Search

In this research, twenty-four hydrazide–hydrazones of 2,4-dihydroxybenzoic acid were designed, synthesized, and subjected to in vitro and in vivo bioactivity studies. The chemical structure of the obtained compounds was confirmed by spectral methods. Antimicrobial activity screening was performed against a panel of microorganisms for all synthesized hydrazide–hydrazones. The performed assays revealed the interesting antibacterial activity of a few substances against Gram-positive bacterial strains including MRSA—Staphylococcus aureus ATCC 43300 (compound 18: 2,4-dihydroxy-N-[(2-hydroxy-3,5-diiodophenyl)methylidene]benzohydrazide—Minimal Inhibitory Concentration, MIC = 3.91 µg/mL). In addition, we performed the in vitro screening of antiproliferative activity and also assessed the acute toxicity of six hydrazide–hydrazones. The following human cancer cell lines were used: 769-P, HepG2, H1563, and LN-229, and the viability of the cells was assessed using the MTT method. The HEK-293 cell line was used as a reference line. The toxicity was tested in vivo on Danio rerio embryos using the Fish Embryo Acute Toxicity (FET) test procedure according to OECD No. 236. The inhibitory concentration values obtained in the in vitro test showed that N-[(4-nitrophenyl)methylidene]-2,4-dihydroxybenzhydrazide (21) inhibited cancer cell proliferation the most, with an extremely low IC50 (Inhibitory Concentration) value, estimated at 0.77 µM for LN-229. In addition, each of the compounds tested was selective against cancer cell lines. The compounds with a nitrophenyl substituent were the most promising in terms of inhibition cancer cell proliferation. The toxicity against zebrafish embryos and larvae was also very low or moderate. [ABSTRACT FROM AUTHOR]

Two series of 1,1′‐biphenyl analogues with various leaving groups (L=OAc, OCH3, OCHCH=CH2, OCH2Ph, SPh, SePh, and Ph3P+) were synthesized. Their reactivity towards DNA and the reaction mechanism were investigated by determining DNA interstrand cross‐link (ICL) efficiency, radical and carbocation formation, and the cross‐linking reaction sites. All compounds induced DNA ICL formation upon 350 nm irradiation via a carbocation that was generated from oxidation of the corresponding free radicals. The ICL efficiency and the reaction rate strongly depended on the combined effect of the leaving group and the substituent. Among all compounds tested, the high ICL efficiency (30–43 %) and fast reaction rate were observed with compounds carrying a nitrophenyl group and acetate (2 a), ether (2 b and 2 c), or triphenylphosphonium salt (2 g) as leaving groups. Most compounds with a 4‐methoxybenzene group showed similar DNA ICL efficiency (≈30 %) with a slow DNA cross‐linking reaction rate. Both cation trapping and free radical trapping adducts were detected in the photo activation process of these compounds, which provided direct evidence for the proposed mechanism. Heat stability study in combination with sequence study suggested that these photo‐generated benzyl cations alkylate DNA at dG, dA, and dC sites. [ABSTRACT FROM AUTHOR]

Promiscuous enzymes can be modified by protein engineering, which enables the catalysis of non-native substrates. γ-lactamase Sspg from Sulfolobus solfataricus is an enzyme with high activity, high stability, and pronounced tolerance of high concentrations of the γ-lactam substrate. These characteristics suggest Sspg as a robust enzymatic catalyst for the preparation of optically pure γ-lactam. This study investigated the modification of this enzyme to expand its application toward resolving chiral esters. γ-Lactamase-esterase conversion was performed by employing a three-step method: initial sequence alignment, followed by substrate screening, and protein engineering based on the obtained substrate-enzyme docking results. This process of fine-tuning of chemical groups on substrates has been termed "substrate screening." Steric hindrance and chemical reactivity of the substrate are major concerns during this step, since both are determining factors for the enzyme-substrate interaction. By employing this three-step method, γ-lactamase Sspg was successfully converted into an esterase with high enantioselectivity towards phenylglycidate substrates (E value > 300). However, since both wild-type Sspg and Sspg mutants did not hydrolyze para-nitrophenyl substrates (pNPs), this esterase activity was termed "atypical esterase activity." The γ-lactamase activity and stability of the Sspg mutants were not severely compromised. The proposed method can be applied to find novel multi-functional enzyme catalysts within existing enzyme pools. [ABSTRACT FROM AUTHOR]

Arabinofuranosidase plays an essential role in the process of hydrolysis of arabinoxylan (AX). Thermostable, versatile, and efficient arabinofuranosidase is thus of great interest for the biorefinery industry. A GH51 arabinofuranosidase, Abf51, from Hungateiclostridium clariflavum DSM 19732 was heterogeneously expressed in Escherichia coli. Abf51 was found to have an optimal pH and temperature of 6.5 and 60 °C, respectively, with very high thermostability. At the optimal working temperature (60 °C), Abf51 retained over 90% activity after a 2-day incubation and over 60% activity after a 6-day incubation. Abf51 could effectively remove the arabinofuranosyls from three kinds of AX oligosaccharides [23-α-l-arabinofuranosyl-xylotriose (A2XX), 32-α-l-arabinofuranosyl-xylobiose (A3X), and 2333-di-α-l-arabinofuranosyl-xylotriose (A2 + 3XX)], which characterized as either single substitution or double substitution by arabinofuranosyls on terminal xylopyranosyl units. The maximal catalytic efficiency (Kcat/Km) was observed using p-nitrophenyl-α-l-arabinofuranoside (pNPAF) as a substrate (205.0 s−1 mM−1), followed by using A3X (22.8 s−1 mM−1), A2XX (6.9 s−1 mM−1), and A2 + 3XX (0.5 s−1 mM−1) as substrates. Moreover, the presence of Abf51 significantly stimulated the saccharification level of AX (18.5 g L−1) up to six times along with a β-xylanase as well as a β-xylosidase. Interestingly, in our survey of top thermostable arabinofuranosidases, most members were found from GH51, probably due to their owning of (β/α)8-barrel architectures. Our results suggested the great importance of GH51s as candidates for thermostable, versatile, and efficient arabinofuranosidases toward industry application. [ABSTRACT FROM AUTHOR]

