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Carduus marianus L.
Carduus marianus L.
Silybum marianum has other common names include cardus marianus, milk thistle, blessed milk thistle, Marian Thistle, Mary Thistle, Saint Mary's Thistle, Mediterranean milk thistle, variegated thistle and Scotch thistle. This species is an annual or biennial plant of the Asteraceae family. This fairly typical thistle has red to purple flowers and shiny pale green leaves with white veins. Originally a native of Southern Europe through to Asia, it is now found throughout the world. The medicinal parts of the plant are the ripe seeds.
It grows 30 to 200 cm tall, having an overall conical shape with an approx. 160 cm max. diameter base. The stem is grooved and more or less cottony. With the largest specimens the stem is hollow.
The leaves are oblong to lanceolate. They are either lobate or pinnate, with spiny edges. They are hairless, shiny green, with milk-white veins.
The flower heads are 4 to 12 cm long and wide, of red-purple colour. They flower from June to August in the North or December to February in the Southern Hemisphere ( Summer through Autumn ).
The bracts are hairless, with triangular, spine-edged appendages, tipped with a stout yellow spine.
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Possibly native near the coast of south east England. It has been widely introduced outside its natural range, for example into Iran, North America, Australia, and New Zealand where it is considered an invasive weed. Cultivated fields for the production of raw-material for the pharmaceutical industry exists on a larger scale in Austria (Region Waldviertel), Germany, Hungary, Poland, China and Argentina. In Europe it is sown yearly in March–April. The harvest in 2 steps (cutting and threshing) takes place in August, about 2–3 weeks after the flowering.
Traditional milk thistle extract is made from the seeds, which contain approximately 4–6% silymarin. The extract consists of about 65–80% silymarin (a flavonolignan complex) and 20–35% fatty acids, including linoleic acid. Silymarin is a complex mixture of polyphenolic molecules, including seven closely related flavonolignans (silybin A, silybin B, isosilybin A, isosilybin B, silychristin, isosilychristin, silydianin) and one flavonoid (taxifolin). Silibinin, a semipurified fraction of silymarin, is primarily a mixture of 2 diastereoisomers, silybin A and silybin B, in a roughly 1: 1 ratio. In clinical trials silymarin has typically been administered in amounts ranging from 420–480 mg per day in two to three divided doses. However higher doses have been studied, such as 600 mg daily in the treatment of type II diabetes and 600 or 1200 mg daily in patients chronically infected with hepatitis C virus. An optimal dosage for milk thistle preparations has not been established. Milk thistle, along with dandelion and other extracts are often referred to as hangover cures as the bitter tincture helps organs rid toxins after heavy drinking.
In herbalism, it is used in cases of liver diseases (cirrhosis, jaundice and hepatitis), gallbladder disease, and is claimed to protect the liver against poisons. Silibinin (syn. silybin, sylimarin I) is a hepatoprotective (antihepatotoxic), antioxidant (radical-scavenging agent), thus stabilizing and protecting the membrane lipids of the hepatocytes (liver cells). Silicristin inhibits the enzymes peroxidase and lipoxygenase. Silidianin is a plant growth regulator. A 2000 study of such claims by the AHRQ concluded that "clinical efficacy of milk thistle is not clearly established". However a more recent study did show activity against liver cancer cells in vitro. A 2005 Cochrane Review considered thirteen randomized clinical trials which assessed milk thistle in 915 patients with alcoholic and/or hepatitis B or C virus liver diseases. They question the beneficial effects of milk thistle for patients with alcoholic and/or hepatitis B or C virus liver diseases and highlight the lack of high-quality evidence to support this intervention. Cochrane concluded that more good quality randomized clinical trials on milk thistle versus placebo are needed.
Its potent extract is used in medicine under the name silymarin (a flavonolignane complex consisting of silibinin A and B/silybin/silymarin I, isosilibinin A and B, silicristin/silymarin II, silidianin). Silibinin is used against poisoning by amanitas, such as the Death Cap (Amanita phalloides) as well as in cerebral edema and acute hepatitis therapy.
