25496-36-0Relevant articles and documents
Substrate-assisted catalysis in glycosidases
Wang, Qingping,Withers, Stephen G.
, p. 10137 - 10138 (1995)
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Decomposition of aspirin in the solid state in the presence of limited amounts of moisture III: Effect of temperature and a possible mechanism.
Carstensen,Attarchi
, p. 318 - 321 (1988)
In a previous study, we showed that aspirin in the presence of limited amounts of moisture falls to follow Leeson-Mattocks kinetics at 62.5 degrees C. This system has been tested at a series of temperatures, and several plausible models have been tested. It is shown that the data are explained by a model in which the reaction is limited to a surface interaction between aspirin and water from the sorbed bulk moisture layer.
Decomposition of aspirin in the solid state in the presence of limited amounts of moisture II: Kinetics and salting-in of aspirin in aqueous acetic acid solutions.
Carstensen,Attarchi
, p. 314 - 317 (1988)
The solubility of aspirin in saturated solutions of salicylic acid (and vice versa) was studied in 0 to 16 M aqueous solutions of acetic acid. The solubilities, when expressed in molarity, go through a maximum at an acetic acid concentration of approximately 12 M. The temperature dependence of the solubilities is such that the logarithm of the solubility is linear in reciprocal absolute temperature. The calculated enthalpies are of the order of 11 kcal/mol. The kinetics of aspirin decomposition was also studied at the different acetic acid concentrations, and it was found that the second-order hydrolysis rate constant is fairly independent of acetic acid concentration. Aspirin decomposition follows an Arrhenius equation and has an activation energy of 18 kcal/mol.
Micellar catalysis of organic reactions. Kinetic studies of the hydrolysis of aspirin derivatives in micelles
Broxton,Christie,Sango
, p. 4814 - 4817 (1987)
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Sex differences in the enzymatic hydrolysis of acetylsalicylic acid by microsomes from various rat tissues
Loza, Ana Ma. Julieta Vargas,Sanchez Montes De Oca, Elsa I.,Posadas Del Rio, Francisco A.
, p. 347 - 351 (1997)
We studied the in vitro hydrolysis of acetylsalicylic acid (ASA) to salicylic acid (SA) catalysed by microsomal preparations from liver, kidney, small intestine and stomach mucosas and blood serum of adult female and male rats. Hepatic microsomes from male rats had the highest specific activity: 42.3 ± 6.0 nmol SA mg-1 min-1 (mean ± SEM). Kidney, intestine, stomach and serum activities were 60, 30, 14 and 0.7% with regard to the liver. In contrast, gastric microsomes from female rats showed the highest specific activity: 53 ± 22.1 nmol SA mg-1 min-1 (mean ± SEM) whereas intestine, liver, kidney and serum activities were 60, 43, 40 and 1.7% with regard to the stomach mucosa. Hepatic, renal and intestinal microsomes had a pH, optimum of 5-6. Male rats had V(max) and K(m) values of 95.5, 83.4 and 29.4 nmol SA mg-1 min-1 and 2.9, 1.27 and 6.4 mM, while for female rats they were 54.8, 75.8 and 59.4 nmol SA mg-1 min-1 and 2.6, 1.35 and 3.4 mM for hepatic, renal and intestinal microsomes, respectively. Parathion inhibited the hydrolysis of ASA with an IC50 of 1.2 x 10-5 M for liver and kidney and 5 x 10-6 M for intestine from male rats.
Phenolic acid glucosides from the seeds of Entada phaseoloides Merill
Singh, Onkar,Ali, Mohd,Akhtar, Nida
, p. 682 - 687 (2011)
Phytochemical investigation of the defatted seeds of Entada phaseoloides Merill. (Mimosaceae) led to the isolation of three new phenolic acid glucosides, which were characterized as 2-hydroxy-5-methylbenzoyl-β-L-glucopyranoside (p-cresotyl glucoside, 1), 2-hydroxy-5-methylbenzoyl-β-L-glucopyranosyl (2 → 1)-β-L-glucopyranosyl (2 → 1)-β-L-glucopyranoside (p-cresotyl triglucoside, 2), and 2-hydroxybenzoyl-β-L-glucopyranosyl (2 → 1)-β-L-glucopyranosyl (2 → 1)-β-L-glucopyranosyl (2 → 1)-β-L-glucopyranoside (salicylic acid tetraglucoside, 5), along with sucrose and triglucoside. The structures of these phytoconstituents have been established on the basis of spectral data analysis and chemical reactions.
