Structural analysis of N-linked carbohydrate chains of funnel web spider (Agelenopsis aperta) venom peptide isomerase

The structure of the N-linked carbohydrate chains of peptide isomerase from the venom of the funnel web spider (Agelenopsis aperta) has been analyzed. Carbohydrates were released from peptide isomerase by hydrazinolysis and reductively aminated with 2-aminopyridine. The fluorescent derivatives were purified by phenol/chloroform extraction, followed by size-exclusion HPLC. The structure of the purified pyridylamino (PA-) carbohydrate chains were analyzed by a combination of two-dimensional HPLC mapping, sugar composition analysis, sequential exoglycosidase digestions, and mass spectrometry. The peptide isomerase contains six kinds of N-linked carbohydrate chains of truncated high-mannose type, with a fucose alpha 1-6 linked to the reducing N-acetylglucosamine in approximately 80% of them.

Stable capillary coating with successive multiple ionic polymer layers

A stable modification of the inner wall of a fused silica capillary was established by a simple coating procedure, successive multiple ionic-polymer layer (SMIL) coating. An anionic polymer was tightly fixed to the capillary wall by the SMIL coating, in which a cationic polymer was sandwiched between the anionic polymer and the uncoated fused silica capillary by noncovalent bonding. The SMIL-coated capillary showed a long lifetime. The endurance of the SMIL-coated capillary was more than 100 runs, and it was also tolerant to organic solvents, 1 M NaOH, and a surfactant. The coating efficiency did not depend on capillary sources, and the relative standard deviation of capillary-to-capillary reproducibility was less than 1%. In this study, dextran sulfate (DS) was used as the anionic polymer, and Polybrene was used as the cationic polymer for SMIL modification. The DS-modified capillary (SMIL-DS capillary) exhibited a pH-independent electroosmotic flow (EOF) from anode to cathode in the pH range of 2-11. The SMIL-DS capillary showed good performance for acidic protein analyses under physiological conditions (pH 7.4). Also, the presence of EOF under acidic conditions permitted new applications. Simultaneous separations of cationic, anionic, and neutral amino acids were achieved by capillary zone electrophoresis, and separations of cresol isomers were achieved by micellar electrokinetic chromatography under the acidic conditions. The SMIL-DS capillary was also useful for fast and precise determination of the pKa of acidic functional groups.

Release behavior of poly(lactic acid-co-glycolic acid) implants containing phosphorothioate oligodeoxynucleotide

The release behavior of phosphorothioate oligodeoxynucleotide, 5'-GCCGAGGTCCATGTCGTACGC-3' (ODN), from poly(lactic acid-co-glycolic acid) (PLGA) implant was studied. The pillar shape implant was fabricated by the heating mold method. About 20% of ODN were released initially, and the subsequent pseudo-zero-order release lasted for more than 20 d from a PLGA10000 implant loaded with 8.4% ODN in phosphate buffered saline, pH 7.4. The duration of ODN release did not depend on the molecular weights of PLGA, and pseudo-zero-order release may be achieved by changing the loaded amount of ODN in fabrication of the PLGA implant. Almost the same release profiles were obtained in the pH range of 7.2 to 7.6, which is known as the physiological pH of a vitreous body. Furthermore, the duration of intact ODN release in bovine vitreous was found. The implant in the present study may possibly be applicable to intravitreal implantation for the treatment of ocular disease.

Simultaneous quantitative determination method for sphingolipid metabolites by liquid chromatography/ionspray ionization tandem mass spectrometry

Sphingolipid metabolites ceramide, sphingomyelin, sphingosine, psycosine, sphingosylphosphorylcholine, and dimethylsphingosine were separated and simulataneously quantitated by liquid chromatography/ionspray ionization tandem mass spectrometry (LC/MS/ MS). The use of glassware throughout minimized losses due to adsorption and the pretreatment of this method consisted of simple liquid-liquid extraction procedure with a mixture of chloroform and methanol. After separation on a short C18 silica column eluted in a gradient mode, the metabolites were detected by MS/ MS. This assay allows simultaneously quantification of these metabolites over a range of at least 0.1 to 100 ng/ 10(6) cells. The LC/MS/MS analyses took 10 to 15 min per sample and we could examine up to 50 samples per day. We also detected endogenous sphingosine 1-phosphate in HL-60 cells. The utility of the method was demonstrated by examining changes in metabolites levels in HL-60 cells after treatment with sphingomyelinase. It was found that sphingomyelinase from Bacillus cereus may have selectivity for acyl chain length.

