Fully automated high-performance liquid chromatographic separation of DL-amino acids derivatized witho-phthaldialdehyde together withN-isobutyryl-cysteine. Application to food samples

Summary A method is presented that enables the fully automated precolumn derivatization of mixtures of DL-amino acids (DL-AA) witho-phthaldialdehyde together withN-isobutyryl-L(orD)-cysteine. HPLC on a 250 mm×4 mm i.d. column packed with Shandon Hypersil ODS, 5 μm, and a linear gradient formed from 23 mM sodium acetate (pH 6.0) and methanol/acetonitrile (600 ml+50 ml) separates completely an AA standard composed of 17 pairs of DL-AA (including Asn and Gln), Gly and the internal standard L-homo-Arg, within 75 min at a flow rate at 1 ml/min. Applications are shown of the determination of free D-AA isolated from an orange juice concentrate and from soy sauce, and the detection of D-AA in a gelatine total hydrolysate. In the case of these foodstuffs fluorescence detection (excitation at 230 nm, emission at 445 nm) allows the routine detection of 5–10 pmol per AA; and approx. 0.2–1% D-AA, in an excess of L-AA, are quantifiable. Presented in part at the “International Symposium on Separation of Peptides, Proteins and Polynucleotides”, October 29–31, 1990, Wiesbaden (abstract 620), ANAKON '91, April 22–24, Baden-Baden (abstract C 5), and at the “15th International Symposium on Column Liquid Chromatography”, June 3–7, 1991, Basel (abstract P26/2).     

Resolution of amine enantiomers using precolumn derivatization with dansyl-L-proline and reversed-phase liquid chromatography

A derivatization procedure was developed for converting enantiomeric amino acids, amino alcohols and amines into diastereoisomers for resolution by liquid chromatography. Dansyl-L-proline (DLP) was used as a chiral reagent for the precolumn derivatization of many enantiomeric compounds bearing primary and secondary amino groups. The diastereoisomeric amides that were formed in the presence of diethyl phosphorocyanidate can be resolved efficiently on a conventional reversed-phase column. The resolution was optimized by varying the mobile phase. Intramolecular hydrogen bonding of the diastereoisomeric amide is shown to be very important for the efficient resolution of enantiomers. The detection limits for DLP derivatives were 4 × 10^?14?5 × 10^?14 mol.     

Enantioseparation of α-phenylglycine by HPLC on an ODS column coated with chiral crown ether

Summary Previous work has demonstrated the possibility of crcating chiral stationary phases by coating a suitable support material via the mobile phase. The result is a wide variety of chiral phase systems which can be used in liquid chromatogrphy to separate enantiomers by a liquid-solid adsorption mechanism. The present paper demonstrates the potential of this technique for chiral crown ethers incorporating an -D-mannopyranoside unit using the separation of phenyglycine enantiomers as an example.     

Synthesis of 1-(dihydroxypropyl)-5-substituted uracils

Novel 1-(dihydroxypropyl)-5-substituted uracils were synthesized in the reaction of 1-(4-nitrophenyl)-5-substituted uracil derivatives with appropriate aminopropanediols under mild conditions. In the case of 3-amino-1,2-propanediol both racemic and enantiomerically enriched products were obtained. These compounds may be considered as new building blocks for oligonucleotide synthesis.     

低剂量氯化钐对大鼠血清激素水平的影响

应用放射免疫法测定了经腹腔注射、灌胃入尾静脉注射等３种不同方式，隔日给预寺鼠低剂量氯化钐０．０５ｍｇ／ｋｇ，一个月后，测试血清中生长激素，甲状腺素Ｔ３、Ｔ３及胰岛素水平。结果显示各实验组动物血清中生长激素、胰岛素水平均明显增高，甲状腺素Ｔ４及腹腔注射增高，其余两组无明显变化。     

Synthesis of 1,3,5-triazabicyclo[3.1.0]hexanes containing the fragments of α-amino acids and their esters at the N(3) atom

With 3,3-pentamethylene-1,2H-diaziridine as an example, it was shown that 3,3-dialkyl-1,2H-diaziridines can undergo cyclocondensation with -amino acids and their esters to give the corresponding N(3)-substituted 1,3,5-triazabicyclo[3.1.0]hexanes, including pure enantiomers.     

Heliflex chirasil-Val; GC of amino acid enantiomers

Heliflex Chirasil-Val, a modified form of the original Chirasil-Val phase coated on fused silica capillary, has been investigated with regard to its resolution efficiency and the separation profile for various enantiomeric derivatives of amino acid. The best results could be obtained with TFA-Et derivatives by reason of the relatively low column temperature required.     

Resolution of enantiomers of ketoprofen by HPLC: a review

Today, a heightened awareness of the applicability of enantiomers in medicine and clinical practice has been gene-rated due to the continuous evolvement of the field of chirality. In this context, this article provides a review of separation of ketoprofen, an important drug, in a popular class of non-steroidal anti-inflammatory drugs (i.e. profens). This review highlights various methodologies, logistical considerations for separation and provides an exhaustive list of applications mainly focusing on the pharmacokinetic aspects. Clearly, the application of enantioselective methods for drug racemates paves the way to understand the in vivo behavior of individual enantiomer and hence an opportunity for an alternate and/or better option for treating the disease.