ChemInform Abstract: New Method of Orthoesterification Under Kinetic Control. Formation and Selective Hydrolysis of Methoxyethylidene Derivatives of Carbohydrates

ChemInform ◽  
1990 ◽  
Vol 21 (33) ◽  
Author(s):  
M. BOUCHRA ◽  
P. CALINAUD ◽  
J. GELAS
Keyword(s):  
New Method ◽  
Kinetic Control ◽  
Selective Hydrolysis ◽  
Hydrolysis Of ◽  
Derivatives Of

O-Benzylidene Derivatives of D-Arabinose Diethyl and Dipropyl Dithioacetal

1996 ◽  
Vol 49 (3) ◽  
pp. 273 ◽  
Author(s):  
J Kuszmann ◽  
E Gacsbaitz
Keyword(s):  
Hydrochloric Acid ◽  
Zinc Chloride ◽  
Partial Hydrolysis ◽  
Kinetic Control ◽  
Toluenesulfonic Acid ◽  
Thermodynamic Phase ◽  
Hydrolysis Of ◽  
Derivatives Of

Benzylidenation of D-arabinose diethyl and dipropyl dithioacetals with α,α-dimethoxytoluene in the presence of p-toluenesulfonic acid has been studied in detail. Under kinetic control the two terminal dioxolan -type 4,5-O-(R)- and 4,5-O-(S)-benzylidene diastereomers are formed first which are in equilibrium with each other In the thermodynamic phase of the reaction the corresponding dioxan -type 3,5-O-(R)- benzylidene isomer is formed too, but all three monobenzylidene isomers are gradually converted into the four possible dioxolan -type 2,3 : 4,5-di-O benzylidene diastereomers . The dioxan -type 2,4:3,5-di-O-benzylidene isomer was present only in trace amounts. When benzaldehyde was used as reagent in the presence of hydrochloric acid or zinc chloride only the 2,3: 4,5-di-O-benzylidene diastereomers were formed. Partial hydrolysis of the dibenzylidene derivatives yielded the corresponding 2,3-O-benzylidene diastereomers. Structures, including the chirality of the benzylidene groups, were determined by n.m.r. spectroscopy. A mechanism suggested for the reaction was partially supported by equilibration studies.

scholarly journals Fine Modulation of the Catalytic Properties of Rhizomucor miehei Lipase Driven by Different Immobilization Strategies for the Selective Hydrolysis of Fish Oil

Molecules ◽  
2020 ◽  
Vol 25 (3) ◽  
pp. 545 ◽  
Author(s):  
Maryam Yousefi ◽  
Marzia Marciello ◽  
Jose Manuel Guisan ◽  
Gloria Fernandez-Lorente ◽  
Mehdi Mohammadi ◽  
...  
Keyword(s):  
Fish Oil ◽  
Catalytic Properties ◽  
Iminodiacetic Acid ◽  
Rhizomucor Miehei ◽  
Rhizomucor Miehei Lipase ◽  
Selective Hydrolysis ◽  
Specific Activities ◽  
Miehei Lipase ◽  
Hydrolysis Of ◽  
Derivatives Of

Functional properties of each enzyme strictly depend on immobilization protocol used for linking enzyme and carrier. Different strategies were applied to prepare the immobilized derivatives of Rhizomucor miehei lipase (RML) and chemically aminated RML (NH2-RML). Both RML and NH2-RML forms were covalently immobilized on glyoxyl sepharose (Gx-RML and Gx-NH2-RML), glyoxyl sepharose dithiothreitol (Gx-DTT-RML and Gx-DTT-NH2-RML), activated sepharose with cyanogen bromide (CNBr-RML and CNBr-NH2-RML) and heterofunctional epoxy support partially modified with iminodiacetic acid (epoxy-IDA-RML and epoxy-IDA-NH2-RML). Immobilization varied from 11% up to 88% yields producing specific activities ranging from 0.5 up to 1.9 UI/mg. Great improvement in thermal stability for Gx-DTT-NH2-RML and epoxy-IDA-NH2-RML derivatives was obtained by retaining 49% and 37% of their initial activities at 70 °C, respectively. The regioselectivity of each derivative was also examined in hydrolysis of fish oil at three different conditions. All the derivatives were selective between cis-5,8,11,14,17-eicosapentaenoic acid (EPA) and cis-4,7,10,13,16,19-docosahexaenoic acid (DHA) in favor of EPA. The highest selectivity (32.9 folds) was observed for epoxy-IDA-NH2-RML derivative in the hydrolysis reaction performed at pH 5 and 4 °C. Recyclability study showed good capability of the immobilized biocatalysts to be used repeatedly, retaining 50–91% of their initial activities after five cycles of the reaction.

