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Coltsfoot

Scientific Name(s): Tussilago farfara L. Family: Asteraceae (daisies)

Common Name(s): Coltsfoot , coughwort , feuilles de tussilage (Fr.) , horse-hoof , huflattichblätter (Ger.) , kuandong hua

Uses

Coltsfoot has been used to treat sore throats, asthma, and some related conditions such as bronchitis, laryngitis, pertussis, influenza, and lung congestion.

Dosing

Historical use of 4.5 to 6 g/day of crude herb has been documented. 1

Contraindications

Because of the content of hepatotoxic pyrrolizidine alkaloids, coltsfoot is not recommended for internal use.

Pregnancy/Lactation

Documented adverse effects (hepatotoxic pyrrolizidine alkaloids, risk of fatal hepatic veno-occlusive disease, abortifacient effects). Avoid use. 2 , 3 , 4

Interactions

None well documented.

Adverse Reactions

Allergic reactions may occur.

Toxicology

Coltsfoot has an “undefined safety” classification by the FDA. Avoid prolonged use of the plant; it may increase blood pressure and pose a risk of carcinogenicity, hepatotoxicity, or mutagenicity.

Botany

Coltsfoot is a low-growing perennial (up to 30 cm high) with fleshy, woolly leaves. In early spring, the plant produces a stem with a single golden-yellow, narrow, ligulate flower head that blooms from April to June. As the stem dies, the hoof-shaped leaves appear. The plant is native to Europe, but also grows widely in sandy places throughout the United States and Canada. 5 Coltsfoot is collected widely from wild plants in the Balkans, Eastern Europe (Bulgaria, Czechoslovakia, Hungary, Poland, the former Yugoslavia), and Italy. 6 It has also been a part of Chinese folk medicine for centuries. The morphology and anatomy of coltsfoot have been described in detail, including the plant's underground parts. 7 A later report on leaf differentiation is also available. 8

History

As part of its Latin name Tussilago implies, coltsfoot is reputed as an antitussive. 9 The buds, flowers, and leaves of coltsfoot have long been used in traditional medicine for dry cough and throat irritation. The plant has found particular use in Chinese herbal medicine for the treatment of respiratory diseases, including cough, asthma, and acute and chronic bronchitis. It is also a component of numerous European commercial herbal preparations for the treatment of respiratory disorders. A mixture containing coltsfoot has been smoked for the management of coughs and wheezes, but the smoke is potentially irritating. Its silky seeds were once used as a stuffing for mattresses and pillows. 10 Extracts of coltsfoot had once been used as flavorings for candies. All early references emphasize the usefulness of coltsfoot's mucilage for soothing throat and mouth irritation. 6

Chemistry

Coltsfoot contains a number of diverse components including tannins, a mucilage, terpene alcohols, carotenoids, and flavonoids. 11 The mucilage is present in a concentration of approximately 8%. It yields sugars following hydrolysis including arabinose, fructose, galactose, glucose, and others. 12 Water-soluble polysaccharides from coltsfoot leaves have been reported. 13 , 14 Mucilaginous polysaccharides have been investigated in another report. 15 Tussilagone, a sesquiterpene, has been isolated from ether extracts of the plant. It is a potent cardiovascular and respiratory stimulant. 16

Acids found in coltsfoot include caffeic, caffeoyltartaric, ferulic, gallic, p-hydroxybenzoic, tannic, malic, and tartaric. 12

Farfaratin, a novel sesquiterpenoid compound, has been isolated from flower buds collected from the Shaanxi Province in China. 17 At least 7 pyrrolizidine alkaloids, 18 including tussilagin, 19 senkirkine, 20 and senecionine 10 have been identified in coltsfoot. Coltsfoot leaves contain 2.8 to 4.1 ppm and the flowers 2.4 ppm senkirkine. 21 Quantitative gas chromatographical analyses of pyrrolizidine alkaloids have been performed for various commercial coltsfoot preparations. 22

Other constituents in coltsfoot include choline, paraffin, phytosterols, amyrin, and volatile oil. 10 , 12 A recent report reviews chemistry and other aspects of the plant. 23

Uses and Pharmacology

Demulcent

Coltsfoot preparations have long been used to soothe sore throats. The mucilage is most likely responsible for the demulcent effect of the plant. The mucilage is destroyed by burning; smoking the plant or inhaling vapors of the leaves steeped in water would not be expected to provide any degree of symptomatic relief. Instead, the smoke may exacerbate existing respiratory conditions. However, one source mentions coltsfoot in the form of a medicinal cigarette to help relieve asthma. 20 Related conditions for which coltsfoot has been used include bronchitis, laryngitis, pertussis, influenza, and lung congestion. 9 , 10 , 12 It is one of the most popular European remedies to treat chest ailments. 24

