- Fluorescence detection of hydroxyl radical generated from oxygen reduction on Fe/N/C catalyst
-
Pyrolyzed Fe/N/C catalyst has been considered as the most promising candidate to replace Pt for oxygen reduction reaction (ORR) in fuel cells. However, poor stability of Fe/N/C catalyst, mainly attributed to the oxidation corrosion by aggressive ?OH radical, severely hampers its applications. However, the exact mechanism for generation of ?OH is unclear yet. Herein, we developed a fluorescent method to effectively detect ?OH generated from ORR on Fe/N/C catalyst by using coumarin as a fluorescent probe. A great difference in potential dependence between ?OH and H2O2 generated from the ORR was observed, which suggests that ?OH is not generated from the decomposition of H2O2 as traditional viewpoint.
- Chen, Li-Na,Yu, Wen-Song,Wang, Tao,Yang, Xiao-Dong,Yang, Hui-Juan,Chen, Zhi-Xin,Wang, Tan,Tian, Na,Zhou, Zhi-You,Sun, Shi-Gang
-
-
Read Online
- Hydrothermal synthesis of Mn-doped CdS hollow sphere nanocomposites as efficient visible-light driven photocatalysts
-
A series of Mn-doped CdS hollow sphere photocatalysts has been directly synthesized by a simple and facile hydrothermal route for the first time. It was demonstrated that GSH acts as the S source and a gas bubble-template in this process. The products were characterized by XRD, SEM, TEM, HRTEM, XPS, and UV-vis spectroscopy. The as-prepared CdS and Mn-doped CdS hollow spheres all showed much higher activity than P25 under visible light (λ > 420 nm) irradiation. Among them, the 2.0 mol% Mn-doped CdS sample exhibited the highest photoactivity for the removal of organic pollutant RhB, and about 99.2% MO was decomposed after 50 min of visible light irradiation. Moreover, this catalyst also showed good stability, and after four cycles, the degradation efficiency still remained at 85%. The excellent photoactivity of the as-prepared Mn-doped CdS hollow spheres could be attributed to the synergistic effects of its appropriate band-gap structure and the special porous spherical morphology. The unique hollow sphere structure may favor the harvesting of excited light due to its special multiple scattering effect within the interior space, and the doping of Mn2+ may facilitate the generation of photoinduced electrons and hole pairs, and inhibit their recombination rate by acting as temporary trapping sites. This material may have great application potentials in environmental remediation and energy harvesting.
- Zhang, Chunyan,Lai, Jiasheng,Hu, Juncheng
-
-
Read Online
- Functional characterization of allelic variants of polymorphic human cytochrome P450 2A6 (CYP2A6*5, *7, *8, *18, *19, and *35)
-
Cytochrome P450 2A6 (CYP2A6) catalyzes important metabolic reactions of many xenobiotic compounds, including coumarin, nicotine, cotinine, and clinical drugs. Genetic polymorphisms of CYP2A6 can influence its metabolic activities. This study analyzed the functional activities of six CYP2A6 allelic variants (CYP2A6*5,*7,*8,*18,*19, and *35) containing nonsynonymous single-nucleotide polymorphisms. Recombinant variant enzymes of CYP2A6*7,*8,*18,*19, and *35 were successfully expressed in Escherichia coli and purified. However, a P450 holoenzyme spectrum was not detected for the CYP2A6*5 allelic variant (G479V). Structural analysis shows that the G479V mutation may alter the interaction between the A helix and the F-G helices. Enzyme kinetic analyses indicated that the effects of mutations in CYP2A6 allelic variants on drug metabolism are dependent on the substrates. In the case of coumarin 7-hydroxylation, CYP2A6*8 and *35 displayed increased Km values whereas CYP2A6*18 and *19 showed decreased kcat values, which resulted in lower catalytic efficiencies (kcat/Km). In the case of nicotine 5-oxidation, the CYP2A6*19 variant exhibited an increased Km value, whereas CYP2A6*18 and *35 showed much greater decreases in kcatvalues. These results suggest that individuals carrying these allelic variants are likely to have different metabolisms for different CYP2A6 substrates. Functional characterization of these allelic variants of CYP2A6 can help determine the importance of CYP2A6 polymorphisms in the metabolism of many clinical drugs.
- Han, Songhee,Choi, Seunghye,Chun, Young-Jin,Yun, Chul-Ho,Lee, Chang Hoon,Shin, Hee Jung,Na, Han Sung,Chung, Myeon Woo,Kim, Donghak
-
-
Read Online
- A sensitive and selective fluorescence probe for the detection of superoxide radical anion in vivo based on a protection-deprotection process
-
Superoxide radical anion (O2·?) plays vital roles in numerous physiological and pathological processes. Thus, it is in great demand to develop an efficient fluorescence probe for the measurement of O2·?. In the investigation, a new fluorescence probe NAP-SCM was developed for detection of O2·? on the basis of a protection-deprotection process. This probe, which utilizes coumarin as the fluorescent platform and 1,8-naphthalimidesulfonyl as the masking moiety, could monitor O2·? with good specificity, rapid response and low detection limit. More importantly, probe NAP-SCM displayed negligible cytotoxicity, good bio-compatibility and excellent capability of tracking the endogenous superoxide radical anion in live cells and live animals. The favorable observations illustrated that this probe has the promising potential to provide a valuable support for exploring the role(s) played by O2·? in the biologically functional processes.
- Chen, Liyan,Lu, Xin,Wu, Di,Xiao, Fengping
-
-
Read Online
- Synthesis of 7-hydroxycoumarins catalysed by solid acid catalysts
-
Syntheses of substituted 7-hydroxycoumarins via reactions of 1,3-dihydroxybenzene with ethyl acetoacetate (Pechmann reaction) and with propenoic acid and propynoic acids are reported, in which the production of environmentally harmful waste streams is minimized by the use of solid acid catalysts.
- Hoefnagel,Gunnewegh,Downing,Van Bekkum
-
-
Read Online
- Sn-Doped defect pyrochlore oxide KNbWO6·H2O microcrystals and their photocatalytic reduction of CO2
-
It is highly desirable to develop new semiconductors for the photocatalytic reduction of CO2 to CH4 and CO to solve greenhouse effect and energy issues. Defect pyrochlore oxides have a flexible composition and the electron/hole mobility can be manipulated by introducing foreign cations into the structure. Through Sn doping into the defect pyrochlore oxide KNbWO6·H2O, we successfully obtained a 2-times higher photocatalytic activity for converting CO2 to CO, CH4 and O2 compared to the original KNbWO6·H2O. According to the data from UV-vis, photoluminescence, and hydroxyl radical amount-related fluorescence spectra, and CO2 adsorption, the improved photocatalytic activity can be attributed to the extended visible light response, the enhanced charge separation and the improved CO2 adsorption due to Sn doping. Our results provide a new strategy for developing high-performance photocatalysts.
- Zeng, Xu,Chen, Yan,Jiao, Shihui,Fang, Zhenxing,Wang, Boran,Pang, Guangsheng,Feng, Shouhua
-
-
Read Online
- Surface-Binding Peptide Facilitates Electricity-Driven NADPH-Free Cytochrome P450 Catalysis
-
Industrial biotechnology aims to exploit cytochrome P450 enzymes to access their sophisticated catalytic activity for challenging chemical reactions on inert C?H bonds. Limited by the need for NADPH, approaches to bind P450 enzymes to electrode surfaces for an artificial electron supply are promising. Here, we demonstrate that a recombinant fusion of an indium tin oxide binding peptide and the multi-domain class VIII cytochrome P450 BM3 can be used in electrically driven catalysis. Bioelectrocatalytic activity is analyzed by direct product quantification resulting in superior activity of the specifically immobilized P450 BM3 in contrast to unspecifically adsorbed enzyme. Spacer and anchor point studies imply that enzyme flexibility and alignment are crucial factors to achieve high activity on the electrode. Furthermore, we demonstrate that our approach is also feasible for pharmaceutical application using naringenin as substrate.
- Zernia, Sarah,Frank, Ronny,Wei?e, Renato H.-J.,Jahnke, Heinz-Georg,Bellmann-Sickert, Kathrin,Prager, Andrea,Abel, Bernd,Str?ter, Norbert,Robitzki, Andrea,Beck-Sickinger, Annette G.
-
-
Read Online
- LICRED: A versatile drop-in vector for rapid generation of redox-self-sufficient cytochrome P450s
-
Cytochromes P450 (P450s) are a family of haem-containing oxidases with considerable potential as tools for industrial biocatalysis. Organismal genomes are revealing thousands of gene sequences that encode P450s of as yet unknown function, the exploitation of which will require high-throughput tools for their isolation and characterisation. In this report, a ligation-independent cloning vector "LICRED" is described that enables the high-throughput generation of libraries of redox-self-sufficient P450s by fusing a range of P450 haem domains to the reductase of P450RhF (RhF-Red) in a robust and generically applicable way. Cloning and expression of fusions of RhF-Red with the haem domains of P450cam and P450-XplA resulted in soluble, active, redox-self-sufficient, chimeric enzymes. In vitro studies also revealed that electron transfer from NADPH to haem was primarily intramolecular. The general applicability of the LICRED platform was then demonstrated through the creation of a library of RhF-Red fusion constructs by using the diverse complement of P450 haem domains identified in the genome of Nocardia farcinica. The resultant fusion-protein library was then screened against a panel of substrates; this revealed chimeric enzymes competent for the hydroxylation of testosterone and methyltestosterone, and the dealkylation of 7-ethoxycoumarin.
- Sabbadin, Federico,Hyde, Ralph,Robin, Aelig,Hilgarth, Eva-Maria,Delenne, Marie,Flitsch, Sabine,Turner, Nicholas,Grogan, Gideon,Bruce, Neil C.
-
-
Read Online
- New fluorogenic probes for neutral and alkaline ceramidases
-
New fluorogenic ceramidase substrates derived from the N-acyl modification of our previously reported probes (RBM14) are reported. While none of the new probes were superior to the known RBM14C12 as acid ceramidase substrates, the corresponding nervonic acid amide (RBM14C24:1) is an efficient and selective substrate for the recombinant human neutral ceramidase, both in cell lysates and in intact cells. A second generation of substrates, incorporating the natural 2-(N-acylamino)-1,3-diol-4-ene framework (compounds RBM15) is also reported. Among them, the corresponding fatty acyl amides with an unsaturated N-acyl chain can be used as substrates to determine alkaline ceramidase (ACER)1 and ACER2 activities. In particular, compound RBM15C18:1 has emerged as the best fluorogenic probe reported so far to measure ACER1 and ACER2 activities in a 96-well plate format.