Sulfation is an important way for detoxifying xenobiotics and endobiotics including catechols. Enzymatic sulfation occurs usually with high chemo- and/or regioselectivity under mild reaction conditions. In this study, a two-step p-NPS-4-AAP screening system for laboratory evolution of aryl sulfotransferase B (ASTB) was developed in 96-well microtiter plates to improve the sulfate transfer efficiency toward catechols. Increased transfer efficiency and improved sulfation stoichiometry are achieved through the two-step screening procedure in a one-pot reaction. In the first step, the p-NPS assay is used (detection of the colorimetric by-product, p-nitrophenol) to determine the apparent ASTB activity. The sulfated product, 3-chlorocatechol-1-monosulfate, is quantified by the 4-aminoantipyrine (4-AAP) assay in the second step. Comparison of product formation to p-NPS consumption ensures successful directed evolution campaigns of ASTB. Optimization yielded a coefficient of variation below 15% for the two-step screening system (p-NPS-4-AAP). In total, 1760 clones from an ASTB-SeSaM library were screened toward the improved sulfation activity of 3-chlorocatechol. The turnover number (kcat = 41 ± 2 s−1) and catalytic efficiency (kcat/KM = 0.41 μM−1 s−1) of the final variant ASTB-M5 were improved 2.4- and 2.3-fold compared with ASTB-WT. HPLC analysis confirmed the improved sulfate stoichiometry of ASTB-M5 with a conversion of 58% (ASTB-WT 29%; two–fold improvement). Mass spectrometry (MS) and nuclear magnetic resonance spectroscopy (NMR) confirmed the chemo- and regioselectivity, which yielded exclusively 3-chlorocatechol-1-monosulfate. For all five additionally investigated catechols, the variant ASTB-M5 achieved an improved kcat value of up to 4.5-fold and sulfate transfer efficiency was also increased (up to 2.3-fold). [ABSTRACT FROM AUTHOR]

Protein misfolding and aberrant aggregations are associated with multiple prevalent and intractable diseases. Inhibition of amyloid assembly is a promising strategy for the treatment of amyloidosis. Reported here is the design and synthesis of a reactive conjugated polymer, a poly(p‐phenylene vinylene) derivative, functionalized with p‐nitrophenyl esters (PPV‐NP) and it inhibits the assembly of amyloid proteins, degrades preformed fibrils, and reduces the cytotoxicity of amyloid aggregations in living cells. PPV‐NP is attached to the proteins through hydrophobic interactions and irreversible covalent linkage. PPV‐NP also exhibited the capacity to eliminate Aβ plaques in brain slices in ex vivo assays. This work represents an innovative attempt to inhibit protein pathogenic aggregates, and may offer insights into the development of therapeutic strategies for amyloidosis. [ABSTRACT FROM AUTHOR]

Abstract In the present study, a series of substituted 1,3,4-thiadiazole derivatives 4(a – o), 5(a – m) and 6(a – j) were synthesized and characterized by IR, 1H NMR, 13C NMR and mass spectroscopic technique. The synthesized compounds were evaluated for their in vitro anti-mycobacterial activity against the Mycobacterium tuberculosis H37Rv and resistance MDR-TB strain. Among the compounds tested N-(5-(4-nitrophenyl)-1,3,4-thiadiazol- 2-yl)furan-2-carboxamide (4h) showed significant inhibitory activity with MIC of 9.87 μM (H37Rv strain) and 9.87 μM (MDR-TB strain) compared to isoniazide [MIC of 3.64 μM (H37Rv) and >200 μM (MDR-TB strain)] and rifampin [MIC of 0.152 μM (H37Rv) and 128 μM (MDR-TB strain)]. In addition, these compounds have also been assessed for their cyto-toxicity to a mammalian Vero cell line using the MTT assay. The result shows that these compounds exhibit anti-tubercular activity at non-cytototoxic concentrations. Graphical abstract Image 1 Highlights • Substituted [1,3,4]thiadiazole derivatives 4(a – o), 7(a – m) and 10(a – j) were synthesized. • Characterized by IR, 1H NMR, 13C NMR and mass spectral technique. • Evaluated in vitro against the H37Rv and resistance MDR-TB strain. [ABSTRACT FROM AUTHOR]

Arylation of 2-acetylfuran with o-, m-, and p-nitrophenyldiazonium salts under the conditions of the Gomberg-Bachmann reaction has afforded the corresponding 5-(nitrophenyl)-2-acetylfurans. Their carbo-ethoxyhydrazones have undergone the cyclization into stable 4-(5-nitrophenylfur-2-yl)-1,2,3-thiadiazoles under the conditions of the Hurd-Mori reaction. Analogous semicarbazones have afforded the corresponding selenadiazoles upon oxidation with selenium dioxide. The analysis of electronic absorption spectra of the obtained hybrid heterocycles has shown that the conjugation of the phenyl and the furan ring in o-nitrophenyl derivatives is distorted due to steric hindrance, whereas the effect of direct polar conjugation leading to strong bathochromic shift of the absorption band has been observed in the case of the p-nitro derivatives. The position and intensity of the bands in the electronic absorption spectra of the studied compounds are determined by electronic as well as steric factors. The difference in the length of conjugation chain determined by the position of the nitro group in the phenyl fragment also contributes to the observed trend. The introduction of selenadiazole fragment instead of thiadiazole one has caused slight bathochromic shift of the band in the electron absorption spectra. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract Three types of polymer-coated glass slides were prepared by acylation of their γ–aminopropyl derivatives with succinic anhydride or poly(p -nitrophenyl acylate) (PNPA) at various reaction times. The variations in duration of chemical adsorption of PNPA allowed control over nano-corrugation of the reactive surfaces employed for biosensing. The visually smooth and optically clear polymer-coated slides were used for immobilization of a conjugate of bovine serum albumin with chloramphenicol (CAP) and label-free measurement of concentration of this antibiotic. The sensor chips prepared in this way provided strong biosensing response due to fast biomolecular interactions and efficient competition of the target analyte during indirect immunoassay. The kinetics of formation and dissociation of immune complexes "conjugate-antibody" on the sensor chip surface was registered by the label-free methods of spectral-correlation and spectral-phase interferometry. The average thickness of immune complex adsorption layers was in the range of 5–12 nm. The highest value of kinetic association constant (k on = 5 × 104 M−1s−1) and the lowest equilibrium dissociation constant (K diss = 2 × 10-8 M−1) were achieved with the chips originated in the PNPA-coated slides, which were produced under short (2 min) polymer chemisorption and exhibited nano-corrugation almost unchanged with respect to the parent glass, according to the atomic-force microscopy. The detection limit for CAP detection was 80 pg/mL, and the dynamic range was 5 orders. The proposed methods for fabrication of sensor chips with nano-corrugated surface, the results of their characterization, as well as the developed assay can be employed for high-throughput recording of multiple molecular interactions by spectral interferometry and in a wide range of biosensing platforms for registration of biologically active compounds in medicine, veterinary, food control and ecological monitoring. [ABSTRACT FROM AUTHOR]