Animal data

Coltsfoot components have been found to increase the cilia activity in the frog esophagus, and this action may contribute to the plant's expectorant effect. 25

Clinical data

Coltsfoot, in a mixture of Chinese herbs, has been evaluated in 66 cases of convalescent asthmatics and found useful in decreasing airway obstruction. 26

Anti-inflammatory

Coltsfoot polysaccharides and flavonoids have anti-inflammatory actions. 24 This effect was similar to that of indomethacin in one report. 27

Animal data

Weak anti-inflammatory actions have also been observed when tested against induced rat paw edema. 12

A compound designated L-652,469, was isolated from coltsfoot buds. This compound has been found to be a platelet-activating factor (PAF) inhibitor and a calcium channel blocker. PAF is known to be an integral component of the complex cascade mechanism involved in both acute and chronic asthma, and a number of naturally occurring PAF antagonists are being clinically evaluated for the treatment of this and other inflammatory diseases. The isolation of PAF antagonists from coltsfoot indicates that the traditional uses of the plant in the management of certain inflammatory respiratory diseases may be verifiable. 28

Clinical data

Research reveals little or no clinical data on the anti-inflammatory action of coltsfoot.

Other uses

L-652,469 is also a competitive inhibitor of the calcium channel in the rat aorta, but the clinical importance of this finding has not been explored.

Tussilagone is a potent cardiovascular stimulant. When administered intravenously (0.02 to 0.3 mg/kg), it produced a rapid and dose-dependent pressor effect in dogs. This increase in blood pressure was similar to that observed following the administration of the cardiac stimulant dopamine. The increase in blood pressure was short-lived, lasting about 5 minutes. Tussilagone also increased the rate of respiration. The cardiovascular effects appear to be peripherally mediated, while the site of respiratory stimulation is central. 16

Aqueous leaf extracts and phenolic components have been found to have in vitro antibacterial activity generally limited to gram-negative bacteria. 29 Some of these organisms include Staphylococcus aureus , Bordetella pertussis , Pseudomonas aeruginosa , and Proteus vulgaris . 12

A report discusses coltsfoot's historical, traditional, and modern medical uses, along with the plant's pharmacology and toxicity. 30

Dosage

Because of the content of hepatotoxic pyrrolizidine alkaloids, coltsfoot is not recommended for internal use. Historical use of 4.5 to 6 g/day of crude herb has been documented. 1

Pregnancy/Lactation

Documented adverse effects (hepatotoxic pyrrolizidine alkaloids, risk of fatal hepatic veno-occlusive disease, abortifacient effects). Avoid use. 2 , 3 , 4

Interactions

None well documented.

Adverse Reactions

Several members of this family of plants (eg, chamomile, ragweed) cause common allergies, and some people may exhibit a cross-sensitivity to coltsfoot. 31 While coltsfoot is only a weak topical sensitizer in guinea pigs, other members of the family are strong sensitizers (blessed thistle, dwarf sunflower), and cross-sensitivity may exist. 32

Toxicology

The use of teas prepared from coltsfoot has not generally been associated with acute toxicity.

Several reports have noted the presence of hepatotoxic pyrrolizidine alkaloids in coltsfoot. Pre-blooming flowers have been reported to contain the highest concentration of these alkaloids, although considerable loss of both senkirkine and senecionine occurs upon prolonged storage of the plant. 12 In one long-term safety study, the alkaloid senkirkine (0.015% by weight in dried flowers) was incorporated into rat diets in concentrations of up to 8% of the diet for 2 years. Among the rats fed the 8% meal, two-thirds developed cancerous tumors of the liver characteristic of pyrrolizidine toxicity. 19 This alkaloid is also present in the leaves. 33 The acute intravenous LD-50 of tussilagone is 28.9 mg/kg. 16 These pyrrolizidine alkaloids have well documented toxicities in humans as well, presenting as anorexia, lethargy, abdominal pain and swelling, and liver changes. The alkaloids destroy the liver's hepatocytes and damage small branches of the hepatic vein. In Germany, consumption of more than 1 mg of pyrrolizidine alkaloids per day is prohibited. 34

Of interest is a case of reversible hepatic veno-occlusive disease in an infant after consumption of coltsfoot, later found to be Adenostyles alliariae (these two plants can be easily confused, especially after the time of flowering.) Seneciphylline and related hepatotoxins were identified via thin-layer chromatography, mass spectrometry, and NMR spectroscopy. 35

