- Structural studies on the stereoisomerism of a natural dye miraxanthin I
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The chemical structure of a yellow dye present in Mirabilis jalapa L., miraxanthin I, was characterized by NMR spectroscopy. The extract of M. jalapa was analysed by a high-performance liquid chromatographic system (LC-DAD-FL-ESI-MS/MS) and the presence of miraxanthin I among other betaxanthins was confirmed. This dye was synthesized from previously generated methionine-betaxanthin by oxidation with 10% H2O2. The E/Z stereoisomers of miraxanthin I were found by NMR analysis to occur in a 50?:?33?:?10?:?7 ratio in aqueous solution (7E,9E?:?7Z,9E?:?7E,9Z?:?7Z,9Z configurations, respectively). Comparison of NMR data with chemical shifts obtained from quantum chemical calculations strongly suggests the presence of intramolecular hydrogen bonds which may favour a more rigid structure of the dye. This explains the highest fluorescence quantum yield among betaxanthins. The observed changes in the 1H NMR spectra during the measurements indicate on miraxanthin I hydrolysis for which a mechanism is proposed. The first step during the hydrolysis process is protonation of the nitrogen atom within the central bridge bond system which is observed in the ZE stereoisomer by NMR.
- Niziński, Stanis?aw,Popenda, ?ukasz,Rode, Micha? F.,Kumorkiewicz, Agnieszka,Fojud, Zbigniew,Paluch-Lubawa, Ewelina,Wybraniec, S?awomir,Burdziński, Gotard
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- Thiabendazole-based Rh(III) and Ir(III) biscyclometallated complexes with mitochondria-targeted anticancer activity and metal-sensitive photodynamic activity
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Two pairs of Rh(III) and Ir(III) biscyclometallated complexes with thiabendazole (L1), named [Ir-a]Cl and [Rh-a]Cl, and N-benzyl-thiabendazole (L2), named [Ir-b]Cl and [Rh-b]Cl, have been designed and synthesized to explore the photophysical and biological effects that arise from changing both the metal center and the ancillary ligand. In the dark, the four metal complexes exhibit greater cytotoxicity than cisplatin against human colon (SW480) and human lung (A549) adenocarcinoma cell lines. Moreover, the pair of complexes bearing the ligand L2 is markedly more cytotoxic and present higher uptake values than complexes with L1, thereby their biological properties were studied further to determine their mechanism of action. Interestingly, in spite of the different metal center both the [Ir-b]Cl and [Rh-b]Cl complexes are responsible for the loss of mitochondrial functionality and the activation of apoptotic cell death pathways. Moreover, the photodynamic activity of the four complexes, [Ir-a,b]Cl and [Rh-a,b]Cl, was tested using visible blue light (460 nm) under soft irradiation conditions (20 min, 5.5 mW cm?2). While the Rh complexes are not photopotentiated, the phototoxicity index (IC50 non-irradiated/IC50 irradiated) of [Ir-a]Cl and [Ir-b]Cl complexes was 15.8 and 3.6, respectively. We also demonstrate that only the Ir derivatives are capable of photocatalyzing the oxidation of S-containing L-amino acids under blue light irradiation, [Ir-a]Cl being more active than [Ir-b]Cl, which provides a reasonable mechanism for their biological action (oxidative stress could be selectively promoted through a photocatalytic action) upon irradiation. This different PDT behaviour depending on the metal center and the ancillary substituent may be useful for future rational design of metal-based photosensitizers.
- Pérez-Arnaiz, Cristina,Acu?a, María Isabel,Busto, Natalia,Echevarría, Igor,Martínez-Alonso, Marta,Espino, Gustavo,García, Bego?a,Domínguez, Fernando
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- Diastereomers of Methionine S-Oxide in the Hinge-Ligament Proteins of Molluscan Bivalve Species
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The diastereomer ratio was analyzed on methionine S-oxide residues formed by in vivo posttranslational oxidation of methionine residues in a protein.The hinge-ligament protein of molluscan bivalves is distinct from usual proteins in containing a large amount of methionine S-oxide.The methionine S-oxide was released from the protein by proteolytic digestions and was found to be a mixture of approximately equall amounts of two diastereomers, (5S)- and (5R)-L-methionine S-oxide.
- Kikuchi, Yasuo,Higashi, Kiyoshi,Tamiya, Nobuo
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- Type I Photosensitized Oxidation of Methionine?
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Methionine (Met) is an essential sulfur-containing amino acid, sensitive to oxidation. The oxidation of Met can occur by numerous pathways, including enzymatic modifications and oxidative stress, being able to cause relevant alterations in protein functio
- Casta?o, Carolina,Thomas, Andrés H.,Lorente, Carolina
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- Kinetics and mechanism of the oxidation of DL-methionine by tetrakis(pyridine)silver dichromate
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The oxidation of methionine by tetrakis(pyridine)silver dichromate in dimethyl sulphoxide leads to the formation of corresponding sulphoxide. The reaction is of first order with respect to tetrakis(pyridine)silver dichromate. Michaelis-Menten type kinetic
- Patel,Mathur,Jha,Kothari,Shastri,Sharma, Pradeep K.
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- Modulation of amyloid fibrillation of bovine β-lactoglobulin by selective methionine oxidation
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Deposition of oxidation-modified proteins during normal aging and oxidative stress are directly associated with systemic amyloidoses. Methionine (Met) is believed to be one of the most readily oxidisable amino acid residues of protein. Bovine beta-lactogl
- Maity, Sanhita,Sepay, Nayim,Pal, Sampa,Sardar, Subrata,Parvej, Hasan,Pal, Swarnali,Chakraborty, Jishnu,Pradhan, Anirban,Halder, Umesh Chandra
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- Periodate influencing diperiodatocuprate(III) oxidation of sulfur containing amino acid in aqueous alkaline medium
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The diperiodatocuprate(III) (DPC) oxidation of DL-methionine, a sulfur containing amino acid, was studied spectrophotometrically in alkaline solution. The reaction rate was first order in the concentration of DPC and fractional order in the concentration
- Sharanabasamma,Salunke, Manjali S.,Tuwar, Suresh M.