Six new compounds were synthesized that have no alkyl chains in their structure: 4-nitrocinnonates of 4-hydroxyazobenzene, 4-nitro-4'-hydroxyazobenzene, 4-fluoro-4'-hydroxyazobenzene, 4-chloro-4'-hydroxyazobenzene, 4-bromo-4'-hydroxyazobenzene and 4-iodo-4'-hydroxyazobenzene. Using the polarizing microscopy and differential scanning calorimetry, enthalpies and temperatures of phase transitions were determined. All investigated compounds have an enantiotropic nematic phase. These compounds proved to be extremely thermally stable. Thermal decomposition was observed in temperatures above 300°C. Investigated compounds contain two different chromophore groups (i.e. azo and ethene moieties), which influenced the complex trans-cis isomerization processes of both groups (three time-separated processes were observed). It was shown that the presence of the ethene group significantly shifts the π-π* band towards higher energies. The substituent polarity in the azo group also affected the energy of this absorption band. A weak luminescence effect was observed in the 4-nitrocinnonates of 4-hydroxyazobenzene compound. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Microwave-assisted approach to nitrophenyl pyrabactin analogues. • Excellent yields (91%–97%) and broad substrate scope. • Very suitable to prepare flusulfamide (fungicide). • Enhancing POD activity in response to heavy metal stress. Abstract A facile and efficient approach to N -(2-nitrophenyl) benzenesulfonamides was developed under microwave irradiation. A series of pyrabactin analogues containing nitrophenyl scaffold was obtained in excellent yields. In addition, the method was pretty suitable to prepare flusulfamide. Significantly, the 3ae could enhance POD activity in response to heavy metal stress. [ABSTRACT FROM AUTHOR]

Boron(III) 5‐arylsubporphyrins and BIII subporphine are promising precursors for functional BIII subporphyrins bearing asymmetric meso‐substituents. Herein, we report the first synthesis of these molecules. Among many aryl acid chlorides examined, 4‐nitrobenzoyl chloride gave BIII 5‐(4‐nitrophenyl)subporphyrin in 10 % yield in condensation with triethylamine‐tri‐N‐tripyrromethene‐borane. The nitro group of this BIII subporphyrin was reduced with NaBH4 to prepare BIII 5‐(aminophenyl)subporphyrin, which was converted into BIII 5‐phenylsubporphyrin via the corresponding diazonium salt. BIII subporphine was synthesized by condensation of triethyl orthoformate with triethylamine‐tri‐N‐tripyrromethene‐borane. Progressive removal of meso‐phenyl substituents leads to continuous changes in the optical properties, whereas the BIII subporphine deviates from this trend in some properties. Rotational relaxation: BIII 5‐arylsubporphyrins and BIII subporphine were synthesized for the first time by the condensation reactions of triethylamine‐tri‐N‐tripyrromethene‐borane with aryl acid chloride and ethyl orthoformate, respectively. Removal of meso‐phenyl substituents leads to progressive changes in the optical properties up to BIII 5‐arylsubporphyrin but BIII subporphine deviates from this trend (see figure). [ABSTRACT FROM AUTHOR]

Abstract S -Methyl-β- N -(3-(2-nitrophenyl)allylidene)dithiocarbazate (HL), Schiff base of S -methyl dithiocarbazate, was synthesized by 1:1 condensation between S -methyl dithiocarbazate and trans -o-nitro cinnamaldehyde. It's in-vitro cytotoxicity is assayed against two habitually infection causing bacteria strains including gram-positive Staphylococcus aureus and gram-negative Escherichia coli for antibacterial activity. The results showed appreciable biological activity and the activity increased with increase in concentration. This nitrogen-sulfur based Schiff base (HL) was characterized by Mass, FT-IR, 1H-NMR, 13C NMR, Raman, and UV–Vis spectroscopic techniques. Theoretical quantum chemical calculation has been performed using DFT in combination with B3LYP exchange correlation functional and 6–311++ G (d, p) basis sets level. The computed parameters were: Chemical potential of compound (μ) −0.174 eV, HOMO-LUMO energy gap −0.11093 eV, chemical hardness (ɳ) −0.055 eV, softness (S) 2.164 eV, ionization energy (IE) −0.23026 eV, electron affinity (EA) −0.11933eV, the electronegativity (EN) 0.174 eV, dipole moment (D) 1.3383 Debye and relative stabilization energy −1536.982 eV. In the theoretical FT-IR spectrum analysis 81 fundamental vibrational modes has be observed because of non-linear structure of HL, with potential energy distribution percentage (PED%) by using VEDA-4 package. Theoretically calculated parameters like 1H-NMR, 13C NMR, FT-IR, UV-VIS, Raman, electrostatic potential and HOMO-LUMO energy gap were in conformity with experimental results. Thermal reactivity of the ligand was studied by TGA decomposes completely to give gaseous products. Highlights • Synthesis of novel dithiocarbazate Schiff base with SMDTC. • Computational study by Guassian 03, GAUSSVIEW and VEDA-4 packages. • Meticulous zone of inhibition against S. aureus and E. coli. [ABSTRACT FROM AUTHOR]

Highlights • Four different mixer spacing arrangements were used for a liquid-liquid reaction. • Four organic solvents were used: nBuOH, nHeOH, MTBE and toluene. • In drop flow, the reactors performed similarly for a given energy dissipation rate. • Droplet diameters were as low as 4–16 times the Kolmogorov length. • An algorithm for identifying and scaling at optimal operating conditions is presented. Abstract The effect of geometrical arrangements of a residence time channel (RTC) positioned in between LL-Rhombus static mixing elements on interphase mass transfer rates is investigated. Four variations of a micro-reactor plate are tested with four immiscible aqueous-organic systems: water coupled with n-butanol, n-hexanol, methyl tert-butyl ether and toluene. The alkaline hydrolysis of 4-nitrophenyl acetate is used to determine the overall volumetric mass transfer coefficient (K d a). For all solvent pairs, the micro-reactor without a RTC has the greatest K d a at a given flow rate due to a greater energy dissipation rate (ɛ) and the fact that drops can re-coalesce leading to reduced advective transfer in the RTC pending the flow regime. An increase in flow rate results in a rise in conversion up to a maximum, after which viscous dissipation impedes further turbulent breakdown of the droplets as they near the Kolmogorov length scale. When the resulting flow is finely dispersed, interphase mass transfer rates no longer depend on reactor geometry but was correlated to the solvent system and rate of energy dissipated. The negative impact of operating at greater ɛ values than at maximum conversion is shown via the required pressure loss to achieve a certain conversion or residence time. Lastly, relevant to production rates in the fine chemical and pharmaceutical industry, an algorithm for scaling a generic mass transfer-limited liquid-liquid reaction at identified optimal operating conditions is presented. [ABSTRACT FROM AUTHOR]

A neutral one-dimensional CdII coordination polymer [Cd(NO2-BDC)(NPT)(H2O)2]n (1) (NO2-H2BDC=5- nitro-1,3-benzenedicarboxylic acid, NPT=1-(4-nitrophenyl)-1,2,4-triazole) is prepared and characterized through IR, elemental and thermal analyses, and single crystal X-ray diffraction. The single crystal X-ray diffraction analysis reveals that complex 1 is comprised of neutral 1D zigzag chains. The luminescence and thermal stability of complex 1 are investigated. [ABSTRACT FROM AUTHOR]

