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Explanation of Enantioseparation of Amino Acid Derivatives in Gas Chromatography and the Mechanism of Supermolecular Compounds of Cyclodextrins and Chloamphenicol

Author: ZhuHuaiQin
Tutor: FengZuo
School: Beijing University of Chemical Technology
Course: Chemical Engineering and Technology
Keywords: Cyclodextrin Chiral Separation Gas Chromatography Molecular dynamics simulations Chloromycetin Inclusion Complex
CLC: TQ461
Type: Master's thesis
Year: 2010
Downloads: 191
Quote: 2
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Abstract

Cyclodextrin preparation, properties, and applications made tremendous progress since the advent of β-cyclodextrin (β-CD) 1903, has been widely used in many fields, such as medicine, food, environmental protection, analysis chemistry, supramolecular chemistry together, and this is the forefront of today's chemical research areas. Cyclodextrin due to its special structure, as the supramolecular host more attention has been paid. Cyclodextrin is a combination of α-1, 4 glycosidic bond by a plurality of D-glucose units arranged in a class of cyclic oligosaccharides, cyclodextrins family mainly includes three cyclic oligosaccharide, that is, the α-CD , β-CD and γ-CD. Cyclodextrin is a tapered cylindrical hollow structure, and internal ether bond and a hydrocarbon bond, the outer surface containing a hydroxyl group, so that the interior of the cavity to render a hydrophobic external hydrophilic characteristics. Cyclodextrin and its derivatives, the topic for the host molecules, to do the work of the following two aspects: 1 to study the molecular dynamics simulations of permethylated cyclodextrin stationary phase gas chromatography chiral separation of amino acids derivatives; 2 the nature and mechanism of inclusion complexes of cyclodextrin with chloramphenicol. 1, enantiomer separation and analysis in the field of modern biochemistry, pharmaceutical chemistry and organic synthetic chemistry has a very important significance chiral chromatography as a fast and convenient, accurate and sensitive methods of separation and analysis of enantiomers In recent years, rapid development and wide application. Cyclodextrin and its derivatives have a wide range of chiral recognition ability of cyclodextrins and their derivatives as chiral stationary phase gas chromatography in recent years, gained widespread attention. However, the current lack of a broad interpretation of its chiral recognition phenomenon better method, proposed the application of molecular dynamics simulations to study the mechanism of chiral recognition, from the molecular level to elaborate the nature of chiral recognition, understanding hand sexual recognition of part of its force on the stationary phase. This part of the study a full-methyl-β-cyclodextrin as GC stationary phase separation of amino acid derivatives in methyl-β-cyclodextrin and an amino acid derivative molecular recognition process to obtain a conclusion consistent with the experimental . This section include the following: (1) the application of molecular docking and MD simulation of the amino acid derivative N-TFA-AAA-OEt full-methyl-β-cyclodextrin (PM-β-CD) as well as with the interval chiral recognition of the group methyl-β-cyclodextrin (MUPM-β-CD), has been retained sequential chromatography experiments consistent enantiomer. The simulated results: the sites of action of enantiomeric molecules with cyclodextrins, methyl-β-cyclodextrin cavity interior; chiral recognition process for the the different enantiomers molecule, the existence of different hand separation of the dominant driving force; conformation induced matching process can also occur simultaneously, amino acid derivative the enantiomers with cyclodextrins conformation during induction stereoselective. (2) Analog also examined closer with the experimental conditions of the simulated system, i.e., a main body of the system of the molecules on a plurality of guest molecules. Specifically, the simulation system comprises a MUPM-beta-CD molecule, D-type and L-type molecules 10. Centroid distance and frequency of distribution by the energy in the competitive binding process MUPM-β-CD molecule and the 10 D-type and 10 of the L-type molecules, can well explain the experimental results, and can and experimental data are consistent . (3) through a different body (PM-β-CD and MUPM-beta-CD) for the chiral recognition of the N-TFA-AAA-OEt study found that: a main body for the PM-β-CD on the N-TFA-AAA the-OEt chiral recognition than the latter more in line with the experimental data. Thus, in the cyclodextrin as chiral separation of the main chromatographic separation cyclodextrin for chiral separation of the role of center. 2 to this section to the insoluble drug chloramphenicol as a model drug, β-cyclodextrin and hydroxypropyl-β-cyclodextrin inclusion material prepared chloramphenicol clathrate, preferably screened clathrate material is hydroxypropyl-β-cyclodextrin. And the use of molecular dynamics simulation method simulation study the cyclodextrin drug molecules chloramphenicol inclusion process, from the atomic level to conduct a study of the the role sites and the inclusion way. This section mainly include the following: Two Cyclodextrins in cooperation with the chloramphenicol drug package, using ultraviolet spectrophotometry, infrared spectrophotometry and phase solubility method of cooperation package between the host and guest molecules with inclusion ratio, inclusion spatial configuration. The results show that β-cyclodextrin and hydroxypropyl-β-cyclodextrin with chloramphenicol are formed in the solution a soluble complex of 1:1 molar ratio, and hydroxypropyl-β-cyclodextrin The effect is more obvious; confirmed by UV spectrophotometry spectrophotometry and infrared spectrophotometry study, β-cyclodextrin and hydroxypropyl-β-cyclodextrin to form inclusion complexes with chloramphenicol, and hydroxypropyl - β-cyclodextrin inclusion with more stability. In addition, the use of the simulation method of molecular dynamics simulations to study the environment of the three solutions (pure water system, 10% aqueous ethanol system, as well as 20% aqueous ethanol system) of chloramphenicol and β-CD and HP-β-CD package and process, and compared with the experimental results, the experimental results are consistent simulation conclusion.

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