Hydrolysis of aspirin studied by spectrophotometric and fluorometric variable-temperature kinetics
Alibrandi, Giuseppe,Micai, Norberto,Trusso, Sebastiano,Villari, Antonino
, p. 1105 - 1108 (1996)
Pseudo-first-order rate constants for the hydrolysis of acetylsalicylic acid as a function of temperature have been obtained by variable-temperature kinetic experiments. A method, based on a generalization of non-isothermal analysis, has been used that takes advantage of the capabilities of modem data collection and processing systems. Both spectrophotometric and, for the first time under non-isothermal conditions, fluorometric measurements have been carried out. The results obtained are identical to those obtained under the same conditions but using traditional constant-temperature kinetic runs. This provides the possibility of reducing the amounts of time and chemicals usually spent in collecting kinetic data in mechanistic studies in solution by an order of magnitude.
Kinetics and mechanism of the base-catalyzed oxygenation of flavonol in DMSO-H2O solution
Balogh-Hergovich, Eva,Speier, Gabor
, p. 7974 - 7978 (2001)
The kinetics of the base-catalyzed oxygenation of flavonol have been investigated in 50% DMSO-H2O solution in the pH range 6.4-10.8 and an ionic strength of 0.1 mol L-1 using spectrophotometric techniques at temperatures between 70 and 90 °C. The rate law -d[flaH]/dt = kobs [OH-][flaH][O2] (kobs = kK1/[H2O]) describes the kinetic data. The rate constant, activation enthalpy, and entropy at 353.16 K are as follows: k/mol-1 L s-1 = (4.53 ± 0.07) × 10-2, ΔH?/kJ mol-1= 59 ± 4, ΔS?/J mol-1 K-1 = -110 ± 11. The reaction showed specific base catalysis. It fits a Hammett linear free energy relationship for 4′-substituted flavonols and electron-releasing substituents enhanced the reaction rate. The linear correlation between the oxidation potential of the flavonols and the rate constants supports that a higher electron density on the flavonolate ion makes them more nucleophilic and the electrophilic attack of O2 easier.
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Volkert,Schulte-Frohlinde
, p. 2151 (1968)
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Use of system peaks in liquid chromatography for continuous on-line monitoring of chemical reactions
Mizrotsky, Nira,Grushka, Eli
, p. 1737 - 1741 (1995)
System peaks, which occur in chromatography with multicomponent mobile phases, can he used for the continuous on-line monitoring of chemical reactions. The mobile phase reservoir is the chemical reactor, and the mobile phase, which contains the reaction mixture, is recycled continuously through the column. At predetermined times, a neat solvent, normally the solvent of the reaction, is injected. The system peaks that result reflect the status of the reaction. We describe here the use of system peaks to follow the progress of two reactions: titration of aniline and hydrolysis of aspirin. In the case of aniline titration, we obtained a titration curve by plotting the capacity ratio of the aniline system peak versus the acid volume added during the titration. The experimental endpoint agreed very well with the theoretical equivalence point A plot of the capacity factor as a function of mobile phase pH behaves similarly to such plots in conventional chromatography. In the hydrolysis of aspirin, we followed the progress of the reaction by monitoring the formation of salicylic acid via its system peak. The data allowed us to calculate the apparent hydrolysis rate constant The value obtained is in excellent agreement with literature values.
