ABSTRACT
Therapeutic monoclonal antibodies (mAbs) are successful biomedicines; however, evaluation of their pharmacokinetics and pharmacodynamics demands highly specific discrimination from human immunoglobulin G naturally present in the blood. Here, we developed a novel anti-idiotype aptamer (termed A14#1) with extraordinary specificity against the anti-vascular endothelial growth factor therapeutic mAb, bevacizumab. Structural analysis of the antibody-aptamer complex showed that several bases of A14#1 recognized only the complementarity determining region (CDR) of bevacizumab, thereby contributing to its extraordinary specificity. As the CDR of bevacizumab is predicted to be highly positively charged under mildly acidic conditions and that DNA is negatively charged, the affinity of A14#1 to bevacizumab markedly increased at pH 4.7 (KD = 44 pM) than at pH 7.4 (KD = 12 nM). A14#1-based electrochemical detection method capable of detecting 31 pM of bevacizumab at pH 4.7 was thus developed. A14#1 could be potentially useful for therapeutic drug measurement as a novel ligand of bevacizumab.
Subject(s)
Aptamers, Nucleotide , Biosensing Techniques , Antibodies, Monoclonal , Antibody Affinity , Aptamers, Nucleotide/chemistry , Complementarity Determining Regions/chemistry , Complementarity Determining Regions/genetics , Humans , Hydrogen-Ion ConcentrationABSTRACT
Asymmetric conjugate additions of phosphonates to trans-crotonophenone and chalcone derivatives using a diaminomethylenemalononitrile organocatalyst resulted in the generation of the corresponding chiral γ-ketophosphonates in high yields with excellent enantioselectivities (up to 95% ee). This report is the first successful example of asymmetric 1,4-additions of phosphonate to α,ß-unsaturated ketones using an organocatalyst.
ABSTRACT
An organocatalyzed method for synthesizing chiral γ,γ-disubstituted γ-butenolides via direct vinylogous aldol reactions of γ-substituted ß,γ-butenolides with aldehydes is reported. This reaction is catalyzed by a squaramide-sulfonamide organocatalyst to afford a range of anti-aldol adducts possessing vicinal quaternary and tertiary stereocenters with high to excellent enantioselectivities (reaching 95% ee). This is the first report of a successful stereoselective direct vinylogous aldol reaction of aldehydes with γ-substituted ß,γ-butenolides.
ABSTRACT
This study presents two simple and rapid methods for the quantification of therapeutic mAbs based on LC. Two mAbs (bevacizumab and infliximab) in plasma samples were purified using magnetic beads immobilized with a commercially-available idiotype antibody for each mAb. Purified mAbs were separated with HT-RPLC and detected with their native fluorescence. Using immunoaffinity beads, each mAb was selectively purified and detected as a single peak in the chromatogram. The HT-RPLC achieved good separation for the mAbs with sharp peaks within 20 min. The calibration curves of the two mAbs ranged from 1 to 20 µg mL(-1) (bevacizumab) and 1-10 µg mL(-1) (infliximab), and they had strong correlation coefficients (r(2) > 0.998). The LOD of bevacizumab and infliximab was 0.07 and 0.15 µg mL(-1), and the LLOQ of bevacizumab and infliximab was 0.12 and 0.25 µg mL(-1), respectively. Thus, the sensitivities were sufficient for clinical analysis. Immunoaffinity purification with HT-RPLC produced a selective and accurate bioanalysis without an LC-MS/MS instrument. Both methods could become general-purpose analytical methods and complement the results obtained with conventional LBA.
Subject(s)
Bevacizumab/blood , Chromatography, Affinity/methods , Chromatography, Reverse-Phase/methods , Hot Temperature , Infliximab/blood , Spectrometry, Fluorescence/methods , Calibration , Magnetics , Reproducibility of ResultsABSTRACT
In this study, a novel pre-column excimer fluorescence derivatization reagent, 2-chloro-4-methoxy-6-(4-(pyren-4-yl)butoxy)-1,3,5-triazine (CMPT), was developed for polyamines, specifically histamine. By CMPT derivatization, the polyamines, histamine and tyramine were converted to polypyrene derivatives, and emitted intra-molecular excimer fluorescence at 475nm. This could clearly be distinguished from the normal fluorescence emitted from reagent blanks at 375 nm. Unlike conventional excimer fluorescence derivatization reagents, CMPT is chemically stable and its reactivity sustained over at least 36 days even in solution state. We successfully applied this reagent to the sensitive and selective analysis of histamine in different kinds of Japanese commercial soy sauces. The detection and quantification limits of histamine were 15 and 50 µg L(-1), respectively, equating to 1.35 pmol and 4.5 pmol for a 6 µL injection. This sensitivity helped the direct analysis of soy sauce samples only treated by one-step liquid-liquid extraction without concentration. The histamine levels of commercial soy sauce samples (koikuchi, usukuchi and saishikomi) investigated were 1.24-768.5 mg L(-1).