Plasma direct injection high-performance liquid chromatographic method for simultaneously determining E3810 enantiomers and their metabolites by using flavoprotein-conjugated column

A high-performance liquid chromatographic method using the column-switching technique was developed for the simultaneous determination of E3810 and its metabolites (M1-M4). An avidin column was used for in-line pretreatment to exclude plasma proteins, allowing direct injection of a large volume of plasma. A flavoprotein-conjugated chiral stationary phase in a gradient elution mode then gave baseline separation of E3810 and the four metabolites. The enantiomers of E3810 and M3 were also separated. The method is simple, rapid, accurate, and precise. Since no extraction procedure is employed, which might involve different recoveries of different metabolites, no internal standard is necessary. The method was applied to analyze E3810 and its metabolites in plasma after intravenous injection of the drug in beagle dogs.

Synthetic cationic amphiphile for liposome-mediated DNA transfection with less cytotoxicity

A cationic peptide amphiphile comprising an L-alanine residue interposed between a charged head group and a double-chain segment, N,N-dihexadecyl-N alpha-[6-(trimethylammonio)- hexanoyl]-L-alaninamide bromide (NC5Ala2C16), was synthesized and used to prepare sonicated liposomes. We examined the efficiency of this liposome in gene transfer according to the transient expression of chloramphenicol acetyltransferase (CAT). This cationic liposome reagent facilitates efficient DNA transfection in COS-7 cells. We determined the optimum conditions for NC5Ala2C16 liposome-mediated transfection. The optimal amounts of the amphiphile and plasmid DNA were determined to be about 100 micrograms and 10 micrograms per 35-mm dish, respectively. The activity of this liposome was greater than that of commercial reagents, lipofectin, and N-[1-(2,3-dioleoyloxy)propyl]-N,N,N-trimethyl-ammonium methylsulfate (DOTAP), and it was less toxic than lipofectin and DOTAP in COS-7 cells.

Mechanism of inhibition of H+, K(+)-ATPase by sodium 2-[[4-(3- methoxypropoxy)-3-methylpyridin-2-yl]methylsulfinyl]-1H-benzimidazole (E3810)

Sodium 2-[[4-(3-methoxypropoxy)-3-methylpyridin-2-yl]methylsulfinyl ]- 1H-benzimidazole (E3810) and omeprazole inhibit gastric acid secretion through inhibition of the activity of H+, K(+)-ATPase present in parietal cell membrane vesicles, by chemical modification of SH groups in the enzyme molecule. In order to clarify the mechanism of the chemical modification, reaction products of E3810 and omeprazole with 2-mercaptoethanol under acidic conditions (pH 3, 4, 5, 6) were isolated by HPLC, and subjected to structural analysis by UV, 1H-NMR and mass spectrometry. E3810 and omeprazole appeared to undergo two kinds of reactions, affording disulfide-type products (type I reaction) and sulfide-type products (type II reaction). The rates of these reactions were determined by HPLC, and the stability of the products in the presence and absence of glutathione was investigated. In the case of E3810, type I reaction was found to proceed faster than type II reaction at every pH value studied. The type I reaction of E3810 was faster than that of omeprazole. The rate of type I reaction decreased at pH 5 and 6, especially for omeprazole, and the contribution of type II reaction increased as the pH of the reaction mixture was increased. The sulfide-type modification products were stable, whereas the formation of the disulfide-type modification products was reversed by the action of endogenous SH compounds such as glutathione. These results suggest that higher inhibitory activity of E3810 against gastric acid secretion and faster recovery of the enzyme activity after inhibition by E3810 can be expected, as compared with those of omeprazole.

