97-59-6Relevant articles and documents
Synergistic effect of 1-(2,5-dioxoimidazolidin-4-yl)urea and Tween-80 towards the corrosion mitigation of mild steel in HCl
Zhang, Weiwei,Li, Hui-Jing,Wang, Chen,Wang, Li-Juan,Li, Gen,Ma, Hengyu,Pan, Qianwen,Wu, Yan-Chao
, p. 13899 - 13910 (2019)
Herein, the synergistic effect of 1-(2,5-dioxoimidazolidin-4-yl)urea (DMU) and Tween-80 on the corrosion of mild steel in a 1 mol L-1 HCl solution was investigated by weight-loss tests, electrochemical methods and surface analysis (SEM/SECM). The experiments revealed that the combination of DMU and Tween-80 strongly inhibited the corrosion of mild steel as compared to individual inhibitors, and the adsorption mode belonged to the Langmuir isothermal type. Based on the electrochemical results, DMU and DMU-Tween-80 behaved as mixed-type inhibitors, and their best inhibition efficiencies were 77.31% and 96.35%, respectively. The calculated synergistic parameter value was larger than unity, indicating that the enhancement of inhibition efficiency was due to the synergistic effect of DMU and Tween-80. Surface analysis techniques confirmed the presence of inhibitors on the mild steel surface. Quantum chemical parameters based on density functional theory provided a further insight into the mechanism of inhibition. Moreover, molecular dynamics simulations were carried out to explore the configurational adsorption behaviour of DMU on an Fe(110) surface.
Ultrasensitive detection of uric acid in serum of patients with gout by a new assay based on Pt&at;Ag nanoflowers
Chen, Shujun,Lin, Daiqin,Qiu, Ping,Tang, Xiaomin,Wang, Xue
, p. 36578 - 36585 (2019)
A ultrasensitive assay for the determination of uric acid (UA) based on Pt&at;Ag nanoflowers (Pt&at;Ag NFs) was constructed. H2O2 was formed by the reaction of uricase and UA and produced the hydroxyl radical (OH). The system was catalyzed by Pt&at;Ag NFs to change the color of 3,3′,5,5′-tetramethylbenzidine (TMB) from colorless to blue, and the morphology and chemical properties of Pt&at;Ag NFs were characterized by transmission electron microscopy and X-ray photoelectron spectroscopy. Under the optimized conditions, a linear relationship between the absorbance and UA concentration was in the range of 0.5-150 μM (R2 = 0.995) with a limit of detection of 0.3 μM (S/N = 3). The method can be applied to detection of UA in actual samples with satisfactory results. The proposed assay was successfully applied to the detection of UA in human serum with recoveries over 96.8percent. Thus, these results imply that the UA assay provides an effective tool in fast clinical analysis of gout.
Kinetics and mechanism of allantoin racemization
Kahn, Kalju,Tipton, Peter A.
, p. 62 - 72 (2000)
The kinetics and mechanism of racemization of allantoin have been examined; racemization proceeds via two independent pathways that can be separately monitored. One pathway involves proton exchange at C5 with solvent, The other pathway occurs via intramolecular attack of N8 on C4 to form a symmetrical bicyclic intermediate, which can decompose to form either enantiomer of allantoin. The intramolecular pathway proceeds more rapidly from the allantoin anion than from neutral allantoin. This result is explained by conformational analyses based on experimental NMR data and computational results, which suggest that the ureido arm of anionic allantoin adopts a cis-conformation, allowing intramolecular attack. Neutral allantoin adopts a trans-conformation. The proton exchange pathway is buffer-catalyzed and also proceeds more rapidly at basic pH, although it is suggested that the reaction occurs from neutral allantoin. The relatively slow rate of racemization, particularly at physiological pH, suggests that nonenzymatic racemization of allantoin is not a viable mechanism for the in vivo generation of (S)-allantoin. (C) 2000 Academic Press.
