12736465/
9. Zalte RR, Festa AA, Demidov SA, Awuku SO, Golubenkova AS, Mironov YY, Golantsov NE, Storozhenko OA, Novikov AP, Voskressensky LG (2025). Total synthesis of the taraxacine A natural product via Ag(I)-catalysed imidate-alkyne cyclization. Organic & Biomolecular Chemistry 23(6):1386–1393. https://pubmed.ncbi.nlm.nih.gov/39717940/
10. Skariyachan S, Jayaprakash N, Bharadwaj N, Narayanappa R (2014). Exploring insights for virulent gene inhibition of multidrug resistant Salmonella typhi, Vibrio cholerae, and Staphylococcus aureus by potential phytoligands via in silico screening. Journal of Biomolecular Structure & Dynamics 32(9):1379–1395. https://pubmed.ncbi.nlm.nih.gov/23876154/
11. Serri R, Dehneh N, Ghannam M, Sirri MR (2025). Synergistic effects of sesame oil, extra virgin olive oil, psyllium extract, and dandelion extract on cholesterol gallstone dissolution: an in vitro comparative study against Rowachol. PLoS One 20(10):e0334477. https://pubmed.ncbi.nlm.nih.gov/41086186/
12. Brockhoff A, Behrens M, Massarotti A, Appendino G, Meyerhof W (2007). Broad tuning of the human bitter taste receptor hTAS2R46 to various sesquiterpene lactones, clerodane and labdane diterpenoids, strychnine, and denatonium — in vitro. Journal of Agricultural and Food Chemistry 55(15):6236–6243. https://pubmed.ncbi.nlm.nih.gov/17595105/
13. Yanagisawa T, Misaka T (2021). Characterization of the human bitter taste receptor response to sesquiterpene lactones from edible Asteraceae species and suppression of bitterness through pH control — in vitro. ACS Omega 6(6):4401–4407. https://pubmed.ncbi.nlm.nih.gov/33644553/
14. Paulsen E, Andersen KE, Hausen BM (2001). Sensitization and cross-reaction patterns in Danish Compositae-allergic patients — patch-test study in patients. Contact Dermatitis 45(4):197–204. https://pubmed.ncbi.nlm.nih.gov/11683829/
15. Fan M, Zhang X, Song H, Zhang Y (2023). Dandelion (Taraxacum genus): a review of chemical constituents and pharmacological effects. Molecules 28(13):5022. https://pubmed.ncbi.nlm.nih.gov/37446683/
16. PubChem Compound Summary, CID 5241825 — Taraxacin (C₁₅H₁₄O₃; 1,5,8-trimethyl-3a,4-dihydroazuleno[6,5-b]furan-2,6-dione; CAS 284666-72-4). National Center for Biotechnology Information — chemical database record, accessed July 2026. https://pubchem.ncbi.nlm.nih.gov/compound/5241825

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