- Higher-energy collision-induced dissociation for the quantification by liquid chromatography/tandem ion trap mass spectrometry of nitric oxide metabolites coming from S-nitroso-glutathione in an in vitro model of the intestinal barrier
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Rationale: The potency of S-nitrosoglutathione (GSNO) as a nitric oxide (NO) donor to treat cardiovascular diseases (CVDs) has been highlighted in numerous studies. In order to study its bioavailability after oral administration, which represents the most convenient route for the chronic treatment of CVDs, it is essential to develop an analytical method permitting (i) the simultaneous measurement of GSNO metabolites, i.e. nitrite, S-nitrosothiols (RSNOs) and nitrate and (ii) to distinguish them from other sources (endogenous synthesis and diet). Methods: Exogenous GSNO was labeled with 15N, and the GS15NO metabolites after conversion into the nitrite ion were derivatized with 2,3-diaminonaphthalene. The resulting 2,3-naphthotriazole was quantified by liquid chromatography/tandem ion trap mass spectrometry (LC/ITMS/MS) in multiple reaction monitoring mode after Higher-energy Collision-induced Dissociation (HCD). Finally, the validated method was applied to an in vitro model of the intestinal barrier (monolayer of Caco-2 cells) to study GS15NO intestinal permeability. Results: A LC/ITMS/MS method based on an original transition (m/z 171 to 156) for sodium 15N-nitrite, GS15NO and sodium 15N-nitrate measurements was validated, with recoveries of 100.8 ± 3.8, 98.0 ± 2.7 and 104.1 ± 3.3%, respectively. Intra- and inter-day variabilities were below 13.4 and 12.6%, and the limit of quantification reached 5 nM (signal over blank = 4). The permeability of labeled GS15NO (10–100 μM) was evaluated by calculating its apparent permeability coefficient (Papp). Conclusions: A quantitative LC/ITMS/MS method using HCD was developed for the first time to selectively monitor GS15NO metabolites. The assay allowed evaluation of GS15NO intestinal permeability and situated this drug candidate within the middle permeability class according to FDA guidelines. In addition, the present method has opened the perspective of a more fundamental work aiming at studying the fragmentation mechanism leading to the ion at m/z 156 in HCD tandem mass spectrometry in the presence of acetonitrile.
- Yu, Haiyan,Bonetti, Justine,Gaucher, Caroline,Fries, Isabelle,Vernex-Loset, Lionel,Leroy, Pierre,Chaimbault, Patrick
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- Nickel-Catalyzed Reductive Cross-Coupling of N-Acyl and N-Sulfonyl Benzotriazoles with Diverse Nitro Compounds: Rapid Access to Amides and Sulfonamides
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Herein we report a Ni-catalyzed reductive transamidation of conveniently available N-acyl benzotriazoles with alkyl, alkenyl, and aryl nitro compounds, which afforded various amides with good yields and a broad substrate scope. The same catalytic reaction conditions were also applicable for N-sulfonyl benzotriazoles, which could undergo smooth reductive coupling with nitroarenes and nitroalkanes to afford the corresponding sulfonamides.
- Qu, Erdong,Li, Shangzhang,Bai, Jin,Zheng, Yan,Li, Wanfang
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supporting information
p. 58 - 63
(2021/12/27)
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- Selective Synthesis of N-H and N-Aryl Benzotriazoles by the [3 + 2] Annulation of Sodium Azide with Arynes
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The synthetic utility of NaN3 as the azide component in the [3 + 2] annulation with arynes generated from 2-(trimethylsilyl)aryltriflates resulting in the transition-metal-free synthesis of N-H and N-aryl benzotriazoles has been demonstrated. Using CsF as the fluoride source in CH3CN, the N-H benzotriazoles are formed in high selectivity instead of the expected azidobenzene. Interestingly, N-aryl benzotriazoles are formed using KF and THF as solvent in an open-flask reaction. Moreover, a method for the N1-arylation of benzotriazole is also presented.
- Guin, Avishek,Gaykar, Rahul N.,Bhattacharjee, Subrata,Biju, Akkattu T.
