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With the goal of generating a (peroxo)tricopper species analogous to the Peroxy Intermediate proposed for multicopper oxidases, solutions of the copper-superoxide complex [K(Krypt)][LCuO 2 ] (L = N,N'-bis(2,6-diisopropylphenyl)-2,6-pyridinedicarboxamide, Krypt = 4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo[8.8.8]hexacosane) were reacted with the dicopper(I) complex [(TPBN)Cu 2 (MeCN) 2 ][PF 6 ] 2 at -70 °C (TPBN = N,N,N',N'-tetrakis-(2-pyridylmethyl)-1,4-diaminobutane). A metastable intermediate formed, which on the basis of UV-vis, EPR, and resonance Raman spectroscopy was proposed to derive from reaction of two equivalents of the copper-superoxide with one equivalent of the dicopper(I) complex to yield a complex with two (peroxo)dicopper moieties rather than the desired (peroxo)tricopper PI model. A similar intermediate formed upon reaction of [K(Krypt)][LCuO 2 ] with [(BPMA)Cu(MeCN)][PF 6 ] (BPMA = N,N-bis(2-pyridylmethyl)-methyl-amine), which contained the same donor set as provided by TPBN. Comparison of resonance Raman data and consideration of structural preferences for LCuX species led to hypothesis of a μ-η 1 :η 2 -peroxo structure for both intermediates., (Copyright © 2021 Elsevier Inc. All rights reserved.)

This study evaluated the inhibitory potential of various beta-lactamase inhibitors such as mechanism-based inhibitors (MBIs), carbapenems, monobactam, and non-beta-lactam inhibitors against Bla1, a class-A beta-lactamase encoded by Bacillus anthracis. The binding potential of different inhibitors was estimated using competitive kinetic assay, isothermal titration calorimetry, and Biolayer interferometry. We observed that tazobactam has better inhibition among other MBIs with a characteristics inhibition dissociation constant of 0.51 ± 0.13 μM. Avibactam was also identified as good inhibitor with an inhibition efficiency of 0.6 ± 0.04 μM. All the MBIs (K D  = 1.90E-04 M, 2.05E-05 M, 3.55E-04 M for clavulanate, sulbactam and tazobactam) showed significantly better binding potential than carbapenems (K D  = 1.02E-03 M, 2.74E-03 M, 1.24E-03 M for ertapenem, imipenem and biapenem respectively). Molecular dynamics simulations were carried out using Bla1-inhibitor complexes to understand the dynamics and stability. The minimum inhibitory concentration (MIC) was carried out by taking various substrates and inhibitors, and later it was followed by cell viability assay. Together, our study helps develop a proper understanding of Bla1 beta-lactamase and its interaction with inhibitory molecules. This study would facilitate comprehending the catalytic divergence of beta-lactamases and the newly emergent resistant strains, focusing on the new generation of therapeutics being less prone to antimicrobial resistance., Competing Interests: Declaration of competing interest Authors agree to the terms andcondition provided., (Copyright © 2021. Published by Elsevier B.V.)

The objective of this study is to understand the behavior of a peptide in a medium containing supercritical carbon dioxide mixed with an alcohol (methanol) and acidic or basic additives in uncommonly high concentrations. Chirobiotic TAG is a chromatographic column made of silica bonded with a macrocyclic peptide, teicoplanin aglycone. With this stationary phase, two additives (trifluoroacetic acid and isopropylamine) were tested under extreme concentration conditions to observe the behavior of this peptide. Indeed, concentrations exceeding 1 M in the methanol co-solvent (>0.1 M overall concentration in the CO 2 -methanol mixture) were used whereas usual additive concentrations employed in supercritical fluid chromatography (SFC) rarely exceed 50 mM in the co-solvent. One purpose was to modify the apparent pH of the fluid, which is normally slightly acidic (around 5) and consequently possibly changing the ionization state of the peptide. Firstly, the effect of acidic and basic additives on the polarity and the apparent pH were evaluated with the help of color indicators. This served to assess the ionization state of the peptide under the selected operating conditions. Secondly, 54 achiral and 24 chiral molecules were injected in the chromatographic column at different levels of additives. The achiral species served at establishing retention models based on linear solvation energy relationships (LSER), while the chiral species were examined for their enantioresolution. From the LSER equations and observation of chromatograms, it appeared that specific interactions between the peptide-based stationary phase and the analytes evolved when increasing the concentration of additives, particularly hydrogen bonds and ionic interactions. A bare silica stationary phase (Acquity BEH) served as reference to deconvolute the contributions of silica support and bonded peptide. This study, with these extreme conditions of mobile phase, could be useful to understand the behavior of such peptides in SFC mobile phases and also improve the knowledge of the effects of additives in SFC, which should be helpful in the future prospect of analyzing large biomolecules in SFC., (Copyright © 2019. Published by Elsevier B.V.)

