Synthesis and properties of thermoplastic propyl-etherified amylose

Amylose was etherified with 1-bromopropane in DMSO. The degree of substitution (DS) was varied by altering the feed ratio of 1-bromopropane. The structures of the products were characterized by IR and 1H-NMR spectroscopy. When the molar feed ratio of 1-bromopropane to hydroxyl groups of amylose was beyond 7.5, the hydroxyl groups were completely substituted with propyl ether groups. The etherified amylose with DS 1.9 showed a glass transition temperature (T_g), and that with DS 2.3 or 3.0 showed both T_g and melting temperature (T_m) (DS 3.0 means complete substitution). The etherification imparted melt processability and solubility in nonpolar organic solvent to amylose.     

Solvatochromic Determination of Second-order Polarizabilities of Chromophore-functionalized Dextran and Amylose Derivatives

Linear dextran and helix amylose were covalently bonded with nonlinear optical (NLO) chromophores. The influence of the conformation of the polymer matrix on the NLO behavior of the supramolecular structure has been studied. The second order hyperpolarizability depends not only on the secondary structure of the biopolymer, but also on the position of the chromophore towards the polymeric backbone. Functionalization of NLO-phores with biopolymers led to increased thermo- and photostability.     

直链淀粉手性固定相对8种外消旋硫代缩水甘油醚的直接拆分

利用高效液相色谱进行不对称拆分是十分有效的方法,其中多糖类手性固定相是非常重要的一种,它主要包括纤维素和淀粉两大类,Ｏｋａｍｏｔｏ等［１～３］合成了大量的纤维素和直链淀粉的衍生物,并将其涂敷在大孔硅胶表面,从而制备了手性拆分能力较强的多种固定相,这类...     

Comparison of HPLC enantioseparation of substituted binaphthyls on CD‐, polysaccharide‐ and synthetic polymer‐based chiral stationary phases

Retention and enantioseparation behavior of ten 2,2′‐disubstituted or 2,3,2′‐trisubstituted 1,1′‐binaphthyls and 8,3′‐disubstituted 1,2′‐binaphthyls, which are used as catalysts in asymmetric synthesis, was investigated on eight chiral stationary phases (CSPs) based on β‐CD, polysaccharides (tris(3,5‐dimethylphenylcarbamate) cellulose or amylose CSPs) and new synthetic polymers (trans‐1,2‐diamino‐cyclohexane, trans‐1,2‐diphenylethylenediamine and trans‐9,10‐dihydro‐9,10‐ethanoanthracene‐(11S,12S)‐11,12‐dicarboxylic acid CSPs). Normal‐, reversed‐phase and polar‐organic separation modes were employed. The effect of the mobile phase composition was examined. The enantiomeric separation of binaphthyl derivatives, which possess quite similar structures, was possible in different enantioselective environments. The substituents and their positions on the binaphthyl skeleton affect their properties and, as a consequence, the separation system suitable for their enantioseparation. In general, the presence of ionizable groups on the binaphthyl skeleton, substitution with non‐identical groups and a chiral axis in the 1,2′ position had the greatest impact on the enantiomeric discrimination. The 8,3′‐disubstituted 1,2′‐binaphthyl derivatives were the most easily separated compounds in several separation systems. From all the chiral stationary phases tested, cellulose‐based columns were shown to be the most convenient for enantioseparation of the studied analytes. However, the polymeric CSPs with their complementary behavior provided good enantioselective environments for some derivatives that could be hardly separated in any other chromatographic system.     

高效液相色谱的4种商品手性柱对38种手性化合物的拆分研究

采用纤维素-三(3,5-二甲基苯基氨基甲酸酯)涂敷型手性固定相(Chiralcel OD柱)、直链淀粉-三(3,5-二甲基苯基氨基甲酸酯)涂敷型手性固定相(Chiralpak AD柱)、直链淀粉-三(3,5-二甲基苯基氨基甲酸酯)键合型手性固定相(Chiralpak IA柱)和Pirkle型的(S,S)-Whelk-01手性固定相对38种外消旋体化合物进行手性拆分。实验结果表明,4种固定相的手性识别能力为:OD>AD>IA>(S,S)-Whelk-01,OD固定相的手性识别率达到60%,并且它们之间的手性识别性能还具有一定的互补性。本研究对4种常用手性固定相的拆分能力进行了对比,为拆分手性化合物时有的放矢地选择手性固定相提供了参考。     

Enantiospecific resolution of rabeprazole by liquid chromatography on amylose-derived chiral stationary phase using photo diode array and polarimetric detectors in series