- Casasampere, Mireia,Bielsa, Núria,Riba, Daniel,Bassas, Laura,Xu, Ruijuan,Mao, Cungui,Fabriàs, Gemma,Abad, José-Luis,Delgado, Antonio,Casas, Josefina
-
-
Read Online
- Is surface fluorination of TiO2 effective for water purification? The degradation vs. mineralization of phenolic pollutants
-
The photocatalytic activity of surface fluorinated TiO2 (F-TiO2) for both the degradation and mineralization of bisphenol A (BPA) was compared with that of pure TiO2. The degradation rate of BPA (i.e., the conversion rate of BPA to intermediates) was enhanced, but the mineralization rate (i.e., the conversion rate of BPA to CO2) was reduced by surface fluorination. These behaviors are different from the general trend in photocatalysis, in which the photocatalyst with a higher activity for the degradation also shows a higher activity for the mineralization. The surface fluorination of TiO2 enhanced the production of the hydroxyl radical ([rad]OH), which is primarily responsible for the degradation of BPA, by altering the [rad]OH generation pathway. However, the lower mineralization on F-TiO2, which produced more [rad]OH, implies that the role of [rad]OH in the photocatalytic mineralization process is minor. The production of superoxide/hydroperoxyl radical (O2[rad]?/HO2[rad]), which is suggested as an essential oxidant for the mineralization of phenolic pollutants, by F-TiO2 was lower than that exhibited by pure TiO2. The reduced photocurrent (Iph) generation and the enhanced H2O2 production on F-TiO2 indicate that fluorides on the TiO2 surface reduce the interfacial electron transfer rate (i.e., the production of O2[rad]?/HO2[rad]) and enhance the reduction of O2[rad]?/HO2[rad] to H2O2. The degradation rate increased, but the mineralization efficiency decreased with increasing the surface coverage of fluorides, which depends on the pH and fluoride concentration in the solution. The reduced mineralization efficiency of other phenolic pollutants (4-chlorophenol, phenol, methylene blue, rhodamine B, and acid orange 7) was also observed on F-TiO2. This result indicates that the negative effect of surface fluorination on the mineralization of phenolic pollutants is pervasive and is not restricted to BPA.
- Ryu, Jungho,Kim, Wooyul,Kim, Jaesung,Ju, Jinjung,Kim, Jungwon
-
-
Read Online
- Microwave Synthesis of Spinel MgFe2O4Nanoparticles and the Effect of Annealing on Photocatalysis
-
Through microwave heating in ethanol and with subsequent annealing, crystalline MgFe2O4 nanoparticles are produced rapidly and in high yields >99%. Under varied annealing temperatures, the degree of Mg and Fe site inversion changes the optical, electronic, and composition of the nanoparticles. A small particle size of ～10 nm is achievable with the aid of an ammonium salt mineralizer that caps the particles during nucleation and growth. Particles with the lowest inversion parameter and limited sintering upon annealing (at 600 °C) exhibit the greatest production of hydroxyl radicals under visible light illumination. As such, these particles also facilitate the degradation of methylene blue dye faster than those particles annealed at higher temperature and show a rate constant of 0.061 h-1 for degrading 10 ppm methylene blue with 20 mg of catalyst.
- McDonald, Kori D.,Bartlett, Bart M.
-
-
Read Online
- Remarkable Enhancement of 7-Ethoxycoumarin O-Deethylation by Lys250, Arg251 and Lys253 Mutations of Cytochrome P450 1A2
-
Catalytic efficiency, kcat/Km, for 7-ethoxycoumarin O-deethylation was remarkably enhanced up to 6-fold by mutations at Lys250, Arg251 or Lys253 in cytochrome P450 1A2, while that for methanol hydroxylation was not changed by the same mutations.It is thus suggested that this ionic site is located at or near one of the hydrophobic substrate-interacting sites of this enzyme.
- Sato, Hideaki,Shimizu, Toru,Murakami, Yoshinori,Hatano, Masahiro
-
-
Read Online
- Improved photoactivities for CO2 conversion and phenol degradation of α-Fe2O3 nanoparticles by co-coupling nano-sized BiPO4 and CuO to modulate electrons
-
It's highly desired to design and fabricate effective α-Fe2O3-based photocatalysts by increasing the surface area, promoting the charge separation and providing catalytic function. Herein, specific surface area-enlarged α-Fe2O3 (SE-FO) nanoparticles have been successfully synthesized by a functional molecule-modulated phase-separated hydrothermal method, with high photocatalytic activities for CO2 conversion and phenol degradation. The photocatalytic activities of SE-FO could be greatly improved by coupling nano-sized BiPO4 via an in-situ introduction method. This is attributed to the coupled BiPO4 as a high-energy platform to accept photogenerated electrons from α-Fe2O3 so as to enhance the charge separation mainly by means of surface photovoltage spectra and fluorescence spectra-related to the amount of produced ?OH species. Moreover, the photocatalytic activities are further improved by introducing a proper amount of nanocrystalline CuO via a simple impregnation process. It is confirmed based on the temperature-programmed desorption and electrochemical reduction measurements that the improved photoactivity is attributed to the introduced CuO as the co-catalyst for promoting electron-induced reduction reactions. Remarkably, the optimized α-Fe2O3 nanocomposite exhibits about 3-time photoactivity improvement compared with the pristine α-Fe2O3. This work would provide a feasible route to fabricate high-activity α-Fe2O3-based photocatalysts for CO2 conversion and phenol degradation.
- Chen, Shuangying,Mu, Zhiyuan,Yan, Rui,Zhang, Xuliang,Khan, Iltaf,Li, Zhijun,Sun, Ning,Zhang, Qingyang,Jing, Liqiang
-
-
Read Online
- Catalytic reaction of basidiomycete Lentinula edodes cytochrome P450, Le.CYP1 enzyme produced in yeast
-
The basidiomycete Lentinula edodes (Le.) cytochrome P450, Le.CYP1 was functionally expressed in Saccharomyces cerevisiae. The microsomal fraction containing Le.CYP1 was prepared from the recombinant yeast and the Le.CYP1 was analyzed. The 7-ethoxycoumarin and benzo(a)pyrene were found to be the substrates of Le.CYP1 enzyme. Le.CYP1 converted 7-ethoxycoumarin to 7-hydroxycoumarin.
- Akiyama, Ryoko,Kajiwara, Susumu,Shishido, Kazuo
-
-
Read Online
- Development of a highly selective H2S fluorescent probe and its application to evaluate CSE inhibitors
-
In this paper, we developed a novel fluorescent probe C359 for highly selective detection of H2S over other relevant biothiols. C359 is designed to contain a thiol-specific cleavable disulfide bond. H2S-mediated the disulfide cleavage and subsequent intramolecular cyclization released the masked 7-hydroxyl coumarin, displaying a remarkable fluorescence enhancement. With the promising features in hand, C359 has been applied to detect the activity of CSE (one of H2S-producing enzyme) and build up an assay for screening CSE inhibitors. We anticipated that the enzyme assay using C359 could provide a powerful methodology for screening more potent and selective enzyme inhibitors. This journal is
- Gu, Xianfeng,Zhu, Huikun,Yang, Suna,Zhu, Yi-Chun,Zhu, Yi-Zhun
-
-
Read Online
- Kinetic delay of cyclization/elimination-coupled enzyme assays: Analysis and solution
-
A kinetic analysis of an enzyme assay employing a synthetic substrate that produces a detectable signal through a spontaneous organic cyclization/ elimination reaction following the enzymatic reaction was conducted. The results from the calculation were used to predict the lag period and provide accurate measurements of the activity of alkaline phosphatase using the fluorogenic substrate (1).
- Xue, Fengtian,Seto, Christopher T.
-
-
Read Online
- Fluorogenic Cyanohydrin Esters as Chiral Probes for Esterase and Lipase Activity
-
Fluorogenic cyanohydrin esters were prepared that release the fluorescent product umbelliferone by secondary decomposition of the primary cyanohydrin reaction product by cyanide elimination to the aldehyde and subsequent β-elimination. Whereas butyrate 1b and octanoate 1d show the highest reaction rates with enzymes, the highest relative rates above the non-catalyzed background reaction are achieved with pivalate 1c and benzoate 1e. Enantioselective reactions are detected when the conversion stabilizes at 50% of the maximum fluorescence release, and enantioselectivity is confirmed by chiral-phase HPLC analysis of the unreacted cyanohydrin ester substrate.
- Leroy, Emmanuel,Bensel, Nicolas,Reymond, Jean-Louis
-
-
Read Online
- A novel fluorescent off-on probe for the sensitive and selective detection of fluoride ions
-
A highly sensitive and selective fluorescent probe for fluoride ions has been developed by incorporating the dimethylphosphinothionyl group as a recognition moiety into the fluorophore of coumarin. The detection mechanism is based on the fluoride ion-triggered cleavage of the dimethylphosphinothionyl group, followed by the release of coumarin, which leads to a large fluorescence enhancement at 455 nm (λex = 385 nm). Under the optimized conditions, the fluorescence enhancement of the probe is directly proportional to the concentration of fluoride ions in the range of 0-30 μM with a detection limit of 0.29 μM, which is much lower than the maximum content of fluoride ions guided by WHO. Notably, satisfying results have been obtained by utilizing the probe to determine fluoride ions in real-water samples and commercially available toothpaste samples. The proposed probe is rather simple and may be useful in the detection of fluoride ions in more real samples.
- Li, Lihong,Zhang, Min,Chang, Kaijing,Kang, Yu,Ren, Guodong,Hou, Xiaoyu,Liu, Wen,Wang, Haojiang,Wang, Bin,Diao, Haipeng
-
-
Read Online
- Co-MOF as an electron donor for promoting visible-light photoactivities of g-C3N4 nanosheets for CO2 reduction
-
A possible mechanism for boosting the visible-light photoactivities of graphitic carbon nitride (g-C3N4) nanosheets for CO2 reduction via coupling with the electron donor Co-metal-organic framework (MOF) is proposed in this study. Specifically, Co-MOF as an electron donor is capable of transferring the photogenerated electrons in the lowest unoccupied molecular orbital (LUMO) to the conduction band of g-C3N4 to facilitate charge separation. As expected, the prepared Co-MOF/g-C3N4 nanocomposites display excellent visible-light-driven photocatalytic CO2 reduction activities. The CO production rate of 6.75 μmol g?1 h?1 and CH4 evolution rate of 5.47 μmol g?1 h?1 are obtained, which are approximately 2 times those obtained with the original g-C3N4 under the same conditions. Based on a series of analyses, it is shown that the introduction of Co-MOF not only broadens the range of visible-light absorption but also enhances the charge separation, which improves the photocatalytic activity of g-C3N4 to a higher level. In particular, the hydroxyl radical (?OH) experiment was operated under 590 nm (single-wavelength) irradiation, which further proved that the photogenerated electrons in the LUMO of Co-MOF can successfully migrate to g-C3N4. This work may provide an important strategy for the design of highly efficient g-C3N4-based photocatalysts for CO2 reduction.
- Chen, Qiuyu,Li, Sijia,Xu, Hongyi,Wang, Guofeng,Qu, Yang,Zhu, Peifen,Wang, Dingsheng
-
-
Read Online
- Detection of hydroxyl radicals formed on an anodically polarized diamond electrode surface in aqueous media
-
Electrochemically generated hydroxyl radicals at anodically polarized boron-doped diamond electrodes in aqueous media have been suggested to be responsible for their ability to electrochemically incinerate organic waste. In this letter, for the first time, we provide experimental evidence for the generation of hydroxyl radicals by using coumarin followed by the fluorescence detection of its hydroxylated product.