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- Kinetics and mechanism of oxidation of DL-methionine by hexacyanoferrate(III) in aqueous alkaline medium
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The title reaction was studied spectrophotometrically. The reaction was found to be first order in [HCF] and fractional order each in [dl-methionine] and [OH-]. Initially added products did not alter the rate of reaction. The variation of ionic
- Sharanabasamma,Tuwar, Suresh M.
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- Characterization by mass spectrometry and IRMPD spectroscopy of the sulfoxide group in oxidized methionine and related compounds
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Methionine protein residues are prone to oxidation. To unravel the controversy about the mechanism of its one-electron oxidation, we characterised the main biological product, methionine sulfoxide, using mass spectrometry and IR multiple photon dissociation spectroscopy. Gas phase IR spectra in the 800-2000 cm-1 range of protonated methionine and its sulfoxide were recorded and compared to those computed for the lowest energy structures. The signature of the SO bond was clearly identified at around 1000 cm-1. Oxidation of methionine-lysine dipeptide by OH radicals in the presence of catalase revealed the formation of methionine sulfoxide upon one-electron oxidation.
- Ignasiak, Marta,Scuderi, Debora,De Oliveira, Pedro,Pedzinski, Tomasz,Rayah, Yamina,Houée Levin, Chantal
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- Kinetic and mechanistic study of oxidation of L-methionine by Waugh-type enneamolybdomanganate(IV) in perchloric acid
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The reaction between methionine and enneamolybdomanganate(IV) in perchloric acid was carried out under pseudo-first-order conditions keeping large excess of methionine. The orders in oxidant and substrate were found to be unity and 0.91, respectively. The reaction proceeds with rapid formation of complex between the reactants followed by its decomposition in a rate determining step. The accelerating effect of hydrogen ions on the reaction is due to the formation of active hexaprotonated oxidant species. The product of the reaction was found to be methionine sulfoxide. The reaction involves direct two-electron transfer step without any free radical intervention. The effect of ionic strength, solvent polarity and the activation parameters were also in support of the mechanism proposed.
- Gurame,Supale,Gokavi, Gavisiddappa S.
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- Electron transfer reactions of methionine peptides with photochemically generated ruthenium(III)-polypyridyl complexes
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The dynamics of the oxidation of five methionine carrying peptides with six Ru(III)-polypyridyl complexes in aqueous acetonitrile medium have been followed by spectrophotometric technique. The electron transfer (ET) reaction of [Ru(NN)3]3+
- Thiruppathi, Dharmaraj,Karuppasamy, Periyakaruppan,Ganesan, Muniyandi,Sivasubramanian, Veluchamy Kamaraj,Rajendran, Thangamuthu,Rajagopal, Seenivasan
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- Squamins C–F, four cyclopeptides from the seeds of Annona globiflora
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Four cyclic octapeptides, squamins C–F, were isolated from the seeds of Annona globiflora Schltdl. These compounds share part of their amino acid sequence, -Pro-Met(O)-Tyr-Gly-Thr-, with previously reported squamins A and B. Their structures were determined using NMR spectroscopic techniques together with quantum mechanical calculations (QM-NMR), ESI-HRMS data and a modified version of Marfey's chromatographic method. All compounds showed cytotoxic activity against DU-145 (human prostate cancer) and HeLa (human cervical carcinoma) cell lines. Clearly, A. globiflora is an important source of bioactive molecules, which could promote the sustainable exploitation of this undervalued specie.
- Sosa-Rueda, Javier,Domínguez-Meléndez, Vanihamin,Ortiz-Celiseo, Araceli,López-Fentanes, Fernando C.,Cuadrado, Cristina,Fernández, José J.,Daranas, Antonio Hernández,Cen-Pacheco, Francisco
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- Accelerated Oxidation of Organic Sulfides by Microdroplet Chemistry
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We report the rapid oxidation of organic sulfides to sulfoxides by means of microdroplet chemistry at room temperature using a spray solution containing an organic sulfide dissolved in water/methanol, dilute (11%-14%) sodium hypochlorite (NaClO), and 5% chloroauric acid (HAuCl4). Ultrasonic nebulization, easy ambient sonic-spray ionization, or electrosonic spray ionization serves as the microdroplet source. High-resolution mass spectrometry was used as an online detector, and nuclear magnetic resonance was used as an offline detector. We found that the sulfoxide yields vary between 66 and 95%, the highest rate of product formation is 195 mg/min for benzyl phenyl sulfoxide, and the time required is a few minutes, which is much less than that required for the conventional means of achieving this chemical transformation. We also applied this microdroplet method to protein fingerprinting. We found that protein sequences containing methionine can be quickly oxidized, providing useful information for protein structure determinations.
- Li, Jia,Liu, Chengyuan,Chen, Hao,Zare, Richard N.
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p. 5011 - 5015
(2021/04/02)
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- Selective synthesis of sulfoxides and sulfonesviacontrollable oxidation of sulfides withN-fluorobenzenesulfonimide
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A practical and mild method for the switchable synthesis of sulfoxides or sulfonesviaselective oxidation of sulfides using cheapN-fluorobenzenesulfonimide (NFSI) as the oxidant has been developed. These highly chemoselective transformations were simply achieved by varying the NFSI loading with H2O as the green solvent and oxygen source without any additives. The good functional group tolerance makes the strategy valuable.
