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Alfieri ML, Panzella L, Amorati R, Cariola A, Valgimigli L, Napolitano A. Role of Sulphur and Heavier Chalcogens on the Antioxidant Power and Bioactivity of Natural Phenolic Compounds. Biomolecules 2022; 12:90. [PMID: 35053239 PMCID: PMC8774257 DOI: 10.3390/biom12010090] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Revised: 01/03/2022] [Accepted: 01/04/2022] [Indexed: 02/06/2023] Open
Abstract
The activity of natural phenols is primarily associated to their antioxidant potential, but is ultimately expressed in a variety of biological effects. Molecular scaffold manipulation of this large variety of compounds is a currently pursued approach to boost or modulate their properties. Insertion of S/Se/Te containing substituents on phenols may increase/decrease their H-donor/acceptor ability by electronic and stereo-electronic effects related to the site of substitution and geometrical constrains. Oxygen to sulphur/selenium isosteric replacement in resveratrol or ferulic acid leads to an increase in the radical scavenging activity with respect to the parent phenol. Several chalcogen-substituted phenols inspired by Vitamin E and flavonoids have been prepared, which in some cases prove to be chain-breaking antioxidants, far better than the natural counterparts. Conjugation of catechols with biological thiols (cysteine, glutathione, dihydrolipoic acid) is easily achieved by addition to the corresponding ortho-quinones. Noticeable examples of compounds with potentiated antioxidant activities are the human metabolite 5-S-cysteinyldopa, with high iron-induced lipid peroxidation inhibitory activity, due to strong iron (III) binding, 5-S-glutathionylpiceatannol a most effective inhibitor of nitrosation processes, and 5-S-lipoylhydroxytyrosol, and its polysulfides that proved valuable oxidative-stress protective agents in various cellular models. Different methodologies have been used for evaluation of the antioxidant power of these compounds against the parent compounds. These include kinetics of inhibition of lipid peroxidation alkylperoxyl radicals, common chemical assays of radical scavenging, inhibition of the OH• mediated hydroxylation/oxidation of model systems, ferric- or copper-reducing power, scavenging of nitrosating species. In addition, computational methods allowed researchers to determine the Bond Dissociation Enthalpy values of the OH groups of chalcogen modified phenolics and predict the best performing derivative. Finally, the activity of Se and Te containing compounds as mimic of glutathione peroxidase has been evaluated, together with other biological activities including anticancer action and (neuro)protective effects in various cellular models. These and other achievements are discussed and rationalized to guide future development in the field.
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Affiliation(s)
- Maria Laura Alfieri
- Department of Chemical Sciences, University of Naples “Federico II”, Via Cintia 21, I-80126 Naples, Italy; (M.L.A.); (L.P.)
| | - Lucia Panzella
- Department of Chemical Sciences, University of Naples “Federico II”, Via Cintia 21, I-80126 Naples, Italy; (M.L.A.); (L.P.)
| | - Riccardo Amorati
- Department of Chemistry “Giacomo Ciamician”, University of Bologna, Via S. Giacomo 11, I-40126 Bologna, Italy; (R.A.); (A.C.)
| | - Alice Cariola
- Department of Chemistry “Giacomo Ciamician”, University of Bologna, Via S. Giacomo 11, I-40126 Bologna, Italy; (R.A.); (A.C.)
| | - Luca Valgimigli
- Department of Chemistry “Giacomo Ciamician”, University of Bologna, Via S. Giacomo 11, I-40126 Bologna, Italy; (R.A.); (A.C.)
| | - Alessandra Napolitano
- Department of Chemical Sciences, University of Naples “Federico II”, Via Cintia 21, I-80126 Naples, Italy; (M.L.A.); (L.P.)
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Upadhyay A, Singh Bhakuni B, Meena R, Kumar S. Radical Chain Breaking Bis(
ortho
‐organoselenium) Substituted Phenolic Antioxidants. Chem Asian J 2021; 16:966-973. [DOI: 10.1002/asia.202100139] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Revised: 02/26/2021] [Indexed: 12/24/2022]
Affiliation(s)
- Aditya Upadhyay
- Department of Chemistry Indian Institute of Science Education and Research Bhopal By-Pass Road Bhauri, Bhopal 462 066 Madhya Pradesh India
| | - Bhagat Singh Bhakuni
- Department of Chemistry Indian Institute of Science Education and Research Bhopal By-Pass Road Bhauri, Bhopal 462 066 Madhya Pradesh India
| | - Rahul Meena
- Department of Chemistry Indian Institute of Science Education and Research Bhopal By-Pass Road Bhauri, Bhopal 462 066 Madhya Pradesh India
| | - Sangit Kumar
- Department of Chemistry Indian Institute of Science Education and Research Bhopal By-Pass Road Bhauri, Bhopal 462 066 Madhya Pradesh India
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3
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Upadhyay A, Batabyal M, Kanika, Kumar S. Organoseleniums: Generated and Exploited in Oxidative Reactions. CHEM LETT 2020. [DOI: 10.1246/cl.200015] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Aditya Upadhyay
- Department of Chemistry, Indian Institute of Science Education and Research (IISER) Bhopal, Bhopal By-pass Road, Bhauri, Bhopal 462066, Madhya Pradesh India
| | - Monojit Batabyal
- Department of Chemistry, Indian Institute of Science Education and Research (IISER) Bhopal, Bhopal By-pass Road, Bhauri, Bhopal 462066, Madhya Pradesh India
| | - Kanika
- Department of Chemistry, Indian Institute of Science Education and Research (IISER) Bhopal, Bhopal By-pass Road, Bhauri, Bhopal 462066, Madhya Pradesh India
| | - Sangit Kumar
- Department of Chemistry, Indian Institute of Science Education and Research (IISER) Bhopal, Bhopal By-pass Road, Bhauri, Bhopal 462066, Madhya Pradesh India
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Viglianisi C, Menichetti S. Chain Breaking Antioxidant Activity of Heavy (S, Se, Te) Chalcogens Substituted Polyphenols. Antioxidants (Basel) 2019; 8:antiox8100487. [PMID: 31623080 PMCID: PMC6826409 DOI: 10.3390/antiox8100487] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Revised: 10/12/2019] [Accepted: 10/15/2019] [Indexed: 12/13/2022] Open
Abstract
Polyphenols are probably the most important family of natural and synthetic chain-breaking antioxidants. Since long ago, chemists have studied how structural (bioinspired) modifications can improve the antioxidant activity of these compounds in terms of reaction rate with radical reactive oxygen species (ROS), catalytic character, multi-defence action, hydrophilicity/lipophilicity, biodistribution etc. In this framework, we will discuss the effect played on the overall antioxidant profile by the insertion of heavy chalcogens (S, Se and Te) in the phenolic skeleton.