Enantioselective high-performance liquid chromatographic assay for determination of the enantiomers of a new anti-ulcer agent, E3810, in beagle dog plasma and rat plasma

An enantioselective high-performance liquid chromatographic method for the determination of E3810, a new anti-ulcer agent, in Beagle dog plasma and rat plasma has been developed. After extraction from plasma with ethyl acetate, E3810 enantiomers were measured by reversed-phase high-performance liquid chromatography on a Chiralcel OD-R column. The enantiomers were detected by ultraviolet absorbance detection at 290 nm. The recoveries of E3810 enantiomers and internal standard were greater than 91%. The calibration curves were linear from 0.03 to 20 micrograms/ml for Beagle dog plasma and from 0.1 to 100 micrograms/ml for rat plasma. The limits of quantification of both enantiomers were 0.03 micrograms/ml for Beagle dog plasma and 0.1 micrograms/ml for rat plasma. The intra- and inter-day accuracy and precision data showed good reproducibility of the method. The assay was applied for the analysis of E3810 enantiomers in plasma after intravenous administration of racemic E3810 to Beagle dogs and rats. This method should be very useful for enantioselective pharmacokinetic studies of E3810.

Quantitation of platelet-activating factor in biological samples using liquid chromatography/mass spectrometry with column-switching technique

A procedure is described for the fully automated quantitative determination of platelet-activating factor (PAF) using liquid chromatography/fast atom bombardment mass spectrometry (LC/FAB-MS) with two types of column-switching techniques. Various parameters in LC/FAB-MS were optimized, and the use of a microbore column allowed highly selective detection of PAF. A column-switching system was incorporated to minimize band broadening and to increase the permissible injection volume. Analysis of authentic PAF indicated that the limit of quantitation was at the low picogram level (about 50 pg/ml). Another system using both a strong cation-exchange column and an ODS column in tandem was developed for the analysis of PAF in blood samples. These methods were validated with standard samples and applied to the determination of PAF in human polymorphonuclear neutrophils stimulated by addition of a calcium ionophore and in human blood.

Kinetic study on the inhibition of acetylcholinesterase by 1-benzyl-4-[(5,6-dimethoxy-1-indanon)-2-yl]methylpiperidine hydrochloride (E2020)

E2020 (1-benzyl-4-[(5,6-dimethoxy-1-indanon)-2-yl]methylpiperidine hydrochloride) is currently being developed as a treatment for senile dementia of the Alzheimer type. Its mechanism of action is to increase central cholinergic activity by inhibiting acetylcholinesterase (AChE) in the brain. In this study, the kinetics of the inhibitory action of E2020 on AChE was examined in comparison with its derivatives (2A1050 and 2A1034) and the reference compound tetrahydroaminoacridine (THA) all of which have a similar action. Analysis of the data using Lineweaver-Burk plots shows that inhibition by the test compounds fell into the category of mixed type. Inhibitor dissociation constants for the free enzyme (KI) and acetyl-enzyme (KI) of E2020 are one or two orders of magnitude lower than those of 2A1050, 2A1034 and THA. These findings indicate the strong inhibitory effect of E2020 on AChE.

Direct determination of E2020 enantiomers in plasma by liquid chromatography-mass spectrometry and column-switching techniques

High-performance liquid chromatography with column switching and mass spectrometry (MS) was applied to the on-line determination and resolution of the enantiomers of E2020 (acetylcholinesterase inhibitor) in plasma. This system employs two avidin columns and fast atom bombardment (FAB)-MS. A plasma sample was injected directly into an avidin trapping column (10 mm x 4.0 mm I.D.). The plasma protein was washed out from the trapping column immediately while E2020 was retained. After the column-switching procedure, E2020 was separated enantioselectivity in an avidin analytical column. The separated E2020 enantiomers were specifically detected by FAB-MS without interference from metabolites of E2020 and plasma constituents. The limit of quantification for each enantiomer of E2020 in plasma was 1.0 ng/ml and the intra- and inter-assay relative standard deviations for the method were less than 5.2%. The assay was validated for enantioselective pharmacokinetic studies in the dog.

Microscale determination of dissociation constants of multivalent pharmaceuticals by capillary electrophoresis

Dissociation constants (pKaS) of acidic, basic, and amphoteric pharmaceuticals were exactly determined by capillary electrophoresis. A general equation for use in calculation of pKaS from solute mobilities observed at different pHs was derived to be suitable for a multivalent compound with close pKaS such as angiotensins, which are bioactive octa- or decapeptides. The obtained pKa values were highly consistent with the values determined by conventional methods. For verapamil, the detection limit was 9.8 microM (49 fmol), the total analysis time was 12 min, and the relative standard deviation of the obtained pKa value was 0.11%. This method was also applicable to a mixture of two components, e.g., a bioactive compound and the prodrug, because they have different mobilities and are separated from each other.