- Cao, Zhong-Yan,Li, Xiaolong,Lu, Hao,Wang, Panpan,Wang, Shengqiang,Xu, Xiaobo,Yan, Leyu,Yang, A-Xiu
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supporting information
p. 8691 - 8695
(2021/10/22)
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- A Donor-Acceptor [2]Catenane for Visible Light Photocatalysis
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Colored charge-transfer complexes can be formed by the association between electron-rich donor and electron-deficient acceptor molecules, bringing about the narrowing of HOMO-LUMO energy gaps so that they become capable of harnessing visible light. In an effort to facilitate the use of these widespread, but nonetheless weak, interactions for visible light photocatalysis, it is important to render the interactions strong and robust. Herein, we employ a well-known donor-acceptor [2]catenane - formed by the mechanical interlocking of cyclobis(paraquat-p-phenylene) and 1,5-dinaphtho[38]crown-10 - in which the charge-transfer interactions between two 4,4′-bipyridinium and two 1,5-dioxynaphthalene units are enhanced by mechanical bonding, leading to increased absorption of visible light, even at low concentrations in solution. As a result, since this [2]catenane can generate persistent bipyridinium radical cations under continuous visible-light irradiation without the need for additional photosensitizers, it can display good catalytic activity in both photo-reductions and -oxidations, as demonstrated by hydrogen production - in the presence of platinum nanoparticles - and aerobic oxidation of organic sulfides, such as l-methionine, respectively. This research, which highlights the usefulness of nanoconfinement present in mechanically interlocked molecules for the reinforcement of weak interactions, can not only expand the potential of charge-transfer interactions in solar energy conversion and synthetic photocatalysis but also open up new possibilities for the development of active artificial molecular shuttles, switches, and machines.
- ?or?evi?, Luka,Cai, Kang,Chen, Hongliang,Chen, Xiao-Yang,Feng, Yuanning,Jaynes, Tyler,Jiao, Yang,Mao, Haochuan,Qiu, Yunyan,Stoddart, J. Fraser,Stupp, Samuel I.,Wasielewski, Michael R.,Young, Ryan M.,Zhang, Long
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supporting information
p. 8000 - 8010
(2021/06/27)
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- Direct monitoring of biocatalytic deacetylation of amino acid substrates by1H NMR reveals fine details of substrate specificity
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Amino acids are key synthetic building blocks that can be prepared in an enantiopure form by biocatalytic methods. We show that thel-selective ornithine deacetylase ArgE catalyses hydrolysis of a wide-range ofN-acyl-amino acid substrates. This activity was revealed by1H NMR spectroscopy that monitored the appearance of the well resolved signal of the acetate product. Furthermore, the assay was used to probe the subtle structural selectivity of the biocatalyst using a substrate that could adopt different rotameric conformations.
- De Cesare, Silvia,McKenna, Catherine A.,Mulholland, Nicholas,Murray, Lorna,Bella, Juraj,Campopiano, Dominic J.
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supporting information
p. 4904 - 4909
(2021/06/16)
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- Photocatalytic water-soluble cationic platinum(II) complexes bearing quinolinate and phosphine ligands
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Cationic Pt(II) complexes ([Pt(QO/S)(PΛP)]X), having 8-oxy or 8-thioquinolinate (QO/S) and seven different mono- or bidentate phosphines as ligands, have been synthesized and characterized. The photophysical, stability, and photocatalytic properties of th
- Alemán, José,Cabrera, Silvia,Casado-Sánchez, Antonio,Domingo-Legarda, Pablo,Marzo, Leyre
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p. 13845 - 13857
(2020/11/02)
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- Biological activity and photocatalytic properties of a naphthyl-imidazo phenanthroline (HNAIP) ligand and its [Ir(ppy)2(HNAIP)]Cl and [Rh(ppy)2(HNAIP)]Cl complexes
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The synthesized 2-(hydroxy-1-naphtyl)imidazo-[4,5-f][1,10]phenanthroline (HNAIP) ligand and its new iridium ([Ir(ppy)2(HNAIP)]Cl) and rhodium ([Rh(ppy)2(HNAIP)]Cl) complexes, being ppy = 2-phenylpiridinate, show cytotoxic effects in SW480 (colon adenocarcinoma) and A549 (epithelial lung adenocarcinoma) cells. They all are cytotoxic in the tested cell lines. HNAIP and [Rh(ppy)2(HNAIP)]+ are the most cytotoxic, whereas [Ir(ppy)2(HNAIP)]+ displays negligible cytotoxicity towards A549 cells and moderate activity towards SW480. The interaction of all three compounds with Bovine Serum Albumin (BSA), L-glutathione reduced (GSH), nicotinamide adenine dinucleotide (NADH) and DNA was studied to explain the differences found in terms of cytotoxicity. None of them are able to interact with BSA, thus excluding bioavailability due to plasma protein interaction as the possible differentiating factor in their biological activity. By contrast, small differences have been observed regarding DNA interaction. In addition, taking advantage of the emission properties of these molecules, they have been visualized in the cytoplasmic region of A549 cells. Inductively coupled plasma mass spectrometry (ICP-MS) experiments show, in turn, that the internalization ability follow the sequence [Rh(ppy)2(HNAIP)]+ > [Ir(ppy)2(HNAIP)]+ > cisplatin. Therefore, it seems clear that the cellular uptake by tumour cells is the key factor affecting the different cytotoxicity of the metal complexes and that this cellular uptake is influenced by the hydrophobicity of the studied complexes. On the other hand, preliminary catalytic experiments performed on the photo-oxidation of GSH and some amino acids such as L-methionine (Met), L-cysteine (Cys) and L-tryptophan (Trp) provide evidence for the photocatalytic activity of the Ir(III) complex in this type of reactions.