Synthesis of 4-O- and 6-O-monoacryloyl derivatives of sucrose by selective hydrolysis of 4,6-O-(1-ethoxy-2-propenylidene)sucrose. Polymerization and copolymerization with styrene

1993 ◽  
Vol 240 ◽  
pp. 143-152 ◽  
Author(s):  
Elisabeth Fanton ◽  
Catherine Fayet ◽  
Jacques Gelas ◽  
Alain Deffieux ◽  
Michel Fontanille ◽  
...  
Keyword(s):  
Selective Hydrolysis ◽  
Hydrolysis Of ◽  
Derivatives Of

The formation of hex-5-enopyranosides and their selective hydrolysis in methylated polysaccharides

1978 ◽  
Vol 56 (5) ◽  
pp. 680-684 ◽  
Author(s):  
Gerald Oliver Aspinall ◽  
Karl-Gunnar Rosell
Keyword(s):  
Uronic Acid ◽  
Gum Arabic ◽  
Hydroxyl Groups ◽  
Triphenyl Phosphite ◽  
Reaction Sequence ◽  
Selective Hydrolysis ◽  
Acidic Polysaccharides ◽  
Hydrolysis Of ◽  
Derivatives Of

The introduction of hex-5-enopyranoside residues into methylated acidic polysaccharides is effected by reduction of uronic acid residues, followed by reaction with triphenyl phosphite methiodide, and dehydroiodination. The selective hydrolysis of hex-5-enopyranosidic linkages with characterization of the 6-deoxyglycos-5-uloses thus formed and location of the aglyconic hydroxyl groups thus exposed has been demonstrated for methylated derivatives of birch xylan and gum arabic. The reaction sequence provides a new method for linkage analysis of acidic polysaccharides.

Selective hydrolysis of flavonoid glycosides by Curvularia lunata

2014 ◽  
Vol 11 (6) ◽  
pp. 684-689 ◽  
Author(s):  
Jing-Yuan LIU ◽  
He-Shui YU ◽  
Bing FENG ◽  
Li-Ping KANG ◽  
Xu PANG ◽  
...  
Keyword(s):  
Flavonoid Glycosides ◽  
Curvularia Lunata ◽  
Selective Hydrolysis ◽  
Hydrolysis Of

Theoretical Study of the Process of Passage of Glycoside Amides through the Cell Membrane of Cancer Cell

2020 ◽  
Vol 20 ◽  
Author(s):  
Vasil Tsanov ◽  
Hristo Tsanov
Keyword(s):  
Cell Membrane ◽  
Cancer Cells ◽  
Cancer Cell ◽  
Quantum Chemical ◽  
Density Functional ◽  
Enzyme Regulation ◽  
Amide Derivatives ◽  
Pass Through ◽  
Hydrolysis Of ◽  
Derivatives Of

Background:: This article concentrates on the processes occurring in the medium around the cancer cell and the transfer of glycoside amides through their cell membrane. They are obtained by modification of natural glycoside-nitriles (cyano-glycosides). Hydrolysis of starting materials in the blood medium and associated volume around physiologically active healthy and cancer cells, based on quantum-chemical semi-empirical methods, is considered. Objective:: Based on the fact that the cancer cell feeds primarily on carbohydrates, it is likely that organisms have adapted to take food containing nitrile glycosides and / or modified forms to counteract "external" bioactive activity. Cancers, for their part, have evolved to create conditions around their cells that eliminate their active apoptotic forms. This is far more appropriate for them than changing their entire enzyme regulation to counteract it. In this way, it protects itself and the gene sets and develops according to its instructions. Methods:: Derived pedestal that closely defines the processes of hydrolysis in the blood, the transfer of a specific molecular hydrolytic form to the cancer cell membrane and with the help of time-dependent density-functional quantum- chemical methods, its passage and the processes of re-hydrolysis within the cell itself, to forms causing chemical apoptosis of the cell - independent of its non-genetic set, which seeks to counteract the process. Results:: Used in oncology it could turn a cancer from a lethal to a chronic disease (such as diabetes). The causative agent and conditions for the development of the disease are not eliminated, but the amount of cancer cells could be kept low for a long time (even a lifetime). Conclusion:: The amide derivatives of nitrile glycosides exhibit anti-cancer activity, the cancer cell probably seeks to displace hydrolysis of these derivatives in a direction that would not pass through its cell membrane and the amide- carboxyl derivatives of nitrile glycosides could deliver extremely toxic compounds within the cancer cell itself and thus block and / or permanently damage its normal physiology.

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