Subject(s)
Fluorescent Dyes/chemistry , Histamine/analysis , Soy Foods/analysis , Spectrometry, Fluorescence , Triazines/chemistry , Chromatography, High Pressure Liquid , Fluorescent Dyes/chemical synthesis , Histamine/chemistry , Histamine/isolation & purification , Japan , Limit of Detection , Liquid-Liquid Extraction , Polyamines/analysis , Triazines/chemical synthesisABSTRACT
A sensitive, versatile, and reproducible automatic analyzer for highly polar carboxylic acids based on a fluorescence derivatization-liquid chromatography (LC) method was developed. In this method, carboxylic acids were automatically and fluorescently derivatized with 4-(N,N-dimethylaminosulfonyl)-7-piperazino-2,1,3-benzoxadiazole (DBD-PZ) in the presence of 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride by adopting a pretreatment program installed in an LC autosampler. All of the DBD-PZ-carboxylic acid derivatives were separated on the ODS column within 30 min by gradient elution. The peak of DBD-PZ did not interfere with the separation and the quantification of all the acids with the exception of lactic acid. From the LC-MS/MS analysis, we confirmed that lactic acid was converted to an oxytriazinyl derivative, which was further modified with a dimethoxy triazine group of 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride (DMT-MM). We detected this oxytriazinyl derivative to quantify lactic acid. The detection limits (signal-to-noise ratio = 3) for the examined acids ranged from 0.19 to 1.1 µm, which correspond to 95-550 fmol per injection. The intra- and inter-day precisions of typical, highly polar carboxylic acids were all <9.0%. The developed method was successfully applied to the comprehensive analysis of carboxylic acids in various samples, which included fruit juices, red wine and media from cultured tumor cells.
Subject(s)
Carboxylic Acids/analysis , Chromatography, High Pressure Liquid/methods , Automation , Beverages/analysis , Carboxylic Acids/chemistry , Chromatography, High Pressure Liquid/instrumentation , Chromatography, Liquid/methods , Culture Media/analysis , Culture Media/chemistry , Fluorescent Dyes/chemistry , Fruit/chemistry , Humans , Limit of Detection , Morpholines/chemistry , Oxadiazoles/chemistry , Piperazines/chemistry , Reproducibility of Results , Signal-To-Noise Ratio , Sulfonamides/chemistry , Tandem Mass Spectrometry/methods , Tumor Cells, Cultured , Wine/analysisABSTRACT
We have developed a convenient method for predicting the LC resolution of amino acid diastereomers through computational calculations. For acquiring experimental data, we derivatized 10 amino acids using o-phthalaldehyde and N-acetyl-L-cysteine as fluorogenic diastereomer-forming reagents and analyzed the diastereomers using reversed-phase LC and fluorescence detection. For theoretical chemical calculations, we used the publicly available semi-empirical calculation software MOPAC2012. Using the obtained experimental and theoretical data, we determined the change in analytical resolution with differences in the structure of the diastereomers. From the results obtained, we concluded that greater conformational change through diastereomeric derivatization induced an increase in the contact area with the stationary phase, leading to higher resolution.
Subject(s)
Amino Acids/analysis , Fluorescent Dyes/chemistry , Models, Chemical , o-Phthalaldehyde/chemistry , Acetylcysteine/chemistry , Amino Acids/chemistry , Chromatography, High Pressure Liquid , Models, Molecular , Molecular Structure , Software , StereoisomerismABSTRACT
This paper reports a novel fluorescence chiral derivatization-liquid chromatography (LC) method for the analysis of d- and l-lactic acids (LAs) using 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride (DMT-MM) as an enantioseparation enhancer. In this method, the dl-LAs were fluorescently derivatized with (S)-(+)-4-(N,N-dimethylaminosulfonyl)-7-(3-aminopyrrolidin-1-yl)-2,1,3-benzoxadiazole [(S)-(+)-DBD-APy] in the presence of DMT-MM as a condensing agent. These conditions resulted in the hydroxyl group of the LA derivative being etherified by the triazine unit of DMT-MM, producing sterically bulky diastereoisomers. The resulting fluorescent diastereoisomers of d- and l-LAs could be discriminated and successfully enantioseparated through reversed-phase LC. The enhancement effect of the derivatization agent DMT-MM when using seven other commercially available chiral amines was also demonstrated. Finally, this method was successfully applied to quantification of dl-LAs in foodstuffs (yogurts and fermented milk drinks).