- Komatsu, Masaharu,Rao, Tata Narasinga,Fujishima, Akira
-
-
Read Online
- Drastic enhancement on Fenton oxidation of organic contaminants by accelerating Fe(III)/Fe(II) cycle with l-cysteine
-
The development of a highly efficient and pH-tolerant Fenton system has been one of the most important and challenging goals in water remediation. Herein, a green natural organic ligand, l-cysteine (Cys), was innovatively introduced into Fenton's reagent to construct an excellent catalytic oxidation system. The introduction of Cys into the Fenton system expanded the effective pH range up to 6.5 and achieved a superior oxidation efficiency, representing about 70% higher removal ratio and 12 times higher reaction rate constant with methylene blue dye as the probe compound. The Cys-driven Fenton reaction presented an outstanding pH adaptability and oxidative activity compared with other common organic ligands or reducing agent-modified Fenton reactions. An investigation of the reaction mechanism indicated that the addition of Cys into the system accelerated the Fe(iii)/Fe(ii) cycle, and led to a relatively steady Fe(ii) recovery, which enhances the generation of hydroxyl radicals (OH). The presence of Cys in the Fenton system remarkably reduced the apparent activation energy from 95.90 to 47.93 kJ mol-1. The findings from this study provide a feasible approach for a highly efficient and pH-tolerant wastewater treatment process with environmentally benign characteristics, and initiates an inspiring research domain of amino acids in the environmental catalysis field.
- Luo, Lianshun,Yao, Yuyuan,Gong, Fei,Huang, Zhenfu,Lu, Wangyang,Chen, Wenxing,Zhang, Li
-
-
Read Online
- Facile preparation of Ti3+ self-doped TiO2 nanosheets with dominant {0 0 1} facets using zinc powder as reductant
-
Ti3+ self-doped TiO2 nanosheets with dominant {0 0 1} facets for excellent visible-light photocatalytic activity were prepared by a facile one-pot hydrothermal reaction strategy using tetrabutyl titanate (TBT) as titanium source, hydrofluoric acid (HF) as structure-directing agent and zinc powder (Zn) as reductant. The synthesized catalysts were characterized by transmission electron microscope (TEM), X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectra (XPS), diffuse reflectance spectrum (DRS) and nitrogen adsorption-desorption isotherms. The photocatalytic activity of the photocatalyst was evaluated by measure the formation rate of photo-induced hydroxyl radicals (OH) under visible-light irradiation (λ = 420 ± 10 nm) using coumarin as a probe. It was found that the presence of zinc shows little effect on the morphology, phase structure, BET surface areas and pore structure. However, the addition of Zn powder resulted in the formation of Ti3+ self-doped anatase TiO2 nanosheets with dominant {0 0 1} facets, which is responsible for the enhanced visible-light photocatalytic activity. The sample prepared with zinc/TBT molar ratio of 0.3 showed the highest visible-light photocatalytic activity, which is 1.9 times higher than that of commercial P25 TiO2.
- Si, Lingling,Huang, Ze'Ai,Lv, Kangle,Tang, Dingguo,Yang, Changjun
-
-
Read Online
- Ethnic-related differences in coumarin 7-hydroxylation activities catalyzed by cytochrome P4502A6 in liver microsomes of Japanese and Caucasian populations
-
Interethnic differences in cytochrome P4502A6 (CYP2A6) levels and coumarin 7-hydroxylation activities were determined in liver microsomes of 30 Japanese and 30 Caucasians. Although CYP2A6 levels and coumarin 7-hydroxylation activities varied very significantly in the 60 human samples examined, both CYP2A6 levels and coumarin 7-hydroxylation activities were found to be higher in Caucasian than Japanese population. Interestingly, eight of the 30 Japanese examined showed very low or undetectable levels of coumarin 7-hydroxylation activities as well as of CYP2A6 in liver microsomes. All of the Caucasians, however, had significant CYP2A6 levels and variable 7-hydroxylation activities. Kinetic analysis of coumarin 7-hydroxylation activities in liver microsomes of various human samples suggested that although there were ~260-fold differences in V(max)'s in 10 human samples examined, the K(m)'s were very similar (2.1 ± 0.7 μM); a value consistent with that obtained (1.2 μM) with purified CYP2A6 in reconstituted system. The results suggest that CYP2A6 is actually involved in the 7-hydroxylation of coumarin in human liver microsomes, and that interethnic differences in coumarin 7-hydroxylation activities in Japanese and Caucasian population may be ascribed to the differences in expression of CYP2A6 protein.
- Shimada,Yamazaki,Guengerich
-
-
Read Online
- Functional characterization of cytochrome P450 2A6 allelic variants CYP2A6*15, CYP2A6*16, CYP2A6*21, and CYP2A6*22
-
Variation in CYP2A6 levels and activity can be attributed to genetic polymorphism and, thus, functional characterization of allelic variants is necessary to define the importance of CYP2A6 polymorphism in humans. The aim of the present study was to investigate the reported alleles CYP2A6*15, CYP2A6*16, CYP2A6*21, and CYP2A6*22, in terms of the functional consequences of their mutations on the enzyme catalytic activity. With use of the wild-type CYP2A6 cDNA as template, site-directed mutagenesis was performed to introduce nucleotide changes encoding K194E substitution in CYP2A6*15, R203S substitution in CYP2A6*16, K476R substitution in CYP2A6*21, and concurrent D158E and L160I substitutions in CYP2A6*22. Upon sequence verification, the CYP2A6 wild-type and mutant constructs were individually coexpressed with NADPH-cytochrome P450 reductase in Escherichia coli. A kinetic study using a coumarin 7-hydroxylase assay indicated that CYP2A6*15 exhibited higher Vmax than the wild type, whereas all mutant constructs, except for variant CYP2A6*16, exhibited higher Km values. Analysis of the Vmax/K m ratio revealed that all mutants demonstrated 0.85- to 1.05-fold differences from the wild type, with the exception of variant CYP2A6*22, which only portrayed 39% of the wild-type intrinsic clearance. These data suggested that individuals carrying the CYP2A6*22 allele are likely to have lower metabolism of CYP2A6 substrate than individuals expressing CYP2A6*15, CYP2A6*16, CYP2A6*21, and the wild type. Copyright
- Tiong, Kai Hung,Yiap, Beow Chin,Tan, Eng Lai,Ismail, Rusli,Ong, Chin Eng
-
-
Read Online
- Purified fusion enzyme between rat cytochrome P4501A1 and yeast NADPH-cytochrome P450 oxidoreductase
-
A genetically engineered fusion enzyme between rat P4501A1 and yeast P450 reductase in the microsomal fraction of the recombinant yeast AH22/pAFCR1 was purified. The purified enzyme showed a typical CO-difference spectrum of P4501A1 and a single band with an apparent molecular weight of 125,000 on sodium dodecyl sulfate polyacrylamide gel electrophoresis. This agreed with the molecular weight of 131,202 calculated from the amino acid sequence. The purified enzyme showed both 7-ethoxycoumarin o-deethylase activity and horse heart cytochrome c reductase activity in the presence of NADPH. The 7-ethoxycoumarin o-deethylase activity depended on the species of lipid used for the reconstitution of the purified fusion enzyme although the purified enzyme showed the activity without reconstitution. The purified fusion enzyme had the Km value of 26 μM for 7-ethoxycoumarin and the maximal turnover rate of 29 mol product/min/mol enzyme at 30°C.
- Hara, Masayuki,Miyake, Jun,Asada, Yasuo,Ohkawa, Hideo
-
-
Read Online
- Electrochemical detection of human cytochrome P450 2A6 inhibition: A step toward reducing dependence on smoking
-
Inhibition of human cytochrome P450 2A6 has been demonstrated to play an important role in nicotine metabolism and consequent smoking habits. Here, the "molecular Lego" approach was used to achieve the first reported electrochemical signal of human CYP2A6 and to improve its catalytic efficiency on electrode surfaces. The enzyme was fused at the genetic level to flavodoxin from Desulfovibrio vulgaris (FLD) to create the chimeric CYP2A6-FLD. Electrochemical characterization by cyclic voltammetry shows clearly defined redox transitions of the haem domain in both CYP2A6 and CYP2A6-FLD. Electrocatalysis experiments using coumarin as substrate followed by fluorimetric quantification of the product were performed with immobilized CYP2A6 and CYP2A6-FLD. Comparison of the kinetic parameters showed that coumarin catalysis was carried out with a higher efficiency by the immobilized CYP2A6-FLD, with a calculated kcatvalue significantly higher (P M) remained unaltered. The chimeric system was also successfully used to demonstrate the inhibition of the electrochemical activity of the immobilized CYP2A6-FLD, toward both coumarin and nicotine substrates, by tranylcypromine, a potent and selective CYP2A6 inhibitor. This work shows that CYP2A6 turnover efficiency is improved when the protein is linked to the FLD redox module, and this strategy can be utilized for the development of new clinically relevant biotechnological approaches suitable for deciphering the metabolic implications of CYP2A6 polymorphism and for the screening of CYP2A6 substrates and inhibitors.
- Castrignano, Silvia,Ortolani, Alex,Sadeghi, Sheila J.,Di Nardo, Giovanna,Allegra, Paola,Gilardi, Gianfranco
-
-
Read Online
- 7-Ethoxycoumarin O-deethylase kinetics in isolated rat, dog and human hepatocyte suspensions
-
A comparative study of the kinetics of the O-deethylation of 7-ethoxycoumarin has been carried out in freshly isolated rat, dog and human hepatocytes. Biphasic kinetics were observed for all three species with apparent K(m) and V(max) values of 11.5, 2.2 and 3.9 μM and 0.30, 0.21, 0.007 nmol/min/106 cells from rat, dog and man, respectively, for the high affinity-low capacity component, and 560, 40, 470 μM and 1.52, 0.74, 0.057 nmol/min/106 cells, respectively, for the low affinity-high capacity component. These observed kinetic parameters in hepatocytes from rat and man were similar to published values for microsomes for the same two species. Values for intrinsic clearance of 7-ethoxycoumarin for the three species calculated from the K(m) and V(max) data were 152, 631 and 6 ml/min/kg for rat, dog and human hepatocytes, respectively. These intrinsic clearance values predict that 7-ethoxycoumarin would be subject to a high hepatic clearance in rat and dog, and low hepatic clearance in man. These values are supported by published data on rat which show that 7-ethoxycoumarin is subject to high clearance.
- Bayliss,Bell,Wilson,Park
-
-
Read Online
- CYP2A6 genetic polymorphisms and liver microsomal coumarin and nicotine oxidation activities in Japanese and Caucasians
-
Genotypes of CYP2A6, namely CYP2A6*1 (wild-type), CYP2A6*2, and CYP2A6*3, were examined in liver DNA of 39 Japanese and 43 Caucasians using two-step polymerase chain reaction (PCR) methods. We first amplified a DNA fragment (1725 bp) located between near middle of exon 1 and end of exon 4 of the CYP2A6 gene and further amplified using a forward primer 'wt' or 'mut' (middle of exon 3) and a reverse primer 'E3R' (middle of intron 3) for the detection of CYP2A6*2-genetic polymorphism. The 1725 bp fragment was also used for the amplification between exon 3 and near middle of intron 3 of the CYP2A6 gene and the fragment thus obtained digested with XcmI or DdeI to detect and confirm the CYP2A6*2- and CYP2A6*3-types, respectively. Only one DNA sample from a Japanese origin (J18) was not amplified by CYP2A6-specific primers; liver microsomes from this individual had very low activity of coumarin 7-hydroxylation and were devoid of protein(s) immunoreactive to anti-CYP2A6 antibody. Thus, this individual was suggested to be due to the gene deletion in CYP2A6. By analyzing the remaining 38 Japanese and 43 Caucasians, we found that there were no cases of CYP2A6*3-type polymorphism in the samples examined in this study, and no cases of CYP2A6*2-type polymorphism in the Japanese samples. Of Caucasians studied two individuals were classified into heterozygous CYP2A6*1/*2-type. Liver microsomal coumarin 7-hydroxylation activities in these two Caucasians were found to be lower than those of the other 41 Caucasians. Kinetic analysis showed that two CYP2A6*1/*2 individuals had a very low ratio of V(max) to K(m) for nicotine C-oxidation as well as coumarin 7-hydroxylation in liver microsomes, compared with those of homozygous CYP2A6*1-type. These results suggest that among 39 Japanese and 43 Caucasians examined one Japanese is classified to be CYP2A6 gene deletion and two Caucasians are heterozygous CYP2A6*1/*2-genotype. Thus the race-related differences in the occurrence of CYP2A6 genetic polymorphisms were supported.