Milk thistle has been grown as a medicinal plant in monastery gardens since ancient times. The seed is the part of the plant used medicinally.
A 2007 study found that silybum marianum blocked Hepatitis C virus (HCV) cell culture infection of human hepatoma cultures. A subsequent study in 2010 found that eight major compounds that comprise silybum, including seven flavonolignans—silybin A, silybin B, isosilybin A, isosilybin B, silychristin, isosilychristin, silydianin, and one flavonoid, taxifolin—are inhibitors of HCV RNA-dependent RNA polymerase.
Isosilybin A was described as the main component of Silybum marianum acting as partial agonist of the peroxisome proliferator-activated receptor type gamma, current pharmacological target in the metabolic syndrome and diabetes type 2.
Research suggests that milk thistle extracts both prevent and repair damage to the liver from toluene and/or xylene. Workers who had been exposed to vapors from toluene and/or xylene for 5–20 years were given either a standardized milk thistle extract (80% silymarin) or placebo for 30 days. The workers taking the milk thistle extract showed significant improvement in liver function tests (ALT and AST) and platelet counts vs. the placebo group.
The efficacy of silymarin in preventing drug-induced liver damage in patients taking psychotropic drugs long-term has been investigated and silymarin was found to reduce damage to the liver caused by lipid peroxidation in patients taking butyrophenones or phenothiazines.
A clinical trial in humans showed that silymarin (140 mg orally 3 times daily) was not effective when used for 1 year in combination with ursodeoxycholic acid (UDCA) for the treatment of primary biliary cirrhosis. A study in baboons indicated that continuous intragastric infusion of silymarin retarded the development of alcohol-induced hepatic fibrosis over a 3-year period. The authors suggested that the failure of silymarin to show beneficial effects in other clinical trials may have been due to poor compliance with treatment, resulting in insufficient dosing.
In a 2010 study published in the journal Cancer, milk thistle was associated with a trend towards reducing the liver damaging effects of chemotherapy in a randomized double-blind placebo controlled study of 50 children.
There has been no controlled clinical study of any treatment suggested for mushroom poisoning. Amanita Phalloides poisoning is relatively rare, and such hard evidence as is available comes from animal studies, e.g.,. The efficacy of thirty different treatments was analyzed in a retrospective study of 205 cases of Amanita phalloides (death cap) mushroom poisoning. Both [penicillamine] and hyperbaric oxygen independently contributed to a higher rate of survival. When silybin [silibinin] was added to the penicillamine treatment, survival was increased even more. In another 18 cases of death cap poisoning, a correlation was found between the time elapsed before initiation of silybin therapy, and the severity of the poisoning. The data appear to indicate that severe liver damage in Amanita phalloides poisoning can be prevented effectively when administration of silybin begins within 48 hours of mushroom intake. Case control studies also suggest that silibinin reduces mortality from mushroom poisoning.
Beside benefits for liver disease, other unproven treatment claims include:
Milk thistle has also been known to be used as food. Around the 16th century the milk thistle became quite popular and almost all parts of it were eaten. The roots can be eaten raw or boiled and buttered or par-boiled and roasted. The young shoots in spring can be cut down to the root and boiled and buttered. The spiny bracts on the flower head were eaten in the past like globe artichoke, and the stems (after peeling) can be soaked overnight to remove bitterness and then stewed. The leaves can be trimmed of prickles and boiled and make a good spinach substitute or they can also be added raw to salads.
Because of potassium nitrate content, the plant has been found to be toxic to cattle and sheep. When potassium nitrate is eaten by ruminants, the bacteria in animal's stomach breaks the chemical down, producing a nitrite ion. Nitrite ion then combines with hemoglobin to produce methaemoglobin, blocking the transport of oxygen. The result is a form of oxygen deprivation.
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