3316-09-4Relevant articles and documents
SYNTHESIS AND SOLVATOCHROMIC AND ACID-BASE REACTIONS OF A BETAINE AND SALTS OF 4-N-PYRIDINIUMCATECHOL
Neiland, O. Ya.,Kraupsha, I. L.,Gudele, I. Ya.
, p. 1428 - 1434 (1993)
Oxidation of catechol by phenyliodosyldiacetate in the presence of pyridine gives 4-N-pyridiniumcatechol salts whose structures are confirmed by an independent synthesis from 2,2-dimethyl-5-aminobenzodioxole.The spectroscopically determined ionization constants for the 4-N-pyridiniumcatechol cation depend on the nature of the buffer cation solution (sodium, ammonium, tetraethylammonium).The large solvatochromic shift in the long wavelength absorption band of the betaine of 4-N-pyridinium-catechol followed the empirical scale of solvent polarity ENT.Introduction of the N-pyridinium group in position 4 increases the acidity of the catechol by 2.7 pK units, which is an almost identical effect to the introduction of a 4-nitro group.However, the solvatochromism for the anion of 4-nitrocatechol is insignificant.The compounds were characterized by their 1H NMR and IR spectra.
Cooperative effects for CYP2E1 differ between styrene and its metabolites
Hartman, Jessica H.,Boysen, Gunnar,Miller, Grover P.
, p. 755 - 764 (2013)
1. Cooperative interactions are frequently observed in the metabolism of drugs and pollutants by cytochrome P450s; nevertheless, the molecular determinants for cooperativity remain elusive. Previously, we demonstrated that steady-state styrene metabolism by CYP2E1 exhibits positive cooperativity. 2. We hypothesized that styrene metabolites have lower affinity than styrene toward CYP2E1 and limited ability to induce cooperative effects during metabolism. To test the hypothesis, we determined the potency and mechanism of inhibition for styrene and its metabolites toward oxidation of 4-nitrophenol using CYP2E1 Supersomes and human liver microsomes. 3. Styrene inhibited the reaction through a mixed cooperative mechanism with high affinity for the catalytic site (67μM) and lower affinity for the cooperative site (1100μM), while increasing substrate turnover at high concentrations. Styrene oxide and 4-vinylphenol possessed similar affinity for CYP2E1. Styrene oxide behaved cooperatively like styrene, but 4-vinylphenol decreased turnover at high concentrations. Styrene glycol was a very poor competitive inhibitor. Among all compounds, there was a positive correlation with binding and hydrophobicity. 4. Taken together, these findings for CYP2E1 further validate contributions of cooperative mechanisms to metabolic processes, demonstrate the role of molecular structure on those mechanisms and underscore the potential for heterotropic cooperative effects between different compounds.
Potentiometric determination of arylsulfatase activity using a novel nitrocatechol sulfate PVC membrane sensor
Hassan, Saad S. M.,Marzouk,Abdel-Fattah,Shouckry
, p. 1887 - 1891 (1995)
A novel potentiometric assay method for arylsulfatase enzyme is described based on measuring the initial reaction rate of hydrolysis of 4-nitrocatechol sulfate (4-NCS) substrate under optimized conditions. A monitoring sensor incorporating a PVC membrane with a nickel(II) bathophenanthroline-4-NCS ion-pair complex as electroactive material and 2-nitrophenyl phenyl ether as solvent mediator is developed and characterized. The sensor exhibits fast and stable linear response for 8 × 10-3-7.5 × 10-6 M 4-NCS with an anionic slope of 58.5 ± 0.2 mV/decade over the pH range 3-6. The sensor is used to follow up the decrease in a fixed concentration of 4-NCS (2 × 10-4 M) as a function of arylsulfatase activity at pH 5.6 and 37 °C. A linear relationship between the initial rate of substrate hydrolysis and enzyme activity holds for 0.2-2.4 IU/mL (SD 2%). Activity measurement of arylsulfatase enzyme isolated from camel liver gives results that compare favorably well with data obtained using the standard spectrophotometric assay method. Significant advantages over many of the previously described spectroscopic methods are offered by the proposed potentiometric technique.
Nitrocatechols versus nitrocatecholamines as novel competitive inhibitors of neuronal nitric oxide synthase: Lack of the aminoethyl side chain determines loss of tetrahydrobiopterin-antagonizing properties
Palumbo, Anna,Napolitano, Alessandra,D'Ischia, Marco
, p. 13 - 16 (2002)
6-Nitrocatecholamines were recently described as novel neuronal nitric oxide synthase inhibitors competing with both L-arginine and tetrahydrobiopterin (BH4). We report now that simple nitrocatechols are also competitive inhibitors, lacking however BH4-antagonizing properties. It is argued that 6-nitrocatecholamines interact with the L-arginine- and BH4-binding sites through the nitrocatechol and aminoethyl moieties, respectively.
