CZE Separation of New Drugs for Treatment of Leukemia

Imatinib, bosutinib, dasatinib, pazopanib, erlotinib, canertinib and vatalanib are new developed anticancer drugs, especially for treatment of leukemia. In this article, a fast and high throughput capillary zone electrophoresis method has been developed and validated for analysis of these new drugs in pharmaceutical formulas. The method can be easily utilized for determination of all the drugs in one run what is advantageous for the quality control in pharmaceutical industry because there is no need for changing and optimization of separation conditions when changing the analyte. The separation was performed using an uncoated fused silica capillary with 100 mmol L^?1 sodium phosphate buffer pH 2.75, voltage of 25 kV, hydrodynamic injection time of 5 s by 50 mbar, and detection at 214 nm. Under these conditions, the analysis took about 8 min. The validation of all the drugs resulted in recoveries in the range of 84–100 %. The method showed to be precise for all the drugs with RSDs of migration times lower than 0.9 % (interday precision). A very good linearity in the validated range (5–100 μg mL^?1) and the limits of detection (LODs) in the range of 0.5–2.0 (μg mL^?1) were achieved. Finally, we proved that the method is robust by the Youden’s test. Therefore, our method can be successfully applied for analysis of the real pharmaceutical samples.     

A high-throughput liquid chromatography-tandem mass spectrometry method for simultaneous determination of direct oral anticoagulants in human plasma

Direct oral anticoagulants are widely used in many indications to prevent thromboembolic events. Routine therapeutic monitoring is not required; however, there is increasing evidence suggesting the benefit of plasma level measurement in some situations. In addition, laboratory monitoring might help improve patient and drug non-compliance and thus individualize therapy. In the present study, we developed a sensitive and high throughput ultra-high-performance liquid chromatography-tandem mass spectrometry method for simultaneous quantification of apixaban, dabigatran, edoxaban, and rivaroxaban in human plasma. A one-step extraction procedure in 96-well formate for phospholipid and protein removal was used for sample pre-treatment, and analytes were separated using gradient elution over 4.2 min. Analytes were detected on a triple quadrupole tandem mass spectrometer by multiple reaction monitoring mode. The method was validated according to the European Medicine Agency guideline for the selectivity, linearity, and lower limit of detection, precision and accuracy, matrix effects, extraction recovery, carryover, dilution integrity, and stability over a concentration range of 3.0–1000 ng/ml for all analytes. The validated method was applied to real clinical samples of patients treated with one of the drugs. Therefore, we can conclude that our method is suitable for therapeutic drug monitoring of direct oral anticoagulants.     

Preparation of trisodium O-monoalkyl and O-monoaryl diphosphates

Trisodium O-methyl, O-butyl, O-phenyl, and O-(4-nitrophenyl) diphosphates were synthesized from sodium dimethylamido-O-(2-cyanoethyl) phosphate and O-alkyl-and O-aryl phosphoric acids. While in the previously described method, sodium hydroxide was used for the preparation of O-phenyl diphosphate, in our current work, we present an improved protocol, where sodium methoxide is used to increase the yields of O-alkyl and O-aryl diphosphates. The structures of final compounds were determined by ¹H NMR, ³¹P NMR, and IR spectroscopy. The sodium O-alkyl- and O-aryl diphosphate salts prepared by this method may be used for the study of biological activity of diphosphate analogues.     

A theoretical study of AmOn and CmOn (n = 1, 2)

Americium and curium oxides AmOn and CmOn (n = 1, 2) were studied using state-of-the-art multiconfigurational, relativistic, quantum chemical methods. Spectroscopic properties for the ground state and several excited states of the four target compounds were determined. The computed dissociation energy of AmO (4.6 eV) agrees fairly well with estimates derived from experimental studies (5.73 +/- 0.37 eV) while the computed dissociation energy of CmO (7.1 eV) agrees well with the experimental value (7.5 eV). The computed ionization energy of AmO (6.3 eV) is in good agreement with the current experimental value (5.9 +/- 0.2 eV).     

Binary and ternary recombination of para-H3(+) and ortho-H3(+) with electrons: state selective study at 77-200 K

Measurements in H(3)(+) afterglow plasmas with spectroscopically determined relative abundances of H(3)(+) ions in the para-nuclear and ortho-nuclear spin states provide clear evidence that at low temperatures (77-200 K) para-H(3)(+) ions recombine significantly faster with electrons than ions in the ortho state, in agreement with a recent theoretical prediction. The cavity ring-down absorption spectroscopy used here provides an in situ determination of the para/ortho abundance ratio and yields additional information on the translational and rotational temperatures of the recombining ions. The results show that H(3)(+) recombination with electrons occurs by both binary recombination and third-body (helium) assisted recombination, and that both the two-body and three-body rate coefficients depend on the nuclear spin states. Electron-stabilized (collisional-radiative) recombination appears to make only a small contribution.     