Understanding Methyl Salicylate Hydrolysis in the Presence of Amino Acids
Cheng, Chi-Yuan,Brinzari, Tatiana V.,Hao, Zhigang,Wang, Xiaotai,Pan, Long
, p. 6013 - 6021 (2021)
Methyl salicylate, the major flavor component in wintergreen oil, is commonly used as food additives. It was found that amino acids can unexpectedly expedite methyl salicylate hydrolysis in an alkaline environment, while the detailed mechanism of this reaction merits investigation. Herein, the role of amino acid, more specifically, glycine, in methyl salicylate hydrolysis in aqueous solution was explored. 1H NMR spectroscopy, combined with density functional theory calculations, was employed to investigate the methyl salicylate hydrolysis in the presence and absence of glycine at pH 9. The addition of glycine was found to accelerate the hydrolysis by an order of magnitude at pH 9, compared to that at pH 7. The end hydrolyzed product was confirmed to be salicylic acid, suggesting that glycine does not directly form an amide bond with methyl salicylate via aminolysis. Importantly, our results indicate that the ortho-hydroxyl substituent in methyl salicylate is essential for its hydrolysis due to an intramolecular hydrogen bond, and the carboxyl group of glycine is crucial to methyl salicylate hydrolysis. This study gains a new understanding of methyl salicylate hydrolysis that will be helpful in finding ways of stabilizing wintergreen oil as a flavorant in consumer food products that also contain amino acids.
Studies on whisker growth on the tablet surface. III. Mechanism of whisker growth on aspirin tablet and its effect on the mechanical strength of the tablet
Yuasa,Kanaya,Asahina
, p. 850 - 857 (1986)
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Deiodination kinetics of water-soluble radiopaques
Wang
, p. 671 - 675 (1980)
Deiodination of diatrizoic acid, an anionic radiopaque, was found to be catalyzed by Cu(II). Through a detailed study of o-iodobenzoic acid, a model compound, the copper-catalyzed S(N)1 mechanism was established based on observations of common ion, salt, and pH effects. Meta- and para-iodobenzoic acids were unreactive. Deiodination thus was facilitated by a neighboring carboxylate that attracted copper. Iopamidol, a nonionic radiopaque, also underwent deiodination. At pH 7 or above, the hydroxide-ion substitution predominated. At pH below 7, the reaction is in favor of the copper-catalyzed S(N)1 mechanism.
Bioinspired Trispyrazolylborato Nickel(II) Flavonolate Complexes and Their Reactivity Toward Dioxygen
Hoof, Santina,Limberg, Christian
, p. 170 - 174 (2019)
Aiming at structural and functional mimics of the active site of the NiII containing quercetin-2,4-dioxygenase NiII flavonolate complexes Tp*NiX [Tp* = hydrotris(3,5-dimethyl)pyrazolylborate, X = 3-hydroxy flavonolate (Fla), 3-hydroxy thioflavonolate (SFla), 3-hydroxy selenoflavonolate (SeFla)] were synthesized and characterized by spectroscopic methods and X-ray crystallography. The complex Tp*NiFla reacts with O2 via dioxygenation of bound flavonolate to benzoic acid and salicylic acid as one should expect for a functional model of the enzyme. Modification of the carbonyl function of the flavonolate to the corresponding C=S and C=Se compounds retained dioxygenase like reactivity, but did not lead to an increase of reaction rate as had been anticipated due to a weaker interaction of S/Se with the central nickel atom.
Iron(III) Complex-Functionalized Gold Nanocomposite as a Strategic Tool for Targeted Photochemotherapy in Red Light
Biswas, Arunima,Kunwar, Amit,Musib, Dulal,Pal, Maynak,Ramu, Vanitha,Roy, Mithun
, p. 6283 - 6297 (2021)
