|Systematic (IUPAC) name|
|AHFS/Drugs.com||International Drug Names|
|ATC code||A05BA03 (WHO)|
|Molar mass||482.44 g/mol|
|(what is this?)|
Silibinin (INN), also known as silybin (both from Silybum, the generic name of the plant from which it is extracted), is the major active constituent of silymarin, a standardized extract of the milk thistle seeds, containing a mixture of flavonolignans consisting of silibinin, isosilibinin, silicristin, silidianin, and others. Silibinin itself is mixture of two diastereomers, silybin A and silybin B, in approximately equimolar ratio. The mixture exhibits a number of pharmacological effects, particularly in the liver, and there is some clinical evidence for the use of silibinin as a supportive element in alcoholic and child grade 'A' liver cirrhosis.
Poor water solubility and bioavailability of silymarin led to the development of enhanced formulations. Silipide (trade name Siliphos), a complex of silymarin and phosphatidylcholine (lecithin), is about 10 times more bioavailable than silymarin. An earlier study had concluded Siliphos to have 4.6 fold higher bioavailability. It has been also reported that silymarin inclusion complex with β-cyclodextrin is much more soluble than silymarin itself. There have also been prepared glycosides of silybin, which show better water solubility and even stronger hepatoprotective effect.
Silymarin, as other flavonoids, has been shown to inhibit P-glycoprotein-mediated cellular efflux. The modulation of P-glycoprotein activity may result in altered absorption and bioavailability of drugs that are P-glycoprotein substrates. It has been reported that silymarin inhibits cytochrome P450 enzymes and an interaction with drugs primarily cleared by P450s cannot be excluded.
Use of Siliphos in Hard Water Treatment (see "Talk" comments)
3M developed a product using Silphos to bind calcium and magnesium hardness minerals, preventing them from precipitating out of solution and building up on metallic surfaces. The specific purpose of this product is to condition the water supply for tankless water heaters to protect the water system from the buildup in the piping that is heated to very high temperatures within the heater itself. This product has been marketed as a way to avoid installing a whole house water softener to achieve the same effect. In addition, polyphosphates from the siliphide also form a thin protective layer on the pipe wall or metallic surface which helps to eliminate hardness build-up and corrosion.
A phase I clinical trial in humans with prostate cancer designed to study the effects of high dose silibinin found 13 grams daily to be well tolerated in patients with advanced prostate cancer with asymptomatic liver toxicity (hyperbilirubinemia and elevation of alanine aminotransferase) being the most commonly seen adverse event.
Silibinin is available as drug (Legalon® SIL (Madaus) (D, CH, A) and Silimarit® (Bionorica), a Silymarin product) in some EU countries and used in the treatment of toxic liver damage (e.g. IV treatment in case of death cap poisoning); as adjunctive therapy in chronic hepatitis and cirrhosis. See also Silybum marianum#Medicinal use
Potential medical uses
Silibinin also has a number of potential mechanisms that could benefit the skin. These include chemoprotective effects from environmental toxins, anti-inflammatory effects, protection from UV induced photocarcinogenesis, protection from sunburn, protection from UVB-induced epidermal hyperplasia, and DNA repair for UV induced DNA damage (double strand breaks).
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- Silymarin at the US National Library of Medicine Medical Subject Headings (MeSH)