Larix decidua / Larix

MELEZE Larix decidua Mill. Conifères

Le Mélèze est surtout répandu aux Alpes dans le bassin de la Haute Durance, où Queyras et Briançonnais le possèdent en vastes peuplements. L'arbre perd ses aiguilles en automne et se reconnaît l'été à ses bouquets de feuilles nombreuses plus claires et moins dures que celles des Pins.

Au sujet de cet arbre, l'abbé Gave, né près de Boëge en 1846, rapporte l'usage populaire déjà très ancien : « Ses feuilles, dit-il, transsudent, lorsque les nuits sont chaudes et humides, une sorte de manne, la miellée, que les abeilles recueillent avec empressement aux premières heures de la matinée. C'est cette manne qui donne au miel de nos montagnes, notamment à celui de Chamonix, ce parfum et cette blancheur qui le distinguent et l'ont fait apprécier dès les temps anciens. Strabon, célèbre géographe grec, vante déjà, avant l'ère chrétienne, le miel de l'Allobrogie. Nos montagnards recueillent la résine de Mélèze et en font l'usage que voici. Il n'est pas rare que les bêtes à cornes, en avalant du foin, avalent aussi des substances indigestes, telles que crin, laine, plumes, lesquelles parfois leur restent collées au gosier. Pour les en débarrasser, rien de mieux que de leur donner de cette résine mélangée avec du miel et étendue sur une tranche de pain. Cette tartine, fortement gluante, entraîne infailliblement dans l'estomac ces sortes de substances ». La substance émise par les feuilles, dite « manne de Briançon », contient un sucre, la mélézitose, auquel sont dues les propriétés laxatives qui la firent employer jadis comme purgatif.



Larix / Lork antroposofisch bekeken
Van alle naaldbomen is de larix (Larix decidua) het minst aan verharding onderhevig. Hij verliest in de herfst, na prachtig geel te zijn verkleurd, net als een loofboom al zijn naalden, die al spoedig tot humus geworden, bodem worden voor allerlei kruiden. De larix is een boom van de door licht overgoten bergen. In groepen of afzonderlijk gedijt hij ook op steile hellingen tot op grote hoogte. Dichte, donkere wouden zoals wij die van dennen en sparren kennen, maakt de larix niet. Hij kan n.l. niet groeien zonder licht van alle kanten te ontvangen; hij onttrekt ook niet zoveel zonlicht aan zijn omgeving als de andere naaldbo­men. De kroon van de larix blijft toch luchtig en laat het licht door; daardoor maakt hij een jeugdige en blije indruk. De larix houdt van de volle kracht van de zomerzon; daarom groeit hij ‘t liefst op zuidhellin­gen, als ‘t kan op kalkgrond. Maar hij is ongevoelig voor de strengste vorst. Nog voor of tijdens het te voorschijn komen van de nieuwe scheuten ziet men de rode kegelbloesems aan de takken, die later tot kleine, bijna kegelronde, zachte kegeltjes uitgroeien.
Anders dan de spar en de den concentreert de larix nauwelijks geurende harsen in zijn naalden. De stam evenwel bevat grote hoeveelheden van een zachte, honingachtige hars. Door een gat in de schors te boren wint men sinds oude tijden in bergstreken deze hars, die voor allerlei doeleinden dient: uitwendig voor zalven en pleisters, inwendig tegen hoest en andere soorten van katar. Het stevige, roodachtige larixhout is van oudsher voor talloze doeleinden veel gevraagd, omdat het houdbaar en ongevoelig voor weersinvloeden en vocht is.
In de larix zien wij een uniek samenspel van naar binnen gerichte warmteprocessen (zoals alle coniferen in het vormen van balsemieke harsen vertonen) en een sterke relatie tot het licht. Daardoor onderscheidt hij zich van de andere naaldbomen.
Hierdoor wordt het begrijpelijk, dat geneesmiddelen uit larixhars bereid, behalve bij bovengenoemde toepassingen, ook bij ziekten van de ogen, de lichtorganen van de mens, een weldadige werking ontplooien.

(Weledaberichten nr.120 april 1980)


Monograph Larix decidua

Botany
Larch trees are deciduous conifers. One example, L. decidua , grows to 50 m and has needle-like leaves and small, light brown cones. 1

History
Larch trees were said to have been introduced into Great Britain in 1639 and cultivated there since the early 19th century. The tree is grown mainly for its timber, but the inner bark and resin are also used. 1 Arabinogalactan constituents from certain Larix species have gained popularity because of their ability to enhance the immune system. 2

Chemistry
Arabinogalactans are present in species L. dahurica and L. occidentalis . 3 , 4 , 5 Arabinogalactans are long, densely branched, high molecular weight polysaccharides found throughout the plant kingdom and in some microbial systems. They are abundant in the genus Larix and are most often covalently linked to pectin and protein. 2 , 3 The powdered extract from the pine bark of the western larch tree, for example, is 98% arabinogalactan. This substance has a pine odor, a sweet taste, and is easily soluble in water. 2 All arabinogalactans isolated thus far from Larix , are the 3,6-beta-D-galactan type. 3 The extract is harvested from already fallen trees, otherwise a waste product from the lumber industry. A benefit of this natural polymer is that it possesses great uniformity. Batch variation is not a problem among larch trees that it is with other natural products. 2 Arabinogalactans from L. occidentalis have been isolated, characterized, and purified as discussed in one report. 5 Properties of arabinogalactans from L. dahurica have been documented as well, finding a homogeneous product with very narrow molecular weight distribution. 3