Correction: Absolute stereochemistry and preferred conformations of urate degradation intermediates from computed and experimental circular dichroism spectra (Org. Biomol. Chem. (2011) 9 (5149-5155))
Pipolo, Silvio,Percudani, Riccardo,Cammi, Roberto
, p. 3654 - 3654 (2016)
Correction for 'Absolute stereochemistry and preferred conformations of urate degradation intermediates from computed and experimental circular dichroism spectra' by Silvio Pipolo et al., Org. Biomol. Chem., 2011, 9, 5149-5155.
Synthesis of highly pure 14C-labelled DL-allantoin and 13C NMR analysis of labelling integrity
Patching, Simon G.
, p. 401 - 404 (2009)
A number of synthetic approaches are assessed to prepare allantoin labelled with 14C given certain requirements and technical limitations. A method that fulfils these criteria is described to achieve the synthesis of highly pure 14C-labelled allantoin with the label introduced to the ureido carbonyl group in the final step by reaction of 5-chlorohydantoin with [14C]urea. The chosen method favours high purity at the expense of radiochemical yield, which is achieved at a level of 8%. The integrity of the label is then investigated by performing an NMR analysis of 13C- labelled allantoin synthesized by the same method. The 13C NMR spectrum confirms partial scrambling of the label to the C-2 position by equilibration of the product via a putative bicyclic intermediate, which had been suggested by other workers. The 14C-labelled allantoin synthesized by this method is therefore assigned as DL-[H2N 14CO/14C-2]allantoin. This study also includes the first full characterization of a side product, 5-hydroxy-5-methoxyhydantoin, obtained by the reaction of a 5-hydroxyhydantoin intermediate with the methanol solvent. Copyright
Uricase-catalyzed oxidation of uric acid using an artificial electron acceptor and fabrication of amperometric uric acid sensors with use of a redox ladder polymer
Nakaminami, Takahiro
, p. 1928 - 1934 (1999)
Electrochemical oxidation of uric acid catalyzed by uricase (uric acid oxidase, UOx; EC 1.7.3.3) was studied using several redox compounds including 5-methylphenazinium (MP) and 1-methoxy-5-methylphenazinium (MMP) as electron acceptors for UOx, which does not contain any redox cofactor. It was found that MP and MMP were useful to mediate electrons from UOx to an electrode in the enzymatic oxidation of uric acid. A novel redox polymer, poly(N-methyl-o-phenyIenediamine) (poly-MPD), containing the MP units was also found to possess the mediation ability for UOx, and poly-MPD was immobilized together with UOx onto an electrode substrate covered with a self-assembled monolayer of 2-aminoethanethiolate with use of glutaraldehyde as a binding agent The resulting electrode (pory-MPD/UOx/Au) exhibited amperometric responses to uric acid with very fast response of ～30 s, allowing reagentless amperometric determination in a concentration range covering that in the blood of a healthy human being. Kinetic parameters of the apparent Michaelis constant and the maximum current response obtained at the poly-MPD/UOx/Au suggested that electrochemical oxidation of uric acid was controlled by diffusion of uric acid into the enzyme film and that the redox polymer worked well in mediating between active sites of UOx molecules and the electrode substrate.
Identification of the true product of the urate oxidase reaction
Kahn, Kalju,Serfozo, Peter,Tipton, Peter A.
, p. 5435 - 5442 (1997)
The O2-dependent oxidation of urate catalyzed by urate oxidase has been examined in order to identify the immediate product of the enzymatic reaction. Specifically labeled [13C]urates were utilized as substrates, and the time courses were monitored by 13C NMR. On the basis of chemical shift values and 18O labeling, the product of the reaction was identified as 5- hydroxyisourate. This identification was substantiated by calculation of the 13C NMR spectrum of 5-hydroxyisourate using ab initio density functional theory methods. The predominant tautomers of urate and allantoin in aqueous solution were identified from 13C NMR titration data; the ionization behavior of urate and 5-hydroxyisourate were also examined by computational methods. The nonenzymatic pathway for production of allantoin from 5- hydroxyisourate was delineated; the reaction proceeds by the hydrolysis of the N1-C6 bond, followed by an unusual 1,2-carboxylate shift and decarboxylation to form allantoin.