A simple, fast, sensitive and stability-indicating derivative spectrofluorimetric method is presented for the assay of zopiclone (ZOP), a drug with hypnotic effect, and its main degradation product and major contaminant, 2-amino-5-chloropyridine (ACP). The method is based on measuring the inherent fluorescence intensity of both drugs at λex=300nm in methanol, then differentiation using D1 (first derivative technique). The developed method was found to be rectilinear over a range of 0.2-4μg/mL of ZOP and 4-100ng/mL of ACP. The limits of detection were 0.05μg/mL of ZOP and 0.2ng/mL of ACP with the limit of quantitation of 0.17μg/mL of ZOP and 0.7ng/mL of ACP. The outcoming results of the proposed method were compared to those obtained by a reference method showing no significant statistical difference between them concerning precision and accuracy. Additionally, the developed method was applied for detecting ACP in spiked human urine and plasma specimens as a tool of clinical evidence of zopiclone intake that can be easily implemented in forensic laboratories. The proposed method was validated as per ICH guidelines., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Camels are raised in harsh desert environment for hundreds of years ago. By modernization of live and the growing industrial revolution in camels rearing areas, camels are exposed to considerable amount of chemicals, industrial waste, environmental pollutions and drugs. Furthermore, camels have unique gene evolution of some genes to withstand living in harsh environments. In this work, the camel cytochrome P450 2E1 (CYP2E1) is compromised to detect its evolution rate and its power to bind with various chemicals, protoxins, procarcinogens, industrial toxins and drugs. In comparison with human CYP2E1, camel CYP2E1 more efficiently binds to small toxins as aniline, benzene, catechol, amides, butadiene, toluene and acrylamide. Larger compounds were more preferentially bound to the human CYP2E1 in comparison with camel CYP2E1. The binding of inhalant anesthetics was almost similar in both camel and human CYP2E1 coinciding with similar anesthetic effect as well as toxicity profiles. Furthermore, evolutionary analysis indicated the high evolution rate of camel CYP2E1 in comparison with human, farm and companion animals. The evolution rate of camel CYP2E1 was among the highest evolution rate in a subset of 57 different organisms. These results indicate rapid evolution and potent toxin binding power of camel CYP2E1., (Copyright © 2016. Published by Elsevier Ltd.)

