Chemistry of silybin

Abstract

Silybin, a secondary metabolite isolated from the seeds of the blessed milk thistle (Silybum marianum) was discovered as the first member of a new family of natural compounds called flavonolignans in 1959. Over the years it has received the research attention of many organic chemists. This research has resulted in a number of semisynthetic derivatives prepared in an effort to modulate and better target the biological activities of silybin or to improve its physical properties, such as its solubility. A fundamental breakthrough in silybin chemistry was the determination of the absolute configurations of silybin A and silybin B, and the development of methods for their separation. This review covers articles dealing with silybin chemistry and also summarizes all the derivatives prepared.

Sulfated Metabolites of Flavonolignans and 2,3-Dehydroflavonolignans: Preparation and Properties

“…120501). Silybin [3] was isolated by the standard method. Briefly, silymarin was suspended in MeOH and after brief stirring, undissolved solid was filtered out and washed with MeOH, giving silybin of 95% purity.…”

“…Silymarin has antioxidant and hepatoprotective effects, as well as anticancer, chemoprotective, dermatoprotective, and hypocholesterolemic activities [2]. Silybin is the major flavonolignan of silymarin, and literature focuses primarily on this compound mainly because of its commercial availability and relatively easy isolation [3]. Although silychristin and silydianin were described more than 40 years ago [4], their biological properties were not investigated until very recently, mainly because of separation problems [5,6].…”

Synthesis and biology of 1,4-benzodioxane lignan natural products

“…Owing to their benecial effects, their dietary uptake has increased over recent years. 4 Encompassed in the broad class of avonoids is a small subclass of compounds previous dened as, and also called here, avonolignans. As their name suggests, they contain both a phenylpropanoid and a avone component.…”

“…3 Condensation of an epoxide precursor 4. 4 Transition metal assisted methods 4.4.1 Palladium-catalysed etherication of aryl halides 4.4.2 Palladium-catalysed coupling of allylic biscarbonsates with diols 4.4.3 Copper-catalysed ring-opening/coupling cyclisation 4.5 Mitsunobu coupling of phenols and chiral alcohols 4. 6 Alternative syntheses of the 1,4-benzodioxane structure 4.6.1 Protection of an asymmetric diol (alternative to the formation of an asymmetric epoxide) 4.6.2 [4 + 2] cycloaddition of a cinnamyl alcohol and oquinone 4.6.3 Intramolecular cyclisation of tosylates 5 Summary and conclusions 6 References 1 Introduction 1,4-Benzodioxane lignans are a group of natural products that exhibit a wide range of interesting biological activities which has resulted in them receiving much synthetic attention over the years.…”

The Therapeutic Potential of Milk Thistle in Diabetes

“…Silibin is an equimolar mixture of silibin A (2R,3R)-2-((2R,3R)-2,3-dihydro-3-(4-hydroxy-3-methoxyphenyl)-2-(hydroxymethyl)-1,4-benzodioxin-6-yl)-2,3-dihydro-3,5,7-trihydroxy-4H-1-benzopyran-4-one and silibin B (2R,3R)-2-(2S,3S)-2,3-dihydro-3-(4-hydroxy-3-methoxyphenyl)-2-(hydroxymethyl)-1,4-benzodioxin-6-yl)-2,3-dihydro-3,5,7-trihydroxy-4H-1-benzopyran-4-one. Silibin is a compound that oxidizes swiftly, even in atmospheric oxygen; it has a low solubility in water which increases significantly as pH and temperature rise [4].…”