An unsymmetrical tridentate Schiff base 4-((E)-(2-amino-5-nitrophenylimino)methyl)-5-(hydroxymethyl)- 2-methylpyridin-3-ol is newly synthesized and characterized experimentally. Its geometrical parameters, the assignment of IR bands and NMR chemical shifts are also computed by the density functional theory (DFT) method. In addition, the atoms in molecules (AIM) analysisis employed to investigate its geometry. Only one of the diamine-NH2 groups undergoes the condensation reaction. In the structure of the synthesized Schiff base, the remaining aminogroup lies in the para position with respect to the nitro group (isomer 1). In both gas and solution phases, isomer 1 is more stable than isomer 2 with the meta orientation of the amino and nitro groups. The NMR chemical shifts and the AIM analysis show that isomer 1 is a more favorite structure for the synthesized Schiff base. It has no planar structure. The phenolic proton is engaged in the intramolecular hydrogen bond with the azomethine nitrogen atom. The experimental results are in good agreement with the theoretical ones, confirming the validity of the optimized geometry. [ABSTRACT FROM AUTHOR]

A kinetic study is reported on nucleophilic substitution reactions of p-nitrophenyl acetate (1a) with three α-effect nucleophiles, benzohydroxamate (BHA–), p-methylbenzohydroxamate (MBHA–), and p-methyl-N-methylbenzohydroxamate (M2BHA–), and a reference nucleophile, m-chlorophenoxide (m-ClPhO–), in DMSO–H2O mixtures of varying compositions at 25.0 ± 0.1 °C. Second-order rate constants for the reactions with BHA– and MBHA– decrease upon addition of DMSO to the reaction medium up to 60 mol % DMSO and then increase thereafter only a little. In contrast, M2BHA– and m-ClPhO– become much more reactive as the DMSO content in the medium increases. Such contrasting medium effects on reactivity are consistent with the report that hydroxamic acids behave as OH acids in H2O but as NH acids in dipolar aprotic solvents (e.g., DMSO and MeCN). It has been concluded that BHA– and MBHA– form an equilibrium of a reactive form I with less reactive species II in DMSO–H2O mixtures and the position of the equilibrium is dependent on solvent compositions. BHA– and MBHA– exhibit the α-effect in H2O but not in in 90 mol % DMSO. In contrast, the α-effect yielded by M2BHA– increases steeply up to 70 mol % DMSO and then levels off thereafter. [ABSTRACT FROM AUTHOR]

The kinetics of dehydrochlorination of 1,1,1-trichloro-2,2-bis(4-nitrophenyl)ethane with sodium nitrite in dipolar aprotic solvents have been studied. Quantum chemical simulation of the process has been performed, and its thermodynamic parameters have been determined. The effects of dissociation and solvation on the rate constant have been considered. The reaction mechanism has been identified as E2H. [ABSTRACT FROM AUTHOR]

Four free base corroles, 1 – 4 , A 2 B, (where A = nitrophenyl, and B = pentafluorophenyl, 2, 6-difluoro, 3, 4, 5-trifluoro and 4-carboxymethylphenyl group) have been synthesized, characterized and demonstrated as excellent chemosensor for the detection of fluoride ions selectively in toluene solution. The reported corroles shows highest quantum yield in free base form of porphyrinoid systems so far. All these corrole, 1 – 4 , have the excellent ability to sense fluoride ion. Cumulative effect of static and dynamic factors is responsible for the quenching of fluorescence which indicates the detection of fluoride ion in solution. [ABSTRACT FROM AUTHOR]

In order to provide global energy applications, solar energy resources will desire remarkable advances in solar energy technologies. In this paper, the novel synthesis of the functionalization of Multi-wall Carbon Nanotube(MWCNT) with Azobenzene molecule (4-(4-nitrophenylazoyl)-phenol) by esterification method was approached. The covalent bond of carbonyl was revealed in FTIR Test (Fourier-Transform Infrared Spectroscopy). Templating Azobenzene molecules on the side wall of MWCNT increased the stored energy per Azobenzene molecule and created hybrid Solar Thermal Fuels (STF). The DSC Test (Differential Scanning Calorimetry) showed that Solar Thermal Fuels composed of a photoswitchable molecules indicates significantly increased energy storage capabilities over the generation of a nano-templated structure. [ABSTRACT FROM AUTHOR]

Chalcone and its derivatives are well-known for their high non-linear optical behavior and charge transfer characteristics. The effectiveness of charge transfer via ethylenic group and increase in NLO response of the chalcone upon substitutions are of great interest. The present study focuses the structural, charge transfer and non-linear optical properties of a new chalcone derivative “3-(4-nitrophenyl)-1-(pyridine-3-yl) prop-2-en-1-one” (hereafter abbreviated as 4 NP3AP). To accomplish this task, we have incorporated the experimental FT-IR, FT-Raman and UV–vis spectroscopic studies along with quantum chemical calculations. The frequency assignments of peaks in IR and Raman have been done on the basis of potential energy distribution and the results were compared with the earlier reports on similar kind of molecules. For obtaining the electronic transition details of 4 NP3AP, UV–vis spectrum has been simulated by considering both gaseous and solvent phase using time-dependent density functional theory (TD-DFT). The HOMO-LUMO energy gap, most important factor to be considered for studying charge transfer properties of the molecule has been calculated. The electron density surface map corresponding to the net electrostatic point charges has been generated to obtain the electrophilic and nucleophilic sites. The charge transfer originating from the occupied (donor) and unoccupied (acceptor) molecular orbitals have been analyzed with the help of natural bond orbital theory. Moreover, the estimation of second-hyperpolarizability of the molecule confirms the non-linear optical behavior of the molecule. [ABSTRACT FROM AUTHOR]

A novel exo-arabinase (GH93, exo-ABN) enzyme produced by the ascomycete Penicillium canescens has been studied. Cloning of the abn1 gene coding for exo-ABN into the recipient P. canescens strain RN3-11-7 yielded recombinant producing strains characterized by a high yield of extracellular exo- ABN production (20-30% of the total amount of extracellular protein). Chromatographic purification yielded a homogenous exo-ABN with a molecular weight of 47 kDa, as shown by SDS-PAGE. The enzyme showed high specific activity towards linear arabinan (117 U/mg) and low specific activity towards branched arabinan and arabinoxylan (4-5 U/mg) and para-nitrophenyl-α-L-arabinofuranoside (0.3 U/mg), whereas arabinogalactan and para-nitrophenyl-α-L-arabinopyranoside, the substrates that contained the pyranose form of arabinose, were not hydrolyzed. Arabinohexaose was the major product of linear arabinan hydrolysis. Exo-ABN had a pH optimum at 5.0 and a temperature optimum at 60°C. The enzyme was stable in a broad pH range (4.0-7.0) and upon heating to 50°C during 180 min. Extensive hydrolysis of linear and branched arabinans by exo- and endo-arabinase mixtures, arabinofuranosidase, and arabinofuran-arabinoxylan hydrolase has been performed. The degree of substrate conversion amounted to 67 and 83% of the maximal possible value, respectively. [ABSTRACT FROM AUTHOR]