A Novel Cascade Nanoreactor Integrating Two-Dimensional Pd-Ru Nanozyme, Uricase and Red Blood Cell Membrane for Highly Efficient Hyperuricemia Treatment
Ming, Jiang,Zhu, Tianbao,Li, Jingchao,Ye, Zichen,Shi, Changrong,Guo, Zhide,Wang, Jingjuan,Chen, Xiaolan,Zheng, Nanfeng
, (2021/10/21)
Nanozyme-based cascade reaction has emerged as an effective strategy for disease treatment because of its high efficiency and low side effects. Herein, a new and highly active two-dimensional Pd-Ru nanozyme is prepared and then integrated with uricase and red blood cell (RBC) membrane to fabricate a tandem nanoreactor, Pd-Ru/Uricase@RBC, for hyperuricemia treatment. The designed Pd-Ru/Uricase@RBC nanoreactor displayed not only good stability against extreme pH, temperature and proteolytic degradation, but also long circulation half-life and excellent safety. The nanoreactor can effectively degrade UA by uricase to allantoin and H2O2 and remove H2O2 by using Pd-Ru nanosheets (NSs) with the catalase (CAT)-like activity. More importantly, the finally produced O2 from H2O2 decomposition can in turn facilitate the catalytic oxidation of UA, as the degradation of UA is an O2 consumption process. By integrating the high-efficiency enzymatic activity, long circulation capability, and good biocompatibility, the designed Pd-Ru/Uricase@RBC can effectively and safely treat hyperuricemia without side effects. The study affords a new alternative for the exploration of clinical treatment of hyperuricemia.
Method for producing allantoin for cosmetics
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Paragraph 0016-0017; 0019-0020; 0022-0023; 0025-0026; 0029, (2020/11/10)
The invention discloses a method for producing allantoin for cosmetics, which comprises the following steps: adding a glyoxylic acid solution, urea and a catalyst into a microwave reactor, filtering and separating the product after the reaction is finished, and recrystallizing to obtain the allantoin finished product. By preparing a mesoporous Nb2O5-ZrO2 composite oxide, preparing solid superacidMoO3/Nb2O5-ZrO2, preparing an ionic liquid precursor PyPS, preparing phosphomolybdic vanadic acid, and carrying out in-situ loading on Co-based solid ionic liquid, the catalyst prepared by in-situ compounding of the solid superacid MoO3/Nb2O5-ZrO2 and the Co-based solid ionic liquid is obtained. The prepared composite catalyst can solve the problem that the catalyst is difficult to separate from aproduct, can also overcome the defect that the catalyst is inactivated due to the fact that the acidity of the catalyst is easy to lose, can keep a solid state, and is non-corrosive to a reaction device, high in catalytic efficiency and good in selectivity.
(2,5-Dioxoimidazolidin-4-ylidene)aminocarbonylcarbamic Acid as a Precursor of Parabanic Acid, the Singlet Oxygen-Specific Oxidation Product of Uric Acid
Iida, Sayaka,Yamamoto, Yorihiro,Fujisawa, Akio
, (2019/03/19)
Previously, we identified that parabanic acid (PA) and its hydrolysate, oxaluric acid (OUA), are the singlet oxygen-specific oxidation products of uric acid (UA). In this study, we investigated the PA formation mechanism by using HPLC and a time-of-flight mass spectrometry technique and identified unknown intermediates as (2,5-dioxoimidazolidin-4-ylidene)aminocarbonylcarbamic acid (DIAA), dehydroallantoin, and 4-hydroxyallantoin (4-HAL). DIAA is the key to PA production, and its formation pathway was characterized using 18O2 and H218O. Two oxygen atoms were confirmed to be incorporated into DIAA: the 5-oxo- oxygen from singlet oxygen and the carboxylic oxygen from water. Isolated DIAA and 4-HAL gave PA stoichiometrically. A plausible reaction scheme in which two pathways branch out from DIAA is presented, and the potential for PA as an endogenous probe for biological formation of singlet oxygen is discussed.
