Names | |
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IUPAC name Silychristin A = (2R,3R)-3,5,7-trihydroxy-2-((2R,3S)-7-hydroxy-2-(4-hydroxy-3-methoxyphenyl)-3-(hydroxymethyl)-2,3-dihydrobenzofuran-5-yl)chroman-4-one Silychristin B = (2R,3R)-3,5,7-trihydroxy-2-((2S,3R)-7-hydroxy-2-(4-hydroxy-3-methoxyphenyl)-3-(hydroxymethyl)-2,3-dihydrobenzofuran-5-yl)chroman-4-one | |
Other names Silichristin, Silicristin, Silycristin | |
Identifiers | |
3D model (JSmol) | |
ChEBI | |
ChEMBL | |
ChemSpider | |
EC Number |
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KEGG | |
PubChem CID | |
UNII | |
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Properties | |
C25H22O10 | |
Molar mass | 482.4 g/mol |
Hazards | |
GHS labelling: | |
Warning | |
H302 | |
P264, P270, P301+P312, P330, P501 | |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). |
Silychristin (also known as silichristin) is a natural product and one of the constituents of silymarin, the standardized, active extract of the fruit of milk thistle, Silybum marianum . [1] [2] It is the second most abundant constituent in silymarin, after silybin. [3] Silychristin is a flavonolignan, along with many other silymarin constituents (such as silybin, isosilybin, silydianin, etc.), meaning it is composed up of a flavonoid and a lignan. [3] It is estimated that up to 65–80% of silymarin extract is made up of flavonolignans, like silychristin, which give silymarin its well known potent antioxidant and hepatoprotective properties. [4] [5] Silychristin can exist as two stereoisomers, silychristin A (2R, 3S) and silychristin B (2S, 3R). The marianum variety of S. marianum (purple corollas) includes silychristin A as a major flavonolignan constituent, while the lesser known and studied albiflorum variety (white corollas) includes unique flavonolignans, including silyhermin, (–)-silandrin, and (+)-silymonin. [6]
Several studies have documented the potentially dangerous effects of silychristin and of the silymarin mixture in general on the thyroid system. All of the flavonolignan compounds found in the silymarin mixture seem to block the uptake of thyroid hormones into the cells by selectively blocking the MCT8 transmembrane transporter. [7] The authors of this study noted that especially silychristin seems to be perhaps the most powerful and selective inhibitor known so far for the MCT8 transporter. [7] Due to the essential role played by the thyroid hormone in human metabolism in general it is believed that the intake of silymarin can lead to disruptions of the thyroid system. [7] Because the thyroid hormones and the MCT8 as well are known to play a critical role during early and fetal development, the administration of silymarin during pregnancy is especially thought to be dangerous, potentially leading to the Allan–Herndon–Dudley syndrome, a brain development disorder that causes both moderate to severe intellectual disability and problems with speech and movement. [8]
Natural flavonolignans, which include silychristin, are biosynthesized by the oxidative coupling of a flavonoid and a phenylpropanoid moiety. The flavonoid moiety can be any number of flavonoids, including taxifolin, naringenin, luteolin, etc., while the pheylpropanoid moiety includes coniferyl alcohol, a monolignol, in most all flavonolignans. The two biosynthetic precursors specifically for silychristin are taxifolin and coniferyl alcohol, which are both biosynthesized via the phenylpropanoid pathway, a pathway which converts phenylalanine into 4-coumaroyl-CoA. [9]
Still much is not known today about the specific enzymes and mechanism of the biosynthesis of silychristin and its related flavononlignan counterparts in S. marianum. The most widely accepted hypothesis for the biosynthesis of flavonolignans is via an oxidative radicalization of both the flavonoid precursor and coniferyl alcohol, followed by coupling of the two radicals, and then proton transfer(s) in order to aromatize the intermediate to get the final product. Although the enzyme catalyzing this oxidative coupling of flavonolignans has not yet been fully characterized, peroxidase enzymes have been hypothesized as likely candidates because they are radical generators. [9]
Antioxidants are compounds that inhibit oxidation, a chemical reaction that can produce free radicals and chain reactions that may damage the cells of organisms. Antioxidants such as thiols or ascorbic acid may act to inhibit these reactions. To balance oxidative stress, plants and animals maintain complex systems of overlapping antioxidants, such as glutathione.
Thiamine, also known as thiamin and vitamin B1, is a vitamin, an essential micronutrient, which cannot be made in the body. It is found in food and commercially synthesized to be a dietary supplement or medication. Food sources of thiamine include whole grains, legumes, and some meats and fish. Grain processing removes much of the thiamine content, so in many countries cereals and flours are enriched with thiamine. Supplements and medications are available to treat and prevent thiamine deficiency and disorders that result from it, including beriberi and Wernicke encephalopathy. Other uses include the treatment of maple syrup urine disease and Leigh syndrome. They are typically taken by mouth, but may also be given by intravenous or intramuscular injection.
