Use of a hepta-Tyr antibiotic modified silica stationary phase for the enantiomeric resolution of D,L-loxiglumide by electrochromatography and nano-liquid chromatography.

Hepta-Tyr antibiotic modified silica stationary phase was used for the chiral resolution of D,L-loxiglumide, a new drug under investigation proposed for the treatment of gastrointestinal diseases. The chiral stationary phase was packed into fused silica capillaries of 75 microm i.d. for a length of only 7 cm and used for both capillary electrochromatography (CEC) and nano-liquid chromatography (nano-LC) running the experiments with the same instrumentation; in order to increase the electroosmotic flow (EOF) the antibiotic stationary phase was mixed with amino-silica particles (3:1, w/w) generating a relatively high reversed EOF. The enantiomeric resolution of loxiglumide by CEC was strongly influenced by several experimental parameters such as applied electric field, mobile phase composition, capillary temperature, etc. Optimum experimental conditions were found applying 15 kV at 20 degrees C and eluting with acetonitrile-sodium phosphate buffer at pH 6 (1:1, v/v). The same capillary was tested for nano-LC experiments. Good chiral separation of loxiglumide was achieved selecting the appropriate mobile phase considering the type and concentration of organic modifier. The nano-LC optimised method was therefore validated and applied to the analysis of a pharmaceutical formulation declared to contain only D-loxiglumide.

Effect of Dai-kenchu-to (Da-Jian-Zhong-Tang) on the delayed intestinal propulsion induced by chlorpromazine in mice.

This study was conducted to evaluate the effect of Dai-kenchu-to on chlorpromazine-induced hypoperistalsis in mice. Oral administration of Dai-kenchu-to (30-300 mg/kg) dose-dependently improved small intestinal and distal colonic propulsion decreased by chlorpromazine (3 mg/kg, p.o.). Although the improvement of small intestinal propulsion due to Dai-kenchu-to was partially inhibited by atropine (1 mg/kg, s.c.), this action was completely inhibited by the concomitant administration of lorglumide (10 mg/kg, i.p.), a CCKA receptor antagonist. The distal colonic propulsion-improving effect of Dai-kenchu-to was abolished by atropine (1 mg/kg, s.c.). When the effects of the respective components of Dai-kenchu-to were evaluated, oral administration of Zanthoxylum Fruit improved both delayed small intestinal and distal colonic propulsion caused by chlorpromazine. On the other hand, Malt Sugar was effective against only delayed small intestinal propulsion. The action of Zanthoxylum Fruit was completely inhibited by atropine (1 mg/kg, s.c.), and the effect of Malt Sugar was inhibited by lorglumide (10 mg/kg, i.p.). These results demonstrated that Dai-kenchu-to improves chlorpromazine-induced hypoperistalsis via cholinergic systems and that Zanthoxylum Fruit is the main contributor to this action of Dai-kenchu-to. In addition, endogenous CCK due to Malt Sugar may also contribute to this effect of Dai-kenchu-to.

Resolution of (RS)-proglumide using lipase from Candida cylindraceae.

Proglumide is used in the treatment of neuropathic pain. It acts by inhibiting peptide cholecystokinin (CCK). Neural injury produces an elevation in plasma CCK. Proglumide has been also shown to augment the analgesic effect of sustained release morphine in neuropathic pain. Currently proglumide is administered as a racemic mixture. In the present study, an attempt is made to separate the racemic mixture of the drug using lipase obtained from Candida cylindracea by stereoselective esterification. Enzymatic stereoselective esterification was carried out in organic solvents. The resolution was studied using a chromatographic column with a chiral support and mass spectrometry. The reaction conditions for stereoselective esterification including amount of substrate, amount of enzyme, alcohol, solvent and temperature were optimised during the present investigation. Butanol and hexanol were found to be suitable for formation of S and R esters, respectively. Hexane was the best solvent for esterification and the optimum temperature was found to be 30 degreesC.