Correlation of octanol-water partition coefficients with capacity factors measured by micellar electrokinetic chromatography

Micellar electrokinetic chromatography (MEKC) was used to measure hydrophobicity of 18 aromatic compounds. The capacity factors, which are proportional to the micelle-water distribution coefficients, were closely correlated with the octanol-water partition coefficients. The addition of Brij 35 to the charged micelle was effective in improving the correlation because the surface charges of the micelle were shielded.

Resolution of 4-(4-chlorobenzyl)-2-(hexahydro-1-methyl-1H-azepin-4yl)-1(2H)-phthalazi none enantiomers in plasma with frit-FAB LC-MS using a conalbumin column

A new column-switching method for analysis of drug enantiomers in plasma has been developed with liquid chromatography-frit fast atom bombardment mass spectrometry in combination with a chiral resolution column, which consists of conalbumin (egg-white glycoprotein) immobilized on silica gel and can be used in the reversed-phase separation mode. This method makes it possible to inject a large volume of deproteinized plasma and obtain resolution of drug enantiomers with high sensitivity. The optimum mobile phase, including a non-volatile buffer such as phosphate buffer, for separation of drugs from a large amount of endogenous compounds can be used, because of inclusion of a trapping column with a desalting function. This method is very simple and rapid, and should be very powerful in studies requiring high-sensitivity analysis with chiral separation of drugs from biological samples such as plasma.

Adjuvant-independent enhanced immune responses to recombinant herpes simplex virus type 1 glycoprotein D by fusion with biologically active interleukin-2

A truncated herpes simplex virus (HSV) type 1 glycoprotein D (t-gD) gene was fused to the human interleukin-2 (IL-2) gene (t-gD-IL-2 gene) and introduced into mouse myeloma Sp2/0 cells. The gene product, t-gD-IL-2, secreted from the cells was immunoprecipitated with five monoclonal antibodies specific for native gD. Purified t-gD-IL-2 supported the growth of IL-2-dependent cells, with a specific activity almost comparable to that of recombinant human IL-2. Mice immunized with t-gD-IL-2 in an adjuvant-free form showed superior anti-HSV antibody responses, and were completely protected against HSV challenge, whereas immunization with t-gD adsorbed onto aluminum hydroxide (alum) partially failed to prevent the virus infection. The high immunogenicity of t-gD-IL-2 was due to the biological activity of the fused IL-2 rather than to a hapten-carrier effect of the IL-2 moiety, because mice primed with t-gD-IL-2 showed delayed-type hypersensitivity against stimulation with gD, but not against that with IL-2 antigen, and because a booster immunization with t-gD-IL-2 extensively augmented the response of anti-gD antibody, but not that of the anti-human IL-2 antibody. The serological half-life of IL-2 activity in mice injected with t-gD-IL-2 was prolonged to about four times that of rIL-2. However, when t-gD-IL-2 was co-administered with human albumin (HSA), the mouse anti-HSA antibody response was slightly enhanced.(ABSTRACT TRUNCATED AT 250 WORDS)

Conalbumin-conjugated silica gel, a new chiral stationary phase for high-performance liquid chromatogaphy

A new chiral stationary phase using conalbumin (from chicken egg white) was developed for high-performance liquid chromatography. Chiral resolution of racemic azelastine, an antiallergic drug, was achieved on a conalbumin-conjugated silica gel column. The effects of the pH, the concentration of organic solvents and salts in the mobile phase, and the temperature on the capacity factor and resolution of racemic azelastine were examined. This column shows good stability and can separate optical isomers with an aqueous mobile phase. It should be very useful in studies on pharmacokinetics and in clinical chemistry.

[Effect of cefclidin and E1077, new cephalosporins, on the alcohol-metabolizing system in rats]

Administration of latamoxef and cefoperazone, reported to act like disulfiram in humans, caused a depression of mitochondrial low Km aldehyde dehydrogenase (low Km ALDH) activity in rats. In addition, a marked increase of blood acetaldehyde concentration was observed when rats were given alcohol orally at 18 hours after administration of these cephalosporins. However, mitochondrial low Km ALDH activity and blood acetaldehyde level were not altered by repeated administration of 300 mg and 1,000 mg of cefclidin (CFCL, E1040) or E1077 per kg. From these results, it was concluded that neither CFCLn or E1077 affected the alcohol metabolizing-system.