- Inoue, Kiyoshi,Yamazaki, Hiroshi,Shimada, Tsutomu
-
-
Read Online
- Carbon-centered radicals can transfer hydrogen atoms between amino acid side chains
-
Radical migration between aliphatic amino acid side chains can occur in solution and intramolecularly in peptides. The kinetic constant of the hydrogen transfer reaction was measured by using competition kinetics, and the half-life as well as the distance that a radical can move within a protein was calculated. Copyright
- Raffy, Quentin,Buisson, David-Alexandre,Cintrat, Jean-Christophe,Rousseau, Bernard,Pin, Serge,Renault, Jean Philippe
-
-
Read Online
- Synthesis and characterization of Ni doped SnO2 microspheres with enhanced visible-light photocatalytic activity
-
Nickel-doped tin dioxide (NDT) microspheres with various doping levels were prepared by hydrothermal synthesis and characterized by using X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, high-resolution transmission electron microscopy, energy-dispersive spectroscopy analysis, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and UV-vis absorption spectroscopy. The formation mechanism of NDT microspheres was discussed. All samples prepared with different Sn/Ni ratios shows higher photocatalytic activity than that of pure SnO2 and pure NiO under visible light irradiation (λ > 420 nm). The photocatalytic activity is closely related to the composition of as-prepared photocatalysts. It is noted that the NDT microspheres with the doping content of 33.3 mol% exhibit the highest photoactivity. Moreover, this catalyst showed improved stability, and the activity did not weaken significantly after four recycles. The higher activity of NDT microspheres may be attributed to the combined effect of its demonstrated doping levels and appropriate band gap. And the doping of Ni2+ may facilitate the generation of electron and hole pairs and inhibit their recombination rate by acting as temporary trapping sites of photoinduced electrons.
- Chen, Huan,Ding, Liyong,Sun, Wen,Jiang, Qingqing,Hu, Juncheng,Li, Jinlin
-
-
Read Online
- Enantioselective fluorogenic assay of acetate hydrolysis for detecting lipase catalytic antibodies
-
An enantioselective fluorogenic assay for the kinetic resolution of chiral alkyl acetates is demonstrated with 7-(3-acetoxybutoxy)-2H-1- benzopyran-2-ones (R)- and (S)-4 or 7-(3-acetoxy-2-methylpropoxy)-2H-1- benzopyran-2-ones (R)-4 and (S)-6. The alcohols released by hydrolysis of these acetates are oxidized by horseliver alcohol dehydrogenase to unstable β-(aryloxy)carbonyl compounds, which undergo β-elimination of the strongly fluorescent product umbelliferone (= 7-hydroxy-2H-1 -benzopyran-2-one; 3) (λ(em) = 460 ± 20 nm, λ(ex)= 360 ± 20 nm). Enantioselectivities are calculated from the reaction rates for each enantiomeric acetate. For a series of representative lipases, the reactivities and enantioselectivities under preparative conditions are predicted accurately. This highly sensitive enantioselective assay detects as little as 10 μg/ml of hydrolytic enzyme, can be carried out in 96-well microtiter plates, and is compatible with cell- culture media. It is, therefore. suited for screening libraries of antibodies for enantioselective lipase catalytic antibodies.
- Klein, Gerard,Reymond, Jean-Louis
-
-
Read Online
- A sensitive and selective high-throughput screening fluorescence assay for lipases and esterases
-
Long-chain fatty acid esters of 7-(3,4-dihydroxybutyloxy)-2H-1-benzopyran-2-one (6) such as octanoate 2a are shown to be exceptionally sensitive and selective fluorogenic substrates for lipases and esterases. Umbelliferone (8) is released upon hydrolysis of the ester function in 2a in the presence of bovine serum albumin and sodium periodate. These substrates are at least by one order of magnitude more sensitive to lipases than the commercial fluorogenic substrate 4-methylumbelliferyl heptanoate. Furthermore, they are stable to a broad range of pH-induced- and thermal-hydrolysis conditions and do not react with non-catalytic proteins such as bovine serum albumin (BSA).
- Nyfeler, Erich,Grognux, Johann,Wahler, Denis,Reymond, Jean-Louis
-
-
Read Online
- AN APIOSE-CONTAINING COUMARIN GLYCOSIDE FROM GMELINA ARBOREA ROOT
-
Umbelliferone 7-apiosylglucoside has been characterized from the root of Gmelina arborea. Key Word Index - Gmelina arborea; Verbenaceae; root; coumarin; β-apiofuranosyl-(1->6)-β-D-glucopyranosyl-umbelliferone.
- Satyanarayana, P.,Subrahmanyam, P.,Kasai, R.,Tanaka, O.
-
-
Read Online
- Preparation and photocatalytic performance of Bi nanoparticles by microwave-assisted method using ascorbic acid as reducing agent
-
Bismuth nanoparticles (NPs) were prepared by using microwave (MW) as heating source and ascorbic acid as reducing agent. Pure phase of Bi NPs was obtained and the size was uniform with the mean value of 70 nm. The visible light absorption was good and the optical band gap was 1.77 eV. The photocatalytic efficiency was 2.7 times that of the sample by solvothermal method for degradation of methyl blue (MB) under visible light irradiation. The hydroxyl radicals during photocatalysis were detected due to the transition of Bi from semimetal to semiconductor. The small size effect was considered to contribute a lot to the efficient photocatalytic activity.
- Cui, Zhankui,Zhang, Yange,Li, Senlin,Ge, Suxiang
-
-
Read Online
- Facile synthesis of monodisperse porous ZnO nanospheres for organic pollutant degradation under simulated sunlight irradiation: The effect of operational parameters
-
Monodisperse porous ZnO nanospheres were successfully fabricated through a facile and cost-effective polyol-mediated preparation approach, followed by annealing at 400 °C for 2 h. The photocatalytic activity of the ZnO products was evaluated by the decolorization of rhodamine B (RhB) solution under simulated sunlight irradiation. The effects of operational parameters on the photo-degradation reaction progress, including catalyst dosage, initial dye concentration, reaction temperature, initial pH value, and the addition of inorganic oxidants, transition-metal ions and inorganic anions were investigated in detail. In addition, reactive species in the oxidation of RhB solution were pinpointed by adding a series of scavengers into the photocatalytic reaction system and O2[rad]? were determined to be the main reactive species. A potential mechanism of photocatalysis of RhB under simulated sunlight irradiation is proposed. The catalyst is found to be reusable.
- Yang, Chong,Yu, Jisheng,Li, Qingsong,Yu, Yingmin
-
-
Read Online
- In vitro evaluations for pharmacokinetic drug-drug interactions of a novel serotonin-dopamine activity modulator, brexpiprazole
-
Brexpiprazole, a serotonin-dopamine activity modulator, is indicated for the treatment of schizophrenia and also adjunctive therapy to antidepressants for the treatment of Major Depressive Disorder. To determine the drug–drug interaction risk for cytochrome P450, and SLC and ABC transporters, brexpiprazole and its metabolite, DM-3411 were assessed in this in?vitro investigation. Brexpiprazole exhibited weak inhibitory effects (IC50 >13 μmol/L) on CYP2C9, CYP2C19, CYP2D6 and CYP3A4 activities, but had moderate inhibitor activity on CYP2B6 (IC50 8.19 μmol/L). The ratio of systemic unbound concentration (3.8 nmol/L) to the Ki value was sufficiently low. DM-3411 had comparable inhibitory potentials with brexpiprazole only for CYP2D6 and CYP3A4. The mRNA expressions of CYP1A2, CYP2B6 and CYP3A4 were not changed by the exposure of brexpiprazole to human hepatocytes. Brexpiprazole and DM-3411 exhibited weak or no inhibitory effects for hepatic and renal transporters (OATPs, OATs, OCTs, MATE1, and BSEP), except for MATE-2K (0.156 μmol/L of DM-3411), even for which the ratio to systemic unbound concentration (5.3 nmol/L) was sufficiently low. Brexpiprazole effected the functions of P-gp and BCRP with IC50 values of 6.31 and 1.16 μmol/L, respectively, however, the pharmacokinetic alteration was not observed in the clinical concomitant study on P-gp and BCRP substrates. These in?vitro data suggest that brexpiprazole is unlikely to cause clinically relevant drug interactions resulting from the effects on CYPs or transporters mediating the absorption, metabolism, and/or disposition of co-administered drugs.
- Sasabe, Hiroyuki,Koga, Toshihisa,Furukawa, Masayuki,Matsunaga, Masayuki,Sasahara, Katsunori,Hashizume, Kenta,Oozone, Yoshihiro,Amunom, Immaculate,Torii, Mikako,Umehara, Ken,Kashiyama, Eiji,Takeuchi, Kenji
-
supporting information
p. 522 - 535
(2021/03/19)
-
- Antagonistic activity of hydroxycoumarin-based antioxidants as possible singlet oxygen precursor photosensitizers
-
Coumarins are phenolic-type compounds with efficient antioxidant activity due to their ability to scavenge reactive oxygen species. Nevertheless, their ability to behave as photosensitizers capable of generating reactive oxygen species, such as singlet oxygen, has been less studied. In this work, the photosensitizing ability of seven hydroxycoumarins was evaluated through the photooxidation of ergosterol by quantifying the conversion of ergosterol into ergosterol peroxide. In our experimental conditions, we found that almost every tested antioxidant coumarin promotes the peroxidation of ergosterol. The results suggest that the hydroxycoumarins exhibit potential photosensitizing activity by promoting singlet oxygen generation by a Type II photochemical mechanism. Density functional theory (DFT) calculations were also performed to obtain further insight into the chemical reactivity of tested compounds; the observed tendency in the group of antioxidant coumarins to promote the reaction was their hardness due to the principle of maximum hardness. To evaluate our conclusion, we performed the reaction using a highly polarizable coumarin as a photosensitizer, which resulted in an increased photosensitizing capacity supported with DFT calculations, which reinforces our analysis. Finally, we found that hydroxycoumarins can be potentially pro-oxidants since some of them can act as photosensitizers and generate singlet oxygen in the presence of UV–Vis light, a characteristic that must be considered when these compounds are used as antioxidants.