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Affiliation(s)
- Caterina Viglianisi
- Department of Chemistry "Ugo Schiff", University of Florence, Via Della Lastruccia 3-13, 50019 Sesto Fiorentino, Italy.
| | - Stefano Menichetti
- Department of Chemistry "Ugo Schiff", University of Florence, Via Della Lastruccia 3-13, 50019 Sesto Fiorentino, Italy.
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Viglianisi C, Vasa K, Tanini D, Capperucci A, Amorati R, Valgimigli L, Baschieri A, Menichetti S. Ditocopheryl Sulfides and Disulfides: Synthesis and Antioxidant Profile. Chemistry 2019; 25:9108-9116. [PMID: 31017702 DOI: 10.1002/chem.201901537] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Indexed: 12/14/2022]
Abstract
Symmetrical ditocopheryl disulfides (Toc)2 S2 and symmetrical and unsymmetrical ditocopheryl sulfides (Toc)2 S were simply prepared under remarkably mild conditions with complete control of the regiochemistry by using δ-, γ-, and β-tocopheryl-N-thiophthalimides (Toc-NSPht) as common starting materials. The roles of sulfur atom(s), H-bond and aryl ring substitution pattern on the antioxidant profile of these new compounds, which were assembled by linking together two tocopheryl units, are also discussed.
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Affiliation(s)
- Caterina Viglianisi
- Department of Chemistry "Ugo Schiff", University of Florence, Via Della Lastruccia 3-13, Sesto Fiorentino, Firenze, Italy
| | - Kristian Vasa
- Department of Chemistry "Ugo Schiff", University of Florence, Via Della Lastruccia 3-13, Sesto Fiorentino, Firenze, Italy
| | - Damiano Tanini
- Department of Chemistry "Ugo Schiff", University of Florence, Via Della Lastruccia 3-13, Sesto Fiorentino, Firenze, Italy
| | - Antonella Capperucci
- Department of Chemistry "Ugo Schiff", University of Florence, Via Della Lastruccia 3-13, Sesto Fiorentino, Firenze, Italy
| | - Riccardo Amorati
- Department of Chemistry "G. Ciamician", University of Bologna, Via S. Giacomo 11, 40126, Bologna, Italy
| | - Luca Valgimigli
- Department of Chemistry "G. Ciamician", University of Bologna, Via S. Giacomo 11, 40126, Bologna, Italy
| | - Andrea Baschieri
- Department of Chemistry "G. Ciamician", University of Bologna, Via S. Giacomo 11, 40126, Bologna, Italy
| | - Stefano Menichetti
- Department of Chemistry "Ugo Schiff", University of Florence, Via Della Lastruccia 3-13, Sesto Fiorentino, Firenze, Italy
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6
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Crystal and molecular structure of the reaction product of 7-mercapto-4-methylcoumarin with iodine. Russ Chem Bull 2019. [DOI: 10.1007/s11172-019-2544-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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7
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Amorati R, Baschieri A, Valgimigli L. The role of sulfur and heavier chalcogens in the chemistry of antioxidants. PHOSPHORUS SULFUR 2019. [DOI: 10.1080/10426507.2019.1602620] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Affiliation(s)
- Riccardo Amorati
- Department of Chemistry “G. Ciamician”, University of Bologna, Bologna, Italy
| | - Andrea Baschieri
- Department of Chemistry “G. Ciamician”, University of Bologna, Bologna, Italy
| | - Luca Valgimigli
- Department of Chemistry “G. Ciamician”, University of Bologna, Bologna, Italy
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Yagunov SE, Kholshin SV, Kandalintseva NV, Prosenko AE. 5-Hydroxy-2,3-dihydrobenzofuran-derived polyfunctional antioxidants. Russ Chem Bull 2017. [DOI: 10.1007/s11172-017-1850-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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9
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Singh VP, Yan J, Poon JF, Gates PJ, Butcher RJ, Engman L. Chain-Breaking Phenolic 2,3-Dihydrobenzo[b]selenophene Antioxidants: Proximity Effects and Regeneration Studies. Chemistry 2017; 23:15080-15088. [PMID: 28857289 DOI: 10.1002/chem.201702350] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Indexed: 11/07/2022]
Abstract
Phenolic 2,3-dihydrobenzo[b]selenophene antioxidants bearing an OH-group ortho (9), meta (10, 11) and para (8) to the Se were prepared by seleno-Claisen rearrangement/intramolecular hydroselenation. meta-Isomer (11) was studied by X-ray crystallography. The radical-trapping activity and regenerability of compounds 8-11 were evaluated using a two-phase system in which linoleic acid was undergoing peroxidation in the lipid phase while regeneration of the antioxidant by co-antioxidants (N-acetylcysteine, glutathione, dithiothreitol, ascorbic acid, tris(carboxyethyl)phosphine hydrochloride) was ongoing in the aqueous layer. Compound 9 quenched peroxyl radicals more efficiently than α-tocopherol. It also provided the most long-lasting antioxidant protection. With thiol co-antioxidants it could inhibit peroxidation for more than five-fold longer than the natural product. Regeneration was more efficient when the aqueous phase pH was slightly acidic. Since calculated O-H bond dissociation energies for 8-11 were substantially larger than for α-tocopherol, an antioxidant mechanism involving O-atom transfer from peroxyl to selenium was proposed. The resulting phenolic selenoxide/alkoxyl radical would then exchange a hydrogen atom in a solvent cage before antioxidant regeneration at the aqueous lipid interphase.