The name destroying angel applies to several similar, closely related species of deadly all-white mushrooms in the genus Amanita. They are Amanita bisporigera and A. ocreata in eastern and western North America, and A. virosa in Europe. Another very similar species, A. verna or fool's mushroom, was first described in France.
Flavonoids are a class of polyphenolic secondary metabolites found in plants, and thus commonly consumed in the diets of humans.
Polyphenols are a large family of naturally occurring organic compounds characterized by multiples of phenol units. They are abundant in plants and structurally diverse. Polyphenols include flavonoids, tannic acid, and ellagitannin, some of which have been used historically as dyes and for tanning garments.
Hepatotoxicity implies chemical-driven liver damage. Drug-induced liver injury is a cause of acute and chronic liver disease caused specifically by medications and the most common reason for a drug to be withdrawn from the market after approval.
Silybum is a genus of two species of thistles in the daisy family. The plants are native to the Mediterranean regions of Europe, North Africa, and the Middle East. One species has been introduced elsewhere, including in North America. The name "milk thistle" derives from a feature of the leaves, which are prominently banded with splashes of white. Historically, these milky bands were said to be Mother Mary's milk, and this is the origin of another common name, St. Mary's thistle. The most widespread species is Silybum marianum.
This is a list of terms related to oncology. The original source for this list was the US National Cancer Institute's public domain Dictionary of Cancer Terms.
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, silychristin, silidianin, and others. Silibinin itself is a mixture of two diastereomers, silybin A and silybin B, in approximately equimolar ratio. The mixture exhibits a number of pharmacological effects, particularly in the fatty liver, non-alcoholic fatty liver, non-alcoholic steatohepatitis, and there is great clinical evidence for the use of silibinin as a supportive element in alcoholic and Child–Pugh grade 'A' liver cirrhosis. However, despite its several beneficial effects on the liver, silibinin and all the other compounds found in silymarin, especially silychristin seem to act as potent disruptors of the thyroid system by blocking the MCT8 transporter. The long term intake of silymarin can lead to some form of thyroid disease and if taken during pregnancy, silymarin can cause the development of the Allan–Herndon–Dudley syndrome. Although this information is not being taken into consideration by all regulatory bodies, several studies now consider silymarin and especially silychristin to be important inhibitors of the MCT8 transporter and a potential disruptor of the thyroid hormone functions.
Quercetin is a plant flavonol from the flavonoid group of polyphenols. It is found in many fruits, vegetables, leaves, seeds, and grains; capers, red onions, and kale are common foods containing appreciable amounts of it. It has a bitter flavor and is used as an ingredient in dietary supplements, beverages, and foods.
Silybum marianum is a species of thistle. It has various common names including milk thistle, blessed milkthistle, 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 family Asteraceae. 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.
Hesperidin is a flavanone glycoside found in citrus fruits. Its aglycone form is called hesperetin. Its name is derived from the word "hesperidium", for fruit produced by citrus trees.
Amanita ocreata, commonly known as the death angel, destroying angel, angel of death or more precisely western North American destroying angel, is a deadly poisonous basidiomycete fungus, one of many in the genus Amanita. Occurring in the Pacific Northwest and California floristic provinces of North America, A. ocreata associates with oak trees. The large fruiting bodies generally appear in spring; the cap may be white or ochre and often develops a brownish centre, while the stipe, ring, gill and volva are all white.
Allan–Herndon–Dudley syndrome is a rare X-linked inherited disorder of brain development that causes both moderate to severe intellectual disability and problems with speech and movement.
Protandim is a herbal dietary supplement marketed with unsupported claims that it can treat a number of medical conditions. The product is a patented mix of five herbal ingredients and sold by LifeVantage Corporation, a Utah-based multi-level marketing company. The manufacturers of Protandim claim it can prevent or cure a wide variety of medical conditions, including diabetes and cancer. In 2017, LifeVantage was issued a warning letter by the U.S. Food and Drug Administration (FDA) regarding illegal advertising claims on the company's websites suggesting that Protandim can help to cure various ailments, including cancer and diabetes.
Iodine is an essential trace element in biological systems. It has the distinction of being the heaviest element commonly needed by living organisms as well as the second-heaviest known to be used by any form of life. It is a component of biochemical pathways in organisms from all biological kingdoms, suggesting its fundamental significance throughout the evolutionary history of life.
Taxifolin (5,7,3',4'-flavan-on-ol), also known as dihydroquercetin, belongs to the subclass flavanonols in the flavonoids, which in turn is a class of polyphenols.
Flavonolignans are natural phenols composed of a part flavonoid and a part phenylpropane.
Derek Smyth is a British biochemist who specialises in peptide structure and function. In 2002, he was admitted as a Fellow of the Royal Society of Chemistry.