Coltsfoot has been classified by the FDA as an herb of “undefined safety.” 36 However, although the pyrrolizidine alkaloids of coltsfoot are hepatotoxic, mutagenic, and carcinogenic, there is little danger of acute poisoning when it is used as prescribed as an occasional tea or cough preparation. 6 The German Commission E Monographs recommend a limit of 10 micrograms per day of pyrrolizidine alkaloids with the 1,2–unsaturated necine structure, including their N-oxides. 37

Excessive consumption of coltsfoot may interfere with preexisting antihypertensive or cardiovascular therapy. Prolonged ingestion of the plant should be avoided. Duration of administration should not exceed 4 to 6 weeks per year. 37 Because the plant may be an abortifacient, it should not be taken during pregnancy or lactation. 12 The flowers of coltsfoot should not be used. The plant is subject to legal restrictions in some countries. 24

Bibliography

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2. Brinker FJ. Herb Contraindications and Drug Interactions . 2nd ed. Sandy, OR: Eclectic Medical Publications;1998.
3. Newall CA, Anderson LA, Philipson JD, eds. Herbal Medicines: A Guide for Health-Care Professionals . London: Pharmaceutical Press; 1996.
4. Ernst E. Herbal medicinal products during pregnancy: are they safe? BJOG . 2002;109:227-235.
5. Tyler, VE. The New Honest Herbal . Philadelphia: GF Stickley Co., 1987.
6. Bisset NG. Herbal Drugs and Phytopharmaceuticals . Stuttgart: Medpharm Scientific Publishers, 1994.
7. Engalycheva E, et al. Farmatsiia . 1981;30(3):21-26.
8. Saukel J. Scientia Pharmaceutica . 1991(Dec 31);59:307-19.
9. Bruneton J. Pharmacognosy, Phytochemistry, Medicinal Plants, Technique and Documentation . Paris, France, 1995.
10. Duke J. CRC Handbook or Medicinal Herbs . Boca Raton, FL: CRC Press Inc. 1989;493-4.
11. Didry N. Annales Pharmaceutiques Francaises . 1980;38(3):237-41.
12. Newall C, et al. Herbal Medicines . London, England: Pharmaceutical Press, 1996;85–86.
13. Haaland E. Acta Chem Scand . 1969;23(7):2546-48.
14. Engalycheva E, et al. Farmatsiia . 1984;33(3):13-16.
15. Franz G. Planta Medica . 1969(Aug);17:217-20.
16. Li Y, et al. Gen Pharmacol . 1988;19(2):261-63.
17. Wang C, et al. Yao Hsueh Hsueh Pao . 1989;24(12):913-16
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20. Hirono I, et al. Gann . 1976;67(1):125-9
21. Steinbach R, et al. Pharmazeutische Zeitung . 1989(Jun 5);134:25-26, 28-29.
22. Wiedenfeld H, et al. Deutsche Apotheker Zeitung . 1995(Mar 23);135; 17-18, 21-22, 25-26.
23. Berry M. Pharmaceutical Journal . 1996(Feb 17);256:234-5.
24. Chevallier A. Encyclopedia of Medicinal Plants . New York: DK Publishing, 1996;277.
25. Muller-Limmroth W, et al. Fortshr Med . 1980;98(3):95-101.
26. Fu JX. Chung Hsi I Chieh Ho Tsa Chih . 1989;9(11):658.
27. Engalycheva E, et al. Farmatsiia . 1982;31:37-40.
28. Hwang S, et al. Eur J Pharmacol . 1987;141(2):269-81.
29. Didry N, et al. Annales Pharmaceutiques Francaises . 1982;40(1):75-80.
30. Salvador R. Canadian Pharmaceutical Journal . 1996(Jul-Aug);129:48-50.
31. Anonymous. Toxic Reactions to Plant Products Sold in Health Food Stores. Med Lett . 1979;21(7):29.
32. Zeller W, et al. Arch Dermatol Res . 1985;227(1):28.
33. Smith LW, et al. J Nat Prod . 1981;44:129.
34. Schulz V, et al. Rational Phytotherapy — A Physician's Guide to Herbal Medicine , 3rd ed. Berlin, Germany: Springer-Verlag, 1998;34.
35. Sperl W, et al. Eur J Pediatr . 1995;154(2):112-16.
36. DerMarderosian AH, Liberti LE. Natural Products Medicine . Philadelphia: GF Stickley Co., 1988.
37. Blumenthal M, ed. The Complete German Commission E Monographs . Austin, TX: American Botanical Council; Boston: Integrative Medicine Communications, 1998.

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