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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.


Time course study of Novozym 435 catalyzed deacetylation of 22-O-acetyl silychristins A () and B () yielding the corresponding silychristin A () and silychristin B (); () ratio of peak areas of silychristin A:silychristin B (secondary axis y; please note that this axis has a different scale).
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ijms-16-11983-f003: Time course study of Novozym 435 catalyzed deacetylation of 22-O-acetyl silychristins A () and B () yielding the corresponding silychristin A () and silychristin B (); () ratio of peak areas of silychristin A:silychristin B (secondary axis y; please note that this axis has a different scale).

Mentions: The alcoholysis of 22-O-acetyl silychristin (2) was attempted to achieve silychristin diastereomeric discrimination (Scheme 1). Alcoholysis in various solvents (MTBE, tert-amyl alcohol and toluene), previously found to be suitable for the discrimination of 22-O-acetyl silybin, was tested [14]. Among the two previously successful enzymes—Novozym 435 and lipase PS immobilized on diatomite—the only positive result was obtained with Novozym 435 in a mixture of solvents MTBE and n-butanol. The course of the reaction was monitored by HPLC, evaluating the formation of the diastereoisomers, 1a and 1b (Figure 3). Once again, no diastereomeric discrimination good enough for the kinetic resolution of the mixture of 22-O-acetyl silychristin A and B (2) was observed.


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)

Time course study of Novozym 435 catalyzed deacetylation of 22-O-acetyl silychristins A () and B () yielding the corresponding silychristin A () and silychristin B (); () ratio of peak areas of silychristin A:silychristin B (secondary axis y; please note that this axis has a different scale).
© Copyright Policy
Related In: Results  -  Collection

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

ijms-16-11983-f003: Time course study of Novozym 435 catalyzed deacetylation of 22-O-acetyl silychristins A () and B () yielding the corresponding silychristin A () and silychristin B (); () ratio of peak areas of silychristin A:silychristin B (secondary axis y; please note that this axis has a different scale).
Mentions: The alcoholysis of 22-O-acetyl silychristin (2) was attempted to achieve silychristin diastereomeric discrimination (Scheme 1). Alcoholysis in various solvents (MTBE, tert-amyl alcohol and toluene), previously found to be suitable for the discrimination of 22-O-acetyl silybin, was tested [14]. Among the two previously successful enzymes—Novozym 435 and lipase PS immobilized on diatomite—the only positive result was obtained with Novozym 435 in a mixture of solvents MTBE and n-butanol. The course of the reaction was monitored by HPLC, evaluating the formation of the diastereoisomers, 1a and 1b (Figure 3). Once again, no diastereomeric discrimination good enough for the kinetic resolution of the mixture of 22-O-acetyl silychristin A and B (2) was observed.

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.