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Affiliation(s)
- Vijay P Singh
- Department of Chemistry & Centre of Advanced Studies in Chemistry, Panjab University, Chandigarh -, 160 014, India
- Department of Chemistry-BMC, Uppsala University, Box-576, 751 23, Uppsala, Sweden
| | - Jiajie Yan
- Department of Chemistry-BMC, Uppsala University, Box-576, 751 23, Uppsala, Sweden
| | - Jia-Fei Poon
- Department of Chemistry-BMC, Uppsala University, Box-576, 751 23, Uppsala, Sweden
| | | | - Ray J Butcher
- Department of Chemistry, Howard University, Washington, DC, 20059, USA
| | - Lars Engman
- Department of Chemistry-BMC, Uppsala University, Box-576, 751 23, Uppsala, Sweden
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10
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Siddiqi KS, Husen A. Recent advances in plant-mediated engineered gold nanoparticles and their application in biological system. J Trace Elem Med Biol 2017; 40:10-23. [PMID: 28159216 DOI: 10.1016/j.jtemb.2016.11.012] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/20/2016] [Revised: 10/09/2016] [Accepted: 11/22/2016] [Indexed: 12/23/2022]
Abstract
For biosynthesis of gold nanoparticles different parts of a plant are used as they contain metabolites such as alkaloids, flavonoids, phenols, terpenoids, alcohols, sugars and proteins which act as reducing agents to produce nanoparticles. They also act as capping agent and stabilizer for them. They are used in medicine, agriculture and many other technologies. The attention is therefore focussed on all plant species which have either aroma or colour in their leaves, flowers or roots for the synthesis of nanoparticles because they all contain such chemicals which reduce the metal ions to metal nanoparticles. The size and morphology of gold nanoparticles is dependent on the biogenic-synthetic route, incubation time, temperature, concentration and pH of the solution. In this review, we have discussed the latest developments for the fabrication of gold nanoparticles from herbal extract, their characterization by UV-vis., Fourier transform infrared spectroscopy, transmission electron microscopy, scanning electron microscopy, X-ray diffraction, atomic force microscopy, energy-dispersive X-ray spectroscopy, dynamic light scattering and Zeta Potential techniques. Their application in drug delivery, cancer treatment, catalysis and as antimicrobial agent has also been discussed.
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Affiliation(s)
| | - Azamal Husen
- Department of Biology, College of Natural and Computational Sciences, University of Gondar, P.O. Box #196, Gondar, Ethiopia.
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11
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Menichetti S, Amorati R, Meoni V, Tofani L, Caminati G, Viglianisi C. Role of Noncovalent Sulfur···Oxygen Interactions in Phenoxyl Radical Stabilization: Synthesis of Super Tocopherol-like Antioxidants. Org Lett 2016; 18:5464-5467. [DOI: 10.1021/acs.orglett.6b02557] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Stefano Menichetti
- Department
of Chemistry “U. Schiff”, University of Florence, Via della Lastruccia 13, 50019 Sesto Fiorentino, Italy
| | - Riccardo Amorati
- Department
of Chemistry “Ciamician”, University of Bologna, Via San Giacomo 11, 40126 Bologna, Italy
| | - Valentina Meoni
- Department
of Chemistry “U. Schiff”, University of Florence, Via della Lastruccia 13, 50019 Sesto Fiorentino, Italy
| | - Lorenzo Tofani
- Department
of Chemistry “U. Schiff”, University of Florence, Via della Lastruccia 13, 50019 Sesto Fiorentino, Italy
| | - Gabriella Caminati
- Department
of Chemistry “U. Schiff”, University of Florence, Via della Lastruccia 13, 50019 Sesto Fiorentino, Italy
- CSGI, University of Florence, Via della Lastruccia 3, 50019 Sesto Fiorentino, Italy
| | - Caterina Viglianisi
- Department
of Chemistry “U. Schiff”, University of Florence, Via della Lastruccia 13, 50019 Sesto Fiorentino, Italy
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12
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Poon JF, Singh VP, Yan J, Engman L. Regenerable Antioxidants-Introduction of Chalcogen Substituents into Tocopherols. Chemistry 2014; 21:2447-57. [DOI: 10.1002/chem.201405895] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Indexed: 12/13/2022]
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13
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Ingold KU, Pratt DA. Advances in radical-trapping antioxidant chemistry in the 21st century: a kinetics and mechanisms perspective. Chem Rev 2014; 114:9022-46. [PMID: 25180889 DOI: 10.1021/cr500226n] [Citation(s) in RCA: 320] [Impact Index Per Article: 32.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- Keith U Ingold
- National Research Council of Canada, Ottawa, Ontario K1A 0R6, Canada
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14
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Yagunov SE, Khol’shin SV, Kandalintseva NV, Prosenko AE. Synthesis and antioxidant activity of 5-hydroxycoumarans, 6-hydroxychromanes and sulfur-containing derivatives on their base. Russ Chem Bull 2014. [DOI: 10.1007/s11172-013-0200-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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15
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16
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Tocopheramines and tocotrienamines as antioxidants: ESR spectroscopy, rapid kinetics and DFT calculations. Bioorg Med Chem 2013; 21:5039-46. [DOI: 10.1016/j.bmc.2013.06.050] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2013] [Revised: 06/19/2013] [Accepted: 06/20/2013] [Indexed: 11/23/2022]
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17
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Fujimoto A, Inai M, Masuda T. Chemical evidence for the synergistic effect of a cysteinyl thiol on the antioxidant activity of caffeic and dihydrocaffeic esters. Food Chem 2013; 138:1483-92. [DOI: 10.1016/j.foodchem.2012.11.073] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2012] [Revised: 11/12/2012] [Accepted: 11/15/2012] [Indexed: 11/27/2022]
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18