The synthesis of (2‐nitrophenyl)acetyl (NPAc)‐protected glucosyl donors is described that were designed for the neighboring‐group assisted glucosylation of base‐labile natural products also being sensitive to hydrogenolysis. Glycosylation conditions were optimized using a trichloroacetimidate glucosyl donor, and cyclohexylmethanol and (+)‐menthol as model acceptors. The approach was then extended to a one‐pot procedure for the synthesis of 1,2‐trans‐glycosides. This method was finally applied for improved synthesis of the masked mycotoxin T2‐O‐β, d‐glucoside. [ABSTRACT FROM AUTHOR]

A selective separation and preconcentration method for the determination of gold ions in water and ore samples has been developed using dispersive liquid-liquid microextraction, followed by flame atomic absorption spectrometry. 4-Ethyl-1(2-(4-(4-nitrophenyl)piperazin-1-yl)acetyl)thiosemicarbazide) (NPPTSC) has been used for the first time as new chelating reagent. A mixture of ethanol (dispersive solvent) and carbon tetrachloride (extraction solvent) was used. Some parameters affecting the extraction procedure including the type and volume of the extracting and dispersive solvents, HNO3 concentration, the chelating agent amount, volume of sample, and foreign ions have optimized. Also, the complex formation between gold ions and the ligand has been investigated in a methanol-water solution (1:1) using UV-visible spectrometry. The spectrophotometric titration data showed that of Au-NPPTSC complex composition was found to be 3:2. After optimizing the instrumental and experimental parameters, we achieved a detection limit of 1.5 µg L−1, a preconcentration factor of 50, and a linear dynamic range of 10.0-400.0 µg L−1. The relative standard deviation obtained 2.1% at 50 µg L−1 for gold ions (n = 10). The proposed method was successfully performed for the determination of gold in certified reference material, environmental water, and ore samples. [ABSTRACT FROM AUTHOR]

Summary: Biofilms of sulfate‐reducing bacteria (SRB) produce H2S, which contributes to corrosion. Although bacterial cells in biofilms are cemented together, they often dissolve their own biofilm to allow the cells to disperse. Using Desulfovibrio vulgaris as a model SRB, we sought polysaccharide‐degrading enzymes that disperse its biofilm. Using a whole‐genome approach, we identified eight enzymes as putative extracellular glycoside hydrolases including DisH (DVU2239, dispersal hexosaminidase), an enzyme that we demonstrated here, by utilizing various p‐nitrooligosaccharide substrates, to be an N‐acetyl‐β‐D‐hexosaminidase. For N‐acetyl‐β‐D‐galactosamine (GalNAc), Vmax was 3.6 µmol of p‐nitrophenyl/min (mg protein)−1 and Km was 0.8 mM; the specific activity for N‐acetyl β‐D‐glucosamine (GlcNAc) was 7.8 µmol of p‐nitrophenyl/min (mg protein)−1. Since GalNAc is one of the three exopolysaccharide matrix components of D. vulgaris, purified DisH was found to disperse 63 ± 2% biofilm as well as inhibit biofilm formation up to 47 ± 4%. The temperature and pH optima are 60°C and pH 6, respectively; DisH is also inhibited by copper and is secreted. In addition, since polymers of GalNAc and GlcNAc are found in the matrix of diverse bacteria, DisH dispersed biofilms of Pseudomonas aeruginosa, Escherichia coli and Bacillus subtilis. Therefore, DisH has the potential to inhibit and disperse a wide‐range of biofilms. [ABSTRACT FROM AUTHOR]

Purpose: Pharmacokinetics and pharmacodynamics of irinotecan have been reported to be altered in cancer patients with end-stage kidney disease (ESKD). Carboxylesterase (CES) has an important role in metabolism of irinotecan to its active metabolite, SN-38, in human liver. The purpose of the present study was to investigate whether CES activity was altered in ESKD patients.Methods: The present study investigated the effects of uremic serum, uremic toxins, and fatty acids on the hydrolysis of irinotecan and a typical CES substrate, p-nitrophenyl acetate (PNPA), in human liver microsomes. Normal and uremic serum samples were deproteinized by treatment with methanol were used in the present study.Results: The present study showed that both normal and uremic serum significantly inhibited CES-mediated metabolism of both irinotecan and PNPA. The inhibition by uremic serum was weaker than that by normal serum, suggesting that CES activity may be higher in ESKD patients. Although four uremic toxins did not affect PNPA metabolism, arachidonic acid inhibited it. There was no difference in inhibitory effect of PNPA metabolism between both mixtures of seven fatty acids used at concentrations equivalent to those present in 10% normal or uremic serum. Interestingly, those mixtures had a more pronounced effect than either 10% normal or uremic serum.Conclusions: The present study showed that the inhibition of CES activity by uremic serum was weaker than that by normal serum, suggesting that an increase in maximum plasma concentration of SN-38 in cancer patients with ESKD can be attributed to an accelerated CES-mediated irinotecan hydrolysis. [ABSTRACT FROM AUTHOR]

This paper describes the synthesis of giant cyclic molecules having diameters of 10-20 nm. The molecules are prepared through the reactions of a fusion protein building block with small molecule linkers that are terminated in irreversible inhibitors of enzyme domains present in the fusion. This building block has N-terminal cutinase and C-terminal SnapTag domains that react irreversibly with p-nitrophenyl phosphonate (pNPP) and benzylguanine (BG) groups, respectively. We use a bis-BG and a BG-pNPP linker to join these fusion proteins into linear structures that can then react with a bis-pNPP linker that joins the ends into a cyclic product. The last step can occur intramolecularly, to give the macrocycle, or intermolecularly with another equivalent of linker, to give a linear product. Because these are coupled first- and second-order processes, an analysis of product yields from reactions performed at a range of linker concentrations gives rate constants for cyclization. We determined these to be 9.7 x 10[sup -3] s[sup -1], 2.3 x 10[sup -3] s[sup -1], and 8.1 x 10[sup -4] s[sup -1] for the dimer, tetramer, and hexamer, respectively. This work demonstrates an efficient route to cyclic macromolecules having nanoscale dimensions and provides new scaffolds that can be generated using the megamolecule approach. [ABSTRACT FROM AUTHOR]

Two polymorphs (forms I and II) of a new Mannich base 4-methyl-2-((4-(4-nitrophenyl)piperazin-1-yl)methyl)phenol have been isolated and characterized by single crystal and powder (experimental and theoretical) X-ray diffraction, thermal analysis (differential scanning calorimetry), Fourier transform infrared spectroscopy. 1 H and 13 C nuclear magnetic resonance spectroscopy was employed in characterising the new Mannich base. Single crystal X-ray diffraction revealed that the two polymorphs contain different conformers of the Mannich base whose hydrogen bonding schemes and packing arrangements in their respective crystals are different. Thermal analysis led to the conclusion that the two polymorphs are enantiotropically related, with a transition temperature of 138.5 °C. [ABSTRACT FROM AUTHOR]