- Guerrero, Tomás,Vázquez-Ortega, Fernanda,Lagunes, Irene,Ortiz-Blanco, Erik,Sosa-Ortiz, Gabriela,Tovar-Miranda, Ricardo,Medina, Manuel E.,Trigos, ángel
-
-
- Boronic acid with high oxidative stability and utility in biological contexts
-
Despite their desirable attributes, boronic acids have had a minimal impact in biological contexts. A significant problem has been their oxidative instability. At physiological pH, phenylboronic acid and its boronate esters are oxidized by reactive oxygen species at rates comparable to those of thiols. After considering the mechanism and kinetics of the oxidation reaction, we reasoned that diminishing electron density on boron could enhance oxidative stability. We found that a boralactone, in which a carboxyl group serves as an intramolecular ligand for the boron, increases stability by 104-fold. Computational analyses revealed that the resistance to oxidation arises from diminished stabilization of the p orbital of boron that develops in the rate-limiting transition state of the oxidation reaction. Like simple boronic acids and boronate esters, a boralactone binds covalently and reversibly to 1,2-diols such as those in saccharides. The kinetic stability of its complexes is, however, at least 20-fold greater. A boralactone also binds covalently to a serine side chain in a protein. These attributes confer unprecedented utility upon boralactones in the realms of chemical biology and medicinal chemistry.
- Graham, Brian J.,Windsor, Ian W.,Gold, Brian,Raines, Ronald T.
-
-
- Novel boronate probe based on 3-benzothiazol-2-yl-7-hydroxy-chromen-2-one for the detection of peroxynitrite and hypochlorite
-
Derivatives of coumarin, containing oxidant-sensitive boronate group, were recently developed for fluorescent detection of inflammatory oxidants. Here, we report the synthesis and the characterization of 3-(2-benzothiazolyl)-7-coumarin boronic acid pinacol ester (BC-BE) as a fluorescent probe for the detection of peroxynitrite (ONOO– ), with high stability and a fast response time. The BC-BE probe hydrolyzes in phosphate buffer to 3-(2-benzothiazolyl)-7-coumarin boronic acid (BC-BA) which is stable in the solution even after a prolonged incubation time (24 h). BC-BA is slowly oxidized by H2O2 to form the phenolic product, 3-benzothiazol-2-yl-7-hydroxy-chromen-2-one (BC-OH). On the other hand, the BC-BA probe reacts rapidly with ONOO?. The ability of the BC-BA probe to detect ONOO– was measured using both authentic ONOO– and the system co-generating steady-state fluxes of O2?– and?NO. BC-BA is oxidized by ONOO– to BC-OH. However, in this reaction 3-benzothiazol-2-yl-chromen-2-one (BC-H) is formed in the minor pathway, as a peroxynitrite-specific product. BC-OH is also formed in the reaction of BC-BA with HOCl, and subsequent reaction of BC-OH with HOCl leads to the formation of a chlorinated phenolic product, which could be used as a specific product for HOCl. We conclude that BC-BA shows potential as an improved fluorescent probe for the detection of peroxynitrite and hypochlorite in biological settings. Complementation of the fluorescence measurements by HPLC-based identification of oxidant-specific products will help to identify the oxidants detected.
- Grzelakowska, Aleksandra,Modrzejewska, Julia,Podsiad?y, Rados?aw,Szala, Marcin,Zak?os-Szyda, Ma?gorzata,Zielonka, Jacek
-
-
- Light-up lipid droplets for the visualization of lipophagy and atherosclerosis by coumarin-derived bioprobe
-
Lipid droplets (LDs) are intracellular lipid-metabolism organelles that involved in many physiological processes, metabolic disorders as well as diseases such as atherosclerosis. However, the specific probes that can visually locate abnormal LDs-rich tissues and track LDs-associated behavior to the naked eye with adequate biosafety still are rare. Herein, we develop a new design strategy of LDs-targeted probe based on the solvatochromism of coumarin derivatives. The results revealed that the emission wavelength of coumarin fluorophores gradually red shift in different solvents with increasing polarity, while absorption wavelength almost unchanged. As a result, the enlarged stokes shift of coumarin was emerged from oil to water. Furthermore, properly reducing water solubility and adding electronic donor at the structure of coumarins can enlarge this type of solvatochromism. This discovery was utilized to develop suitable probe for the image of LDs and LDs-rich tissues with high resolution and biosafety. Therefore, LDs-associated behavior was visible to the naked eye during the process of lipophagy and atherosclerosis. We deem that the developed probe here offers a new possibility to accurately diagnosis and analyse LDs-related diseases in clinic and preclinical study.
- Zheng, Jinrong,Qin, Shuheng,Gui, Lijuan,Li, Hua,Fan, Lixue,Yang, Yifei,Chen, Haiyan,Xu, Hui,Yuan, Zhenwei
-
supporting information
p. 2385 - 2389
(2021/03/17)
-
- Mechanochemical activation of disulfide-based multifunctional polymers for theranostic drug release
-
Drug delivery systems responsive to physicochemical stimuli allow spatiotemporal control over drug activity to overcome limitations of systemic drug administration. Alongside, the non-invasive real-time tracking of drug release and uptake remains challenging as pharmacophore and reporter function are rarely unified within one molecule. Here, we present an ultrasound-responsive release system based on the mechanochemically induced 5-exo-trigcyclization upon scission of disulfides bearing cargo molecules attachedviaβ-carbonate linker within the center of a water soluble polymer. In this bifunctional theranostic approach, we release one reporter molecule per drug molecule to quantitatively track drug release and distribution within the cell in real-time. We useN-butyl-4-hydroxy-1,8-naphthalimide and umbelliferone as fluorescent reporter molecules to accompany the release of camptothecin and gemcitabine as clinically employed anticancer agents. The generality of this approach paves the way for the theranostic release of a variety of probes and drugs by ultrasound.
- Shi, Zhiyuan,Song, Qingchuan,G?stl, Robert,Herrmann, Andreas
-
p. 1668 - 1674
(2021/02/22)
-
- Photo-induced thiolate catalytic activation of inert Caryl-hetero bonds for radical borylation
-
Substantial effort is currently being devoted to obtaining photoredox catalysts with high redox power. Yet, it remains challenging to apply the currently established methods to the activation of bonds with high bond dissociation energy and to substrates with high reduction potentials. Herein, we introduce a novel photocatalytic strategy for the activation of inert substituted arenes for aryl borylation by using thiolate as a catalyst. This catalytic system exhibits strong reducing ability and engages non-activated Caryl–F, Caryl–X, Caryl–O, Caryl–N, and Caryl–S bonds in productive radical borylation reactions, thus expanding the available aryl radical precursor scope. Despite its high reducing power, the method has a broad substrate scope and good functional-group tolerance. Spectroscopic investigations and control experiments suggest the formation of a charge-transfer complex as the key step to activate the substrates.
- K?nig, Burkhard,Wang, Hua,Wang, Shun
-
supporting information
p. 1653 - 1665
(2021/06/17)
-
- On-Demand Activation of a Bioorthogonal Prodrug of SN-38 with Fast Reaction Kinetics and High Releasing Efficiency in Vivo
-
Although a myriad of bioorthogonal prodrugs have been developed, very few of them present both fast reaction kinetics and complete cleavage. Herein, we report a new bioorthogonal prodrug strategy with both fast reaction kinetics (k2: ～103 M-1 s-1) and complete cleavage (>90% within minutes) using the bioorthogonal reaction pair of N-oxide and boron reagent. Distinctively, an innovative 1,6-elimination-based self-immolative linker is masked by N-oxide, which can be bioorthogonally demasked by a boron reagent for the release of both amino and hydroxy-containing payload in live cells. Such a strategy was applied to prepare a bioorthogonal prodrug for a camptothecin derivative, SN-38, resulting in 10-fold weakened cytotoxicity against A549 cells, 300-fold enhanced water solubility, and on-demand activation upon a click reaction both in vitro and in vivo. This novel bioorthogonal prodrug strategy presents significant advances over the existing ones and may find wide applications in drug delivery in the future.
- Feng, Shun,Ji, Xingyue,Long, Ya-Qiu,Zhou, Jujun,Zhou, Zhou
-
-
- Direct Photorelease of Alcohols from Boron-Alkylated BODIPY Photocages
-
BODIPY photocages allow the release of substrates using visible light irradiation. They have the drawback of requiring reasonably good leaving groups for photorelease. Photorelease of alcohols is often accomplished by attachment with carbonate linkages, which upon photorelease liberate CO2 and generate the alcohol. Here, we show that boron-alkylated BODIPY photocages are capable of directly photoreleasing both aliphatic alcohols and phenols upon irradiation via photocleavage of ether linkages. Direct photorelease of a hydroxycoumarin dye was demonstrated in living HeLa cells.
- Fischer, Logan J.,Gehrmann, Elizabeth J.,Peterson, Julie A.,Shrestha, Pradeep,Smith, Emily A.,Wijesooriya, Chamari S.,Winter, Arthur H.,Yuan, Ding
-
supporting information
p. 5712 - 5717
(2020/05/19)
-
- Benzopyrone or quinolinone compound and application thereof
-
The invention discloses a benzopyrone or quinolinone compound and application thereof in preparation of a medicine for treating prostatic cancer, and belongs to the field of medicines. The benzopyroneand quinolinone compound with the structural formula as shown in the formula (I) has obvious antagonistic activity on androgen receptors and also has inhibitory activity on prostate cancer cells which do not express the androgen receptors. Therefore, the compound can be used as an androgen receptor antagonist to be applied to treatment of diseases related to androgen receptors or treatment of various metastatic prostate cancers, and a new choice is provided for development of drugs for treating prostate cancers.
- -
-
Paragraph 0205-0207
(2020/08/25)
-
- Ethylenic conjugated coumarin thiazolidinediones as new efficient antimicrobial modulators against clinical methicillin-resistant Staphylococcus aureus
-
In an effort for the development of novel antimicrobial agents, ethylenic conjugated coumarin thiazolidinediones as potential multi-targeting new antimicrobial compounds were synthesized through convenient procedures from commercially available resorcinol and were evaluated for their antimicrobial potency. Bioactive evaluation revealed that some of the prepared compounds showed strong antimicrobial activities towards the tested microorganisms including clinically drug-resistant strains. Especially, propargyl derivative 12b exhibited effective anti-MRSA potency with MIC value of 0.006 μmol/mL, which was highly advantageous over clinical antibacterial drug norfloxacin. Compound 12b showed rapid killing effect, low toxicity against hepatocyte LO2 cell line, and no obvious drug resistance development against MRSA. Preliminary exploration of action mechanism manifested that molecule 12b acted upon MRSA through forming stable supramolecular complex with bacterial DNA which might impede DNA replication. Molecular docking showed that compound 12b could bind with DNA-gyrase through hydrogen bonds.