- Rubio, Ana R.,Fidalgo, Jairo,Martin-Vargas, Judit,Pérez-Arnaiz, Cristina,Alonso-Torre, Sara R.,Biver, Tarita,Espino, Gustavo,Busto, Natalia,García, Bego?a
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- A study to develop platinum(iv) complex chemistry for peptide disulfide bond formation
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Platinum(iv) complexes with a heterocyclic ligand and an ancillary ligand have been investigated and applied for treating various tumour cell lines. Another application of the Pt(iv) complexes in forming peptide disulfide bonds was investigated in this work. For development of Pt(iv) complex chemistry for disulfide bond formation in peptides, two Pt(iv) complexes, [PtCl2(phen)(en)]Cl2 and [PtCl2(bpy)(en)]Cl2, were synthesized and characterized using elemental analysis, ESI-MS and NMR. Subsequently, they were investigated as oxidants for the formation of disulfide bonds in various peptides. Excellent purities and yields of disulfide-containing peptides were achieved when the reactions were carried out in aqueous solution. The reactions were completed rapidly in a wide range of pH values even in acidic medium at room temperature. An intramolecular disulfide bond was formed in each of the peptides in a solution containing two dithiol-containing peptides, making the Pt(iv) complexes useful for generating disulfide-containing peptide libraries. In addition, the two Pt(iv) complexes can be used as oxidants for the synthesis of disulfide bonds on a resin, which is a more convenient method to synthesize disulfide-containing peptides through automation.
- Huo, Shuying,Shen, Shigang,Song, Changying,Sun, Jingjing,Zhao, Xiaowei
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supporting information
p. 1736 - 1741
(2020/02/20)
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- Peroxo-Cerium(IV)-Containing Polyoxometalates: [CeIV6(O2)9(GeW10O37)3]24-, a Recyclable Homogeneous Oxidation Catalyst
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The class of peroxo-cerium-containing polyoxometalates has been discovered via the synthesis of the 9-peroxo-6-cerium(IV)-containing 30-tungsto-3-germanate, [CeIV6(O2)9(GeW10O37)3]24- (1). Polyanion 1 consists of a cyclic [Ce6(O2)9]6+ assembly that is stabilized by three dilacunary [GeW10O37]10- Keggin fragments. The title polyanion 1 is solution-stable, on the basis of 183W nuclear magnetic resonance, and was shown to act as a recyclable homogeneous catalyst for the selective, microwave-activated sulfoxidation of the model substrate methionine to the sulfoxide in the absence and to the sulfone in the presence of hydrogen peroxide. Solution and solid-state Raman as well as solid-state infrared studies of 1 demonstrated the complete loss (and regain) of the nine peroxo groups in situ during the catalytic cycle, suggesting that the peroxo-free {Ce6(GeW10)3} skeleton remains most likely intact during the catalytic cycle. Solid-state X-ray photoelectron spectroscopy measurements showed that peroxo loss is accompanied by reduction of the cerium ions from +4 to +3, which is fully reversible. Density functional theory calculations are in complete agreement with all of these observations and furthermore suggest that the reduction of the six cerium(IV) ions is accompanied by the formation of molecular dioxygen.
- Qasim, Hafiz M.,Ayass, Wassim W.,Donfack, Patrice,Mougharbel, Ali S.,Bhattacharya, Saurav,Nisar, Talha,Balster, Torsten,Solé-Daura, Albert,R?mer, Isabella,Goura, Joydeb,Materny, Arnulf,Wagner, Veit,Poblet, Josep M.,Bassil, Bassem S.,Kortz, Ulrich
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supporting information
p. 11300 - 11307
(2019/09/07)
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- Energy-Efficient Solar Photochemistry with Luminescent Solar Concentrator Based Photomicroreactors
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The sun is the most sustainable light source available on our planet, therefore the direct use of sunlight for photochemistry is extremely appealing. Demonstrated here, for the first time, is that a diverse set of photon-driven transformations can be efficiently powered by solar irradiation with the use of solvent-resistant and cheap luminescent solar concentrator based photomicroreactors. Blue, green, and red reactors can accommodate both homogeneous and multiphase reaction conditions, including photochemical oxidations, photocatalytic trifluoromethylation chemistry, and metallaphotoredox transformations, thus spanning applications over the entire visible-light spectrum. To further illustrate the efficacy of these novel solar reactors, medicinally relevant molecules, such as ascaridole and an intermediate of artemisinin, were prepared as well.
- Cambié, Dario,Dobbelaar, Jeroen,Riente, Paola,Vanderspikken, Jochen,Shen, Chong,Seeberger, Peter H.,Gilmore, Kerry,Debije, Michael G.,No?l, Timothy
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supporting information
p. 14374 - 14378
(2019/08/30)
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- Greener Preparation of 5-Ethyl-4a-hydroxyisoalloxazine and Its Use for Catalytic Aerobic Oxygenations
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Isoalloxazine ring systems are found in flavin cofactors in nature, and the simulation of their redox catalyses is an important task for developing sustainable catalytic oxidation reactions. Although 5-ethyl-4a-hydroxyisoalloxazines are among the most promising candidates as catalyst for such purposes, the use of them for laboratorial as well as industrial synthetic chemistry has so far been quite limited presumably due to the lack of their preparation methods readily, safely, and inexpensively available. In this communication, we introduce an environmentally benign and practical preparation of 5-ethyl-4a-hydroxy-3,7,8,10-tetramethylisoalloxazine (1EtOH) from 3,7,8,10-tetramethylisoalloxazine (1), in which conventional synthetic requirements, including (i) operations under inert conditions, (ii) risky or expensive chemicals, and (iii) isolation of labile intermediates, have all been dissolved. In addition, we have presented that 1EtOH could be an effective catalyst for Baeyer–Villiger oxidation as well as sulfoxidation with molecular oxygen (O2) as a terminal oxidant under suitable conditions, which is the first report on aerobic oxygenations catalyzed by 5-alkyl-4a-hydroxyisoalloxazines.