Date-rape drugs have the potential to be used in drug-facilitated sexual assault, organ theft and property theft. Since they are colorless, tasteless and odorless, victims can drink without noticing, when added to the beverages. These drugs must be detected in time, before they are cleared up from the biofluids. A simultaneous extraction and determination method in urine for GHB, ketamine, norketamine, phenobarbital, thiopental, zolpidem, zopiclone and phenytoin (an anticonvulsant and antiepileptic drug) with LC-MS/MS was developed for the first time with analytically acceptable recoveries and validated. A 4 steps liquid-liquid extraction was applied, using only 1.000mL urine. A new age commercial C18 poroshell column with high column efficiency was used for LC-MS/MS analysis with a fast isocratic elution as 5.5min. A new MS transition were introduced for barbital. 222.7>179.8 with the effect of acetonitrile. Recoveries (%) were between 80.98-99.27 for all analytes, except for GHB which was 71.46. LOD and LOQ values were found in the ranges of 0.59-49.50 and 9.20-80.80ngmL(-1) for all the analytes (except for GHB:3.44 and 6.00μgmL(-1)). HorRat values calculated (between 0.25-1.21), revealed that the inter-day and interanalist precisions (RSD%≤14.54%) acceptable. The simultaneous extraction and determination of these 8 analytes in urine is challenging because of the difficulty arising from the different chemical properties of some. Since the procedure can extract drugs from a wide range of polarity and pKa, it increases the window of detection. Group representatives from barbiturates, z-drugs, ketamine, phenytoin and polar acidic drugs (GHB) have been successfully analyzed in this study with low detection limits. The method is important from the point of determining the combined or single use of these drugs in crimes and finding out the reasons of deaths related to these drugs., (Copyright © 2016 Elsevier B.V. All rights reserved.)

It is well known that washing whole-cells containing enzyme activities after fermentation, but prior to biocatalysis can improve their activity in the subsequent reaction. In this paper, we quantify the impact of both the fermentation media and cell washing on the performance of whole-cell biocatalysis. The results are illustrated using a recombinant monoamine oxidase (expressed in Escherichia coli, used in resting state) for the oxidative desymmetrization of 3-azabicyclo[3,3,0]octane. It was shown that the need for washing biocatalyst prior to use in a reaction is dependent upon growth medium. Unlike cells grown in LB medium, washing of the cells was essential for cells grown on TB medium. With TB media, washing the cells improved the final conversion by approximately a factor of two. Additionally, over 50-fold improvement was achieved in initial activity. A potential reason for this improvement in activity was identified to be the increase in transfer of substrates across the cell membrane as a result of cell washing., (Copyright © 2015 Elsevier Inc. All rights reserved.)

[(125)I]Iodo-ASEM, a new radioligand with high affinity and selectivity for α7-nAChRs (K(i) = 0.5 nM; α7/α4β2 = 3414), has been synthesized in radiochemical yield of 33 ± 6% from the corresponding di-butyltriazene derivative and at high specific radioactivity (1600Ci/mmol; 59.2 MBq/μmol). [(125)I]Iodo-ASEM readily entered the brains of normal CD-1 mice and specifically and selectively labeled cerebral α7-nAChRs. [(125)I]iodo-ASEM is a new useful tool for studying α7-nAChR., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Four simple, sensitive and selective spectrophotometric methods are presented for determination of Zopiclone (ZPC) and its impurity, one of its degradation products, namely; 2-amino-5-chloropyridine (ACP). Method A is a dual wavelength spectrophotometry; where two wavelengths (252 and 301 nm for ZPC, and 238 and 261 nm for ACP) were selected for each component in such a way that difference in absorbance is zero for the second one. Method B is isoabsorptive ratio method by combining the isoabsorptive point (259.8 nm) in the ratio spectrum using ACP as a divisor and the ratio difference for a single step determination of both components. Method C is third derivative (D(3)) spectrophotometric method which allows determination of both ZPC at 283.6 nm and ACP at 251.6 nm without interference of each other. Method D is based on measuring the peak amplitude of the first derivative of the ratio spectra (DD(1)) at 263.2 nm for ZPC and 252 nm for ACP. The suggested methods were validated according to ICH guidelines and can be applied for routine analysis in quality control laboratories. Statistical analysis of the results obtained from the proposed methods and those obtained from the reported method has been carried out revealing high accuracy and good precision., (Copyright © 2014 Elsevier B.V. All rights reserved.)