- Hu, Chun-Fang,Zhang, Peng-Li,Sui, Yan-Fei,Lv, Jing-Song,Ansari, Mohammad Fawad,Battini, Narsaiah,Li, Shuo,Zhou, Cheng-He,Geng, Rong-Xia
-
-
- Revisiting terephthalic acid and coumarin as probes for photoluminescent determination of hydroxyl radical formation rate in heterogeneous photocatalysis
-
We investigated in detail the applicability of two radical scavengers – coumarin (COUM) and terephthalic acid (TA) – as probe compounds in a widely used photoluminescent (PL) determination of OH? radical rate formation of photocatalysts. The study reveals that precautions must be taken when using either of the two compounds as neither allows a direct determination of the absolute OH? radical formation rate. Chromatographic analyses of irradiated COUM and TA solutions revealed that both probe compounds reacted via more than one pathway, out of which, only one pathway in each case yielded the measured photoluminescent 7-hydroxycoumarin (7-OHC) and 2-hydroxyterephthalic acid (TAOH), respectively. Applicability of both probes was also tested on three model TiO2-based catalysts (anatase TiO2 nanorods (TNR), anatase TiO2 nanoparticles (TNP), amorphous TiO2 nanorods (a-TNR)). Regardless of the probe compound used, the order of relative OH? radical formation rates determined for these catalysts was the same (TNR a-TNR) and in good correlation with the order of bisphenol A (BPA) degradation rates. This demonstrates that (i) formation of OH? radicals is the predominating criterion when probing a photocatalyst's activity (but not the only one) and that (ii) TA and COUM potentially enable a relative evaluation of photocatalytic materials, despite the numerous shortcomings of these probes. However, in order to allow for general inter-laboratory comparisons the photoluminescence method should clearly be standardized with precisely defined experimental parameters.
- ?erjav, Gregor,Albreht, Alen,Pintar, Albin,Vovk, Irena
-
-
- The biothiol-triggered organotrisulfide-based self-immolative fluorogenic donors of hydrogen sulfide enable lysosomal trafficking
-
Biothiol-reactive organotrisulfide-based self-immolative fluorogenic donors of H2S are rationally designed for the efficient monitoring of intracellular and lysosomal trafficking of H2S with a concomitant turn-on fluorescence. The non-toxic nature of the donors with a sustained release of H2S will certainly be helpful for their biomedical applications in the future.
- Mahato, Sulendar K.,Bhattacherjee, Debojit,Bhabak, Krishna P.
-
supporting information
p. 7769 - 7772
(2020/07/27)
-
- Fluorescent probe for detecting zinc ions and pH values and preparation method and application of fluorescent probe
-
The invention belongs to the technical field of fluorescent probe synthesis and in particular relates to a fluorescent probe for detecting zinc ions and pH values and a preparation method and application of the fluorescent probe. Zn is important for maintaining biological functions, and conventional studies show that the severity of depression is proportional to zinc levels of serum. In addition, related studies show that increase of venous blood pH values of patients suffering from depression has statistical significances. The invention provides a fluorescent probe compound for simultaneously detecting Zn and pH values in brains. A DPA (docosapentaenoic acid) group, a coumarin group and a naphthalene group are coupled through covalent bonds. Animal models and in-vivo imaging verify that the fluorescent probe is capable of breaking through blood-brain barriers and showing good detection signals under a complicated background of intracerebral biology, and has the potential of being used as a reliable depression detection probe.
- -
-
Paragraph 0079-0080
(2020/02/14)
-
- Isonitrile-responsive and bioorthogonally removable tetrazine protecting groups
-
In vivo compatible reactions have a broad range of possible applications in chemical biology and the pharmaceutical sciences. Here we report tetrazines that can be removed by exposure to isonitriles under very mild conditions. Tetrazylmethyl derivatives are easily accessible protecting groups for amines and phenols. The isonitrile-induced removal is rapid and near-quantitative. Intriguingly, the deprotection is especially effective with (trimethylsilyl)methyl isocyanide, and serum albumin can catalyze the elimination under physiological conditions. NMR and computational studies revealed that an imine-tautomerization step is often rate limiting, and the unexpected cleavage of the Si-C bond accelerates this step in the case with (trimethylsilyl)methyl isocyanide. Tetrazylmethyl-removal is compatible with use on biomacromolecules, in cellular environments, and in living organisms as demonstrated by cytotoxicity experiments and fluorophore-release studies on proteins and in zebrafish embryos. By combining tetrazylmethyl derivatives with previously reported tetrazine-responsive 3-isocyanopropyl groups, it was possible to liberate two fluorophores in vertebrates from a single bioorthogonal reaction. This chemistry will open new opportunities towards applications involving multiplexed release schemes and is a valuable asset to the growing toolbox of bioorthogonal dissociative reactions.
- Tu, Julian,Svatunek, Dennis,Parvez, Saba,Eckvahl, Hannah J.,Xu, Minghao,Peterson, Randall T.,Houk,Franzini, Raphael M.
-
p. 169 - 179
(2019/12/30)
-
- Alleviating Cellular Oxidative Stress through Treatment with Superoxide-Triggered Persulfide Prodrugs
-
Overproduction of superoxide anion (O2.?), the primary cellular reactive oxygen species (ROS), is implicated in various human diseases. To reduce cellular oxidative stress caused by overproduction of superoxide, we developed a compound that reacts with O2.? to release a persulfide (RSSH), a type of reactive sulfur species related to the gasotransmitter hydrogen sulfide (H2S). Termed SOPD-NAC, this persulfide donor reacts specifically with O2.?, decomposing to generate N-acetyl cysteine (NAC) persulfide. To enhance persulfide delivery to cells, we conjugated the SOPD motif to a short, self-assembling peptide (Bz-CFFE-NH2) to make a superoxide-responsive, persulfide-donating peptide (SOPD-Pep). Both SOPD-NAC and SOPD-Pep delivered persulfides/H2S to H9C2 cardiomyocytes and lowered ROS levels as confirmed by quantitative in vitro fluorescence imaging studies. Additional in vitro studies on RAW 264.7 macrophages showed that SOPD-Pep mitigated toxicity induced by phorbol 12-myristate 13-acetate (PMA) more effectively than SOPD-NAC and several control compounds, including common H2S donors.
- Dillon, Kearsley M.,Li, Zhao,Matson, John B.,Wang, Yin,Winckler, Ethan W.
-
supporting information
p. 16698 - 16704
(2020/07/27)
-
- Confirming the Formation of Hydroxyl Radicals in the Catalytic Decomposition of H2O2 on Metal Oxides Using Coumarin as a Probe
-
Hydrogen peroxide can be catalytically decomposed to O2 and H2O on metal oxide surfaces in contact with aqueous solutions containing H2O2. The initial step in this process has been proposed to be the formation of surface-bound hydroxyl radicals which has recently been verified using tris as a radical scavenger. Here, we make use of the unique fluorescent product 7-hydroxycoumarin formed in the reaction between hydroxyl radicals and coumarin to probe the formation of surface-bound hydroxyl radicals. The experiments clearly show that 7-hydroxycoumarin is formed upon catalytic decomposition of H2O2 in aqueous suspensions containing ZrO2-particles and coumarin, thereby confirming the formation of surface-bound hydroxyl radicals in this process. The results are quantitatively compared to results on the same system using tris as a probe for hydroxyl radicals. The effects of the two probes on the system under study are compared and it is concluded that coumarin has a significantly lower impact on the system.
- Maier, Annika Carolin,Iglebaek, Ena Herceglija,Jonsson, Mats
-
p. 5435 - 5438
(2019/11/11)
-
- Preparation and application of solid-state upconversion materials based on sodium polyacrylate
-
By loading a microemulsion containing both sensitizer and emitter into porous sodium polyacrylate (PAAS), a water-absorbent resin (WAR) upconversion (UC) material was fabricated for photocatalysis applications. This WAR UC material showed a highly efficient UC process in the ambient environment owing to its liquid/solid encapsulation structure. In the application measurement, the UC emission from WAR UC materials can excite the catalyst Pt/WO3 to produce hydroxyl radicals, yielding 7-hydroxycoumarin by reacting with coumarin. In another case, since the band gap of ZnCdS matches the energy of UC emission, hole-electron pairs can be obtained under the UC irradiation and capture electrons from rhodamine B, leading to the degradation of rhodamine B. The maximum of the photocatalysis efficiency can be up to 97%. This work solves the oxygen quenching problem by preparing a triplet-triplet annihilation upconversion (TTA-UC) O/W microemulsion and loading it into PAAS WAR, and opens a new avenue to solid-state devices for TTA-UC. The applications of photocatalytic synthesis and photocatalytic degradation lay a foundation for future practical applications for TTA-UC materials.
- Ye, Changqing,Ma, Jinsuo,Han, Pengju,Chen, Shuoran,Ding, Ping,Sun, Bin,Wang, Xiaomei
-
p. 17691 - 17697
(2019/06/24)
-
- The effect of flavonoid aglycones on the CYP1A2, CYP2A6, CYP2C8 and CYP2D6 enzymes activity
-
Cytochromes P450 are major metabolic enzymes involved in the biotransformation of xenobiotics. The majority of xenobiotics are metabolized in the liver, in which the highest levels of cytochromes P450 are expressed. Flavonoids are natural compounds to which humans are exposed through everyday diet. In the previous study, selected flavonoid aglycones showed inhibition of CYP3A4 enzyme. Thus, the objective of this study was to determine if these flavonoids inhibit metabolic activity of CYP1A2, CYP2A6, CYP2C8, and CYP2D6 enzymes. For this purpose, the O-deethylation reaction of phenacetin was used for monitoring CYP1A2 enzyme activity, coumarin 7-hydroxylation for CYP2A6 enzyme activity, 6-α-hydroxylation of paclitaxel for CYP2C8 enzyme activity, and dextromethorphan O-demethylation for CYP2D6 enzyme activity. The generated metabolites were monitored by high-performance liquid chromatography coupled with diode array detection. Hesperetin, pinocembrin, chrysin, isorhamnetin, and morin inhibited CYP1A2 activity; apigenin, tangeretin, galangin, and isorhamnetin inhibited CYP2A6 activity; and chrysin, chrysin-dimethylether, and galangin inhibited CYP2C8. None of the analyzed flavonoids showed inhibition of CYP2D6. The flavonoids in this study were mainly reversible inhibitors of CYP1A2 and CYP2A6, while the inhibition of CYP2C8 was of mixed type (reversible and irreversible). The most prominent reversible inhibitor of CYP1A2 was chrysin, and this was confirmed by the docking study.
- Boji?, Mirza,Kond?a, Martin,Rimac, Hrvoje,Benkovi?, Goran,Male?, ?eljan
-
-
- "Close-to-Release": Spontaneous Bioorthogonal Uncaging Resulting from Ring-Closing Metathesis
-
Bioorthogonal uncaging reactions offer versatile tools in chemical biology. In recent years, reactions have been developed to proceed efficiently under physiological conditions. We present herein an uncaging reaction that results from ring-closing metathesis (RCM). A caged molecule, tethered to a diolefinic substrate, is released via spontaneous 1,4-elimination following RCM. Using this strategy, which we term "close-to-release", we show that drugs and fluorescent probes are uncaged with fast rates, including in the presence of mammalian cells or in the periplasm of Escherichia coli. We envision that this tool may find applications in chemical biology, bioengineering and medicine.
- Sabatino, Valerio,Rebelein, Johannes G.,Ward, Thomas R.
