[Determination of a major constituent in deoxyspergualin drug by reversed-phase ion-pair chromatography].

A method was established for the determination of deoxyspergualin using reversed-phase ion-pair chromatography (RP-IPC). Several parameters, such as the chromatographic column, the types and concentration of ion-pair reagents, the concentration of the buffer and the pH value of the mobile phase were evaluated. The optimal separation conditions were as follows: C18 column (250 mm x 4.6 mm, 5 microm); mobile phase, 5 mmol/L di-potassium hydrogen phosphate (containing 5 mmol/L 1-pentanesulfonic acid sodium, pH 3.6 +/- 0.3)-acetonitrile (90: 10, v/v); flow rate, 1.0 mL/min; detection wavelength, 210 nm; column temperature, 30 degrees C; injection volume, 20 microL. Under the optimaized experimental conditions, good linear relationships was obtained and the limit of detection for deoxyspergualin was 0.5 mg/L.

Dynamic selection of novel vancomycin N-terminal derivatives by resin-bound reversed D-Ala-D-Ala.

The most attractive advantage of dynamic combinatorial chemistry (DCC) is that it can screen the compound library as soon as compounds are synthesized. However, it is very difficult to analyze a dynamic combinatorial library with free probes using the state-of-the art analysis technologies. We report herein a method that uses a resin-immobilizing reversed peptide probe to screen vancomycin derivatives and provides a solution to this problem.

Solid-phase synthesis and antibacterial evaluations of N-demethylvancomycin derivatives.

Twenty-five N-demethylvancomycin derivatives were synthesized on solid-support and their structures were determined by LC-MS/MS. Biological evaluation of these compounds indicated that bulky hydrophobic substituent on vancosamine of N-demethylvancomycin can increase antibacterial activity against vancomycin-resistant Enterococcus faecalis.

[Chiral separation and preparation of three new antagonists of alpha 1-adrenoceptors by chiral mobile phase HPLC].

AIM: To establish new methods for the chiral separation and preparation of three new drugs, alfuzosin, terazosin and doxazosin. METHODS: By optimizing factors which affect the chiral separation, modifier of solvent, chiral additive, pH of mobile phase, modifier of organic base and stationary phase, the optimum condition for chiral separation were selected. The preparation of enantiomers was carried out on semi-preparative reverse phase column (7.8 mm x 250 mm C4 5 microns). Acetonitrile-water modified by the addition of carboxymethyl-beta-cyclodextrin (2%-5%, w/v) was applied as chiral mobile phase. RESULTS: The enantiomers of three new drugs were base-line-separated and milligram-scale samples of enantiomer were obtained. CONCLUSION: The newly established method can be used in research and development of the enantiomers of three new drugs.