A new mixed thia-aza macrocyclic complexes with Schiff base viz. 15-thia-3,4,9,10-tetraazabicyclo[10.2.1]pentadeca-1(14),2,10,12-tetraene-5,8-dione containing transition metals, M = Co(II), Ni(II), Cu(II) and Zn(II) and X = Cl(-), NO3(-), OAc(-), has been synthesized, resulting in the final constitution of 1:1:1 M ratio, by the condensation of succinyldihydrazide and thiophenedicarboxaldehyde. The metal complexes have been investigated with the help of various physico-chemical techniques viz. elemental analyses, magnetic susceptibility, thermal, conductivity measurements, spectral (IR, UV, ESR, NMR and mass) and X-ray diffraction techniques. The low value of molar conductivity indicates the non-electrolytic nature of the complexes and a distorted octahedral geometry has been proposed on the basis of various physico-chemical studies. X-ray diffraction indicates the presence of monoclinic crystal system. The complexes have been investigated for in vitro antibacterial, antifungal and antioxidant activity. All the complexes show moderate to significant activity., (Copyright © 2014 Elsevier B.V. All rights reserved.)

The sigma-2 receptor has been identified as a biomarker in proliferating tumors. To date there is no well-established functional assay for defining sigma-2 agonists and antagonists. Many sigma-2 ligands with diverse structures have been shown to induce cell death in a variety of cancer cells by triggering caspase-dependent and independent apoptosis. Therefore, in the current study, we used the cell viability assay and the caspase-3 activity assay to determine sigma-2 agonists and antagonists. Three classes of sigma-2 ligands developed in our laboratory were evaluated for their potency to induce cell death in two tumor cell lines, mouse breast cancer cell line EMT-6 and human melanoma cell line MDA-MB-435. The data showed that the EC50 values of the sigma-2 ligands using the cell viability assay ranged from 11.4μM to >200μM, which were comparable with the EC50 values obtained using the caspase-3 assay. Based on the cytotoxicity of a sigma-2 ligand relative to that of siramesine, a commonly accepted sigma-2 agonist, we have categorized our sigma-2 ligands into agonists, partial agonists, and antagonists. The establishment of functional assays for defining sigma-2 agonists and antagonists will facilitate functional characterization of sigma-2 receptor ligands and sigma-2 receptors., (Copyright © 2013 Elsevier Inc. All rights reserved.)

In the past decade, a large number of enantiopure drugs were introduced to clinical practice, since improved therapeutic effects were demonstrated for one of the enantiomers from originally racemic drug. While the therapeutic effects and safety of enantiopure drugs were tested prior to their approval, various biological enantiospecific activities of these, often "old" drugs, remain to be elucidated. In the current paper, we examined enantiospecific effects of clinically used enantiopure drugs containing one chiral center in the structure (i.e. zopiclone, tamsulosin, tolterodine, modafinil, citalopram) towards aryl hydrocarbon (AhR), glucocorticoid (GR) and pregnane X (PXR) receptors in human reporter cell lines. The cytotoxicity (IC50), agonist (EC50) and antagonist effects (IC50) of R-form, S-form and racemic mixture for each tested drugs were determined and compared in AhR-, GR- and PXR-gene reporter cell lines. Since AhR, GR and PXR are key regulators of drug metabolism, energy metabolism, immunity and play many other physiological functions, the data presented here might be of toxicological significance., (Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.)

