Sesquiterpenes Arnica

Arnica montana L. (Arnica) has been used for treating bruises and swelling in Western medicine on account of its ability to elaborate sesquiterpene lactones, such as hele-nalin and dihydrohelenalin, which are thought to inhibit the activation of transcription factor nuclear factor (NF)-kB, which is responsible for the transcription of genes involved in encoding mediators for the inflammatory process. 

Classical examples of anti-inflammatory Asteraceae are Arnica montana and Calendula officinalis, both used in European medicine to treat bruises and contusions. There is an expanding body of evidences to suggest that Asteraceae could be a useful source of anti-inflammatories, such as sesquiterpene lactones and/or triterpene alcohols, the latter being known to inhibit 12-O-tetra-decanoylphorbol-13-acetate (TPA)-induced inflammation in mice as efficiently as commercial indomethacine by possible inhibition of phospholipase A2 (10). 

Besides sesquiterpene lactones, an alkaloid analyzed as CgH14N203 (45), was isolated from the leaves of Arnica montana L. (80). Distinction between the two possible structures 45 (amide-urethane) and 46 (ester + urea) was accomplished by a selective synthesis from prolinamide. 

T.J. Schmidt and G. Willuhn, Sesquiterpene lactone and flavonoid variability of the Arnica angustofolia aggregate (Asteraceae). Biochem. Syst. Ecol. 28 (2000) 133-142. 

B. gaudichaudiana, which is commonly used for diabetes. Elephantopus scaber contains hydroxylated germacranolides, such as molephantin and molephantinin, which cause diuresis, antipiresis, eliminate bladder stones, and have cytotoxic and antitumor properties. From the Tithonia genus, T, diversifolia is widely used in Mexico and often has been identified erroneously as Arnica montana. Because of this confusion it is used as European arnica to treat hematomas and muscular cramps. The genus is rich in sesquiterpene lactones.11... 

ARNICA FLOWERS are the flower heads of Arnica montana L, family Asteraceae. The flowers contain sesquiterpenes such as helenalin and dihydrohelenalin which have antiinflammatory and analgesic effects which explain the popularity of Arnica as a remedy for bruises and aches and sprains. It must be stressed that Arnica should not be used internally because of cardiotoxicity. Equally important is the fact that the sesquiterpenes, like most if not all of those from the Asteraceae (e.g. in Chamomile and Yarrow), are highly allergenic and patients must be advised to discontinue use if a skin reaction develops and to avoid Arnica and Chamomile if they are known to have a sensitivity to other Asteraceae such as Asters, Daisies and Chrysanthemums. 

E.3 ContactedlerpfensThc sesquiterpene lactones of the Asteraceae, e.g. chrysanthemums, asters and daisies, are well-known causes of contact allergic dermatitis. Patients with such allergies should avoid (and should be advised to avoid) herbs such as Artemisia (Mugwort), Chamomile, Yarrow (Achillea). Feverfew, Echinacea-inA Arnica because of cross-sensitisation. 

B Arnicae flos (A, montana, A. chamissonis 5a-8a). The CHCt, extracts of Arnicae flos ( method see Sect. 7.1.1), developed in system PE, contain sesquiterpene lactones, detectable as violet-grey zones witlt ZM reagent (vis). 

Herrmann, H.D., G. Willuhn, and B.M. Hausen. 1978. Helenalinmethacrylate, a new pseudoguaianolide from the flowers of Arnica rrumtana L. and the sensitizing capacity of their sesquiterpene lactones. Plant a Med. 34(3) 299-304. 

Ci5H g04, Mr 262.31, cryst., mp, 168 °C, [ajp -102° (acetone), soluble in alcohol, chloroform, poorly soluble in water. A toxic sesquiterpene lactone that induces sneezing from Helenium and Arnica species such as, e.g., Helenium autumnale and Arnica mon-tana [LD50 (mouse p.o.) 150 mg/kg]. After intoxication, the symptoms are nasal irritation, vomiting, diarrhea, vertigo, palpitation, respiratory impairment, and finally collapse with a weak, very rapid pulse. In the past deaths have been reported after consumption of Arnica preparations. Contact with the skin leads to dermatitis. 

Reported cases of contact allergic reactions to A. montana preparations are numerous and date from as early as 1844. Cross-reactivity with other plants is also reported (e.g., sunflower, Tagetes, Chrysanthemum). Sesquiterpene lactones, especially helenalin and its derivatives, are known sensitizers. " Data on the safety of Arnica Montana extract, which is made from the dried flower heads of A. montana, are lacking. Ithas an oral LD50 of >5 g/kg in rats, whereas in mice the LD50 was 123 mg/ kg p.o. An extract made from the dried plant showed mutagenic activity in the Ames test, an effect attributed to the flavonol content. ... 

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