- Oonishi, Takahiro,Kawahara, Takayuki,Arakawa, Yukihiro,Minagawa, Keiji,Imada, Yasushi
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p. 1791 - 1795
(2019/02/07)
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- Continuous-flow protocol for the synthesis of enantiomerically pure intermediates of anti epilepsy and anti tuberculosis active pharmaceutical ingredients
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Continuous-flow production of chiral intermediates plays an important role in the development of building blocks for Active Pharmaceutical Ingredients (APIs), being α-amino acids and their derivatives widely applied as building blocks. In this work we developed two different strategies for the synthesis of intermediates used on the synthesis of levetiracetam/brivaracetam and ethambutol. The results obtained show that methionine methyl ester can be continuously converted to the desired ethambutol intermediate by RANEY Nickel dessulfurization/reduction strategy whereas levetiracetam/brivaracetam intermediates could be synthesized by both RANEY Nickel (without H2) and Pd/C-H2 approach or by photochemical desulfurization.
- Aguiar, Renata M.,Le?o, Raquel A. C.,Mata, Alejandro,Cantillo, David,Kappe, C. Oliver,Miranda, Leandro S. M.,De Souza, Rodrigo O. M. A.
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supporting information
p. 1552 - 1557
(2019/02/14)
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- Selective Photooxidation of Sulfides Catalyzed by Bis-cyclometalated IrIII Photosensitizers Bearing 2,2′-Dipyridylamine-Based Ligands
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A new family of heteroleptic bis-cyclometalated IrIII complexes with formula [Ir((Formula presented.))2((Formula presented.))]Cl ((Formula presented.) =2-phenylpyridinate and (Formula presented.) =2,2′-dipyridylamine or N-benzylated 2,2′-dipyridylamines, were synthesized, characterized, and successfully used as photosensitizers in the catalytic photooxidation of an array of dialkyl, dibenzyl, alkyl aryl, and diaryl sulfides, as well as sulfur-containing amino acids. Furthermore, the reactions proceeded with optimal chemoselectivity, and atom economy under mild conditions. Experimental observations support a dual mechanism in which singlet oxygen and superoxide are the actual oxidants.
- Vaquero, Mónica,Ruiz-Riaguas, Alba,Martínez-Alonso, Marta,Jalón, Félix A.,Manzano, Blanca R.,Rodríguez, Ana M.,García-Herbosa, Gabriel,Carbayo, Arancha,García, Bego?a,Espino, Gustavo
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supporting information
p. 10662 - 10671
(2018/07/31)
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- Synthesis of Methionine-Derived Endocyclic Sulfilimines and Sulfoximines
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The asymmetric synthesis of endocyclic methionine sulfilimines and sulfoximines from methionine derivatives was explored. The cyclization was performed by using phenyliodine diacetate (PIDA). In the case of l-methionine, dehydromethionine was obtained, and a deprotonation step by tBuONa was necessary to yield the corresponding sulfilimine. On the other hand, the cyclic sulfilimine of methionine methyl ester, methylthiopropylamine, and l-methioninol were synthesized in a single step by using PIDA. Owing to their instability, the sulfilimines were oxidized to their corresponding sulfoximines in good yields.
- Marzag, Hamid,Schuler, Marie,Tatibou?t, Arnaud,Reboul, Vincent
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supporting information
p. 896 - 900
(2017/02/15)
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- Scalable Photocatalytic Oxidation of Methionine under Continuous-Flow Conditions
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Highly efficient and chemoselective singlet oxygen oxidation of unprotected methionine was performed in water using a continuous mesofluidic reactor. Sustainable process engineering and conditions were combined to maximize process efficiency and atom economy, with virtually no waste generation and safe operating conditions. Three water-soluble metal-free photosensitizers [Rose Bengal, Methylene Blue, and tetrakis(4-carboxyphenyl)porphyrin] were assessed. The best results were obtained with Rose Bengal (0.1 mol %) at room temperature under white light irradiation and a slight excess of oxygen. Process and reaction parameters were monitored in real-time with in-line NMR. Other classical organic substrates (α-terpinene and citronellol) were oxidized under similar conditions with excellent performances.
- Emmanuel, Noémie,Mendoza, Carlos,Winter, Marc,Horn, Clemens R.,Vizza, Alessandra,Dreesen, Laurent,Heinrichs, Beno?t,Monbaliu, Jean-Christophe M.
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supporting information
p. 1435 - 1438
(2017/09/22)
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- Pt(II) coordination complexes as visible light photocatalysts for the oxidation of sulfides using batch and flow processes
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A new catalytic system for the photooxidation of sulfides based on Pt(ii) complexes is presented. The catalyst is capable of oxidizing a large number of sulfides containing aryl, alkyl, allyl, benzyl, as well as more complex structures such as heterocycles and methionine amino acid, with complete chemoselectivity. In addition, the first sulfur oxidation in a continuous flow process has been developed.
- Casado-Sánchez, Antonio,Gómez-Ballesteros, Rocío,Tato, Francisco,Soriano, Francisco J.,Pascual-Coca, Gustavo,Cabrera, Silvia,Alemán, José
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supporting information
p. 9137 - 9140
(2016/07/21)
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- Fused Selenazolinium Salt Derivatives with a Se-N+ Bond: Preparation and Properties
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Convenient methods for the preparation of stable, fused selenazolinium salt systems with a Se-N+ bond have been developed. The mechanism for the formation of the selenazole cycle was investigated in detail by conducting multinuclear NMR experiments. The ability of these compounds to form stable inner salts was demonstrated. We have shown the glutathione peroxidase (GPx) like properties of selenazolopyridinium salts by oxidizing sulfur-containing natural amino acids, as well as aromatic and heteroaromatic aldehydes. The molecular structures of most of the compounds were confirmed by X-ray diffraction studies.
- Arsenyan, Pavel,Vasiljeva, Jelena,Belyakov, Sergey,Liepinsh, Edvards,Petrova, Marina
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supporting information
p. 5842 - 5855
(2015/09/15)
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- Hydrogenation of sulfoxides to sulfides under mild conditions using ruthenium nanoparticle catalysts
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The first demonstration of the hydrogenation of sulfoxides under atmospheric H2 pressure is reported. The highly efficient reaction is facilitated by a heterogeneous Ru nanoparticle catalyst. The mild reaction conditions enable the selective hydrogenation of a wide range of functionalized sulfoxides to the corresponding sulfides. The high redox ability of RuO x nanoparticles plays a key role in the hydrogenation.