The infrared spectra of (1'S, 6'S)-1-cyclopropyl-7-(2,8-diazabicyclo[4.3.0] non-8-yl)-6-fluoro-8-methoxy-4-oxo-1,4-dihydroquinoline-3-carboxylic acid hydrochloride salt (CLF-HCl) were studied and compared with free base. Their fragmentation pathways were investigated using tandem mass spectrometric (MS/MS) techniques on Fourier-transform ion cyclotron resonance spectrum, and many characteristic fragment ions were found., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Tunable nanosystems based on a novel water insoluble pyrimidinic amphiphile are designed. pH dependent aggregates composed of protonated pyrimidinophane 1 are formed at pH<4, which undergo reversible transition to precipitate at neutral and basic conditions. The approach assuming the application of a helper nonionic surfactant Triton-X-100 (TX-100) is used in this work. Different models of a self-assembly were found depending on the molar ratio of components and solution pH. In the equimolar 1-TX-100 solution, mixed assemblies contributed by aggregated molecules of both TX-100 and cationic form of 1 are formed in acidic conditions. Upon alkalization, deprotonated pyrimidinophane molecules shift toward the micellar core. The assemblies undergo reversible precipitation after 4-5h, while the excess of TX-100 leads to the formation of highly stable mixed aggregates. The acidification-alkalization cycles followed by the aggregation/precipitation and the re-charging of aggregates can be multiply repeated. Surprisingly, stable mixed aggregates are also formed under the excess of pyrimidinophane in both the acidic and alkaline conditions, but at a certain component ratio. They are characterized by the highest micellization degree among all the systems studied. The low concentration threshold of these assemblies in alkali solution is probably due to their nonionic character., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Introduction: The alpha-7 nicotinic acetylcholine receptor (α7 nAChR) is key in brain communication and has been implicated in the pathophysiology of diseases of the central nervous system. A positron-emitting radioligand targeting the α7 nAChR would enable better understanding of a variety of neuropsychiatric illnesses, including schizophrenia and Alzheimer's disease, and could enhance the development of new drugs for these and other conditions. We describe our attempt to synthesize an α7 nAChR-selective radiotracer for positron emission tomography (PET)., Methods: We prepared the high-affinity (K(d) = 0.2 nM) α7 nAChR agonist, 5'-(2-[(18)F]fluorophenyl)spiro[1-azabicyclo-[2.2.2]octane]-3,2'-(3'H)furo[2,3-b]pyridine, [(18)F]AZ11637326, in two steps, a nucleophilic fluorination followed by decarbonylation. We studied [(18)F]AZ11637326 in rodents, including mice lacking α7 nAChR, and in non-human primates., Results: [(18)F]AZ11637326 was synthesized in a non-decay-corrected radiochemical yield of 3% from the end of synthesis (90 min) with a radiochemical purity >90% and average specific radioactivity of 140GBq/μmol (3,781 mCi/μmol). Modest rodent brain uptake was observed (2-5% injected dose per gram of tissue, depending on specific activity), with studies comparing CD-1 and α7 nAChR null mice indicating an element of target-specific binding. Blocking studies in non-human primates did not reveal specific binding within the brain., Conclusion: Despite the high affinity and target selectivity of AZ11637326 for α7 nAChR in vitro and encouraging rodent studies, receptor-mediated binding could not be demonstrated in non-human primates. Further structural optimization of compounds of this class will be required for them to serve as suitable radiotracers for PET., (Copyright © 2013 Elsevier Inc. All rights reserved.)

Introduction: α7-nicotinic acetylcholine receptor (α7-nAChR) is one of the major neuronal nAChR subtypes. α7-nAChR is involved in variety of neuronal processes and disorders including schizophrenia and Alzheimer's disease. A number of α7-nAChR PET radioligands have been developed, but a quality radiotracer remains to be discovered., Methods: High binding affinity α7-nAChR ligands A-833834 and A-752274 were radiolabeled with (11)C. Baseline and blockade biodistribution studies in the mouse brain of [(11)C]A-833834 (5-(6-(5-[(11)C]methylhexahydropyrrolo[3,4-c]pyrrol-2(1H)-yl)pyridazin-3-yl)-1H-indole) and [(11)C]A-752274 (2-(6-[(11)C]methyl-3,6-diazabicyclo[3.2.0]heptan-3-yl)-7-(6-methyl-3,6-diazabicyclo[3.2.0]heptan-3-yl)-9H-fluoren-9-one) were performed. [(11)C]A-752274 was evaluated in a baseline baboon PET study., Results: [(11)C]A-833834 and [(11)C]A-752274 were synthesized by radiomethylation of corresponding des-methyl precursors. The radioligands were prepared with radiochemical yield of 12%-32%, high specific radioactivity (330-403GBq/μmol) and radiochemical purity>95%. Dissection studies with [(11)C]A-833834 demonstrated low specific α7-nAChR binding in the mouse brain. [(11)C]A-752274 specifically (~50%) labeled α7-nAChR in the mouse thalamus. However, [(11)CA-752274 exhibited low brain uptake in baboon (%SUV<100)., Conclusion: Two novel α7-nAChR ligands radioligands were synthesized and studied in animals. Specific binding of [(11)C]A-833834 in the mouse brain is low due to the insufficient binding affinity of the radioligand. The very high binding affinity [(11)C]A-752274 exhibited good specific binding in the α7-nAChR-rich mouse brain regions. The low uptake of [(11)C]A-752274 in the baboon brain is due to its high hydrophilicity, rapid metabolism or other properties. Future development of α7-nAChR PET radioligands will be based on compounds with high binding affinities and good blood-brain barrier permeability., (Copyright © 2013 Elsevier Inc. All rights reserved.)