Highly fluorescent colloids based on rhodamine 6G, modified layered silicate, and organic solvent

Synthetic layered silicate saponite was modified with dodecyltrimethylammonium (C12), octadecyltrimethylammonium (C18), and dioctadecyldimethylammonium (2C18) cations for use as sorbents of the laser dye, rhodamine 6G (R6G). Via solvent exchange, transparent colloids in xylene were prepared and investigated using absorption and fluorescence spectroscopies. Molecular aggregation and partial quenching of the fluorescence were observed for the colloids based on 2C18 cations. Maximal fluorescence yields were observed for the colloids with C12 and C18 cations. Transparent gels without an apparent loss of luminescent efficiency could be prepared by concentrating the colloids. These highly fluorescent colloids and gels represent new types of materials with interesting optical properties.     

On-line preconcentration of perfluorooctanoic acid and perfluorooctanesulfonic acid by nonaqueous capillary electrophoresis

Separation of major environmental pollutants as perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) by capillary electrophoresis is reported for the first time. It is not possible to resolve the solutes in an aqueous media. However, the use of methanol and acetonitrile as the background electrolyte (BGE) solvents allowed their rapid separation in an uncoated capillary. A major effort was put into BGE optimization in respect to both separation efficiency and detection for further on‐line preconcentration. 5 mmol.L^?1 naphthalene‐1‐sulfonic acid and 10 mmol.L^?1 triethylamine dissolved in ACN/MeOH (50:50 v/v) provided best separation and detection conditions. Next, the large‐volume sample stacking and the field‐amplified sample injection were applied and compared. Large‐volume sample stacking improved limits of detection (LODs) with regard to the standard injection by 69 times for PFOA and 143 times for PFOS with LODs of 280 and 230 nmol.L^?1, respectively. Field‐amplified sample injection improved LODs 624 times for PFOAand 806 times for PFOS with LODs 31 and 40 nmol.L^?1, respectively. Both preconcentration methods showed repeatabilities of migration times less than 1.2% RSD intraday and 6.6% RSD interday. The method was applied on PFOA and PFOS analysis in a sample of river water treated with solid‐phase extraction, which further improved LOD toward 5.6 × 10^?10 mol.L^?1 for PFOS and 6.4 × 10^?10 mol.L^?1 for PFOA and allows the method to be used for river water contamination screening or decomposition studies.     

DNA strand break: structural and electrostatic properties studied by molecular dynamics simulation

Due to their lethal consequences and a relatively high probability of introduction of repair errors and mutations, single and double strand breaks are among the most important and dangerous DNA lesions. However, the mechanisms of their recognition and repair processes are only poorly known at present. This work defines and analyzes a DNA with single strand break as a template study for future complex analyses of biologically serious double strand break damage and its enzymatic repair mechanisms. Besides a non-damaged DNA serving as a reference system with no surprising results, system with open valences of the atoms at the strand break ends as well as a system with filled valences were simulated. In both cases during the first few nanoseconds the broken ends of strand breaks are significantly exposed to the outside of the molecule. However, with increasing time, the system with single strand break with open valences is partially disrupted. On the contrary, the system with filled valences shows stable conformation with newly created hydrogen bond between the two strand break endings. Moreover, these endings are steadily situated in the inner part of the molecule, thus making the recognition and docking process of a repair enzyme more complicated in the case of filled valences.     

Stereochemistry,tautomerism, and reactions of acridinyl thiosemicarbazides in the synthesis of 1,3‐thiazolidines

Acridin‐9‐yl hydrazine upon treatment with various isothiocyanates (RNCS, R = methyl, allyl, phenyl, p‐methoxy phenyl, and p‐nitro phenyl) yielded the corresponding thiosemicarbazides with acridine substituted on the carbazide‐type side. The alkyl‐substituted compounds were present in solution as equilibria consisting of the major H‐10, H‐12 tautomer (either E or Z or both about the C₁₃‐N₁₄ bond) and the minor H‐10, SH tautomer (either E or Z or both). The major species for the aromatic‐substituted compounds was the H‐10, H‐12 E tautomer, with the evident minor species being the H‐10, H‐12 Z tautomer. The thiosemicarbazides were each quantitatively converted into the analogous semicarbazides upon treatment with mesitylnitrile oxide wherein all structures were present in solution as the H‐10 tautomers with Z conformation about the C₁₃‐N₁₄ bond. Methylation of the compounds with methyl iodide yielded S‐methylated compounds wherein the Z configuration dominated in each case over the E configuration along the N₁₂‐C₁₃ double bond. Treatment of the thiosemicarbazides with methyl bromoacetate resulted in the formation of 1′,3′‐thiazolidin‐4′‐ones wherein the Z configuration predominated in each case over the E configuration along the N₁₂? C₁₃ double bond. With bromoacetonitrile as the bifunctional electrophile, the initial 1′,3′‐thiazolidin‐4′‐imines that formed spontaneously underwent Dimroth‐type rearrangement to the regiosiomeric 1′,3′‐thiazolidin‐4′‐imines.