Straightforward chemo-enzymatic synthesis of new aminocyclitols, analogues of valiolamine and their evaluation as glycosidase inhibitors.

An efficient fructose-1,6-bisphosphate aldolase mediated synthesis of new aminocyclitol analogues of valiolamine is described. The one-pot process where four stereocentres are created involves the formation of two carbon–carbon bonds. One is catalysed by the aldolase, coupling dihydroxyacetone phosphate to nitrobutyraldehydes. The other is the result of a highly stereoselective intramolecular Henry reaction occurring on the intermediate nitroketones. Depending on the configuration of the hydroxyl which is α to the nitro group, two series of configuration are accessible. The lipase resolution of the nitroalcohol ketal, precursor of the nitroaldehyde, is presented. The inhibition properties of the aminocyclitols obtained after the reduction of the nitro group are evaluated towards five commercial glycosidase

Cell wall component and mycotoxin moieties involved in binding of fumonisin B1 and B2 by lactic acid bacteria.

International audienceAims: The ability of lactic acid bacteria (LAB) to bind fumonisins B1 and B2 (FB1, FB2) in fermented foods and feeds and in the gastrointestinal tract could contribute to decrease their bioavailability and toxic effects on farm animals and humans. The aim of this work was to identify the bacterial cell wall component(s) and the functional group(s) of FB involved in the LAB-FB interaction. Methods and Results: The effect of physicochemical, enzymatic and genetic treatments of bacteria and the removal/inactivation of the functional groups of FB on toxin binding were evaluated. Treatments affecting the bacterial wall polysaccharides, lipids and proteins increased binding, while those degrading peptidoglycan (PG) partially decreased it. In addition, purified PG from Gram-positive bacteria bound FB in a manner analogue to that of intact LAB. For FB, tricarballylic acid (TCA) chains play a significant role in binding as hydrolysed FB had less affinity for LAB. Conclusions: Peptidoglycan and TCA are important components of LAB and FB, respectively, involved in the binding interaction. Significance and Impact of the Study: Lactic acid bacteria binding efficiency seems related to the peptide moiety structure of the PG. This information can be used to select probiotics with increased FB binding efficiency

Short synthesis of new salacinol analogues and their evaluation as glycosidase inhibitors

Versatile synthesis of some analogues of the naturally-occurring α-glucosidase inhibitor salacinol (1), involving thioanhydro alditol moieties with erythro, d,l-threo, xylo, ribo, d-arabino and d-manno configurations is described. Nucleophilic attack at the least-hindered carbon atom of an l- or d-protected erythritol cyclic sulfate by the thioanhydro alditol sulfur atom yielded the desired zwitterionic compounds. In addition, the preparation of the cyclic sulfates of 2,4-O-benzylidene-d-erythritol and 2,4-O-isopropylidene-l-erythritol was improved. Enzyme inhibition tests showed that most of the new compounds were weak but specific inhibitors, while good inhibitory activity was found for a six-membered ring analogue (β-glucosidase: Ki=16 μM

A straightforward synthesis of an aminocyclitol based on an enzymatic aldol reaction and a highly stereoselective intramolecular Henry reaction

The reactions of 4-nitroaldehydes 9 and 10 with dihydroxyacetonephosphate (DHAP) catalyzed by fructose-1,6-diphosphate aldolase from rabbit muscle were studied. Starting from 9 or 10, only one main stereomer of nitrocyclitol 8 was isolated. A highly stereoselective intramolecular cyclization (Henry reaction or nitroaldol reaction) took place under acidic conditions during the aldolase catalyzed condensation and phytase catalyzed phosphate hydrolysis coupled step. The catalytic hydrogenation of nitrocyclitol 8 yielded aminocyclitol 7, a valiolamine analogue. Its inhibition properties were evaluated towards five glycosidase

Biocatalytic Aldol Addition of Simple Aliphatic Nucleophiles to Hydroxyaldehydes

This ACS article is provided to You under the terms of this Standard ACS AuthorChoice/Editors' Choice usage agreement between You and the American Chemical Society ("ACS")(https://pubs.acs.org/page/policy/authorchoice_termsofuse.html)Asymmetric aldol addition of simple aldehydes and ketones to electrophiles is a cornerstone reaction for the synthesis of unusual sugars and chiral building blocks. We investigated -fructose-6-phosphate aldolase from E. coli (FSA) D6X variants as catalysts for the aldol additions of ethanal and nonfunctionalized linear and cyclic aliphatic ketones as nucleophiles to nonphosphorylated hydroxyaldehydes. Thus, addition of propanone, cyclobutanone, cyclopentanone, or ethanal to 3-hydroxypropanal or (S)- or (R)-3-hydroxybutanal catalyzed by FSA D6H and D6Q variants furnished rare deoxysugars in 8-77% isolated yields with high stereoselectivity (97:3 dr and >95% ee)

Nitrile biotransformationby aspergillus niger

A nitrile-converting enzyme activity was induced in Aspergillus niger K10 by 3-cyanopyridine. The whole cell biocatalyst was active at pH 3–11 and hydrolyzed the cyano group into acid and/or amide functions in benzonitrile as well as in its meta- and para-substituted derivatives, cyanopyridines, 2-phenylacetonitrile and thiophen-2-acetonitrile. Amides constituted a significant part of the total biotransformation products of 2- and 4-cyanopyridine, 4-chlorobenzonitrile, 4-tolunitrile and 1,4-dicyanobenzene, while α-substituted acrylonitriles gave amides as the sole product

Biotransformation of nitriles to amides using soluble and immobilized nitrile hydratase from Rhodococcus erythropolis A4

A semi-purified nitrile hydratase from Rhodococcus erythropolis A4 was applied to biotransformations of 3-oxonitriles 1a–4a, 3-hydroxy-2-methylenenitriles 5a–7a, 4-hydroxy-2-methylenenitriles 8a–9a, 3-hydroxynitriles 10a–12a and 3-acyloxynitrile 13a into amides 1b–13b. Cross-linked enzyme aggregates (CLEAs) with nitrile hydratase and amidase activities (88% and 77% of the initial activities, respectively) were prepared from cell-free extract of this microorganism and used for nitrile hydration in presence of ammonium sulfate, which selectively inhibited amidase activity. The genes nha1 and nha2 coding for α and β subunits of nitrile hydratase were cloned and sequenced

Exploration des propriétés catalytiques de la Fructose-6-Phosphate aldolase. Application à la synthèse de sucres et analogues

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A mutant D-fructose-6-phosphate aldolase (Ala129Ser) as a powerful improved biocatalyst for direct synthesis of carbohydrates and analogues from dihydroxyacetone

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Immergés dans la chimie !

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