A simple and reliable HPLC method was developed and validated for the simultaneous determination of the hypnotic drug, zopiclone (ZPC) and its degradation product and main impurity, 2-amino-5-chloropyridine (ACP). The analyses were carried out on BDS Hypersil phenyl column (4.6 mm × 250 mm, 5 μm particle size) using micellar mobile phase consisting of 0.15M SDS, 10% n-propanol, 0.3% triethylamine, and 0.02 M orthophosphoric acid (pH 3.5) with timed programmable fluorescence detection. The proposed method was found to be rectilinear over the concentration ranges of 0.5-10.0 μg/mL for ZPC and 2.5-50 ng/mL for ACP. Moreover, the method was applied for the determination of ZPC in commercial tablets with mean percentage recovery of 99.06±1.49. The results of the proposed method were statistically compared with those obtained by the comparison method revealing no significance differences in the performance of the two methods regarding accuracy and precision. Furthermore, the proposed method was applied for the detection and determination of ACP in human urine as a marker for ZPC intake., (Copyright © 2012 Elsevier B.V. All rights reserved.)

In this work, a methodology for the chiral separation of zopiclone (ZPC) by electrokinetic chromatography (EKC) using carboxymethylated-β-cyclodextrin as chiral selector has been developed and applied to the evaluation of the enantioselective binding of ZPC enantiomers to HSA and total plasma proteins. Two mathematical approaches were used to estimate protein binding (PB), affinity constants (K(1)) and enantioselectivity (ES) for both enantiomers of ZPC. Contradictory results in the literature, mainly related to plasma protein binding reported data, suggest that this is an unresolved matter and that more information is needed. Discrepancies and coincidences with previous data are highlighted., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Adsorptive stripping voltammetric (AdSV) techniques were proposed for the direct quantitative determination of zopiclone (ZP) in spiked human urine and tablet dosage forms for first time. The electrochemical oxidation and determination of ZP were easily carried out on glassy carbon electrode (CGE) using a variety of voltammetric techniques. Different conditions were investigated to optimize the analytical determination of ZP. The dependence of the intensities of currents and potentials on pH, concentration, scan rate, deposition time, deposition potential, and nature of the buffer were investigated. Oxidation of ZP was found to be adsorptive-controlled and irreversible. The best results for the determination of ZP were obtained by using differential pulse adsorptive stripping (DPAdSV) and osteryoung square wave voltammetric (OSWAdSV) techniques in Britton-Robinson buffer at pH 7.08 after a pre-concentration period of 120 s at 0.60 V. The peak current showed a linear dependence on the ZP concentration in the range of 6 x 10(-7) to 2 x 10(-5) mol L(-1) for both techniques. The achieved limits of detection and quantitation were 2.78 x 10(-7) and 5.28 x 10(-7) mol L(-1) for DPAdSV; 1.70 x 10(-7) and 5.78 x10(-7) mol L(-1) for OSWAdSV, respectively. The proposed techniques were successfully applied to direct determination of ZP in tablet dosage form and spiked human urine samples. Excipients did not interfere with the determination. Precision and accuracy of the developed method were checked by recovery studies in tablet dosage forms and spiked urine samples.