- Mitsudome, Takato,Takahashi, Yusuke,Mizugaki, Tomoo,Jitsukawa, Koichiro,Kaneda, Kiyotomi
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supporting information
p. 8348 - 8351
(2014/08/18)
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- Electron transfer reactions of photochemically generated ruthenium(III)-polypyridyl complexes with methionines
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The oxidation of methionine (Met) plays an important role during biological conditions of oxidative stress as well as for protein stability. Ruthenium(III)-polypyridyl complexes, [Ru(NN)3]3+, generated from the photochemical oxidation of the corresponding Ru(II) complexes with molecular oxygen, undergo a facile electron transfer reaction with Met to form methionine sulfoxide (MetO) as the final product. Interaction of [Ru(NN)3]3+ with methionine leads to the formation of >S+? and (>S∴S+ species as intermediates during the course of the reaction. The interesting spectral, kinetic, and mechanistic study of the electron transfer reaction of four substituted methionines with six [Ru(NN)3]3+ ions carried out in aqueous CH3CN (1:1, v/v) by a spectrophotometric technique shows that the reaction rate is susceptible to the nature of the ligand in [Ru(NN)3]3+ and the structure of methionine. The rate constants calculated by the application of Marcus semiclassical theory to these redox reactions are in close agreement with the experimental values.
- Thiruppathi, Dharmaraj,Karuppasamy, Periyakaruppan,Ganesan, Muniyandi,Sivasubramanian, Veluchamy Kamaraj,Rajendran, Thangamuthu,Rajagopal, Seenivasan
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p. 606 - 618
(2014/12/09)
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- Studies on the kinetics of tetrahexylammonium bromochromate oxidation of methionine in various percentage of acetic acid + N,N-dimethylformamide mixture
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Methionine (Met) is a naturally occurring sulphur containing amino acid. The kinetics of oxidation of methionine by tetrahexylammonium bromochromate (THexABC) in various percentage of acetic acid + N,N-dimethylformamide mixture (AcOH + DMF) leads to the f
- Mansoor, S. Sheik,Asghar, Basim H.
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p. 1395 - 1401
(2014/01/17)
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- Oxidation of methionine by tripropylammonium fluorochromate-a kinetic and mechanistic study
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The kinetics of oxidation of methionine (Met) by tripropylammonium fluorochromate (TriPAFC) has been studied in the presence of chloroacetic acid in aqueous acetic acid medium. The reaction is first order with respect to methionine, TriPAFC and acid. The
- Mansoor, S. Sheik
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experimental part
p. 643 - 648
(2012/03/13)
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- Reactive ZrIV and HfIV butterfly peroxides on polyoxometalate surfaces: Bridging the gap between homogeneous and heterogeneous catalysis
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At variance with previously known coordination compounds, the polyoxometalate (POM)-embedded ZrIV and HfIV peroxides with formula: [M2(O2)2(α-XW 11O39)2]12- (M=ZrIV, X=Si (1), Ge (2); M=HfIV, X=Si (3)) and [M6(O 2)6(OH)6(γ-SiW10O 36)3]18- (M=ZrIV (4) or Hf IV (5)) are capable of oxygen transfer to suitable acceptors including sulfides and sulfoxides in water. Combined 1HNMR and electrochemical studies allow monitoring of the reaction under both stoichiometric and catalytic conditions. The reactivity of peroxo-POMs 1-5 is compared on the basis of substrate conversion and kinetic. The results show that the reactivity of POMs 1-3 outperforms that of the trimeric derivatives 4 and 5 by two orders of magnitude. Reversible peroxidation of 1-3 occurs by H 2O2 addition to the spent catalysts, restoring oxidation rates and performance of the pristine system. The stability of 1-3 under catalytic regime has been confirmed by FT-IR, UV/Vis, and resonance Raman spectroscopy. The reaction scope has been extended to alcohols, leading to the corresponding carbonyl compounds with yields up to 99 % under microwave (MW) irradiation. DFT calculations revealed that polyanions 1-3 have high-energy peroxo HOMOs, and a remarkable electron density localized on the peroxo sites as indicated by the calculated map of the electrostatic potential (MEP). This evidence suggests that the overall description of the oxygen-transfer mechanism should include possible protonation equilibria in water, favored for peroxo-POMs 1-3. Copyright
- Carraro, Mauro,Nsouli, Nadeen,Oelrich, Holger,Sartorel, Andrea,Soraru, Antonio,Mal, Sib Sankar,Scorrano, Gianfranco,Walder, Lorenz,Kortz, Ulrich,Bonchio, Marcella
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supporting information; experimental part
p. 8371 - 8378
(2011/09/19)
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- Radiation chemical studies of methionine in aqueous solution: Understanding the role of molecular oxygen
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The oxidation of methionine is an important reaction in the biological milieu. Despite a few decades of intense studies, several fundamental aspects remain to be defined. We have investigated in detail the γ-radiolysis of free methionine in the absence and presence of molecular oxygen followed by product characterization and quantification. The primary site of attack by HO? radicals and H? atoms is the sulfur atom of methionine. We have disclosed that HO? radicals do not oxidize methionine to the corresponding sulfoxide in either the presence or the absence of oxygen; the oxidizing species is H2O2 derived either from the radiolysis of water or from the disproportionation of the byproduct O2?-. 3-Methylthiopropionaldehyde is the major product of HO? radical attack in the presence of molecular oxygen. Together with the direct oxidation at sulfur as the major product, the potential of H? atoms is also proven to be highly specific for sulfur atom attack under anoxic and aerobic conditions. The major products derived from the H? atoms attack are found to be α-aminobutyric acid or homoserine, in the absence or presence of oxygen, respectively. All together, these results help clarify the fate of methionine related to a biological environment and offer a molecular basis for envisaging other possible pathways of in vivo degradation as well as other markers.