Iron(III)-phenolate/carboxylate complexes exhibiting photoredox chemistry and photoactivated reactive oxygen species (ROS) generation at their ligand-to-metal charge-transfer (LMCT) bands have emerged as potential strategic tools for photoactivated chemotherapy. Herein, the synthesis, in-depth characterization, photochemical assays, and remarkable red light-induced photocytotoxicities in adenocarcinomic human immortalized human keratinocytes (HaCaT) and alveolar basal epithelial (A549) cells of iron(III)-phenolate/carboxylate complex of molecular formula, [Fe(L1)(L2)] (1), where L1 is bis(3,5 di-tert-butyl-2-hydroxybenzyl)glycine and L2 is 5-(1,2-dithiolan-3-yl)-N-(1,10-phenanthroline-5-yl)pentanamide, and the gold nanocomposite functionalized with complex 1 (1-AuNPs) are reported. There was a significant red shift in the UV-visible absorption band on functionalization of complex 1 to the gold nanoparticles (λmax: 573 nm, 1; λmax: 660 nm, 1-AuNPs), rendering the nanocomposite an ideal candidate for photochemotherapeutic applications. The notable findings in our present studies are (i) the remarkable cytotoxicity of the nanocomposite (1-AuNPs) to A549 (IC50: 0.006 μM) and HaCaT (IC50: 0.0075 μM) cells in red light (600-720 nm, 30 J/cm2) while almost nontoxic (IC50 > 500 μg/mL, 0.053 μM) in the dark, (ii) the nontoxicity of 1-AuNPs to normal human diploid fibroblasts (WI-38) or human peripheral lung epithelial (HPL1D) cells (IC50 > 500 μg/mL, 0.053 μM) both in the dark and red light signifying the target-specific anticancer activity of the nanocomposite, (iii) localization of 1-AuNPs in mitochondria and partly nucleus, (iv) remarkable red light-induced generation of reactive oxygen species (ROS: 1O2, ?OH) in vitro, (v) disruption of the mitochondrial membrane due to enhanced oxidative stress, and (vi) caspase 3/7-dependent apoptosis. A similar cytotoxic profile of complex 1 was another key finding of our studies. Overall, our current investigations show a new red light-absorbing iron(III)-phenolate/carboxylate complex-functionalized gold nanocomposite (1-AuNPs) as the emerging next-generation iron-based photochemotherapeutic agent for targeted cancer treatment modality.
Enzymatic Reaction in Water-in-oil Microemulsions. Part 1. - Rate of Hydrolysis of a Hydrophilic Substrate: Acetylsalicylic Acid
Miyake, Yoshikazu,Owari, Takuya,Matsuura, Kengo,Teramoto, Masaaki
, p. 1993 - 2000 (1993)
The rates of catalytic hydrolysis of a hydrophilic substrate, acetylsalicylic acid (AA), have been measured both in aqueous solution and in water-in-oil (w/o) microemulsions formed by AOT in n-heptane.Catalysts used were lipase from Rhizopus delemar, α-chymotrypsin from Bovine pancreas and imidazole as an acid-base catalyst.Since the hydrolysis of AA proceeds in aqueous solution without catalyst (intramolecular catalysis), the rate of hydrolysis was measured in microemulsions.The rate constant for the hydrolysis of AA increased with increasing concentration ratio of water to AOT, W0 = ov/ov, at constant ov, and was asymptotic to the value obtained in aqueous solution.For constant W0 the rate constant was almost independent of ov over the range 0.15-0.65 mol dm-3.The overall rate constant for the catalytic hydrolysis of AA in microemulsions was obtained by substracting the rate constant for the intramolecular catalysis of AA from the rate constant observed.The intrinsic rate constant in the water pools of the microemulsion was then evaluated by considering the volume fraction of water determined by Karl Fischer titration.For W0 > 10 at ov = 0.5 mol dm-3, the intrinsic rate constant for imidazole-catalysed hydrolysis of AA was equal to that obtained in the aqueous phase.As W0 decreased below 10, the intrinsic rate constant decreased and the value at W0 = 6.5 was 0.6 times that in the aqueous phase.The intrinsic rate constant was independent of ov.The addition of lipase to the aqueous phase did not enhance the rate of hydrolysis of AA.However, the reaction in microemulsions was catalysed by the lipase and was linearly dependent on lipase concentration.Lipase in microemulsions exhibits activity for the hydrolysis of AA owing to a change in the conformation of lipase.The intrinsic rate constant in the water pool is a maximum at W0 = 7 and is independent of ov.The rate of hydrolysis of AA was little affected by the presence of α-chymotrypsin either in the aqueous phase or in microemulsions.
Reactive Species Produced by the 5-Methylphenazinium Methyl Sulfate/Reduced β-Nicotinamide Adenine Dinucleotide/Oxygen System in the Hydroxylation of Benzoic Acid
Richter, Helen W.,Fetrow, Melanie A.,Lewis, Rachel E.,Waddell, Walter H.