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p. 12692 - 12699
(2019/10/11)
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- Synthesis of Structurally Diverse Benzotriazoles via Rapid Diazotization and Intramolecular Cyclization of 1,2-Aryldiamines
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An operationally simple method has been developed for the preparation of N-unsubstituted benzotriazoles by diazotization and intramolecular cyclization of a wide range of 1,2-aryldiamines under mild conditions, using a polymer-supported nitrite reagent and p-tosic acid. The functional group tolerance of this approach was further demonstrated with effective activation and cyclization of N-alkyl, -aryl, and -acyl ortho-aminoanilines leading to the synthesis of N1-substituted benzotriazoles. The synthetic utility of this one-pot heterocyclization process was exemplified with the preparation of a number of biologically and medicinally important benzotriazole scaffolds, including an α-amino acid analogue.
- Faggyas, Réka J.,Sloan, Nikki L.,Buijs, Ned,Sutherland, Andrew
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p. 5344 - 5353
(2019/05/21)
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- Crystal-facet-dependent denitrosylation: Modulation of NO release from S-nitrosothiols by Cu2O polymorphs
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Nitric oxide (NO), a gaseous small molecule generated by the nitric oxide synthase (NOS) enzymes, plays key roles in signal transduction. The thiol groups present in many proteins and small molecules undergo nitrosylation to form the corresponding S-nitrosothiols. The release of NO from S-nitrosothiols is a key strategy to maintain the NO levels in biological systems. However, the controlled release of NO from the nitrosylated compounds at physiological pH remains a challenge. In this paper, we describe the synthesis and NO releasing ability of Cu2O nanomaterials and provide the first experimental evidence that the nanocrystals having different crystal facets within the same crystal system exhibit different activities toward S-nitrosothiols. We used various imaging techniques and time-dependent spectroscopic measurements to understand the nature of catalytically active species involved in the surface reactions. The denitrosylation reactions by Cu2O can be carried out multiple times without affecting the catalytic activity.
- Ghosh, Sourav,Roy, Punarbasu,Prasad, Sanjay,Mugesh, Govindasamy
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p. 5308 - 5318
(2019/05/29)
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- Chemo-, Regio-, and Enantioselective Rhodium-Catalyzed Allylation of Triazoles with Internal Alkynes and Terminal Allenes
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The rhodium-catalyzed asymmetric N1-selective and regioselective coupling of triazole derivatives with internal alkynes and terminal allenes gives access to secondary and tertiary allylic triazoles in very good enantioselectivities. For this process, three new members of the JosPOphos ligand family have been prepared and employed in catalysis. The optimized reaction conditions enable the coupling of triazoles with internal alkynes as well as with allenes, displaying a high tolerance for functional groups. A gram scale reaction provided N1-allyltriazole, which was subjected to various transformations highlighting synthetic utility.
- Berthold, Dino,Breit, Bernhard
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supporting information
p. 598 - 601
(2018/02/10)
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- A two-photon excitable and ratiometric fluorogenic nitric oxide photoreleaser and its biological applications
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We report for the first time the development of a two-photon excitable NO photoreleaser, CNNO, for ratiometric imaging and tracking of NO release in live cells. CNNO exhibits the merits of spatiotemporal control in both the site-specific NO release in the
- Xie, Xilei,Fan, Jilin,Liang, Muwen,Li, Yong,Jiao, Xiaoyun,Wang, Xu,Tang, Bo
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supporting information
p. 11941 - 11944
(2017/11/06)
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- Hydroxylamine as a source for nitric oxide in metal-free 2,2,6,6-tetramethylpiperidine N-oxyl radical (TEMPO) catalyzed aerobic oxidation of alcohols
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The communication reports on the metal-free 2,2,6,6-tetramethylpiperidine N-oxyl radical (TEMPO) catalyzed aerobic oxidation of various alcohols to aldehydes and ketones. A novel catalyst system that uses 1-4 mol% of TEMPO in combination with 4-6 mol% of aqueous hydroxylamine is introduced. No other additives are necessary and corrosive by-products are not formed during oxidation. Nitric oxide which is important for the catalytic cycle is generated in situ by reaction of the hydroxylamine with TEMPO. A catalytic cycle for the overall oxidation process is suggested.
- Wertz, Sebastian,Studer, Armido
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supporting information; experimental part
p. 69 - 72
(2011/04/12)
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