Enzymatically-synthesized xylo-oligosaccharides laurate esters as surfactants of interest

Lipase-catalyzed synthesis of xylo-oligosaccharides esters from pure xylobiose, xylotriose and xylotetraose in the presence of vinyl laurate was investigated. The influence of different experimental parameters such as the loading of lipase, the reaction duration or the use of a co-solvent was studied and the reaction conditions were optimized with xylobiose. Under the best conditions, a regioselective esterification occurred to yield a monoester with the acyl chain at the OH-4 of the xylose unit at the non-reducing end. Surface-active properties of these pure xylo-oligosaccharides fatty esters have been evaluated. They display interesting surfactant activities that differ according to the degree of polymerization (DP) of the glycone moiety. © 202

Solvent-Free Synthesis of Tartramides Under Microwave Activation

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Evaluation of the transglycosylation activities of a GH 39 beta-D-xylosidase for the synthesis of xylose-based glycosides

International audienceThe ability of GH 39 beta-D-Xylosidase (XylBH39) from Bacillus halodurans to catalyze transxylosylation reactions, particularly for the production of alkyl xylosides, has been investigated using p-nitrophenyl (pNP) beta-D-xylopyranoside, xylobiose and xylotriose. Furthermore wheat bran, being rich in xylo-oligosaccharides after enzymatic treatment with an endoxylanase. was used as a source of xylosyl donors. The autocondensation of pNP beta-D-Xylopyranoside was characterized by poor regioselectivity and the production of a variety of short (di- and trimers) oligosaccharides. Compared to xylobiose, xylotriose was a better donor molecule for XylBH39-mediated transxylosylation of primary alcohols presenting chain length from 1- to 5-carbon atoms. Using a wheat bran hydrolysate, generated using an endoxylanase, it was possible to perform XylBH39-mediated transxylosylation of propan-1-ol to produce propyl beta-D-xylopyranoside. This enzymatic process led to synthesis of 0.9 g of propyl beta-D-Xylopyranoside from 20 g of destarched wheat bran

Exploring the aglycone subsite of a GH11 xylanase for the synthesis of xylosides by transglycosylation reactions

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Simultaneous generation of anionic and neutral palladium(II) complexes from eta(3)-allylpalladium chloride dimer and fluorinated beta-enaminones

Reactions between eta(3)-allylpalladium chloride dimer, 1,8-di-azabicyclo[5.4.0]undec-7-ene (DBU) and 1-amino-2-fluoro-1-perfluoroethyl-3 -phenylprop-1-en-3-one or 1,12-diamino-2,11-difluoro-1,12-bis(perfluorobutyl)dodeca-1,11-diene- 3,10-dione simultaneously provided two types of Pd-II complexes. One is an anionic eta(3)-allylpalladium complex with protonated DBU as counterion while the other is a neutral eta(3)-allyl(beta-ketoiminato)palladium complex. A mechanism involving the amidine function of DBU in the formation of the two complexes is proposed. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003

'Click'-xylosides as initiators of the biosynthesis of glycosaminoglycans : Comparison of mono-xylosides with xylobiosides.

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