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Biology
Arnica Montana is a diploid about 18 to 60 cm tall aromatic fragrant, perennial herb. Its basal green ovate-cilitate leaves with rounded tips are bright coloured and level to the ground. In addition, they are somewhat downy on their upper surface, veined and aggregated in rosettes. By contrast, the upper leaves are opposed, spear-shaped and smaller which is an exception within the Asteraceae. The chromosome number is 2n=38.

The flowering season is between Mai and August (Central Europe). The hairy flowers are composed of yellow disc florets in the center and orange-yellow ray florets at the external part. The achenes have a one-piece rough pappus which opens in dry conditions. Arnica montana is hemikryptophyt, which helps the plant to survive the extrem overwintering condition of its habitat. In addition, Arnica forms rhizomes, which is growing in an two years cycle: the rosette part grew at its front meanwhile its tail is slowy dying. Arnica Montana is propagated from seed. Generally, 20 % of seeds do not germinate. For large scale planting, it is recommended to raise plants first in a nursery and then to transplant them in the field. Seeds sprout in 14-20 days but germination rate depends highly of the seed quality. Planting density for Arnica Montana is of 20 plants/m2 such that the maximum yield density will be achieved in the second flowering season. While Arnica Montana has high exigencies of soil quality, analyses should be done before any fertilizer input.

The flowers are harvested when fully developed and dried without their bract nor receptacles. The roots can be harvested in autumn and dried as well after being carefully washed.



Distribution and Habitat
Arnica montana is widespread across most of Europe[4]. It is absent from the British Isles and the Italian,BalkanPeninsulas and Slovakia. In addition, it is considered as extinct in Hungary and Lithuania. Arnica montana grows in nutrient-poor siliceous meadows or clay soils. It mostly grows on alpine meadows and up to nearly 3,000 metres (9,800 ft). In more upland regions, it may also be found on nutrient-poor moors and heaths. However Arnica does not grow on lime soil, thus it is an extremely reliable bioindicator for nutrient poor and acidic soils. It is rare overall, but may be locally abundant. It is becoming rarer, particularly in the north of its distribution, largely due to increasingly intensive agriculture and commercial wild-crafting. Nevertheless, it is large-scaled cultivated in Estonia.



Chemical constituents
The main constituents of Arnica Montana are essential oils, fatty acids, thymol, pseudoguaianolide sesquiterpene lactones and flavanone glycosides. Pseudoguaianolide sesquiterpenes constitute 0.2-0.8 % of the flower head of Arnica Montana. They are helenalin and their fatty esters.

Medicinal uses
We use mostly Arnica Montana as an anti-inflammatory product. Helenalin inhibits the transcription factor (nuclear factor (NF) k-β(19)) which causes  inflammations.

Nevertheless, this plant has an anti-oxidant effect. It decreases the lipid oxidation and increases the activities of enzymes involved in glutathione metabolisms. This is helpful in medicine but also in cosmetic and food.

We use also Arnica Montana to treat other pains such as bruises and ecchymosis. The traditional medicine also uses Arnica Montana to cure indigestion, cardiovascular diseases and rheumatism. Arnica Montana also has acetyl cholinesterase inhibitors. This could be useful to treat neurodegenerative diseases. Finally it may also have benefits against cardiovascular diseases.

Toxicity
Sesquiterpene lactones play a dual role. They exercise the anti-inflammatory effect but they also cause severe allergic reactions. They irritate the mucous membranes such that it can result ingestion, muscle paralysis, increase or decrease in pulse rate, heart palpitations, shortness of breath and death. 70mg is the lethal dose for Arnica Montana.

Market
The demand for Arnica Montana is 50t  per year in Europe. But the supply does not cover the demand. This plant is rare. It is protected in Belgium, in France, in Germany, in Italy, in Poland and in some regions of Switzerland. France and Romania are producing Arnica Montana for the international demand .Changes in agriculture in Europe during the last decades decline the occurrence of Arnica Montana. Extensive agriculture has been replaced by intensive management.