- Barata-Vallejo, Sebastian,Ferreri, Carla,Postigo, Al,Chatgilialoglu, Chryssostomos
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scheme or table
p. 258 - 263
(2011/02/26)
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- Oxyhalogen-sulfur chemistry - Kinetics and mechanism of oxidation of methionine by aqueous iodine and acidified iodate
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The oxidation of methionine (Met) by acidic iodate and aqueous iodine was studied. Though the reaction is a simple two-electron oxidation to give methionine sulfoxide (Met-S=O), the dynamics of the reaction are, however, very complex, characterized by clock reaction characteristics and transient formation of iodine. In excess methionine conditions, the stoichiometry of the reaction was deduced to be IO3- + 3Met → I- + 3Met-S=O. In excess iodate, the iodide product reacts with iodate to give a final product of molecular iodine and a 2:5 stoichiometry: 2IO3 - + 5Met + 2H+ → I2 + 5Met-S=O + H 2O. The direct reaction of iodine and methionine is slow and mildly autoinhibitory, which explains the transient formation of iodine, even in conditions of excess methionine in which iodine is not a final product. The whole reaction scheme could be simulated by a simple network of 11 reactions.
- Chikwana, Edward,Davis, Bradley,Morakinyo, Moshood K.,Simoyi, Reuben H.
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experimental part
p. 689 - 697
(2009/12/04)
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- Tiglicamides A-C, cyclodepsipeptides from the marine cyanobacterium Lyngbya confervoides
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The Floridian marine cyanobacterium Lyngbya confervoides afforded cyclodepsipeptides, termed tiglicamides A-C (1-3), along with their previously reported analogues largamides A-C (4-6), all of which possess an unusual tiglic acid moiety. Their structures
- Matthew, Susan,Paul, Valerie J.,Luesch, Hendrik
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experimental part
p. 2058 - 2063
(2010/07/04)
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- Kinetics and mechanism of the oxidation of DL-methionine by quinolinium bromochromate
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The oxidation of methionine (Met) by quinolinium bromochromate (QBC) in dimethylsulphoxide (DMSO) leads to the formation of corresponding sulphoxide. The reaction is of first order with respect to each QBC and Met. The reaction is catalysed by hydrogen io
- Yajurvedi, Deeksha,Kumbhani,Shashtri,Baghmar,Sharma, Pradeep K.
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body text
p. 459 - 461
(2009/07/25)
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- Dual mechanism of oxidation of dl-methionine by diperiodatoargentate(III) in aqueous alkaline medium (stopped flow technique)
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The kinetics of oxidation of dl-methionine by diperiodatoargentate(III) (DPA) has been studied spectrophotometrically in a wide range, 0.01-1.0 mol dm-3, of alkali at constant ionic strength of 0.50 mol dm-3. In a lower range, 0.01-0
- Thabaj,Chimatadar,Nandibewoor
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body text
p. 88 - 95
(2009/02/02)
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- Oxidation by chlorine dioxide of methionine and cysteine derivatives to sulfoxides
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Methionine and cysteine derivatives were oxidized asymmetrically by chlorine dioxide to sulfinyl derivatives.
- Loginova,Rubtsova,Kuchin
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experimental part
p. 752 - 754
(2009/05/09)
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- Effect of sodium dodecyl sulphate micelles on the oxidation of L-methionine by chromium(VI) in perchloric acid medium
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The kinetics of oxidation of methionine by chromium(VI) in presence of an anionic surfactant, sodium dodecyl sulphate (SDS) has been studied under pseudo-first order conditions in perchloric acid medium. It was found that increase in [SDS] causes a decrease in rate indicating that the reaction is inhibited by anionic micelles. The critical micelle concentration (CMC) for SDS has been determined In 0.2 mol dm-3 ionic strength in presence of the oxidant by surface tension measurements and found to be 4 × 10 -4 mol dm-3. Further, the reaction is first order in [chromium(VI)], [methionine] and [H+]. Methionine sulphoxide is identified to be the main product of oxidation.
- Krishna Kishore,Kalyan Kumar,Annapurna,Vani
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p. 373 - 377
(2008/09/16)
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- Kinetics and mechanism of the oxidation of methionine by benzyltrimethylammonium dichloroiodate
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The oxidation of methionine (MTN) by benzyltrimethylammonium dichloroiodate (BTMACI), in glacial acetic acid in the presence of zinc chloride, leads to the formation of the corresponding sulphoxide. The reaction is first order with respect to each methion
- Garg, Dimple,Kothari, Seema
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p. 172 - 175
(2007/10/03)
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- Kinetics and mechanism of oxidation of DL-methionine by Keggin-type 12-tungstocobaltate(III) in aqueous acetic acid medium
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The kinetics of the reaction of DL-methionine with 12-tungstocobaltate(III) has been studied over the range of 8.4 ≤ 103 [DL-methioninc] ≤ 14.0, 3.0 ≤ pH ≤ 5.0 and 20 ≤ T ≤ 35 °C in aqueous acetic acid medium. The electron transfer reaction sho
- Satpathy,Dash,Acharya,Mohanty
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p. 891 - 894
(2007/10/03)
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- Solvent effects on the kinetics of oxidation of methionine by nicotinium dichromate
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The oxidation of methionine by nicotinium dichromate (NDC) has been studied, in the presence of p-toluene sulphonic acid, in water-DMSO and water-acetic acid mixtures of varying mole fractions. The reaction is first order each with respect to NDC and acid
- Malarvili,Pandeeswaran,Bhuvaneshwari,Elango
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p. 895 - 898
(2007/10/03)
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- Contrasting solvent effects on the kinetics of oxidation of methionine by quinolinium fluorochromate
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The oxidation of methionine by quinolinium fluorochromate (QFC) has been studied, in the presence of chloroacetic acid, in water-DMSO and water-acetic acid mixtures of varying mole fractions. The reaction is first order each with respect to methionine, QFC and acid. The reaction rates have been determined at different temperatures and the activation parameters have been computed. The reaction rate increases with increase in mole fraction of acetic acid in the mixture, where the specific solvent-solvent-solute interactions were found to dominant (56%), while in water-DMSO mixtures the rate decreases with increasing mole fraction of the organic co-solvent, where the transition state was stabilized only to a lesser extent by solvation. A solvation model and a suitable mechanism for the reaction are postulated.