, p. 1666 - 1671 (1982)
Thre hydroxylation of benzoic acid induced by the aqueous chemical system composed of 5-methylphenazinium methyl sulfate, reduced β-nicotinamide adenine dinucleotide (NADH), and dissolved oxygen has been investigated.A quantitative determination of the reaction products was made using high-pressure liquid chromatographic methods.The effect of reaction conditions and of additives on the products yields was examined.Results indicate that the species initiating hydroxylation is the hydroxyl radical, produced from a one-electron reduction of hydrogen peroxide in an adventitions-metal-ion catalyzed Fenton-type reaction.Hydrogen peroxide is thought to be produced directly by the transfer of a hydride ion from a fully reduced 5-methylphenazinium cation to molecular oxygen, not by the disproportionation of superoxide radicals.It ia apparent that superoxide radicals are produced to a very limited extent during reaction and do not contribute substantially to product formation.The sole function of NADH is the reduction of the 5-methylphenazinium cation.
SELECTIVE SYNTHESES USING CYCLODEXTRINS AS CATALYSTS. 2. PARA-ORIENTED CARBOXYLATION OF PHENOLS.
Komiyama,Hirai
, p. 174 - 178 (1984)
4-Hydroxybenzoic acid and 4-hydroxy-3-methylbenzoic acid are synthesized in virtually 100% selectivities and high yields from the corresponding phenols and carbon tetrachloride by using beta -cyclodextrin ( beta -CD) as catalyst. The selective syntheses are successfully achieved by a small molar ratio, even 0. 03, of beta -CD to phenols and are hardly suppressed by oxygen. Kinetic study shows that the selective catalyses by beta -CO originate from both promotion of the para carboxylation and almost complete inhibition of the ortho carboxylation. Heptakis(2,6-di-0-methyl) beta -cyclodextrin in contrast decreases the para selectivity, showing the importance of the hydroxyl groups of beta -CD in its selective catalysis. The selective catalysis by beta -CD proceeds via formation of a molecular complex with the active species, probably the trichloromethyl cation.
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Hasse
, p. 2190 (1877)
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Hydrolysis of acetylsalicylic acid under the conditions of electrolysis
Vedenyapina,Strel'tsova,Rakishev,Vedenyapin
, p. 1078 - 1080 (2008)
The hydrolysis of acetylsalicylic acid in the anolyte under the conditions of electrolysis was studied.
Probing cobalt sites in CoAPO-11 via spectroscopic and activity studies
Sahoo,Badamali
, p. 2197 - 2202 (2017)
A systematic study undertaken for the oxidation state, coordination, stability of cobalt in CoAPO-11 structure by means of spectroscopic and catalytic activity, is presented. AlPO-11 containing Co(II) in the tetrahedral coordination was indicated by powder diffraction, electronic and EPR data. During calcination of Co(II) was partly converted to Co(III) and reverted back to Co(II) upon exposure to atmosphere. Apart from micropores, CoAPO-11 sample contains mesopores, which possibly arise from interparticle void space. The tetrahedral location of Co(II) was inferred from EPR data. The rectangular to spherical shapes of CoAPO-11 material was evident from electron micrographs. Activity studies revealed that o-cresol can selectively be converted to o-hydroxy benzoic acid. Moderate activity of CoAPO-11 along with spectroscopic analysis supports the fact that Co(II) is predominantly located in tetrahedral framework and do not convert to Co(III) effectively, as a consequence Co(II) are stable and do not display appreciable oxidative ability under mild reaction conditions.
The detection for hypochlorite by UV-Vis and fluorescent spectra based on oxidized ring opening and successive hydrolysis reaction
Xiong, Kangming,Yin, Caixia,Chao, Jianbin,Zhang, Yongbin,Huo, Fangjun
, p. 79 - 83 (2016)
In this work, two high selective and sensitive fluorescent probes for ClO-, 7-Hydroxycoumarin and 4-Hydroxycoumarin were designed. The reaction mechanism that we speculated was the oxidized ring opening reaction and hydrolysis. The detection could be realized in quasi-aqueous phase and the detection limits of probe [7] and probe [4] for ClO- were found to be 56.8 nM and 70.5 nM. Furthermore, the probes can be used to cell imagings.