Protein–carbohydrate interactions are at the heart of many biological processes. For lectins, those interactions result simply in the association of two species, whereas for enzymes like glycosidases, association ultimately leads to cleavage and formation of covalent bonds. We have investigated lectin–septanose interactions in the past. Here we report on a route to synthesize p‐nitrophenyl septanosides via the corresponding septanosyl halides. During the investigation we observed differential rates of glycosyl halide formation of the per‐O‐acetyl septanoses based on the stereochemistry at C1 and C2. Further, we observed unexpected stereoselectivities in glycoside bond formation that depended on a number of factors including the electrophilic sugar species, the incoming nucleophile, and reaction conditions. The results provided new parameters to consider when approaching septanose glycosylations. Even more importantly, the synthesis of p‐nitrophenyl septanosides will enable them to be used to interrogate septanose‐glycosidase binding and hydrolysis. [ABSTRACT FROM AUTHOR]

Electromembrane extraction (EME) is a powerful extraction and preconcentration technique for ionizable species. However, the ionic contents in the sample can influence the extraction efficiency and system stability due to electrolysis. In this work, the electromembrane extraction of chromium(VI) was developed using various levels of ionic samples. 2-Nitrophenyl octyl ether was the most suitable supported liquid membrane that delayed the electrolytic occurrence of air bubbles at the electrodes due to its high viscosity and high dielectric constant properties. The electromembrane extraction method was optimized using 5 mM NaCl (630 µS cm−1); the applied potential was 100 V and the extraction time was 15 min. The enrichment factor of 80 was obtained over a linear working range of 10.0–80.0 µg L−1. The method performance was tested using mineral water, drinking water, tap water, and surface water. The method recoveries based on matrix-matched calibration were 95–125% with standard deviations within 15%. [ABSTRACT FROM AUTHOR]

Two regioisomeric phenalenocarbazoles have been synthesized by direct reductive cyclization of 2′-Nitrophenyl-pyrene isomers respectively. Their photophysical properties and crystal structures as well as CV properties were investigated and compared with those of sulfur containing analogues. Although the fluorescence emission properties of 1N are very similar with those of 2N , the HOMO energy level of 1N is 0.16 eV higher than that of 2N indicating that 1N has better electron donating ability. [ABSTRACT FROM AUTHOR]

This paper reports the synthesis and the physicochemical characterization of two series of gellan gum (GG) derivatives functionalized with alkyl chains with different number of carbon, from 8 to 18. In particular, low molecular weight gellan gum samples with 52.6 or 96.7 kDa, respectively, were functionalized with octylamine (C 8 ), dodecylamine (C 12 ) and octadecylamine (C 18 ) by using bis(4-nitrophenyl) carbonate (4-NPBC) as a coupling agent. Thermo-rheological and ionotropic crosslinking properties of these gellan gum-alkyl derivatives were evaluated and related to the degree of derivatization in alkyl chains. Results suggested as length and degree of derivatization differently influenced coil-to-helix gelation mechanism of GG derivatives, ionotropic crosslinking, and strength of crosslinked hydrogels obtained in CaCl 2 0.102 M and NaCl 0.15 M. Statement of hypothesis: The insertion of alkyl chains on the gellan gum backbone interferes with coil-to-helix transition mechanism and allows the production of hydrophobically assembled hydrogels. [ABSTRACT FROM AUTHOR]

In this article we reported the formulation of an ionic liquid (IL)-based microemulsion stabilized by the surfactant tween 20 (without cosurfactant). The enzymatic hydrolysis of p-nitrophenyl butyrate catalyzed by Candida rugosa lipase was used as a model reaction. In this system, the enzymatic activity was measured as a function of lipase concentration, reaction temperature, pH, and W0 (molar ratio of water to surfactant). The experimental results demonstrated that IL-based microemulsion was used instead of the conventional oil reverse micelle to improve the greenness of the enzyme reactions. The combination of enzyme with IL-based microemulsion represented a promising “green” reaction system for bioconversions because of the unique features of both IL and microemulsions. [ABSTRACT FROM AUTHOR]

Abstract: Taking the fingerprint characteristics of Raman spectroscopy, the dimerization of p‐nitrothiophenol (PNTP) to 4‐nitrophenyl disulfide in air was investigated, which could be accelerated by the external laser illumination. The dimerization was qualitatively confirmed by both mass spectroscopy experimentally and by Raman spectrum simulated calculations theoretically and quantitatively analyzed by Raman spectroscopy in a simple and quick manner. On the basis of the inductively coupled plasma optical mass spectrometry analysis, the dimerization was possibly ignited by the trace metal residues as catalyst in the PNTP. This study clearly shows that it is very important to strictly and preciously control the experimental conditions of Raman measurement and other laser‐based spectroscopies to avoid any wrong conclusion during the characterization or identification. Different to the plasmon‐induced photochemical reactions, we reported the photochemical reaction of PNTP to 4‐nitrophenyl disulfide, which is free of the plasmoic effect from the metal nanostrucutres. On the other hand, the photochemical dimerization reaction may provide a new and important guideline for the formation of thiols to disulfides. [ABSTRACT FROM AUTHOR]

Abstract: The kinetics of the hydrolysis of p‐nitrophenyl diphenyl phosphate (PNPDPP) by hydroxamate ions (R'(CO)N(RO−) such as octanohydroxamate (OHA−) and decanohydroxamate (DHA−) was investigated in dioctadecyldimethylammonium chloride (DODAC) and didodecyldimethylammonium bromide (DDAB) vesicles. The physicochemical properties of these surfactants were studied by conductivity and fluorescence measurements at 300 K. The hydrolysis of PNPDPP was studied in a vesicular system by using hydroxamate ions (OHA− and DHA−) at 300 K. The different catalytic effects of hydroxamate ions for the hydrolysis of PNPDPP in the vesicles were determined. All reactions followed pseudofirst‐order kinetics. The reactivity of DHA− was found to be higher than that of OHA− in the vesicular system toward the cleavage of phosphate ester. Further, the binding constants (K) and free energy change (∆G) for the associations of PNPDPP with DODAC and DDAB vesicles were determined spectrophotometrically as well as from the Benesi–Hildebrand (B–H) plots. The pseudophase model was applied for the quantitative treatment of the kinetic data in the vesicle systems. [ABSTRACT FROM AUTHOR]

Recent advancements in micro-flow technologies and a drive toward more efficient, greener and safer processes have led to a renaissance in flow-chemistry for pharmaceutical production. In this work, we demonstrate the use of a stabilized Pd nanoparticle-organic-silica catalyst to selectively catalyze the hydrogenation of N-4-nitrophenyl nicotinamide, a functionalized active pharmaceutical ingredient (API) surrogate. Extensive catalyst and reactor characterization is provided to establish an in-depth understanding of the unique multiphase dynamics within the micro-packed bed reactor, including the identification of a large liquid holdup (74–84%), rapid multiphase mass transfer (kma ＞ 1 s−1), and liquid residence time distributions. A kinetic analysis has revealed that the surface catalyzed hydrogenation progresses through a condensation mechanism whereby an azo dimer intermediate is formed and rapidly consumed. Finally, a parametric study was performed at various pressures, temperatures, residence times and flow regimes to achieve quantitative chemoselective conversion of the nitroarene to the corresponding primary amine. [ABSTRACT FROM AUTHOR]