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Synthesis and screening of novel vitamin E derivatives for anticancer functions. Eur J Med Chem 2012; 58:72-83. [DOI: 10.1016/j.ejmech.2012.09.045] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2012] [Revised: 09/24/2012] [Accepted: 09/27/2012] [Indexed: 12/24/2022]
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Najafi M, Najafi M, Najafi H. DFT/B3LYP Study to Investigate the Possible Ways for the Synthesize of Antioxidants with High Efficiency Based on Vitamin E. B KOREAN CHEM SOC 2012. [DOI: 10.5012/bkcs.2012.33.10.3343] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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20
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Chapelat J, Hengartner U, Chougnet A, Liu K, Huebbe P, Rimbach G, Woggon WD. Asymmetric Synthesis and Biological Activity of nor-α-Tocopherol, a New Vitamin E Analogue. Chembiochem 2010; 12:118-24. [DOI: 10.1002/cbic.201000511] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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21
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Menichetti S, Amorati R, Bartolozzi MG, Pedulli GF, Salvini A, Viglianisi C. A Straightforward Hetero-Diels-Alder Approach to (2-ambo,4′R,8′R)-α/β/γ/δ-4-Thiatocopherol. European J Org Chem 2010. [DOI: 10.1002/ejoc.200901493] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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23
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Nie Z, Liu KJ, Zhong CJ, Wang LF, Yang Y, Tian Q, Liu Y. Enhanced radical scavenging activity by antioxidant-functionalized gold nanoparticles: a novel inspiration for development of new artificial antioxidants. Free Radic Biol Med 2007; 43:1243-54. [PMID: 17893037 DOI: 10.1016/j.freeradbiomed.2007.06.011] [Citation(s) in RCA: 106] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/26/2007] [Revised: 06/12/2007] [Accepted: 06/12/2007] [Indexed: 01/26/2023]
Abstract
Because of its potent antioxidant function and important role in clinical treatment, alpha-tocopherol (vitamin E) is a good starting point in the development of new synthetic antioxidants with improved properties. In this paper the first example of antioxidant-functionalized gold nanoparticles, Au@Trolox, was synthesized by self-assembly of thiol ligands derived from Trolox, a vitamin E analogue, on gold nanoparticles. DPPH* (2,2-diphenyl-1-picrylhydrazyl) radical scavenging experiments revealed that the rate constant for the reaction of Au@Trolox with DPPH* was about eight times greater than that for Trolox. The product analysis showed that both the quinonoid and the diepoxide forms were possible oxidized products of the chromanol group of Au@Trolox treated with DPPH* radical. No remarkable influence was found on the antioxidant activity of Au@Trolox when the coverage rate of the antioxidant group on the surface of the gold was varied. All our results proved that the assembly of chromanol groups on gold nanoparticles could efficiently enhance the activity of the vitamin E-derived antioxidant, which presents a potential new strategy for antioxidant design with novel perspectives in potential applications.
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Affiliation(s)
- Zhou Nie
- State Key Lab for Structural Chemistry of Unstable and Stable Species, Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080, China
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Rosenau T, Kloser E, Gille L, Mazzini F, Netscher T. Vitamin E Chemistry. Studies into Initial Oxidation Intermediates of α-Tocopherol: Disproving the Involvement of 5a-C-Centered “Chromanol Methide” Radicals. J Org Chem 2007; 72:3268-81. [PMID: 17391045 DOI: 10.1021/jo062553j] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Contrary to concepts handed down in the literature from the early days of vitamin E research, one-electron oxidation of vitamin E does not involve 5a-C-centered radicals. A combined approach of analytical techniques, in particular electron paramagnetic resonance spectroscopy (EPR), organic synthesis of special derivatives, isotopic labeling, kinetic studies, and computational chemistry was used to re-evaluate the one-electron and two-electron oxidation chemistry of alpha-tocopherol (alpha-toc). EPR in combination with 5a-13C-labeled compounds provided no indication of the involvement of 5a-C-centered radicals. Oxidation of special tocopherol derivatives were used to disprove the occurrence of 5a-C-centered one-electron intermediates. Additionally it was shown that those vitamin E reactions that were commonly evoked to plead for the involvement of C-centered tocopheryl radicals actually proceeded via heterolytic, i.e., non-radical, intermediates. The results will help to clear widely spread misunderstandings about the chemistry of vitamin E and will have mechanistic implications for the synthesis of tocopherol-based supramolecular structures and 5a-substituted alpha-tocopherol derivatives.
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Affiliation(s)
- Thomas Rosenau
- Department of Chemistry, University of Natural Resources and Applied Life Sciences, Muthgasse 18, A-1190 Vienna, Austria.
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25
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Menichetti S, Pagliuca C, Viglianisi C. Ortho-thioquinones and mediterranean diet: The sulfur connection. HETEROATOM CHEMISTRY 2007. [DOI: 10.1002/hc.20338] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
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26
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Frenette M, MacLean PD, Barclay LRC, Scaiano JC. Radically Different Antioxidants: Thermally Generated Carbon-Centered Radicals as Chain-Breaking Antioxidants. J Am Chem Soc 2006; 128:16432-3. [PMID: 17177355 DOI: 10.1021/ja066870j] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A new class of thermally activated chain-breaking antioxidants is presented. Dimers of persistent carbon-centered radicals are able to inhibit the autoxidation of cumene and styrene with better rate constants than the commercial antioxidant Irganox HP-136 and 3,5-di-tert-butyl-4-hydroxyanisole. A dramatic increase in antioxidant activity is observed with increasing temperature as more dimers dissociate to their corresponding persistent radicals.