Use of a miniature mass spectrometer to support pharmaceutical process chemistry
Hamilton, Simon E.,Mattrey, Fred,Bu, Xiaodong,Murray, David,McCullough, Bryan,Welch, Christopher J.
, p. 103 - 108 (2014)
In this study we describe the evaluation of a recently developed miniaturized single-quadrupole mass spectrometer to support pharmaceutical process research investigations. Mass spectrometry is becoming an indispensable tool for analytical support of synthetic chemistry; however, current mass spectrometers are too expensive and too large for widespread deployment. In addition, current instruments often have features and capabilities that, while useful for trace component or bioanalysis applications, are beyond the comparatively simple requirements of synthetic chemists, where samples are often abundant and unit mass resolution is generally sufficient. An evaluation of the Microsaic 3500 MiD shows this small and inexpensive mass spectrometer to be well-suited for providing reliable support for certain pharmaceutical process research investigations.
Ultrasensitive Fluorescence Detection of Peroxymonosulfate Based on a Sulfate Radical-Mediated Aromatic Hydroxylation
Huang, Gui-Xiang,Si, Jin-Yan,Qian, Chen,Wang, Wei-Kang,Mei, Shu-Chuan,Wang, Chu-Ya,Yu, Han-Qing
, p. 14439 - 14446 (2018)
Recently, peroxymonosulfate (PMS)-based advanced oxidation processes have exhibited broad application prospects in the environment field. Accordingly, a simple, rapid, and ultrasensitive method is highly desired for the specific recognition and accurate quantification of PMS in various aqueous solutions. In this work, SO4?--induced aromatic hydroxylation was explored, and based on that, for the first time, a novel fluorescence method was developed for the PMS determination using Co2+ as a PMS activator and benzoic acid (BA) as a chemical probe. Through a suite of spectral, chromatographic, and mass spectrometric analyses, SO4?- was proven to be the dominant radical species, and salicylic acid was identified as the fluorescent molecule. As a result, a whole radical chain reaction mechanism for the generation of salicylic acid in the BA/PMS/Co2+ system was proposed. This fluorescence method possessed a rapid reaction equilibrium (a wide detection range (0-100 μM). Moreover, it performed well in the presence of possible interfering substances, including two other peroxides (i.e., peroxydisulfate and hydrogen peroxide), some common ions, and organics. The detection results for real water samples further validated the practical utility of the developed fluorescence method. This work provides a new method for the specific recognition and sensitive determination of PMS in complex aqueous solutions.
Salicylic acid induces mitochondrial injury by inhibiting ferrochelatase heme biosynthesis activity
Gupta, Vipul,Liu, Shujie,Ando, Hideki,Ishii, Ryohei,Tateno, Shumpei,Kaneko, Yuki,Yugami, Masato,Sakamoto, Satoshi,Yamaguchi, Yuki,Nureki, Osamu,Handa, Hiroshi
, p. 824 - 833 (2013)
Salicylic acid is a classic nonsteroidal anti-inflammatory drug. Although salicylic acid also induces mitochondrial injury, the mechanism of its antimitochondrial activity is not well understood. In this study, by using a one-step affinity purification scheme with salicylic acid-immobilized beads, ferrochelatase (FECH), a homodimeric enzyme involved in heme biosynthesis in mitochondria, was identified as a new molecular target of salicylic acid. Moreover, the cocrystal structure of the FECH-salicylic acid complex was determined. Structural and biochemical studies showed that salicylic acid binds to the dimer interface of FECH in two possible orientations and inhibits its enzymatic activity. Mutational analysis confirmed that Trp301 and Leu311, hydrophobic amino acid residues located at the dimer interface, are directly involved in salicylic acid binding. On a gel filtration column, salicylic acid caused a shift in the elution profile of FECH, indicating that its conformational change is induced by salicylic acid binding. In cultured human cells, salicylic acid treatment or FECH knockdown inhibited heme synthesis, whereas salicylic acid did not exert its inhibitory effect in FECH knockdown cells. Concordantly, salicylic acid treatment or FECH knockdown inhibited heme synthesis in zebrafish embryos. Strikingly, the salicylic acid-induced effect in zebrafish was partially rescued by FECH overexpression. Taken together, these findings illustrate that FECH is responsible for salicylic acid-induced inhibition of heme synthesis, which may contribute to its antimitochondrial and anti-inflammatory function. This study establishes a novel aspect of the complex pharmacological effects of salicylic acid. Copyright