Anthracene Substituted Co (II) and Cu (II) phthalocyanines; Preparations, Investigation of Catalytical and Electrochemical Behaviors
Saka, Ece Tugba,Biyiklioglu, Zekeriya,Caglar, Yasemin
, (2018)
An approach to investigation of catalytical behaviors of Co (II) and Cu (II) phthalocyanines is reported that is based on changing any parameter to effect these behaviors. Towards this end, new anthracene substituted Co (II) and Cu (II) phthalocyanines were prepared and characterized spectroscopic methods. New cobalt (II) and copper (II) phthalocyanines were used as catalyst for oxidation of different phenolic compounds (such as 2,3-dichlorophenol, 4-methoxyphenol, 4-nitrophenol, 2,3,6-trimethylphenol) with different oxidants. Then, electrochemical characterization of cobalt (II) and copper (II) phthallocyanines were determined by using cyclic voltammetry (CV) and square wave voltammetry (SWV) techniques. Although copper (II) phthalocyanine showed similar Pc based electron transfer processes, cobalt (II) phthalocyanine showed metal and ligand based reduction reactions as expected.
Enhanced electrochemical degradation of 4-Nitrophenol molecules using novel Ti/TiO2-NiO electrodes
Fadillah, Ganjar,Saleh, Tawfik A.,Wahyuningsih, Sayekti
, (2019)
Removal of 4-Nitrophenol (4-NP) compounds by the electrochemical degradation method using Ti/TiO2-NiO electrodes was successfully conducted. This study aims to study the activity of Ti/TiO2-NiO electrodes in the electrocatalytic degradation of 4-NP as organic compound pollutants. Ti/TiO2-NiO preparation was carried out by the wet impregnation technique, then TiO2-NiO composites were sprayed on the surface of Titanium electrodes. The electrode was characterized by X-Ray Diffraction (XRD), a Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM), and Cyclic Voltammetry (CV). A Diffractogram XRD of TiO2-NiO composites showed a characteristic peak of TiO2-NiO at 2θ = 33°. Meanwhile, analysis of the SEM surface morphology showed that NiO with an average particle size of 22.07 μm can be attached to the surface of the Ti/TiO2 plate. Electrocatalytic degradation of 4-NP compounds was found to be optimum at pH 11 and 80 min electrolysis time with a rate constant of 0.0373 min?1. The electrochemical degradation exhibited the percentage of removing 4-NP rate of >95% with good electrode measurement stability.
Nonmicrobial nitrophenol degradation via peroxygenase activity of dehaloperoxidase-hemoglobin from amphitrite ornata
McCombs, Nikolette L.,D'Antonio, Jennifer,Barrios, David A.,Carey, Leiah M.,Ghiladi, Reza A.
, p. 2465 - 2478 (2016)
The marine hemoglobin dehaloperoxidase (DHP) from Amphitrite ornata was found to catalyze the H2O2-dependent oxidation of nitrophenols, an unprecedented nonmicrobial degradation pathway for nitrophenols by a hemoglobin. Using 4-nitrophenol (4-NP) as a representative substrate, the major monooxygenated product was 4-nitrocatechol (4-NC). Isotope labeling studies confirmed that the O atom incorporated was derived exclusively from H2O2, indicative of a peroxygenase mechanism for 4-NP oxidation. Accordingly, X-ray crystal structures of 4-NP (1.87 ?) and 4-NC (1.98 ?) bound to DHP revealed a binding site in close proximity to the heme cofactor. Peroxygenase activity could be initiated from either the ferric or oxyferrous states with equivalent substrate conversion and product distribution. The 4-NC product was itself a peroxidase substrate for DHP, leading to the secondary products 5-nitrobenzene-triol and hydroxy-5-nitro-1,2-benzoquinone. DHP was able to react with 2,4-dinitrophenol (2,4-DNP) but was unreactive against 2,4,6-trinitrophenol (2,4,6-TNP). pH dependence studies demonstrated increased reactivity at lower pH for both 4-NP and 2,4-DNP, suggestive of a pH effect that precludes the reaction with 2,4,6-TNP at or near physiological conditions. Stopped-flow UV-visible spectroscopic studies strongly implicate a role for Compound I in the mechanism of 4-NP oxidation. The results demonstrate that there may be a much larger number of nonmicrobial enzymes that are underrepresented when it comes to understanding the degradation of persistent organic pollutants such as nitrophenols in the environment.