We have set out an equation for partition of 87 neutral molecules from water to o-nitrophenyl octyl ether, NPOE, an equation for partition of the 87 neutral molecules and 21 ionic species from water to NPOE, and an equation for partition of 87 neutral molecules from the gas phase to NPOE. Comparison with equations for partition into other solvents shows that, as regards partition of neutral (nonelectrolyte) compounds, NPOE would be a good model for 1,2-dichloroethane and for nitrobenzene. In terms of partition of ions and ionic species, NPOE is quite similar to 1,2-dichloroethane and not far away from other aprotic solvents such as nitrobenzene. [ABSTRACT FROM AUTHOR]

Three phenoxazinium compounds attached with o -nitrophenyl ( 3a ), m -nitrophenyl ( 3b ) and p -nitrophenyl ( 3c ) groups were prepared, and the pH promoted emission spectra were used to evaluate the deprotonated-protonated equilibrium between phenoxazinium and phenoxazine. They showed nearly ON-OFF emission responses at 650–850 nm around pH 8.0–10.8, and the fluorescence related p K a s of 3a–c were 8.7, 9.2, and 8.9, respectively. Two phenoxazinium compounds attached with pyridinyl groups ( 7a–b ) were further prepared, the pH promoted emission spectra were influenced by both the deprotonated-protonated equilibrium between phenoxazinium and phenoxazine, and the equilibrium between pyridinyl group and pyridinumyl group. They exhibited more strong red and near-infrared emission at 600–850 nm, probe 7a gave p K a ,1 = 3.71 and p K a ,2 = 9.68, and that of probe 7b was 2.75. Moreover, the fluorescent imaging experiment indicated that probe 7a was a lysosome biomarker for V79 and HeLa cells. [ABSTRACT FROM AUTHOR]

Acetohydroxyacid synthase (AHAS, EC: 2.2.1.6) is a target for the development of novel herbicides. Two series of N -nitrophenyl derivatives, type-A and type-B, were designed and synthesized based on the active site of the AHAS structure. All the structures of newly prepared compounds were thorough characterized by IR, and 1 H NMR spectrums. The IC 50 values of all synthesized target compounds against AHAS enzyme and EC 50 values for herbicidal activity against Brassica campestris L. , Amaranthus mangostanus L. and Sorghum sudanense were determined. The bioactive assay results showed that the type-B compounds exhibited highly improved inhibitory activity against the AHAS enzyme and the tested plants comparing to type-A compounds. The IC 50 values of most type-B compounds against the AHAS enzyme were between 25–177 μM. The EC 50 values of several type-B compounds against Sorghum sudanense reached 5.0 mg/L. The differences in the biological activity between type-A and type-B compounds were attributed to two structural features - the orthogonal bend at the N -nitro amides group and the common plane structure of another phenyl with chain bridge. With the structure of the target compounds and the IC 50 values for AHAS enzyme, a statistically significant CoMFA model with high predict abilities (q 2 = 0.606, r 2 = 0.982, N = 4, SEE = 0.058, F = 280.255) was obtained, and its reliability was verified. The model will provide a theoretical basis for the further structural optimization. [ABSTRACT FROM AUTHOR]

In order to utilize the neuroprotective properties of polycyclic cage compounds, and explore the NO-donating ability of nitrophenyl groups, an array of compounds was synthesized where the different nitrophenyl groups were appended on oxa and aza-bridged cage derivatives. Biological evaluations of the compounds were done for cytotoxicity, neuroprotective abilities, the inhibition of N-methyl-d-aspartate (NMDA)-mediated Ca2+ influx, the inhibition of voltage-mediated Ca2+ influx, and S-nitrosylation abilities. All of the compounds showed low toxicity. With a few exceptions, most of the compounds displayed good neuroprotection and showed inhibitory activity for NMDA-mediated and voltage-gated calcium influx, ranging from high (>70%) to low (20–39%) inhibition. In the S-nitrosylation assay, the compounds with the nitro moiety as the NO-donating group exhibited low to good nitrosylation potency compared to the positive controls. From the biological evaluation of the tested compounds, it was not possible to obtain a simple correlation that could explain the results across all of the biological study domains. This can be ascribed to the independent processes evaluated in the different assays, which reiterate that neuroprotection is a result of multifactorial biochemical mechanisms and interactions. However, these results signify the important aspects of the pentacylcoundecylamine neuroprotectants across different biological study realms. [ABSTRACT FROM AUTHOR]

Background: The deep-sea environment harbors a vast pool of novel enzymes. Owing to the limitations of cultivation, cultivation-independent has become an effective method for mining novel enzymes from the environment. Based on a deep-sea sediment metagenomics library, lipolytic-positive clones were obtained by activity-based screening methods. Results: Two novel esterases, DMWf18-543 and DMWf18-558, were obtained from a deep-sea metagenomic library through activity-based screening and high-throughput sequencing methods. These esterases shared 80.7% amino acid identity with each other and were determined to be new members of bacterial lipolytic enzyme family IV. The two enzymes showed the highest activities toward p-nitrophenyl (p-NP) butyrate at pH 7.0 and 35-40 °C and were found to be resistant to some metal ions (Ba2+, Mg2+, and Sr2+) and detergents (Triton X-100, Tween 20, and Tween 80). DMWf18-543 and DMWf18-558 exhibited distinct substrate specificities and preferences. DMWf18-543 showed a catalytic range for substrates of C2-C8, whereas DMWf18-558 presented a wider range of C2-C14. Additionally, DMWf18-543 preferred p-NP butyrate, whereas DMWf18-558 preferred both p-NP butyrate and p-NP hexanoate. To investigate the mechanism underlying the phenotypic differences between the esterases, their three-dimensional structures were compared by using homology modeling. The results suggested that residue Leu199 of DMWf18-543 shortens and blocks the substrate-binding pocket. This hypothesis was confirmed by the finding that the DMWf18-558-A199L mutant showed a similar substrate specificity profile to that of DMWf18-543. Conclusions: This study characterized two novel homologous esterases obtained from a deep-sea sediment metagenomic library. The structural modeling and mutagenesis analysis provided insight into the determinants of their substrate specificity and preference. The characterization and mechanistic analyses of these two novel enzymes should provide a basis for further exploration of their potential biotechnological applications. [ABSTRACT FROM AUTHOR]