Other constituents from Larix have been identified. Larix flavonoids from various species have been analyzed, including flavanones (naringenin, hesperitin, hesperidin), flavones (apigenin, vitexin), and flavonols (kaempferols, quercetins, isorhamnetins, myricetins, and syringetins). 6 L. decidua contains lignans, resins, and volatile oil (mainly alpha- and betapinene and limonene). 1 18-nor-abietatrienes and diterpenes, including abietane-type diterpenes (eg, 7alpha,15-dihydroxyabieta-8,11,13-trien-18-al), have been isolated from species L. kaempferi . 7 , 8 Phenolics (flavonoids) from L. leptolepis have been reported. 9 Resin constituent diterpene from L. europaea has been documented. 10

Uses and Pharmacology
Arabinogalactan displays moisture retention, flavor encapsulation, film-forming capabilities, and desirable viscosities for a pleasant feeling in the mouth as both a natural and functional food ingredient. 2 Also, its role as a dietary fiber and its solubility properties make arabinogalactan an important polysaccharide. Its properties may be influenced by different side chain moieties on the molecule. 3

Arabinogalactan's role as an immune-boosting phytochemical has gained popularity. It has been reported to stimulate macrophages and other immune system components better than echinacea, although echinacea contains some arabinogalactans. Arabinogalactans have also been reported to increase the release of interferons, tumor necrosis factors, and interleukins, all of which are known to enhance immune function.

Animal data
Liver metastases in animals have been inhibited by arabinogalactans. 2 Human peripheral blood mononuclear cells and other cell lines have shown enhancement of natural killer cytotoxicity against certain tumor cells when pretreated with arabinogalactans extracted from L. occidentalis . 11

Arabinogalactan has properties that make it an ideal carrier to deliver agents to hepatocytes via the asialoglycoprotein receptors. Of radiolabeled arabinogalactans, 52.5% (4 mg/kg) were identified in the livers of rats receiving IV injection. 4 Arabinogalactan is highly bound to this receptor in both in vitro and in vivo experimentation. In one study, it was reported that those arabinogalactans with a lower molecular weight may be more desirable for hepatic drug delivery than others. 5 In another study, arabinogalactan conjugated with the antiviral vidarabine was effective in suppressing serum viral DNA titers in woodchucks infected with the hepatitis virus. 12

Clinical data
Research reveals no clinical data regarding the use of larch for immune-boosting effects.

Other uses
Arabinogalactan has also been reported to exhibit anti-inflammatory actions, and it may enhance vascular permeability. 2

L. laricina inhibited xanthine oxidase, thereby reducing uric acid formation, in a study of plant remedies used for gout. This was the greatest inhibition seen among the 26 species from 18 families that were evaluated. 13

Larchwood ( L. decidua ) also possesses astringent and diuretic actions. Its antiseptic actions may be useful in treating cystitis, respiratory infections, and wounds. 1

Dosage
The balsam of larch is used at a concentration of 10% to 20% in gels and ointments for colds and fevers. No clinical trials have been published addressing its safety or efficacy. 14

Pregnancy/Lactation
Information regarding safety and efficacy in pregnancy and lactation is lacking.

Interactions
None well documented.

Adverse Reactions
There is no apparent allergy or toxicity to larch-derived arabinogalactans. 2 One source advises caution with the use of L. decidua in patients suffering from kidney disease. 1

Toxicology
Arabinogalactan produced no adverse reactions in single IV doses administered to mice at 5000 mg/kg or at repeated doses in rats for 90 days at 500 mg/kg/day. 4

Bibliography
1. Chevallier A. Larch. Encyclopedia of Medicinal Plants . New York: DK Publishing, 1996;224.
2. Benedikt H. Arabinogalactans: New Immune Boosting Fiber. Natural Pharmacy 1999;3:12.
3. Odonmazig P, et al. Structural and molecular peoperties of the arabinogalactan isolated from Mongolian larchwood ( Larix dahurica L.). Carbohydr Res 1994;252:317-24.
4. Groman E, et al. Arabinogalactan for hepatic drug delivery. Bioconjug Chem 1994;5(6):547-56.
5. Prescott J, et al. Larch arabinogalactan for hepatic drug delivery: isolation and characterization of a 9 kDa arabinogalactan fragment. Carbohydr Res 1995;278(1):113-28.
6. Niemann G, et al. Phenolics from Larix needles. XΙΙΙ. Analysis of main Larix flavonoids by high-pressure liquid chromatography. Planta Med 1977;31(3):297-301.
7. Ohtsu H, et al. 18-nor-Abietatrienes from the cones of Larix kaempferi. J Nat Prod 1998;61(3):406-408.
8. Ohtsu H, et al. Abietane diterpenoids from the cones of larix kaempferi. J Nat Prod 1998;61(10):1307-9.
9. Niemann G. Phenolics from Larix needles. 8. Flavonoids of L. leptolepis. Planta Med 1974;26(2):101-3.
10. Bruns K. Diterpene. VΙ. Neutral constituent of the resin from Larix europaea D.C. Tetrahedron 1969;25(8):1771-75.
11. Hauer J, et al. Mechanism of stimulation of human natural killer cytotoxicity by arabinogalactan from Larix occidentalis. Cancer Immunol Immunother 1993;36(4):237-44.
12. Enriquez P, et al. Conjugation of adenine arabinoside 5′-monophosphate to arabinogalactan: synthesis, characterization, and antiviral activity. Bioconjug Chem 1995;6(2):195–202.
13. Owen P, et al. Xanthine oxidase inhibitory activity of northeastern North American plant remedies used for gout. J Ethnopharmacol 1999;64(2):149-60.
14. Gruenwald J, ed. PDR for Herbal Medicines . 2nd ed. Montvale, NJ: Thomson Medical Economics; 2000: 457-458.

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