Radioimmunoassay for ubenimex in human serum

Anti-ubenimex antibody was produced by immunization of rabbits with ubenimex-bovine serum albumin (BSA) conjugate which was synthesized by coupling ubenimex directly to BSA using 1-ethyl-3-(3-dimethyl-aminopropyl)carbodiimide. The resulting antibody exhibited little cross-reactivity with p-hydroxyubenimex or (2S,3R)AHPA, (2S,3R)-3-amino-2-hydroxy-4-phenylbutanoic acid present in human serum as metabolites. Ubenimex in human serum could be measured selectively without prior drug extraction and purification. The standard curve prepared using the present assay method gave good linearity in the range 0.25-25 ng per assay tube. The detection limit was 125 pg per assay tube. The concentrations of ubenimex in human serum determined by the present method were in good agreement with those obtained by GC-SIM. The present method with its high sensitivity and specificity may be a valuable tool for the study of the pharmacokinetics of ubenimex.

On-line determination and resolution of the enantiomers of ketoprofen in plasma using coupled achiral-chiral high-performance liquid chromatography

High-performance liquid chromatography (HPLC) using a column-switching technique has been applied to the on-line determination and resolution of the enantiomers of ketoprofen (KPF) as an acidic model compound. The system incorporates a mobile phase conversion stage (LC-2), which has a dilution tube and a trapping column, between the achiral chromatography stage (LC-1) and the chiral chromatography stage (LC-3). KPF in plasma was separated from plasma components and was determined with the aid of an internal standard in LC-1. The eluate containing KPF was selectively transferred to LC-2, where the eluate was adequately diluted with a new mobile phase by using the dilution tube to reduce the influence of the mobile phase from LC-1, and KPF was reconcentrated on the trapping column. Then the KPF enantiomers were resolved in LC-3 after column-switching. This system is accurate and rapid compared with conventional HPLC. Very high sensitivity could be achieved with our system when a microbore ovomucoid column was employed in LC-3. Incorporation of LC-2 allows the most favourable mobile phases for LC-1 and LC-3 to be used independently. This method is greatly superior to usual column-switching HPLC.

Avidin protein-conjugated column for direct injection analysis of drug enantiomers in plasma by high-performance liquid chromatography

A new concept in high-performance liquid chromatography supports is proposed for the direct injection analysis of drug enantiomers in plasma. The new supports are designed with disuccinimidyl suberate as a hydrophobic internal region, and avidin protein as a hydrophilic and bulky surface region. Plasma proteins are excluded by the avidin phase and are eluted immediately from the column, whereas low-molecular-mass analytes can penetrate the surface region and interact with disuccinimidyl suberate. Enantiomers interact differentially with avidin, and are thereby separated. This column was used in reversed-phase high-performance liquid chromatographic analysis to determine ketoprofen enantiomers in plasma by direct injection. The recovery of racemic drug from plasma was almost 100%.

Column-switching high-performance liquid chromatography for on-line simultaneous determination and resolution of enantiomers of verapamil and its metabolites

An on-line simultaneous assay for the enantiomers of verapamil (VA) and its three metabolites in plasma was developed with column-switching HPLC. This system consists of an ovomucoid protein chiral stationary phase coupled to an achiral reversed-phase column via a dilution tube and a trapping column. The reversed-phase column was used to separate and quantitate VA, its metabolites, and internal standard, without interference from plasma components. Then each of the eluates containing VA and its metabolites was selectively switched into a sampling loop, and the samples were transferred successively to the trapping column after dilution with a new mobile phase. After concentration on the trapping column, each sample was passed to the ovomucoid column, where the enantiomers were resolved and quantitated. The mobile phases for both HPLC columns were independently optimized and the diffusion of the sample during column switching was minimized. This method was shown to be efficient and reliable.

Application of an ovomucoid-conjugated polymer column for the enantiospecific determination of chlorprenaline concentrations in plasma

An ovomucoid-conjugated polymer column was prepared for the liquid chromatographic resolution of racemic compounds. The column showed strong retention of acidic solutes, a characteristic attributed to the structure of the stationary phase support gel. Although the efficiency of the column was lower than that of an ovomucoid-conjugated silica gel column, enantiospecific chlorprenaline determination in plasma was achieved with solute amounts from 1.0 ng to 0.1 microgram.