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Affiliation(s)
- Mathieu Frenette
- Department of Chemistry, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada
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27
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Amorati R, Fumo M, Pedulli G, Menichetti S, Pagliuca C, Viglianisi C. Antioxidant and Antiradical Activity of Hydroxy-Substituted 4-Thiaflavanes. Helv Chim Acta 2006. [DOI: 10.1002/hlca.200690226] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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28
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Chen W, Song J, Guo P, Cao W, Bian J. Exploring a possible way to synthesize novel better antioxidants based on vitamin E: a DFT study. Bioorg Med Chem Lett 2006; 16:5874-7. [PMID: 16942877 DOI: 10.1016/j.bmcl.2006.08.063] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2006] [Revised: 07/24/2006] [Accepted: 08/11/2006] [Indexed: 11/19/2022]
Abstract
The promoting effect of heterocyclic ring and heteroatom on the antioxidant properties of vitamin E has been investigated systemically by using density functional theory. The calculated results show that the heteroatom plays a more important role in promoting the antioxidant properties than the heterocyclic ring, indicating that replacing O atom by S or Se is impossible to synthesize the novel better antioxidants. Furthermore, the bond dissociation enthalpy (BDE) and ionization potential (IP) of the corresponding molecules are decreased dramatically when the O atom is replaced by NH. In addition, the calculated results also reveal that reducing the atom number of heterocyclic ring is an ideal way to synthesize novel antioxidants with better antioxidant activity than vitamin E.
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Affiliation(s)
- Weijun Chen
- Department of Chemical Engineering, Northwest University, Xi'an 710069, China.
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Amorati R, Fumo MG, Menichetti S, Mugnaini V, Pedulli GF. Electronic and Hydrogen Bonding Effects on the Chain-Breaking Activity of Sulfur-Containing Phenolic Antioxidants. J Org Chem 2006; 71:6325-32. [PMID: 16901112 DOI: 10.1021/jo060281e] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A kinetic and thermodynamic investigation of phenols para-substituted with thiyl (SR), sulfinyl (SOR), and sulfonyl (SO(2)R) groups and ortho-substituted with thiyl groups is reported. The effect of the sulfur substituents on the O-H bond dissociation enthalpy values, BDE(O-H), was measured by means of the EPR radical equilibration technique and the reactivity toward peroxyl radicals, k(inh), of these phenolic antioxidants was determined by inhibited autoxidation studies. An inverse correlation between these two parameters was found. A p-SMe substituent decreased the BDE(O-H) value to a lesser extent than a p-OMe group (-3.6 vs -4.4 kcal/mol), whereas the effect of the same groups in an ortho position showed an opposite trend (-0.85 vs -0.2 kcal/mol). The latter result is explained in terms of the different strength of the intramolecular hydrogen bond between the OH proton and the sulfur or oxygen substituents in ortho derivatives. ESI-MS analysis of the products formed by reacting the sulfides with peroxyl radicals from the azoinitiator AIBN revealed the formation of a complex mixture of products, which may play an important role in determining the overall antioxidant activity of the parent compounds.
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Affiliation(s)
- Riccardo Amorati
- Dipartimento di Chimica Organica A. Mangini, Università di Bologna, Via S. Donato 11, 40126 Bologna, Italy
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Shanks D, Frisell H, Ottosson H, Engman L. Design principles for α-tocopherol analogues. Org Biomol Chem 2006; 4:846-52. [PMID: 16493468 DOI: 10.1039/b515712a] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
An (RO)B3LYP/LANL2DZdp//B3LYP/LANL2DZ model for the prediction of the homolytic bond dissociation enthalpy (BDE) and adiabatic ionisation potential (IP) of phenolic antioxidants containing heavy chalcogens has been developed. The model has been used to probe the relationship between geometry, chalcogen substitution and activity for a series of alpha-tocopherol analogues of varying ring size. From this, a series of design principles for cyclic antioxidants has emerged, embodied by the compound 4-hydroxy-2,2,3,5,6-pentamethylbenzoselenete (4c). This compound is predicted to have a BDE comparable to alpha-tocopherol, and should act in a dual chain-breaking and hydroperoxide-decomposing manner, by analogy with other selenide antioxidants. The stability of chalcogen-substituted benzoxetes was considered, and the as yet unsynthesised benzotelluretes are predicted to be stable. Finally, an attempt was made to determine antioxidant mechanism by considering calculated BDE and IP data together with experimental rate data.
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Affiliation(s)
- David Shanks
- Department of Chemistry, Organic Chemistry, Box 599, Uppsala University, SE-751 24 Uppsala, Sweden
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Shanks D, Amorati R, Fumo MG, Pedulli GF, Valgimigli L, Engman L. Synthesis and Antioxidant Profile of all-rac-α-Selenotocopherol. J Org Chem 2005; 71:1033-8. [PMID: 16438517 DOI: 10.1021/jo052133e] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
all-rac-alpha-Selenotocopherol (6c) has been synthesized in 11 steps in 6.6% total yield. Key steps include chloromethylation to approach the persubstituted aromatic 9b and cyclization of alcohol precursor 10 by radical homolytic substitution at selenium to form the selenotocopherol heterocycle. Determination of the OH bond dissociation enthalpy (BDE) of 6c by electron paramagnetic resonance (EPR) equilibration techniques gave a value of 78.1 +/- 0.3 kcal mol(-1), approximately 1 kcal mol(-1) higher than that of alpha-tocopherol. Kinetic studies performed by measuring oxygen uptake of the induced oxidation of styrene in the presence of an antioxidant showed that selenotocopherol (6c) was a slightly poorer inhibitor than alpha-tocopherol, in agreement with the BDE values. In contrast to simpler selenotocopherol analogues, 6c was not regenerable in the presence of a stoichiometric coreductant in a two-phase lipid peroxidation model.