- Bhuvaneshwari,John,Pandeeswaran,Elango
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p. 616 - 619
(2007/10/03)
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- Kinetics and mechanism of the oxidation of DL-methionine by quinolinium fluorochromate
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The oxidation of methionine (Met) by quinolinium fluorochromate (QFC) in dimethylsulphoxide (DMSO) leads to the formation of corresponding sulphoxide. The reaction is of first order with respect to QFC. Michaelis-Menten type kinetics was observed with res
- Pohani, Poonam,Sharma, Pradeep K.
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p. 757 - 761
(2007/10/03)
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- Kinetics and mechanism of the oxidation of methionine by benzyltrimethylammonium tribromide
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The oxidation of methionine (MTN) by benzyltrimethylammonium tribromide (BTMAB). in 1:1 aqueous acetic acid, leads to the formation of the corresponding sulphoxide. The reaction is first order with respect to each the methionine and BTMAB. The oxidation o
- Goyal, Archana,Kothari, Seema
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p. 2129 - 2132
(2007/10/03)
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- Chemoselective electrophilic oxidation of heteroatoms by hydroperoxy sultamst
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The synthesis of novel hydroperoxy sultams 1b-d and their potential as renewable chemoselective electrophilic oxidants for a wide range of nitrogen, sulfur, and phosphorus heteroatoms in nonaqueous media is described. Reactions of 1b,c with secondary amines 10f,g yielded the hydroxysultams 2b,c and nitrone 11f or radical 11g depending on the substrate and stoichiometry, while tertiary amines 10a-d gave amine oxides 11a-d. Compounds 1c,d oxidized various thioethers 12a-g to sulfoxides 13a-g smoothly that were isolated by chromatography in nearly quantitative yields. 1c was regenerated from 2c by treatment of the latter with acidified H2O2. Kinetic studies of the reaction of 1c with 1,4-thioxane 12f suggest that the reaction follows the second-order kinetics, first order in substrate and first order in oxidant with the second-order rate constant several orders of magnitude larger than that of the corresponding reaction with hydrogen peroxide and tert-butyl hydroperoxide without the need for any acid or heavy metal catalysts. The phosphines 14a,b were also oxidized by 1c to the respective phosphine oxides 15a,b readily in quantitative yields. The reactions may be conducted at ambient temperature or lower and appear to proceed via a nonradical mechanism. Reactions are sensitive to steric as well as electronic factors.
- Gelalcha, Feyissa Gadissa,Schulze, Baerbel
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p. 8400 - 8406
(2007/10/03)
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- Kinetics and mechanism of oxidation of methionine by pyridinium hydrobromide perbromide
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The oxidation of methionine (Met) by pyridinium hydrobromide perbromide (PHPB) has been studied in acetic acid-water (1:1) solutions. The oxidation reaction leads to the formation of the corresponding sulfoxide. The reaction is first order each in PHPB and Met. The reaction rates have been determined at different temperatures and the activation parameters calculated. A mechanism involving the formation of a halogen-sulfonium cation in the rate- determining step has been proposed.
- Sharma, Vinita,Sharma, Pradeep K.,Banerji, Kalyan K.
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p. 291 - 293
(2007/10/03)
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- First steps in the oxidation of sulfur-containing amino acids by hypohalogenation: Very fast generation of intermediate sulfenyl halides and halosulfonium cations
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Sulfur-containing amino acids show an extraordinary binding towards HOCl/ClO-. During the process, the Cl is transferred from the O to the S of the amino acid. Met reacts with HOCl one order of magnitude faster than the non-S containing amino acids (k((Met+HOCl))=8.7 · 108 mol-1 dm3 s-1). Instead, Cys reacts as its thiolate (RS-), two orders-of-magnitude faster (k((RS- +HOCl))=1.2 · 109 mol-1 dm3 s-1). Cys reacts also with ClO- (k((RS- +ClO-))=1.9 · 105 mol-1 dm3 s-1). Such processes take place much more readily than the corresponding N-halogenation of the non-sulfur containing amino acids. To our knowledge, these are the first kinetic measurements of the rate of formation of sulfenyl halides and halosulfonium cations in aqueous solution. Sulfenyl chlorides and chlorosulfonium ions derived from amino acids are elusive, and sulfide-type amino acids (Met) eventually yield sulfoxides (MetO), while thiol-type amino acids (Cys) lead to disulfides (Cys/Cys) and sulfonic acids (Cya). The fate of sulfur- containing amino acids upon oxidation with HOCl/ClO- seems to be related to their mutagen-inactivation ability. (C) 2000 Elsevier Science Ltd.
- Armesto,Canle L.,Fernández,García,Santaballa
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p. 1103 - 1109
(2007/10/03)
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- Kinetics and mechanism of oxidation of methionine by hexamethylenetetramine-bromine
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The kinetics of oxidation of methionine (MT) by hexamethylenetetramine-bromine (HABR) has been studied in acetic acid. The reaction leads to- the formation of the corresponding sulphoxide. The reaction is first order in HABR. Michaelis-Menten type kinetics has been observed with respect to the methionine. The formation constants of the intermediate complex and the rate constants from its decomposition have been evaluated at different temperatures. The thermodynamic and activation parameters have also been evaluated. The addition of hexamine (HXA) has no effect on the rate. A mechanism involving the formation of a halogenosulphonium cation in the slow step has been proposed.
- Gangwani,Sharma,Banerji
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p. 436 - 438
(2007/10/03)
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