A simple and rapid liquid chromatographic method for enantioselective separation and determination of R-(+) and S-(−) enantiomers of rabeprazole in drugs and pharmaceuticals using photo diode array (PDA) and polarimetric detectors connected in series was developed. Chiralpak AD-H (250 mm × 4.6 mm) 5 μm column packed with amylose tris(3,5-dimethylphenyl carbamate) as a stationary phase and the mobile phase containing n-hexane:ethanol:2-propanol(75:15:10, v/v/v) in an isocratic mode has yielded baseline separation with resolution greater than 3.0 at 40 °C. Effects of ethanol, 2-propanol and temperature on separation were studied for optimum resolution. Lansoprazole sulphone was used as an internal standard (IS) for quantitative determination of individual enantiomers in bulk drugs as well as pharmaceutical formulations. The method was validated in terms of accuracy, precision and linearity according to ICH guidelines. The linearity of the method was studied in the range of 0.5-50 μg/ml and the r² was >0.9997. The inter- and intra-day precision of assay were determined (R.S.D. < 1%) and the recoveries were in the range of 99.63-100.22% with <1% R.S.D. The limits of detection (LOD) and quantification (LOQ) were 0.02 μg/ml and 0.07 μg/ml for both the enantiomers, respectively.     

双波长分光光度法测定河北省多种粮豆作物中直、支链淀粉含量

本文采用双波长分光光度法对河北省不同地区多种粮食豆作物中直,支链淀粉的含量进行了测定,并探讨了杂粮中不同淀粉含量与糖尿病食疗的关系。     

Enantioseparation of novel chiral tetrahedrane-type clusters on an amylose tris (Phenylcarbamate) chiral stationary phase

Summary Amylose tris(phenylcarbamate) (ATPC) coated on a small particle silica gel was prepared. This ATPC chiral stationary phase (ATPC-CSP) was found to be useful for the enantiomeric separation of some novel chiral tetrahedrane-type clusters. Moreover, the influence of mobile phase modifier and of the structure of chiral tetrahedrane-type clusters on the chiral separation and retention were investigated. The results suggest that not only the structure and concentration of alcohol in mobile phase, but also the subtle structural differences in racemates can have a pronounced effect on enantiomeric separation and retention.     

Colonic drug delivery using amylose films: the role of aqueous ethylcellulose dispersions in controlling drug release

Amylose, a plant polysaccharide from starch, can be combined with ethylcellulose to produce a film coating capable of effecting colon specific drug release from a dosage form through bacterial fermentation of the amylose component. Ethylcellulose is present in the system as a structuring agent in the form of the aqueous dispersion Surelease^® grade EA-7100. There are, however, two other grades of Surelease^® (E-7-7050 and E-7-19010), which vary slightly in terms of their composition. The aim of the study was to establish whether these grades differ in their drug release profiles, when used as a film coat, either as one-component coatings, or in combination with amylose. The dissolution profiles of Surelease^® coated pellets were investigated and it was found that there was no difference between the grades when used as coating materials on their own. However, when used in combination with amylose, it was found that grade EA-7100 showed retardation of drug release in simulated upper gastro-intestinal (GI) conditions, whereas grades E-7-7050 and E-7-19010 did not limit the release to the same extent. E-7-19010 showed very poor controlled release properties when combined with amylose. These differences could not be attributed to the minimum film forming temperature (MFT) of the coating formulation, which was found to be independent of the grade of Surelease^®. It was also confirmed that the film coated pellets prepared from amylose and EA-7100 showed good release in human faecal slurry, i.e. simulated colonic conditions. It was concluded that the grades of Surelease^®, when combined with amylose, are not interchangeable.     

Interpretation of chromatographic retentions of simple solutes with an amylose-based sorbent using infrared spectroscopy and DFT modeling

The interactions of amylose tris(3,5-dime- thylphenylcarbamate) (ADMPC, commercially “Chiralpak AD”) with 10 simple solutes—1-propanol, heptane, heptanol, benzene, propylbenzene, benzyl alcohol, pyridine, tetrahydrofuran, diethylamine, and aniline—are studied using attenuated total reflection infrared spectroscopy (ATR-IR) of thin polymer films, DFT modeling, and high performance liquid chromatography (HPLC). ATR-IR is used to determine the changes in the hydrogen bonding states of the C=O and NH groups of the polymer amide I and II bands upon absorption of each of the solutes at 25^∘C. DFT modeling with B3LYP/6-311+g(d,p) level of theory is used to predict the IR wavenumbers, the H-bonding interaction energies, and the hydrogen bonding distances of the polymer side-chains with certain solute molecules. The capacity factors of these solutes with ADMPC have been measured at 25^∘C in hexane/isopropanol (95/5, v/v) solvent. From IR data and DFT modeling, we conclude that the C=O and NH are key binding sites of the polymer and interact with the functional groups of various solutes. The capacity factors are understood on the basis of hydrogen bonding, hydrophobic, and dipole-dipole interactions of the C=O, NH, and phenyl groups of the sorbent with OH, NH, NH₂, O, phenyl, and N functional groups of the solutes.