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Affiliation(s)
- David Shanks
- Department of Chemistry, Organic Chemistry, Box 599, Uppsala University, SE-751 24 Uppsala, Sweden
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Staniek K, Rosenau T, Gregor W, Nohl H, Gille L. The protection of bioenergetic functions in mitochondria by new synthetic chromanols. Biochem Pharmacol 2005; 70:1361-70. [PMID: 16150421 DOI: 10.1016/j.bcp.2005.07.030] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2005] [Revised: 07/29/2005] [Accepted: 07/29/2005] [Indexed: 10/25/2022]
Abstract
alpha-Tocopherol is the most important lipophilic antioxidant of the chromanol type protecting biomembranes from lipid peroxidation (LPO). Therefore, alpha-tocopherol and its derivatives are frequently used in the therapy or prevention of oxygen radical-derived diseases. In the present study, novel chromanol-type antioxidants (twin-chromanol, cis- and trans-oxachromanol) as well as the well-known short-chain analogue of alpha-tocopherol, pentamethyl-chromanol, were tested for their antioxidative potency in rat heart mitochondria (RHM). Our experiments revealed that the bioenergetic parameters of mitochondria were not deteriorated in the presence of chromanols (up to 50 nmol/mg protein). Exposure of RHM to cumene hydroperoxide and Fe2+ (final concentrations 50 microM each), inducing LPO, significantly affected their bioenergetic parameters which were determined in the presence of glutamate and malate (substrates of mitochondrial complex I). Alterations of the bioenergetic parameters were partially prevented in a concentration-dependent manner by preincubating RHM with antioxidants before adding the radical-generating system. In the lower concentration range, twin-chromanol turned out to be more efficient than pentamethyl-chromanol, both being far more protective than cis- and trans-oxachromanol. Measurement of protein-bound SH groups and thiobarbituric acid-reactive substances revealed that this protective effect was due to their antioxidative action. Furthermore, HPLC measurements of alpha-tocopherol and alpha-tocopheryl quinone in rat liver mitochondria demonstrated an alpha-tocopherol-sparing effect of twin-chromanol. In conclusion, new chromanol-type antioxidants, especially twin-chromanol, were able to improve bioenergetic and biochemical parameters of mitochondria exposed to oxidative stress.
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Affiliation(s)
- Katrin Staniek
- Research Institute for Biochemical Pharmacology and Toxicology, University of Veterinary Medicine Vienna, Veterinärplatz 1, A-1210 Vienna, Austria
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Menichetti S, Aversa MC, Cimino F, Contini A, Viglianisi C, Tomaino A. Synthesis and “double-faced” antioxidant activity of polyhydroxylated 4-thiaflavans. Org Biomol Chem 2005; 3:3066-72. [PMID: 16186941 DOI: 10.1039/b507496g] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A simple synthetic methodology, based on the inverse electron demand hetero Diels-Alder reaction of electron-poor dienic o-thioquinones with electron-rich styrenes used as dienophiles, allowed the preparation of several polyhydroxylated 4-thiaflavans. Such compounds, as a function of the nature and position of the substituents on the aromatic rings, as well as of the oxidation state of the sulfur atom, are able to behave in vitro as efficient antioxidants mimicking the action of catechol containing flavonoids or/and tocopherols. The possibility of joining together the potentialities of two relevant families of natural polyphenolic antioxidants appears particularly appealing since an efficient protection against free radicals and other reactive oxygen species (ROS) depends in vivo upon the synergic action of different antioxidant derivatives.
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Affiliation(s)
- Stefano Menichetti
- Dipartimento di Chimica Organica, Polo Scientifico-Università di Firenze, via della Lastruccia 13, 50019, Sesto Fiorentino, Florence, Italy.
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Winterle JS, Mill T, Harris T, Goldbeck RA. Absolute kinetic characterization of 17-beta-estradiol as a radical-scavenging, antioxidant synergist. Arch Biochem Biophys 2001; 392:233-44. [PMID: 11488597 DOI: 10.1006/abbi.2001.2431] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We directly measured the absolute reactivity of 17-beta-estradiol (E2) and several phenolic model compounds for E2 toward t-butoxy radical (t-BuO*) by nanosecond time-resolved optical spectroscopy. Compared to other phenols, E2 is a moderate, but not strong deactivator of oxyradicals. The absolute bimolecular rate constant for H-atom transfer from E2 to t-BuO* is 1.3 +/- 0.3 x 10(9) M(-1) x s(-1) (23 degrees C, benzene). We estimate the O-H bond strength of 17-beta-estradiol to be approximately 85 +/- 2 kcal/mol and calculate the reaction rate constant of E2 toward peroxy radical to be 10(5) M(-1) x s(-1) at 37 degrees C. The conjugate phenoxy radical of 17-beta-estradiol, E2O*, is unusually reactive toward alpha-tocopherol and ascorbate by H-atom transfer in homogeneous solution (10(8)-10(9) M(-1) x s(-1)). Our findings suggest that E2 functions in vivo as a highly localized, synergistic biological antioxidant. This may partly explain the clinical effectiveness of ovarian steroids in delaying the manifestations of Alzheimer's Disease as well as in protecting against cardiovascular pathologies. In the absence of complementary antioxidant synergists, E2O* is expected to be a pro-oxidant.
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Affiliation(s)
- J S Winterle
- Department of Chemistry and Biochemistry, University of California at Santa Cruz, Santa Cruz, California 95064, USA.
