Silybum marianum (L.) Gaertn. - syn. Carduus marianus L. - Asteraceae
(blessed) milk thistle, holy thistle, Lady's thistle, Mariendistel
Erect annual or biennial herb, up to 1.50m high, native to Mediterranean, naturalized in Central Europe, the Americas, also cultivated; leaves shiny green, white blotched, thorny; flowerheads 4-5cm long, only with tube florets (purple); fruit a achene with white, caducous pappus.
The ripe fruits (Cardui mariae fructus) „… are taken as bitter digestive tonic in case of dyspepsia and disorders of the biliary system, while extracts are used for their hepatoprotective properties… Silymarin shows antihepatotoxic effects… Silymarin significantly improves survival of patients with chronic liver disease.“
[Medicinal Plants of the World. Ben-Erik Van Wyk and Michael Wink, Pretoria 2004, 300]
„The flavonoid silymarin and one its structural components, silibinin, have been well characterized as hepato-protective substances… Three levels of action have been proposed for silymarin in experimental animals: a) as an antioxidant, by scavenging prooxidant free radicals and by increasing the intracellular concentration of the tripeptide glutathione; b) regulatory action of the cellular membrane permeability and increase of its stability against xenobiotic injury; c) at the nuclear expression, by increasing the synthesis of ribosomal RNA by stimulating DNA polymerase I and by exerting a steroid-like regulatory action on DNA transcription.“
[Biochemical bases of the pharmacological action of the flavonoid silymarin and of its structural isomer silibinin., Valenzuela, A., Garrido, A., Biological research, 27(2), 1993, 105-112]
„The mechanisms of action of silymarin involve different biochemical events, such as the stimulation of the synthetic rate of ribosomal RNA (rRNA) species through stimulation of polymerase I and rRNA transcription, protecting the cell membrane from radical-induced damage and blockage of the uptake of toxins such as α-amanitin… Silymarin 420 mg/day was also shown to improve indices of liver function [AST, ALT, γ-glutamyl transferase and bilirubin] in patients with liver disease of various aetiology, including those exposed to toxic levels of toluene or xylene; however, it was largely ineffective in patients with viral hepatitis.“
[Silymarin: a review of its clinical properties in the management of hepatic disorders., Wellington, K., Jarvis, B., BioDrugs, 15(7), 2001, 465-489]
„… silymarin appears to be effective to reduce the biochemical, inflammatory and ultrasonic indices of hepatic steatosis. Some parameters indicative of early stage of atherosclerosis were also lowered.“
[Silymarin in non alcoholic fatty liver disease., Cacciapuoti, F., Scognamiglio, A., Palumbo, R., Forte, R., Cacciapuoti, F., World journal of hepatology, 5(3), 2013, 109] http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3612568/
„Silymarin is the entire extract containing seven flavonolignans and taxifolin. Silibinin is a mixture of silybin A and silybin B in a 1:1 ratio. The remaining flavonolignans are: isosilybin A, isosilybin B, silychristin, isosilychristin, and silydianin. The flavonoid found in silymarin is taxifolin…
Presently, there is no clear evidence that any of the currently available over-the-counter preparations have efficacy in the treatment of liver disease. While there are compelling in vitro and animal data supporting the hepatoprotective effects of silymarin and inhibition of in vitro HCV infection, clinical data are equivocal, with some studies suggesting a protective effect of silymarin against progression of liver disease in subjects with hepatitis C, while other studies found no such effect. Thus, there is clinical controversy around whether silymarin and silymarin-derived compounds protect the liver.“
[Hepatoprotective and antiviral functions of silymarin components in hepatitis C virus infection., Polyak, S. J., Ferenci, P., Pawlotsky, J.M., Hepatology, 57(3), 2013, 1262-1271] http://onlinelibrary.wiley.com/doi/10.1002/hep.26179/full
Silybum marianum (L.) Gaertner as Carduus marianus L.
Curtis, William, Flora Londinensis, vol.3, t.54  (1778-1781)