Negative correlations between cultivable and active-yet-uncultivable pyrene degraders explain the postponed bioaugmentation
Jiang, Bo,Chen, Yating,Xing, Yi,Lian, Luning,Shen, Yaoxin,Zhang, Baogang,Zhang, Han,Sun, Guangdong,Li, Junyi,Wang, Xinzi,Zhang, Dayi
, (2021/09/24)
Bioaugmentation is an effective approach to remediate soils contaminated by polycyclic aromatic hydrocarbons (PAHs), but suffers from unsatisfactory performance in engineering practices, which is hypothetically explained by the complicated interactions between indigenous microbes and introduced degraders. This study isolated a cultivable pyrene degrader (Sphingomonas sp. YT1005) and an active pyrene degrading consortium (Gp16, Streptomyces, Pseudonocardia, Panacagrimonas, Methylotenera and Nitrospira) by magnetic-nanoparticle mediated isolation (MMI) from soils. Pyrene biodegradation was postponed in bioaugmentation with Sphingomonas sp. YT1005, whilst increased by 30.17% by the active pyrene degrading consortium. Pyrene dioxygenase encoding genes (nidA, nidA3 and PAH-RHDα-GP) were enriched in MMI isolates and positively correlated with pyrene degradation efficiency. Pyrene degradation by Sphingomonas sp. YT1005 only followed the phthalate pathway, whereas both phthalate and salicylate pathways were observed in the active pyrene degrading consortium. The results indicated that the uncultivable pyrene degraders were suitable for bioaugmentation, rather than cultivable Sphingomonas sp. YT1005. The negative correlations between Sphingomonas sp. YT1005 and the active-yet-uncultivable pyrene degraders were the underlying mechanisms of bioaugmentation postpone in engineering practices.
Synthesis of salicylates from anionically activated aromatic trifluoromethyl group
Lin, Chuankai,Liu, Jin-Biao,Wang, Ruixiang,Xie, Huilin
supporting information, (2021/12/22)
An efficient approach to salicylates via a novel transformation of anionically activated aromatic trifluoromethyl group is described. Anionically activated trifluoromethyl group can react with phenols/alcohols under alkaline conditions to afford aryl/alkyl salicylates in high yields. Mechanism studies indicate that the carbonyl oxygen atom of ester is from the H2O in the solvent.
Oxygenolysis of a series of copper(ii)-flavonolate adducts varying the electronic factors on supporting ligands as a mimic of quercetin 2,4-dioxygenase-like activity
Anoop, Anakuthil,Dey, Subhasis,Mandal, Sukanta,Podder, Nirmalya
supporting information, p. 4338 - 4353 (2022/04/07)
Four copper(ii)-flavonolate compounds of type [Cu(LR)(fla)] {where LR = 2-(p-R-benzyl(dipyridin-2-ylmethyl)amino)acetate; R = -OMe (1), -H (2), -Cl (3) and -NO2 (4)} have been developed as a structural and functional enzyme-substrate (ES) model of the Cu2+-containing quercetin 2,4-dioxygenase enzyme. The ES model complexes 1-4 are synthesized by reacting 3-hydroxyflavone in the presence of a base with the respective acetate-bound copper(ii) complexes, [Cu(LR)(OAc)]. In the presence of dioxygen the ES model complexes undergo enzyme-type oxygenolysis of flavonolate (dioxygenase type bond cleavage reaction) at 80 °C in DMF. The reactivity shows a substituent group dependent order as -OMe (1) > -H (2) > -Cl (3) > ?NO2 (4). Experimental and theoretical studies suggest a single-electron transfer (SET) from flavonolate to dioxygen, rather than valence tautomerism {[CuII(fla?)] ? [CuI(fla˙)]}, to generate the reactive flavonoxy radical (fla˙) that reacts further with the superoxide radical to bring about the oxygenative ring opening reaction. The SET pathway has been further verified by studying the dioxygenation reaction with a redox-inactive Zn2+ complex, [Zn(LOMe)(fla)] (5).