A rapid, simple, and sensitive fluorescent immunochromatographic strip test (ICST) based on quantum dots (QDs) has been developed to detect 1-aminohydantoin (AHD), a major metabolite of nitrofurantoin in animal tissues. To achieve this, QD-labeled antibody conjugates, which consist of CdSe/ZnS QDs and monoclonal antibodies, were prepared by an activated ester method. Under optimal conditions, with the nitrophenyl derivative of AHD as the target, the ICST had a linear range from 0.1 to 100 ng/mL, with a correlation coefficient of 0.9656 and a 50% inhibitory concentration of 4.51 ng/mL. The limit of detection was 0.14 ng/g, which was below the minimum required performance limit of 1 μg/kg for AHD established by the European Commission. The recoveries for AHD ranged from 81.5% to 108.2%, with coefficients of variation below 13%, based on intraday and interday analysis. Furthermore, for AHD in real samples, the ICST showed high reliability and high correlation with liquid chromatography-tandem mass spectrometry (correlation coefficient of 0.9916). To the best of our knowledge, this is the first report of a novel and sensitive method based on a fluorescent ICST to detect AHD below the minimum required performance limit. The ICST demonstrated high reliability, and could be ideally suited for rapid, simple, and on-site screening of AHD contamination in animal tissues. [ABSTRACT FROM AUTHOR]

Herein, supramolecular systems with improved aggregation, solubilization and catalytic activity have been constructed by self-assembly of gemini surfactants with two cationic centers separated by the spacer chain of 10 atoms long and hydroxyl functionality in their head group or in the spacer. It was found that hydroxylic dicationic surfactants capable of forming hydrogen bonds exhibit the ability to micelle formation at a concentration substantially lower than that of their monocationic and non-functionalized dicationic counterparts. They are capable of initiating additional solubilization mechanisms, which are responsible for the enhanced solubilization capacity of the surfactants. The use of the dicationic hydroxylic surfactants in hydrolytic decomposition of esters gives rise to the high catalytic effect and substrate selectivity: the highest, 430-fold, acceleration was observed for p -nitrophenyl caprate. [ABSTRACT FROM AUTHOR]

Monitoring and rapid evaluation of nitrofurantoin metabolite, 1-aminohydantoin (AHD), are important for food safety and human health. Herein, we established the monoclonal antibody-based indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) and quantum dots (QDs)—fabricated fluorescence-linked immunosorbent assay (FLISA). Monoclonal antibody specific to nitrophenyl derivative of AHD was derived from hybridoma cell lines 3.2.4/5A8. For another, CdTe core QDs with emission wavelength of 605 nm were also synthesized. The performances of the proposed ic-ELISA and FLISA were further examined and the corresponding results were also validated by standard LC–MS/MS analysis. The obtained results indicated that both ic-ELISA and FLISA exhibited good dynamic linear detection for NPAHD over the range from 0.1 to 3.0 ng mL −1 . Meanwhile, proposed immunosorbent assays are characterized by satisfactory recovery rates of 81.5–113.7%. The experimental data suggested these two immunoassays could be facile, cost-effective and rapid tools for the prospective quantitative method for AHD analysis in food matrix. [ABSTRACT FROM AUTHOR]

A novel, family GH10 enzyme, Xyn10B from Acidothermus cellulolyticus 11B was cloned and expressed in Escherichia coli. This enzyme was purified to homogeneity by binding to regenerated amorphous cellulose. It had higher binding on Avicel as compared to insoluble xylan due to the presence of cellulose-binding domains, CBM3 and CBM2. This enzyme was optimally active at 70 °C and pH 6.0. It was stable up to 70 °C while the CD spectroscopy analysis showed thermal unfolding at 80 °C. Xyn10B was found to be a trifunctional enzyme having endo-xylanase, arabinofuranosidase and acetyl xylan esterase activities. Its activities against beechwood xylan, p-Nitrophenyl arabinofuranoside and p-Nitrophenyl acetate were found to be 126,480, 10,350 and 17,250 U μmol, respectively. Xyn10B was highly active producing xylobiose and xylose as the major end products, as well as debranching the substrates by removing arabinose and acetyl side chains. Due to its specific characteristics, this enzyme seems to be of importance for industrial applications such as pretreatment of poultry cereals, bio-bleaching of wood pulp and degradation of plant biomass. [ABSTRACT FROM AUTHOR]

In the title compound, C15H14N2 O5, the benzene rings are nearly coplanar, making a dihedral angle of 4.89 (8)°. An intramolecular N-H…O hydrogen bond occurs between the imino and methoxy groups. In the crystal, weak C-H…O hydrogen bonds link the molecules into supramolecular chains propagating along the a-axis direction. Ȱ-Ȱ stacking is observed between parallel benzene rings of neighbouring chains, the centroid-to-centroid distance being 3.6491 (10) Å . Three-dimensional Hirshfeld surface analyses and twodimensional fingerprint plots have been used to analyse the intermolecular interactions present in the crystal. [ABSTRACT FROM AUTHOR]

This review explores the heterocyclic family of N‐nitrophenyl pyrazoles and indazoles covering mainly their structural aspects, with special emphasis on the X‐ray diffraction data. NMR spectroscopy and the theoretical calculations will also be briefly summarized. The synthesis and reactivity aspects will be reported when they are specific to these compounds. [ABSTRACT FROM AUTHOR]

The kinetics of the reaction of a series of α-amino acids with 4-nitrophenyl acetate, 4-nitrophenyl benzoate, and 2,4,6-trinitrophenyl benzoate in aqueous 1,4-dioxane medium has been studied. Kinetics of the reactions involving 4-nitrophenyl acetate and 2,4,6-trinitrophenyl benzoate has complied with the Brønsted dependence and revealed linear correlation between rate constant logarithm and the energy difference of the frontier orbitals of α-amino acids anions. [ABSTRACT FROM AUTHOR]

Carboxylesterase (CES) and arylacetamide deacetylase (AADAC) are the major enzymes responsible for the hydrolysis of various clinical drugs. Our recent study demonstrated that the identity of the responsible hydrolase can be roughly surmised based on the chemical structures of compounds in humans. Dogs are used for preclinical studies in drug development, but the substrate specificities of dog CES and AADAC remain to be clarified. The purpose of this study is to characterize their substrate specificities. We prepared recombinant dog CES1, CES2, and AADAC. p -Nitrophenyl acetate, a general substrate for esterases, was hydrolyzed by dog CES1 and AADAC, while it was not hydrolyzed by CES2. CES2 protein was not substantially detected in the recombinant system or in the dog liver and intestinal microsomes by Western blot using anti-human CES2 antibodies. In silico analyses demonstrated slight differences in the three-dimensional structures of dog CES2 and human CES2, indicating that dog CES2 might be unstable or inactive. By evaluating the hydrolase activities of 22 compounds, which are known to be substrates of human CES and/or AADAC, we found that the activities of dog recombinant CES1 and AADAC as well as dog tissue preparations for nearly all compounds were lower than those of human enzymes. The dog enzymes that were responsible for the hydrolysis of most compounds corresponded to the human enzymes, but the following differences were observed: oseltamivir, irinotecan, and rifampicin were not hydrolyzed in the dog liver or by any of the recombinant esterases and procaine, a human CES2 substrate, was hydrolyzed by dog CES1. In conclusion, the present study could provide new finding to facilitate our understanding of species differences in drug hydrolysis, which can facilitate drug development and drug safety evaluation. [ABSTRACT FROM AUTHOR]