-
p. 17048 - 17052
(2019/10/11)
-
- Development of a self-immolative linker for tetrazine-triggered release of alcohols in cells
-
Bioorthogonal decaging reactions are a promising strategy for prodrug activation because they involve bond cleavage to release a molecule of interest. The trans-cyclooctene (TCO)-tetrazine inverse electron-demand Diels-Alder reaction has been widely applied in vivo for decaging of amine prodrugs, however, the release of alcohol-containing bioactive compounds has been less well studied. Here, we report a TCO-carbamate benzyl ether self-immolative linker for the release of OH-molecules upon reaction with a tetrazine trigger. The benzyl ether linker proved to be highly stable and can rapidly liberate alcohols under physiological conditions upon reaction with tetrazines. The mechanism and decaging yield were systematically examined by fluorescence and HPLC analysis by using a fluorogenic TCO-benzyl ether-coumarin probe and different 3,6-substituted tetrazine derivatives. This study revealed that decaging occurs rapidly (t1/2 = 27 min) and the cycloaddition step happens within seconds (t1/2 = 7 s) with reaction rates of ≈100 M-1 s-1. Importantly, the reaction is compatible with living organisms as demonstrated by the decaging of a prodrug of the antibacterial compound triclosan in the presence of live E. Coli, that resulted in complete cell killing by action of the released "OH-active drug". Overall, this work describes a new linker for masking alcohol functionality that can be rapidly reinstated through tetrazine-triggered decaging.
- Davies, Sarah,Oliveira, Bruno L.,Bernardes, Gon?alo J. L.
-
supporting information
p. 5725 - 5730
(2019/06/19)
-
- Photocatalysis Enables Visible-Light Uncaging of Bioactive Molecules in Live Cells
-
The photo-manipulation of bioactive molecules provides unique advantages due to the high temporal and spatial precision of light. The first visible-light uncaging reaction by photocatalytic deboronative hydroxylation in live cells is now demonstrated. Using Fluorescein and Rhodamine derivatives as photocatalysts and ascorbates as reductants, transient hydrogen peroxides were generated from molecular oxygen to uncage phenol, alcohol, and amine functional groups on bioactive molecules in bacteria and mammalian cells, including neurons. This effective visible-light uncaging reaction enabled the light-inducible protein expression, the photo-manipulation of membrane potentials, and the subcellular-specific photo-release of small molecules.
- Wang, Haoyan,Li, Wei-Guang,Zeng, Kaixing,Wu, Yan-Jiao,Zhang, Yixin,Xu, Tian-Le,Chen, Yiyun
-
supporting information
p. 561 - 565
(2019/01/04)
-
- Iron-Catalyzed Regioselective Decarboxylative Alkylation of Coumarins and Chromones with Alkyl Diacyl Peroxides
-
A facile iron-catalyzed decarboxylative radical coupling of alkyl diacyl peroxides with coumarins or chromones has been developed, affording a highly efficient approach to synthesize a variety of α-alkylated coumarins and β-alkylated chromones. The reaction proceeded smoothly without adding any ligand or additive and provided the corresponding products containing a wide scope of functional groups in moderate to excellent yields. This protocol was highlighted by its high regioselectivity, readily available starting materials, and operational simplicity.
- Jin, Can,Sun, Bin,Xu, Tengwei,Yan, Zhiyang,Zhang, Xun
-
supporting information
p. 1585 - 1591
(2019/08/07)
-
- Panel of New Thermostable CYP116B Self-Sufficient Cytochrome P450 Monooxygenases that Catalyze C?H Activation with a Diverse Substrate Scope
-
The ability of cytochrome P450 monooxygenases to catalyse a wide variety of synthetically challenging C?H activation reactions makes them highly desirable biocatalysts both for the synthesis of chiral intermediates and for late-stage functionalisations. However, P450s are plagued by issues associated with poor expression, solubility and stability. Catalytically self-sufficient P450s, in which the haem and reductase domains are fused in a single protein, obviate the need for additional redox partners and are attractive as biocatalysts. Here we present a panel of natural self-sufficient P450s from thermophilic organisms (CYP116B65 from A. thermoflava, CYP116B64 from A. xiamenense, CYP116B63 from J. thermophila, CYP116B29 from T. bispora and CYP116B46 from T. thermophilus). These P450s display enhanced expression and stability over their mesophilic homologues. Activity profiling of these enzymes revealed that each P450 displayed a different fingerprint in terms of substrate range and reactivity that cover reactions as diverse as hydroxylation, demethylation, epoxidation and sulfoxidation. The productivity of the bio-transformation of diclofenac to produce the 5-hydroxy metabolite increased 42-fold using the thermostable P450-AX (>0.5 g L?1 h?1) compared to the P450-RhF system reported previously. In conclusion, we have generated a toolkit of thermostable self-sufficient P450 biocatalysts with a broad substrate range and reactivity.
- Tavanti, Michele,Porter, Joanne L.,Sabatini, Selina,Turner, Nicholas J.,Flitsch, Sabine L.
-
p. 1042 - 1051
(2018/03/21)
-
- MOF-based ternary nanocomposites for better CO2 photoreduction: Roles of heterojunctions and coordinatively unsaturated metal sites
-
Semiconductors are the most widely used catalysts for CO2 photoreduction. However, their efficiencies are limited by low charge carrier density and poor CO2 activation. Towards solving these issues, a metal-organic framework (MOF)-based ternary nanocomposite was synthesized through self-assembly of TiO2/Cu2O heterojunctions via a microdroplet-based approach followed by in situ growth of Cu3(BTC)2 (BTC = 1,3,5-benzenetricarboxylate). With increased charge carrier density and efficient CO2 activation, the hybrid ternary nanocomposite exhibits a high CO2 conversion efficiency and preferential formation of CH4. Systematic measurements by using gas chromatography, photoluminescence spectroscopy, X-ray photoelectron spectroscopy, and time-resolved in situ diffuse reflectance infrared Fourier transform spectroscopy reveal that the semiconductor heterojunction and the coordinatively unsaturated copper sites within the hybrid nanostructure are attributable to the performance enhancements.
- He, Xiang,Wang, Wei-Ning
-
p. 932 - 940
(2018/02/06)
-
- Functional characterization of 9 CYP2A13 allelic variants by assessment of nicotine C-oxidation and coumarin 7-hydroxylation
-
Cytochrome P450 2A13 (CYP2A13) is responsible for the metabolism of chemical compounds such as nicotine, coumarin, and tobacco-specific nitrosamine. Several of these compounds have been recognized as procarcinogens activated by CYP2A13. We recently showed that CYP2A13*2 contributes to inter-individual variations observed in bladder cancer susceptibility because CYP2A13*2 might cause a decrease in enzymatic activity. Other CYP2A13 allelic variants may also affect cancer susceptibility. In this study, we performed an in vitro analysis of the wild-type enzyme (CYP2A13.1) and 8 CYP2A13 allelic variants, using nicotine and coumarin as representative CYP2A13 substrates. These CYP2A13 variant proteins were heterologously expressed in 293FT cells, and the kinetic parameters of nicotine C-oxidation and coumarin 7-hydroxylation were estimated. The quantities of CYP2A13 holoenzymes in microsomal fractions extracted from 293FT cells were determined by measuring reduced carbon monoxide-difference spectra. The kinetic parameters for CYP2A13.3, CYP2A13.4, and CYP2A13.10 could not be determined because of low metabolite concentrations. Five other CYP2A13 variants (CYP2A13.2, CYP2A13.5, CYP2A13.6, CYP2A13.8, and CYP2A13.9) showed markedly reduced enzymatic activity toward both substrates. These findings provide insights into the mechanism underlying inter-individual differences observed in genotoxicity and cancer susceptibility.
- Kumondai, Masaki,Hosono, Hiroki,Maekawa, Masamitsu,Yamaguchi, Hiroaki,Mano, Nariyasu,Oda, Akifumi,Hirasawa, Noriyasu,Hiratsuka, Masahiro
-
-
- Marmoset pulmonary cytochrome P450 2F1 oxidizes biphenyl and 7-ethoxycoumarin and hepatic human P450 substrates
-
1. A potentially useful animal model for preclinical studies is the common marmoset (Callithrix jacchus). In this study, using reverse-transcription polymerase chain reaction from marmoset livers, we identified a novel cytochrome P450 (P450) 2F1 cDNA with an open reading frame of 1473 bp. 2. High sequence identities of 92-94% with primate P450 2 F amino acid sequences were indicated by deduced amino acid sequences of P450 2F1 cDNA. Phylogenetic analysis indicates that marmoset P450 2F1 is more congruent with primate P450 2 F forms than those of other species such as rodents. 3. Among five tissue types examined, abundant expression of marmoset P450 2F1 mRNA and P450 2F1 protein in lungs was shown. Cynomolgus monkey P450 2F1 mRNA was abundantly expressed in lungs as well as testes and ovaries in 10 tissue types. 4. Similar to those of humans and cynomolgus monkeys, marmoset P450 2F1 heterologously expressed in Escherichia coli membranes efficiently catalyzed 7-ethoxycoumarin O-deethylation and biphenyl hydroxylation, however unlike human P450 2F1, marmoset P450 2F1 exhibited hydroxylation activity toward coumarin and chlorzoxazone. 5. These findings indicated that P450 2F1 enzyme expressed in marmoset lungs and also catalyzed metabolism of xenobiotics, suggesting the importance of P450 2 F-dependent drug metabolism in marmoset lungs.
- Uehara, Shotaro,Uno, Yasuhiro,Oshio, Toru,Inoue, Takashi,Sasaki, Erika,Yamazaki, Hiroshi
-
p. 656 - 662
(2017/10/06)
-
- A highly efficient photoelectrochemical H2O2 production reaction with Co3O4 as a co-catalyst
-
This communication describes an efficient co-catalyst Co3O4 nanoparticle with a tunable two-electron water oxidation reaction pathway in photoelectrochemical H2O2 production. The photoluminescence measurement explains that the promotion effect is due to the accelerated activation of water to OH. The increased Faraday efficiency of H2O2 for the Co3O4/WO3 sample also verifies that the promotion effect to a two-electron water oxidation reaction of Co3O4 is universal to other semiconductor photoanodes.
- Zhang, Jijie,Chang, Xiaoxia,Luo, Zhibin,Wang, Tuo,Gong, Jinlong
-
p. 7026 - 7029
(2018/07/05)
-
- Synthesis and insecticidal activity of novel benzothiazole derivatives containing the coumarin moiety
-
A series of novel benzothiazole derivatives containing a coumarin moiety was designed and synthesized. Their structures were characterized in detail via 1H NMR, 13C NMR, HRMS spectra and single-crystal X-ray diffraction analysis. The bioassay results indicated that some compounds showed encouraging insecticidal activity against Plutella xylostella and Aphis fabae at 400 mg/L. The preliminary structure-activity relationships were also discussed.