Gas-phase IR cross-sections and single crystal structures data for atmospheric relevant nitrocatechols
Arsene, Cecilia,Bejan, Iustinian-Gabriel,Olariu, Romeo-Iulian,Roman, Claudiu,Roman, Tiberiu
, (2021/09/28)
The gas-phase IR absorption cross sections for 3-nitrocatechol, 5-methyl-3-nitrocatechol, 4-nitrocatechol and 4-methyl-5-nitrocatechol were evaluated using the ESC-Q-UAIC (the environmental simulation chamber made of quartz from the “Alexandru Ioan Cuza” University of Iasi, Romania) photoreactor facilities. Specific infrared absorptions and integrated band intensities in the range of 650–4000 cm?1 were investigated by long path gas-phase FT-IR technique. Two different addition methods (solid and liquid transfer methods) of nitrocatechols into the reactor were employed in these investigations. All investigated nitrocatechols were synthesized and characterized by X-ray diffraction spectroscopy techniques beside traditional nuclear magnetic resonance (NMR) and infrared (IR) spectroscopy in order to evaluate their structure-properties relationship in gas and solid phase. This study reports for the first time the gas-phase infrared cross sections and the X-ray diffraction analysis for (methyl) nitrocatechols.
Solar-Powered Whole-Cell P450 Catalytic Platform for C-Hydroxylation Reactions
Le, Thien-Kim,Kim, Jinhyun,Anh Nguyen, Ngoc,Huong Ha Nguyen, Thi,Sun, Eun-Gene,Yee, Su-Min,Kang, Hyung-Sik,Yeom, Soo-Jin,Beum Park, Chan,Yun, Chul-Ho
, p. 3054 - 3058 (2021/06/21)
Photobiocatalysis is a green platform for driving redox enzymatic reactions using solar energy, not needing high-cost cofactors and redox partners. Here, a visible light-driven whole-cell platform for human cytochrome P450 (CYP) photobiocatalysis was developed using natural flavins as a photosensitizer. Photoexcited flavins mediate NADPH/reductase-free, light-driven biocatalysis by human CYP2E1 both in vitro and in the whole-cell systems. In vitro tests demonstrated that the photobiocatalytic activity of CYP2E1 is dependent on the substrate type, the presence of catalase, and the acid type used as a sacificial electron donor. A protective effect of catalase was found against the inactivation of CYP2E1 heme by H2O2 and the direct transfer of photo-induced electrons to the heme iron not by peroxide shunt. Furthermore, the P450 photobiocatalysis in whole cells containing human CYPs 1A1, 1A2, 1B1, and 3A4 demonstrated the general applicability of the solar-powered, flavin-mediated P450 photobiocatalytic system.
Regioselective chemoenzymatic syntheses of ferulate conjugates as chromogenic substrates for feruloyl esterases
Gherbovet, Olga,Ferreira, Fernando,Clément, Apolline,Ragon, Mélanie,Durand, Julien,Bozonnet, Sophie,O'Donohue, Michael J.,Fauré, Régis
, p. 325 - 333 (2021/03/15)
Generally, carbohydrate-active enzymes are studied using chromogenic substrates that provide quick and easy color-based detection of enzyme-mediated hydrolysis. For feruloyl esterases, commercially available chromogenic ferulate derivatives are both costly and limited in terms of their experimental application. In this study, we describe solutions for these two issues, using a chemoenzymatic approach to synthesize different ferulate compounds. The overall synthetic routes towards commercially available 5-bromo-4-chloro-3-indolyl and 4-nitrophenyl 5-O-feruloyl-α-l-arabinofuranosides were significantly shortened (from 7 or 8 to 4-6 steps), and the transesterification yields were enhanced (from 46 to 73% and from 47 to 86%, respectively). This was achieved using enzymatic (immobilized Lipozyme TL IM from Thermomyces lanuginosus) transesterification of unprotected vinyl ferulate to the primary hydroxy group of α‐l‐arabinofuranosides. Moreover, a novel feruloylated 4-nitrocatechol-1-yl-substituted butanetriol analog, containing a cleavable hydroxylated linker, was also synthesized in 32% overall yield in 3 steps (convergent synthesis). The latter route combined the regioselective functionalization of 4-nitrocatechol and enzymatic transferuloylation. The use of this strategy to characterize type A feruloyl esterase from Aspergillus Niger reveals the advantages of this substrate for the characterizations of feruloyl esterases.
