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Regioselective alcoholysis of silychristin acetates catalyzed by lipases.

Vavříková E, Gavezzotti P, Purchartová K, Fuksová K, Biedermann D, Kuzma M, Riva S, Křen V - Int J Mol Sci (2015)

Bottom Line: Acetylation at primary alcoholic group (C-22) of silychristin was accomplished by lipase PS (Pseudomonas cepacia) immobilized on diatomite using vinyl acetate as an acetyl donor, whereas selective deacetylation of 22-O-acetyl silychristin was accomplished by Novozym 435 in methyl tert-butyl ether/ n-butanol.Both of these reactions occurred without diastereomeric discrimination of silychristin A and B.Both of these enzymes were found to be capable to regioselective deacetylation of hexaacetyl silychristin to afford penta-, tetra- and tri-acetyl derivatives, which could be obtained as pure synthons for further selective modifications of the parent molecule.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Biotransformation, Institute of Microbiology, Academy of Sciences of the Czech Republic, Vídeňská 1083, CZ 142 20 Prague, Czech Republic. vavrikova@biomed.cas.cz.

ABSTRACT
A panel of lipases was screened for the selective acetylation and alcoholysis of silychristin and silychristin peracetate, respectively. Acetylation at primary alcoholic group (C-22) of silychristin was accomplished by lipase PS (Pseudomonas cepacia) immobilized on diatomite using vinyl acetate as an acetyl donor, whereas selective deacetylation of 22-O-acetyl silychristin was accomplished by Novozym 435 in methyl tert-butyl ether/ n-butanol. Both of these reactions occurred without diastereomeric discrimination of silychristin A and B. Both of these enzymes were found to be capable to regioselective deacetylation of hexaacetyl silychristin to afford penta-, tetra- and tri-acetyl derivatives, which could be obtained as pure synthons for further selective modifications of the parent molecule.

No MeSH data available.


Structures of silychristin A (1a) and silychristin B (1b).
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ijms-16-11983-f001: Structures of silychristin A (1a) and silychristin B (1b).

Mentions: Silymarin [1], a crude extract from fruits of the milk thistle (Silybum marianum), contains flavonolignans occurring as pairs of diastereoisomers [2] (silybin A and B, isosilybin A and B, silychristin A and B) and other related compounds (silydianin, taxifolin; only single stereoisomers). This unique mixture of flavonolignans is largely used in a plethora of nutraceutics due to their hepatoprotective activity and also to other beneficial effects. So far, silybins A and B, accounting for ca. 30% of silymarin, are the only readily-available pure components from silymarin. The compounds in the remaining fraction of silymarin have only been isolated, up to very recently, in small quantities using laborious procedures, e.g., repetitive preparatory HPLC, and so, they could only be used for analytical standards. In 2014, a novel method for the preparatory separation of the minority silymarin components using Sephadex LH-20 gel chromatography was reported. This protocol gives access mainly to pure silydianin and silychristin (Figure 1) in multi-gram quantities [3].


Regioselective alcoholysis of silychristin acetates catalyzed by lipases.

Vavříková E, Gavezzotti P, Purchartová K, Fuksová K, Biedermann D, Kuzma M, Riva S, Křen V - Int J Mol Sci (2015)

Structures of silychristin A (1a) and silychristin B (1b).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4490424&req=5

ijms-16-11983-f001: Structures of silychristin A (1a) and silychristin B (1b).
Mentions: Silymarin [1], a crude extract from fruits of the milk thistle (Silybum marianum), contains flavonolignans occurring as pairs of diastereoisomers [2] (silybin A and B, isosilybin A and B, silychristin A and B) and other related compounds (silydianin, taxifolin; only single stereoisomers). This unique mixture of flavonolignans is largely used in a plethora of nutraceutics due to their hepatoprotective activity and also to other beneficial effects. So far, silybins A and B, accounting for ca. 30% of silymarin, are the only readily-available pure components from silymarin. The compounds in the remaining fraction of silymarin have only been isolated, up to very recently, in small quantities using laborious procedures, e.g., repetitive preparatory HPLC, and so, they could only be used for analytical standards. In 2014, a novel method for the preparatory separation of the minority silymarin components using Sephadex LH-20 gel chromatography was reported. This protocol gives access mainly to pure silydianin and silychristin (Figure 1) in multi-gram quantities [3].

Bottom Line: Acetylation at primary alcoholic group (C-22) of silychristin was accomplished by lipase PS (Pseudomonas cepacia) immobilized on diatomite using vinyl acetate as an acetyl donor, whereas selective deacetylation of 22-O-acetyl silychristin was accomplished by Novozym 435 in methyl tert-butyl ether/ n-butanol.Both of these reactions occurred without diastereomeric discrimination of silychristin A and B.Both of these enzymes were found to be capable to regioselective deacetylation of hexaacetyl silychristin to afford penta-, tetra- and tri-acetyl derivatives, which could be obtained as pure synthons for further selective modifications of the parent molecule.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Biotransformation, Institute of Microbiology, Academy of Sciences of the Czech Republic, Vídeňská 1083, CZ 142 20 Prague, Czech Republic. vavrikova@biomed.cas.cz.

ABSTRACT
A panel of lipases was screened for the selective acetylation and alcoholysis of silychristin and silychristin peracetate, respectively. Acetylation at primary alcoholic group (C-22) of silychristin was accomplished by lipase PS (Pseudomonas cepacia) immobilized on diatomite using vinyl acetate as an acetyl donor, whereas selective deacetylation of 22-O-acetyl silychristin was accomplished by Novozym 435 in methyl tert-butyl ether/ n-butanol. Both of these reactions occurred without diastereomeric discrimination of silychristin A and B. Both of these enzymes were found to be capable to regioselective deacetylation of hexaacetyl silychristin to afford penta-, tetra- and tri-acetyl derivatives, which could be obtained as pure synthons for further selective modifications of the parent molecule.

No MeSH data available.