- Si, Wei-Jie,Chen, Min,Wang, Xue-Lun,Wang, Meng-Qi,Jiao, Jian,Fu, Xin-Can,Yang, Chun-Long
-
-
- ISOSAMIDIN ANALOG AND SAMIDIN ANALOG PRODUCTION METHOD
-
PROBLEM TO BE SOLVED: To provide a simple method of industrial-scale production of an isosamidin analog or samidin analog. SOLUTION: In the production method, a compound represented by the formula (1) in the figure is 1) senecioylated and 2) acetylated. [X is O or the like; R1 are each independently a C1-3 alkyl group or the like; R2 is H or the like; R3 are each a C1-3 alkyl group; m is an integer from 0 to 2; n is 1 or 2; and the symbol * represents an asymmetric center.] SELECTED DRAWING: None COPYRIGHT: (C)2018,JPOandINPIT
- -
-
Paragraph 0076
(2018/10/19)
-
- Synthesis and antiproliferative activity of 3- and 7-styrylcoumarins
-
A series of styrylcoumarins were obtained via Mizoroki-Heck reactions between 3-bromo-4-methyl-7-(octyloxy)-2H-chromen-2-one or 2-oxo-2H-chromen-7-yl trifluoromethanesulfonate and functionalized styrenes. The structures of the products were elucidated by spectroscopic analysis. All compounds were evaluated against SW480 and CHO-K1 cell lines. A number of hybrids showed good antiproliferative activity. Among the tested compounds, hybrids 6e, 10c, and 10d, exhibited the highest activity (IC50- SW480/48h = 6,92; 1,01 and 5,33 μM, respectively) and selectivity (IS48h = >400; 67,8 and 7,2, respectively). In addition, these compounds were able to preserve their activities over time. The results achieved by these hybrids were even better than the lead compounds (coumarin and resveratrol) and the standard drug (5-FU). As regards structure-activity relationship it seems that the location of the styryl group on the coumarin structure and the presence of the hydroxyl group on the phenyl ring were determinant for the activity.
- Herrera-R, Angie,Castrillón, Wilson,Otero, Elver,Ruiz, Esneyder,Carda, Miguel,Agut, Raúl,Naranjo, Tonny,Moreno, Gustavo,Maldonado, Maria Elena,Cardona-G, Wilson
-
p. 1893 - 1905
(2018/06/25)
-
- Coumarin-dithiocarbamate hybrids as novel multitarget AChE and MAO-B inhibitors against Alzheimer's disease: Design, synthesis and biological evaluation
-
A series of new coumarin-dithiocarbamate hybrids were designed and synthesized as multitarget agents for the treatment of Alzheimer's disease. Most of them showed potent and clearly selective inhibition towards AChE and MAO-B. Among these compounds, compound 8f demonstrated the most potent inhibition to AChE with IC50 values of 0.0068 μM and 0.0089 μM for eeAChE and hAChE, respectively. Compound 8g was identified as the most potent inhibitor to hMAO-B, and it is also a good and balanced inhibitor to both hAChE and hMAO-B (0.114 μM for hAChE; 0.101 μM for hMAO-B). Kinetic and molecular modeling studies revealed that 8g was a dual binding site inhibitor for AChE and a competitive inhibitor for MAO-B. Further studies indicated that 8g could penetrate the BBB and exhibit no toxicity on SH-SY5Y neuroblastoma cells. More importantly, 8g did not display any acute toxicity in mice at doses up to 2500 mg/kg and could reverse the cognitive dysfunction of scopolamine-induced AD mice. Overall, these results highlighted 8g as a potential multitarget agent for AD treatment and offered a starting point for design of new multitarget AChE/MAO-B inhibitors based on dithiocarbamate scaffold.
- He, Qi,Liu, Jing,Lan, Jin-Shuai,Ding, Jiaoli,Sun, Yongbing,Fang, Yuanying,Jiang, Neng,Yang, Zunhua,Sun, Liyuan,Jin, Yi,Xie, Sai-Sai
-
supporting information
p. 512 - 528
(2018/09/29)
-
- Synthesis of 7-Azido-3-Formylcoumarin – A Key Precursor in Bioorthogonally Applicable Fluorogenic Dye Synthesis
-
Coumarins represent an important group of natural products and a common part of various drugs and fluorescent dyestuffs. Herein, we present the synthesis of a coumarin that can serve as a key starting material in the design and synthesis of bioorthogonally applicable fluorogenic dyes. The synthesis of 7-azido-3-formylcoumarin started from 7-diallylaminocoumarin. This allyl protected aminocoumarin is otherwise hard to obtain by conventional methods but was conveniently accessed in good yields by a sequential, Wittig-reaction–UV isomerization process. This sequential approach was studied in more details and applied for the synthesis of a series of substituted coumarins even in one-pot.
- Pünk?sti, Zoltán,Kele, Péter,Herner, András
-
supporting information
p. 1183 - 1188
(2018/03/21)
-
- Synthetic Approach Toward Heterocyclic Hybrids of [1,2,4]Triazolo[3,4- b ][1,3,4]thiadiazines
-
The synthesis of novel heterocyclic [1,2,4]triazolo[3,4- b ][1,3,4]thiadiazine hybrids by a bimolecular reaction of 2-(4-amino-5-mercapto-4 H -[1,2,4]triazol-3-yl)phenol with an aromatic or heterocyclic α-bromoacetyl derivatives is described. This synthetic procedure starts from an unprotected phenol.
- Lechani, Nawel,Hamdi, Maamar,Kheddis-Boutemeur, Baya,Talhi, Oualid,Laichi, Yacine,Bachari, Khaldoun,Silva, Artur M. S.
-
supporting information
p. 1502 - 1504
(2018/05/03)
-
- A DNA-conjugated small molecule catalyst enzyme mimic for site-selective ester hydrolysis
-
The challenge of site-selectivity must be overcome in many chemical research contexts, including selective functionalization in complex natural products and labeling of one biomolecule in a living system. Synthetic catalysts incorporating molecular recognition domains can mimic naturally-occurring enzymes to direct a chemical reaction to a particular instance of a functional group. We propose that DNA-conjugated small molecule catalysts (DCats), prepared by tethering a small molecule catalyst to a DNA aptamer, are a promising class of reagents for site-selective transformations. Specifically, a DNA-imidazole conjugate able to increase the rate of ester hydrolysis in a target ester by >100-fold compared with equimolar untethered imidazole was developed. Other esters are unaffected. Furthermore, DCat-catalyzed hydrolysis follows enzyme-like kinetics and a stimuli-responsive variant of the DCat enables programmable turn on of the desired reaction.
- Flanagan, Moira L.,Arguello, A. Emilia,Colman, Drew E.,Kim, Jiyeon,Krejci, Jesse N.,Liu, Shimu,Yao, Yueyu,Zhang, Yu,Gorin, David J.
-
p. 2105 - 2112
(2018/03/05)
-
- Esterase Sensitive Self-Immolative Sulfur Dioxide Donors
-
A series of cell-permeable esterase-sensitive sulfonates that undergo self-immolation to produce sulfur dioxide (SO2), a gaseous pollutant with new and emerging biological roles, is reported. These compounds should facilitate the study SO2 biology and will lay the platform for newer stimuli-responsive donors of this gas.
- Pardeshi, Kundansingh A.,Ravikumar, Govindan,Chakrapani, Harinath
-
supporting information
p. 4 - 7
(2018/01/12)
-
- Synthesis of Novel Anti-inflammatory Psoralen Derivatives?-?Structures?with?Distinct?Anti-Inflammatory?Activities
-
As a continuum to our work with coumarins, 12 psoralens were synthesized and evaluated for their anti-inflammatory activity. Psoralens were prepared in three steps; at first, 7-hydroxycoumarins were synthesized by von Pechmann condensation and then converted to 7-(2-oxopropoxy)coumarins. In the final step, a fused furan ring was introduced in an intramolecular ring-formation reaction. Based on a SciFinder search, two out of the 12 synthesized psoralen derivatives (compounds 9 and 12) were found to be novel. The derivatives displayed anti-inflammatory activity by suppressing iNOS and IL-6 expression, but their mechanism of action seemed to be dependent on the substitution. Compound 6 with propyl side chain inhibited NF-κB mediated transcription, while compound 10 with a phenyl substituent down-regulated iNOS expression in a posttranscriptional manner. The results introduce psoralen derivatives as promising anti-inflammatory compounds with potential for treatment of conditions involving iNOS and/or IL-6-mediated adverse responses.
- Timonen, Juri M.,Vuolteenaho, Katriina,Lepp?nen, Tiina,Nieminen, Riina M.,Aulaskari, Paula,J?nis, Janne,Vainiotalo, Pirjo,Moilanen, Eeva
-
p. 2590 - 2597
(2018/09/25)
-
- Enhancing the Catalytic Performance of a CYP116B Monooxygenase by Transdomain Combination Mutagenesis
-
The cytochrome P450 monooxygenase discovered in Labrenzia aggregata (P450LaMO) is a self-sufficient redox system with versatile oxygenation functions. However, its catalytic performance is severely hindered by a low reaction rate, poor electron coupling efficiency (CE) and fragile thermostability. Herein, a simple transdomain combination mutation strategy was proposed for engineering this multi-domain P450 enzyme with redox partners fused to the heme domain. After focused mutagenesis on the heme domain, a triple mutant H3 (N119C/V264A/V437G) was hit, that improved the turnover frequency (TOF) and CE of P450LaMO by about 7.8-fold and 3.0-fold, respectively. A redox domain-based mutant with higher cytochrome c reduction activity, MR1 (M612L/K774Y), mediated more efficient electron transfer, elevated the TOF by 4.9-fold, and the coupling efficiency by 4.2-fold. The beneficial effect was further enhanced by combining the mutation sites from different domains, resulting in a combinatorial mutant (N119C/V264A/V437G/M612L/N694D) with a 9.1-fold increase in coupling efficiency, 10-fold in TOF, as well as +3.8 °C in thermostability (T5010). Meanwhile, for series of tetrahydronaphthalene derivatives, this combinator showed higher hydroxylation activity. This work suggested that employing this combinatorial strategy targeting on both the redox and heme domains is efficient to improve holoenzyme activity, CE and stability of a CYP116B subfamily member from the low starting point.
- Li, Ren-Jie,Xu, Jian-He,Chen, Qi,Zhao, Jing,Li, Ai-Tao,Yu, Hui-Lei
-
p. 2962 - 2968
(2018/07/29)
-
- Functional characterization of 34 CYP2A6 allelic variants by assessment of nicotine C-oxidation and coumarin 7-hydroxylation activities
-
CYP2A6, amember of the cytochrome P450 (P450) family, is one of the enzymes responsible for the metabolism of therapeutic drugs and such tobacco components as nicotine, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone, and N-nitrosodiethylamine. Genetic polymorphisms in CYP2A6 are associated with individual variation in smoking behavior, drug toxicities, and the risk of developing several cancers. In this study, we conducted an in vitro analysis of 34 allelic variants of CYP2A6 using nicotine and coumarin as representative CYP2A6 substrates. These variant CYP2A6 proteins were heterologously expressed in 293FT cells, and their enzymatic activitieswere assessed on the basis of nicotine C-oxidation and coumarin 7-hydroxylation activities. Among the 34 CYP2A6 variants, CYP2A6.2, CYP2A6.5, CYP2A6.6, CYP2A6.10, CYP2A6.26, CYP2A6.36, and CYP2A6.37 exhibited no enzymatic activity, whereas 14 other variants exhibited markedly reduced activity toward both nicotine and coumarin. These comprehensive in vitro findings may provide useful insight into individual differences in smoking behavior, drug efficacy, and cancer susceptibility.
- Hosono, Hiroki,Kumondai, Masaki,Maekawa, Masamitsu,Yamaguchi, Hiroaki,Mano, Nariyasu,Oda, Akifumi,Hirasawa, Noriyasu,Hiratsuka, Masahiro
-
p. 279 - 285
(2017/03/11)
-