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Franchi P, Lucarini M, Pedulli GF, Valgimigli L, Lunelli B. Reactivity of Substituted Phenols Toward Alkyl Radicals. J Am Chem Soc 1999. [DOI: 10.1021/ja982405d] [Citation(s) in RCA: 70] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Paola Franchi
- Contribution from the Dipartimento di Chimica Organica “A. Mangini”, Università di Bologna, Via S. Donato 15, I-40127 Bologna, Italy, Dipartimento di Chimica “G. Ciamician”, Via Selmi 2, I-40126 Bologna, Italy, and Istituto di Spettroscopia Molecolare del CNR, Via P. Gobetti 101, I-40129 Bologna, Italy
| | - Marco Lucarini
- Contribution from the Dipartimento di Chimica Organica “A. Mangini”, Università di Bologna, Via S. Donato 15, I-40127 Bologna, Italy, Dipartimento di Chimica “G. Ciamician”, Via Selmi 2, I-40126 Bologna, Italy, and Istituto di Spettroscopia Molecolare del CNR, Via P. Gobetti 101, I-40129 Bologna, Italy
| | - Gian Franco Pedulli
- Contribution from the Dipartimento di Chimica Organica “A. Mangini”, Università di Bologna, Via S. Donato 15, I-40127 Bologna, Italy, Dipartimento di Chimica “G. Ciamician”, Via Selmi 2, I-40126 Bologna, Italy, and Istituto di Spettroscopia Molecolare del CNR, Via P. Gobetti 101, I-40129 Bologna, Italy
| | - Luca Valgimigli
- Contribution from the Dipartimento di Chimica Organica “A. Mangini”, Università di Bologna, Via S. Donato 15, I-40127 Bologna, Italy, Dipartimento di Chimica “G. Ciamician”, Via Selmi 2, I-40126 Bologna, Italy, and Istituto di Spettroscopia Molecolare del CNR, Via P. Gobetti 101, I-40129 Bologna, Italy
| | - Bruno Lunelli
- Contribution from the Dipartimento di Chimica Organica “A. Mangini”, Università di Bologna, Via S. Donato 15, I-40127 Bologna, Italy, Dipartimento di Chimica “G. Ciamician”, Via Selmi 2, I-40126 Bologna, Italy, and Istituto di Spettroscopia Molecolare del CNR, Via P. Gobetti 101, I-40129 Bologna, Italy
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Malmström J, Gupta V, Engman L. Novel Antioxidants: Unexpected Rearrangements in the Radical Cyclization Approach to 2,3-Dihydrobenzo[b]thiophene-5-ol Derivatives. J Org Chem 1998. [DOI: 10.1021/jo972087l] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Jonas Malmström
- Uppsala University, Institute of Chemistry, Department of Organic Chemistry, Box 531, S-751 21 Uppsala, Sweden
| | - Vijay Gupta
- Uppsala University, Institute of Chemistry, Department of Organic Chemistry, Box 531, S-751 21 Uppsala, Sweden
| | - Lars Engman
- Uppsala University, Institute of Chemistry, Department of Organic Chemistry, Box 531, S-751 21 Uppsala, Sweden
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Abstract
Troglitazone (CS-045) is a new oral antidiabetic drug reported to be effective in insulin-resistant diabetes and to show antihypertensive effects. Photooxidation of troglitazone gave the quinone and quinone epoxide as the major final stable products. An intermediate observed by NMR spectroscopy was shown to be the hydroperoxydienone, which is moderately stable at room temperature. The rate constant of singlet oxygen quenching by troglitazone is 2.14 x 10(8) M(-1) s(-1) and the reaction rate constant in acetone-d6 is 8.64 X 10(6) M(-1) s(-1). Only the chroman ring of troglitazone reacts with and quenches singlet oxygen significantly, and its reactivity and products are analogous to those of alpha-tocopherol. The reactivity of CS-45 toward singlet oxygen is much larger than that of the related compounds lacking the chroman ring.
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Affiliation(s)
- Y Fu
- Department of Chemistry and Biochemistry University of California, Los Angeles 90095-1569, USA
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Environmental impacts associated with the application of radical-scavenging stabilizers in polymers. Polym Degrad Stab 1996. [DOI: 10.1016/0141-3910(96)00011-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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40
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Bisby RH, Johnson SA, Parker AW. Quenching of reactive oxidative species by probucol and comparison with other antioxidants. Free Radic Biol Med 1996; 20:411-20. [PMID: 8720913 DOI: 10.1016/0891-5849(95)02094-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
One-electron oxidation of the antiatherogenic and antiatherosclerotic drug probucol has been studied in relation to its activity as an antioxidant. Oxidation by triplet excited states of duroquinone and benzophenone, and by the inorganic radicals Br2.- and N3., lead to the formation of a transient absorption at 500 nm. This was identified by time-resolved resonance Raman spectroscopy as the phenoxyl radical from probucol, formed by hydrogen atom or electron plus proton loss from one of the phenolic groups of probucol. The reactivity of probucol with triplet duroquinone and triplet benzophenone, and as a quencher of singlet oxygen, was compared with the reactivities of other antioxidants (alpha-tocopherol, palmitoyl ascorbic acid, dihydrolipoic acid and N-acetyl cysteine). In quenching of the triplet states the reactivity of probucol was comparable with that of alpha-tocopherol, whereas as a quencher of singlet oxygen probucol (k < 10(6) M-1 s-1) was less effective than alpha-tocopherol (k = 2.0 x 10(8) M-1 s-1) by more than two orders of magnitude. This difference in reactivity may allow the contribution of singlet oxygen towards oxidative stress to be quantified separately.
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Affiliation(s)
- R H Bisby
- Department of Biological Sciences, University of Salford, UK.
