Petasites

Petasites japonicus

Petasites is a genus of flowering plants in the sunflower family, Asteraceae,<ref name="WFO">Template:Cite web</ref> that are commonly referred to as butterburs<ref name=Stace>Template:Cite book</ref><ref>Miller, Philip. 1754. Gardeners Dictionary...Abridged...fourth edition page 1056.</ref><ref>Tropicos, Petasites Mill.</ref> and coltsfoots.<ref name=fna>Petasites. Flora of North America. Volume 20, Page 635. efloras.org.</ref> They are perennial plants with thick, creeping underground rhizomes and large rhubarb-like leaves during the growing season. Most species are native to Asia or southern Europe.

Taxonomy

The genus name is derived from the Greek word Template:Lang petasos, from the plant's broad leaves resembling a wide-brimmed hat.<ref name="drugs">Template:Cite web</ref>

Species

Accepted species<ref name=x/><ref name="WFO"/>

• Petasites albus – white butterbur – Europe, Algeria, Turkey, Caucasus, India
• Petasites fominii – Republic of Georgia
• Petasites formosanus – Taiwan
• Petasites frigidus – Arctic butterbur or Arctic sweet coltsfoot – Scandinavia, Mongolia, Canada, northern USA
• Petasites hybridus – common butterbur – Europe, Mediterranean
• Petasites japonicus – giant butterbur, fuki – China, Japan, Korea
• Petasites kablikianus – southeastern Europe from Poland to Albania
• Petasites kamengicus – Arunachal Pradesh
• Petasites paradoxus – central + southwestern Europe from Spain to Poland
• Petasites pyrenaicus syn. Petasites fragrans - winter heliotrope - from Azores to Ireland + Tunisia
• Petasites radiatus – Mongolia
• Petasites rubellus – Mongolia, Manchuria, Korea
• Petasites sibiricus – Siberia
• Petasites spurius – Europe, Siberia, Caucasus, Central Asia
• Petasites tatewakianus – Siberia, Russian Far East, northeastern China
• Petasites tricholobus – China, Vietnam, Himalayas
• Petasites versipilus – Sichuan, Yunnan

Species of hybrid origin<ref name=x/>

• Petasites × vitifolius

Species formerly included<ref name=x/>

Petasites glacialis (Ledeb.) Polunin - Endocellion glaciale (Ledeb.) Toman

Characteristics

The short spikes of flowers are produced just before the leaves in late winter (e.g. Petasites fragrans<ref name="Stace"/>) or spring, emerging with only a few elongated basal bracts and are usually green, flesh coloured or dull white depending on the species. It is dioecious, with male and female flowers borne on separate plants.<ref>Template:Cite journal</ref>

Butterbur can be found in parts of Asia such as Korea, China, and Japan, as well as Europe and North America.<ref name="Missouri Botanical Garden">Template:Cite web</ref><ref name=Sun-Edelstein>Template:Cite journal</ref> They prefer moist environments such as riverbanks, marshes and ditches.<ref name=fna/><ref name=Sutherland>Template:Cite journal</ref><ref>Petasites. Flora of China. Volume 20-21, Page 461. efloras.org.</ref><ref>Altervista Flora Italiana genere Petasites</ref>

Petasites is closely related to the genera Tussilago and Senecio.

Medicinal uses

Butterbur has been used for over 2000 years to treat a variety of ailments including fever, lung disease, spasms, and pain.<ref name=Sutherland /> Currently, butterbur extract is used for migraine prevention and treatment of allergic rhinitis, which have the most evidence for its effectiveness.<ref name=Sutherland /><ref name="Neurology-2012" /><ref name=Kaufeler>Template:Cite journal</ref>

Migraine

Some butterbur species contain the chemicals petasin and isopetasin which are believed to have potential benefits in treating migraines.<ref name="Sun-Edelstein" /> High concentrations of petasin occur in both butterbur root and leaves, with the leaves containing lower levels of the toxic chemical.<ref name="Taylor-2011" /> Butterbur extracts have been reported to be effective in reducing frequency and severity of migraine headaches.<ref name="Sun-Edelstein" /><ref name="Sutherland" /><ref name="Neurology-2012" /><ref name="Lipton-2004" /> Several double-blind studies have shown that high doses of Petasites hybridus extract, containing petasin and/or isopetasin, are effective both in preventing and in relieving migraine, with the best results in groups taking the higher dose of the supplement.<ref name="Sun-Edelstein" /><ref name="Lipton-2004">Template:Cite journal</ref> Although mainly well tolerated, the adverse effects of butterbur reported in clinical trials include mainly gastrointestinal problems, such as nausea, flatulence, and belching.<ref name="Facts&Comp" /><ref name="Lipton-2004" /> In 2015, the American Academy of Neurology withdrew its original endorsement of butterbur due to safety concerns.<ref name="Neurology-2012">Template:Cite journal</ref> However, the Canadian Headache Society still recommends its use in migraine prevention for a selected number of patients based on their clinical features and co-existing disorders.<ref>Template:Cite journal</ref>

Hay fever or allergic rhinitis

Additionally, a study showed butterbur extract to be an effective treatment for hay fever without the sedative effect of the antihistamine cetirizine, if taken four times daily.<ref>Schapowal, A.Template:Cite journal</ref> Butterbur was also shown to be comparably effective as fexofenadine when compared to placebo for reducing symptoms of allergic rhinitis.<ref name=Schapowal-fexofenadine>Template:Cite journal</ref>

Risks

Butterbur extracts may contain harmful components called pyrrolizidine alkaloids if the preparations are not carefully and fully purified.<ref name=Sun-Edelstein /> The concentration of the toxic alkaloids is often highest in the rhizomes and lowest in the leaves, and may vary depending on where the plants are grown.<ref name="Taylor-2011">Template:Cite journal</ref> These chemicals are toxic to the liver and may cause cancers.<ref>Maxim Hirono I., Mori H., Yamada K. "Carcinogenic activity of petasitenine, a new pyrrolizidine alkaloid isolated from Petasites" Journal of the National Cancer Institute 1977 58:4 (1155-1157)</ref><ref>Template:Cite journal</ref> Thus, due to the potential for contamination, taking butterbur supplements is not recommended during pregnancy or breastfeeding.<ref name=Facts&Comp>Template:Cite web</ref> Some sources say it is safe practice to consume butterbur extract that has been prepared by a reputable laboratory.<ref name=Sun-Edelstein /> Other sources say no butterbur product is safe: "The cases of liver toxicity appear to have occurred with extracts of butterbur where the pyrrolizidine alkaloids had been removed and only small amounts remained. There is some evidence that other constituents found in butterbur such as the sesquiterpene constituents for example petasin may be implicated in the liver toxicity".<ref>Template:Cite web</ref>Template:Unreliable source?

Long-term health effects and interaction of butterbur with other drugs have not been well documented. However, it can theoretically interact with certain blood pressure and heart medications, as well as with drugs that can induce a liver enzyme called CYP3A4 (i.e. St. John's wort, carbamazepine, phenytoin, rifampin); this interaction can potentially lead to increased concentration of the toxic alkaloids.<ref name=Facts&Comp />

External links

• Flora Europaea: Petasites species list and distributions
• eFloras search results: Petasites
• Edibility of Petasites: Visual identification and edible parts of sweet coltsfoot.