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Coltsfoot

SCIENTIFIC NAME(S): Tussilago farfara (L. Family: Compositae)

COMMON NAME(S):Coltsfoot, cough wort, feuilles de tussilage (Fr.),horse-hoof, huflattichbliitter (Ger.), kuandong hua

An effective demulcent and expectorant herb, coltsfoot is one of the most popular remedies for the treatment of a wide range of chest complaints. It is widely available in health food shops. The leaves are commonly used in Europe, though the flowering stems (which contain higher levels of pyrrolizidine alkaloids) are preferred in China.

Coltsfoot was the choice of remedial plants by early herbalists for respiratory difficulties and was either given as a tea or prepared as smoke. 

History

As part of its Latin name Tussilago implies, coltsfoot is reputed as an antitussive. 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. 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.

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. Coltsfoot is collected widely from wild plants in the Balkans, Eastern Europe, and Italy. 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. A later report on leaf differentiation is also available.

Uses of Coltsfoot

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

Side Effects of Coltsfoot

Allergic reactions may occur. Coltsfoot has an "undefined safety" classification by the FDA. Avoid prolonged use of the plant; it may increase !ad pressure and pose a risk of carcinogenicity, hepatotoxicity, or mutageity.

Dosage

Internal use of coltsfoot root is not recommended due to the potential liver toxicity of its pyrrolizidine alkaloids. Tea of coltsfoot leaf or flower is made by steeping 1-2 teaspoons (5-10 grams) in 1 cup (250 ml) hot water for ten to twenty minutes. 6 People can drink three cups (750 ml) daily. Alternatively, 1/2-1 teaspoon (2-4 ml) of tincture of the leaf or flower can be taken three times per day. Some practitioners of herbal medicine have recommended having hot coltsfoot tea ready in a thermos to drink for morning coughs due to emphysema. People should not use coltsfoot for more than one month consecutively unless on the advice of a doctor. Also, preparations guaranteed to be pyrrolizidine-free can be used indefinitely and are preferable.

Toxicology

The use of teas prepared from coltsfoot has not generally been associated with acute toxicity. Several members of this family of plants (eg, chamomile, ragweed) cause common allergies, and some people may exhibit a cross-sensitivity to coltsfoot. 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.

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. 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. This alkaloid is also present in the leaves. The acute intravenous LD-50 of tussilagone is 28.9 mg/kg. 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 > 1 mg of pyrrolizidine alkaloids per day is prohibited.

Of interest is a case of reversible hepatic venoocclusive 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 flowering.) Seneciphylline and related hepatotoxins were identified via thin-layer chromagraphy, mass spectrometry, and NMR spectroscopy.

Coltsfoot has been classified by the FDA as an herb of "undefined safety."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. 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.

Excessive consumption of coltsfoot may interfere with preexisting anti-hypertensive or cardiovascular therapy. Pro­longed ingestion of the plant should be avoided. Duration of administration should not exceed 4 to 6 weeks per year.

Because the plant may be an abortifacient, it should not be taken during pregnancy or lactation. The flowers of coltsfoot should not be used. The plant is subject to legal restrictions in some countries.

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