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Barclay LRC, Dakin KA, Khor JAY. The autoxidation of thiol aminoacids and ascorbate and their cooperative effects as antioxidants with trolox in micelles and lipid bilayers. RESEARCH ON CHEMICAL INTERMEDIATES 1995. [DOI: 10.1007/bf03052271] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Kaneko Y, Kita H, Mukai K, Kawano K. Synthesis and Antioxidant Activity of 4H-1,3-Benzodioxin-6-ol Derivatives: New Vitamin E Analogs. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 1994. [DOI: 10.1246/bcsj.67.1371] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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44
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R�ck M, Schmittel M. Enol cation radicals in solution. 4. An improved Synthesis of 4,6,7-Trimethylbenzofurans by oxidation of ?-mesityl substituted enols. ACTA ACUST UNITED AC 1994. [DOI: 10.1002/prac.19943360409] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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45
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van Acker SA, Koymans LM, Bast A. Molecular pharmacology of vitamin E: structural aspects of antioxidant activity. Free Radic Biol Med 1993; 15:311-28. [PMID: 8406131 DOI: 10.1016/0891-5849(93)90078-9] [Citation(s) in RCA: 207] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
In this review, the involvement of vitamin E in free radical physiology and antioxidant mechanisms is discussed. Moreover, structure-activity relationship (SAR) studies on vitamin E analogues are presented. A molecular explanation for the antioxidant activity often is based on molecular parameters, such as Hammett sigma and Brown sigma +. These parameters correlate with the activity. Using semiempirical calculations, we have found other molecular parameters related to electron distribution and structure (such as the difference in heat of formation between the compound and its radical or the energy of the highest occupied molecular orbital, HOMO) which correlate with the antioxidant action of vitamin E and its derivatives.
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Affiliation(s)
- S A van Acker
- Department of Pharmacochemistry, Faculty of Chemistry, Vrije Universiteit, Amsterdam, The Netherlands
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Alberti A, Carloni P, Greci L, Stipa P, Neri C. Antioxidants and light stabilizers. Part 2. On the thermal stability of indolinonic nitroxides. Polym Degrad Stab 1993. [DOI: 10.1016/0141-3910(93)90098-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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47
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Bisby RH, Parker AW. Reactions of the alpha-tocopheroxyl radical in micellar solutions studied by nanosecond laser flash photolysis. FEBS Lett 1991; 290:205-8. [PMID: 1915875 DOI: 10.1016/0014-5793(91)81260-f] [Citation(s) in RCA: 57] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Laser flash photolysis of alpha-tocopherol in methanol and in aqueous micellar solutions has been shown to produce the alpha-tocopheroxyl radical. The reaction between the alpha-tocopheroxyl radical and ascorbate in positively charged hexadecyltrimethylammonium chloride (HTAC) micelles occurred with a second order rate constant of 7.2 x 10(7) M-1.s-1, whereas in negatively charged sodium dodecyl sulphate (SDS) micelles the rats constant was only 3.8 x 10(4) M-1.s-1. The alpha-tocopheroxyl radical was found to be relatively long-lived in HTAC micelles (t1/2 greater than or equal to 5 min), allowing the slow disappearance of the alpha-tocopheroxyl radical by reaction with glutathione to be observed.
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Affiliation(s)
- R H Bisby
- Department of Biological Sciences, University of Salford, UK
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48
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Letulle M, Guenot P, Ripoll JL. The syntheses of 6-methylene-2,4-cyclohexadien-1-imine and related o-quinonoids by FVT of 1-hetero-1,2,3,4-tetrahydronaphthalenes. Tetrahedron Lett 1991. [DOI: 10.1016/s0040-4039(00)78895-2] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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49
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Landi L, Fiorentini D, Stefanelli C, Pasquali P, Pedulli GF. Inhibition of autoxidation of egg yolk phosphatidylcholine in homogenous solution and in liposomes by oxidized ubiquinone. BIOCHIMICA ET BIOPHYSICA ACTA 1990; 1028:223-8. [PMID: 2223795 DOI: 10.1016/0005-2736(90)90170-s] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The aim of this study was to obtain a quantification of the antioxidant activity of ubiquinone. To this purpose the oxidation of egg yolk phosphatidylcholine both in solvent and in liposomes initiated by an azocompound has been studied either in the absence or in the presence of ubiquinone-3, using alpha-tocopherol as a reference antioxidant. The two experimental systems gave similar results. In the presence of ubiquinone-3 the oxidation rate was reduced with respect to control experiments but was faster than that in the presence of alpha-tocopherol. The amount of ubiquinone required to decrease the autoxidation rate was so high as to prevent detection of the induction period. The stoichiometric factor was greater than 2 and the rate constant of inhibition was two orders of magnitude lower than that of alpha-tocopherol. It is concluded that high concentrations of ubiquinone are required to exhibit significant antioxidant activity. A possible mechanism compatible with the stoichiometric factor larger than 2 for the inhibiting effect of ubiquinone is also suggested.
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Affiliation(s)
- L Landi
- Dipartimento di Biochimica, Università di Bologna, Italy
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50
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Ingold KU, Burton GW, Hughes L, Foster DO, Robillard B. Vitamin E activity of 1-thio-alpha-tocopherol as measured by the rat curative myopathy bioassay. FREE RADICAL RESEARCH COMMUNICATIONS 1990; 11:207-11. [PMID: 2096099 DOI: 10.3109/10715769009088917] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The bioactivity of the acetate of the all-racemic, 1-thio analog of alpha-tocopherol (all-rac-1-thio-alpha-tocopheryl acetate) has been determined by measuring its ability to decrease plasma levels of pyruvate kinase in vitamin E deficient rats using the curative myopathy bioassay. The thio analog is only 0.22 times as active as RRR-alpha-tocopheryl acetate and is therefore approximately 0.33 times as active as all-rac-alpha-tocopheryl acetate, since the latter has been shown to be 1.47 times less active than RRR-alpha-tocopheryl acetate in the same bioassay (H. Weiser, M. Vecchi and M. Schlachter, Internat. J. Vit. Nutr. Res., 55, 149-158 (1985)). The 0.33:1.0 ratio is similar to the ratio of 0.41:1.0 measured for the in vitro antioxidant activities of the corresponding free phenols. This finding lends further support to our view that the vitamin E activity in the curative myopathy bioassay of close structural analogs of alpha-tocopherol is determined primarily by the in vitro antioxidant activity of the analog relative to alpha-tocopherol, consistent with the belief that vitamin E functions primarily as a general purpose, lipid-soluble antioxidant in mammals.
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Affiliation(s)
- K U Ingold
- Division of Chemistry, National Research Council of Canada, Ottawa, Ontario
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