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Kaneko T, Mita Y, Nozawa-Kumada K, Yazaki M, Arisawa M, Niki E, Noguchi N, Saito Y. Antioxidant action of persulfides and polysulfides against free radical-mediated lipid peroxidation. Free Radic Res 2022; 56:677-690. [PMID: 36630595 DOI: 10.1080/10715762.2023.2165918] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Hydrogen sulfide, hydropersulfides, and hydropolysulfides have been revealed to play important physiological roles such as cell signaling and protection against oxidative stress, but the underlying mechanisms and dynamics of action remain elusive. It is generally accepted that these species act by two-electron redox mechanisms, while the involvement of one-electron redox chemistry has received less attention. In this study, the radical-scavenging activity of hydrogen persulfide, hydrogen polysulfides (HSnH n = 2-4), and diallyl- or dialkyl-sulfides (RSnR, n = 1-4) was measured. Furthermore, their antioxidant effects against free radical-mediated human plasma lipid peroxidation were assessed by measuring lipid hydroperoxides. It was found that disodium disulfide, trisulfide, and tetrasulfide acted as potent peroxyl radical scavengers, the rate constant for scavenging peroxyl radical being 3.5 × 105, 4.0 × 105, and 6.0 × 105 M-1 s-1 in PBS pH 7.4 at 37 °C respectively and that they inhibited plasma lipid peroxidation efficiently, the efficacy is increased with the catenation number. Disodium tetrasulfide was 1.5 times as reactive as Trolox toward peroxyl radical and inhibited plasma lipid peroxidation more efficiently than ascorbate and Trolox. On the other hand, diallyl- and dialkyl-sulfides did not exert significant radical-scavenging activity, nor did they inhibit lipid peroxidation efficiently, except for diallyl tetrasulfide, which suppressed plasma lipid peroxidation, despite less significantly than disodium tetrasulfide. Collectively, this study shows that hydrogen persulfide and hydrogen polysulfides act as potent radical-scavenging antioxidants and that, in addition to two-electron redox mechanisms, one electron redox reaction may also play important role in the in vivo defense against deleterious oxidative stress.
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Affiliation(s)
- Takayuki Kaneko
- Laboratory of Molecular Biology and Metabolism, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Japan
| | - Yuichiro Mita
- The Systems Life Sciences Laboratory, Department of Medical Life Systems, Faculty of Life and Medical Sciences, Doshisha University, Kyotanabe, Japan
| | - Kanako Nozawa-Kumada
- Department of Biophysical Chemistry, Graduate School of Pharmaceutical Sciences, Tohoku University, Aoba, Sendai, Japan
| | - Masana Yazaki
- Department of Bioscience and Biotechnology, Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, Fukuoka, Japan
| | - Mieko Arisawa
- Department of Bioscience and Biotechnology, Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, Fukuoka, Japan
| | - Etsuo Niki
- Research Center for Advanced Science and Technology (RCAST), The University of Tokyo, Komaba, Tokyo, Japan
| | - Noriko Noguchi
- The Systems Life Sciences Laboratory, Department of Medical Life Systems, Faculty of Life and Medical Sciences, Doshisha University, Kyotanabe, Japan
| | - Yoshiro Saito
- Laboratory of Molecular Biology and Metabolism, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Japan
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2
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Vo QV, Van Gon T, Van Bay M, Mechler A. Antioxidant Activities of Monosubstituted Indolinonic Hydroxylamines: A Thermodynamic and Kinetic Study. J Phys Chem B 2019; 123:10672-10679. [DOI: 10.1021/acs.jpcb.9b08912] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Affiliation(s)
- Quan V. Vo
- Department for Management of Science and Technology Development, Ton Duc Thang University, Ho Chi Minh City 758307, Vietnam
- Faculty of Applied Sciences, Ton Duc Thang University, Ho Chi Minh City 758307, Vietnam
| | - Tran Van Gon
- Hue University of Sciences − Hue University, 77 Nguyen Hue, Hue City 530000, Vietnam
| | - Mai Van Bay
- Department of Chemistry, The University of Da Nang - University of Science and Education, Da Nang 550000, Vietnam
| | - Adam Mechler
- Department of Chemistry and Physics, La Trobe University, Bundoora, Victoria 3086, Australia
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3
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Morita M, Naito Y, Itoh Y, Niki E. Comparative study on the plasma lipid oxidation induced by peroxynitrite and peroxyl radicals and its inhibition by antioxidants. Free Radic Res 2019; 53:1101-1113. [DOI: 10.1080/10715762.2019.1688799] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Mayuko Morita
- Gastrointestinal Immunology, Kyoto Prefectural University of Medicine, Kyoto, Japan
- Molecular Gastroenterology and Hepatology, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Yuji Naito
- Molecular Gastroenterology and Hepatology, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Yoshito Itoh
- Molecular Gastroenterology and Hepatology, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Etsuo Niki
- Research Center for Advanced Science and Technology, University of Tokyo, Komaba, Japan
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4
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Vo QV, Van Bay M, Nam PC, Mechler A. Is Indolinonic Hydroxylamine a Promising Artificial Antioxidant? J Phys Chem B 2019; 123:7777-7784. [PMID: 31462046 DOI: 10.1021/acs.jpcb.9b05160] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Indolinonic hydroxylamine (IH) is a new-generation artificial antioxidant that, due to its ability to fractionate into apolar environments, is considered for prevention against lipid peroxidation. For this reason, it is important to understand, and compare, its activity in polar and nonpolar environments. In this study, the antioxidant activity of IH has been evaluated against HO• and HOO• radicals in water and, for a lipid-mimetic environment, pentyl ethanoate solvent, using kinetic calculations. It was found that the overall reaction rate constant of the HO• radical scavenging is more than 7 times higher in aqueous (8.98 × 109 M-1 s-1) than in apolar (1.22 × 109 M-1 s-1) media. However, HOO• scavenging was 35 times faster in apolar media (1.00 × 105 M-1 s-1 vs 2.80 × 103 M-1 s-1). In a lipid environment, the HAT mechanism was favored for the antioxidant activity for both radical species, whereas in aqueous solution the SET mechanism defined the HO• scavenging, while HAT described the HOO• scavenging. IH was shown to be one of the most active antioxidants in lipid environment, an essential characteristic for the protection of biological systems.
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Affiliation(s)
- Quan V Vo
- Department for Management of Science and Technology Development , Ton Duc Thang University , Ho Chi Minh City 700000 , Vietnam.,Faculty of Applied Sciences , Ton Duc Thang University , Ho Chi Minh City 700000 , Vietnam
| | - Mai Van Bay
- Department of Chemistry , The University of Da Nang-University of Science and Education , Da Nang 550000 , Vietnam
| | - Pham Cam Nam
- Department of Chemical Engineering , The University of Da Nang, University of Science and Technology , Da Nang 550000 , Vietnam
| | - Adam Mechler
- Department of Chemistry and Physics , La Trobe University , Melbourne , Victoria 3086 , Australia
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5
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Wang LF, Zhang HY. Theoretical Elucidation on Different Lipid-Oxidation Potentials of Aminoxyl Antioxidants. CHINESE J CHEM 2010. [DOI: 10.1002/cjoc.20030211229] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Castagna R, Davis P, Vasu V, Soucek K, Cross C, Greci L, Valacchi G. Nitroxide radical TEMPO reduces ozone-induced chemokine IL-8 production in lung epithelial cells. Toxicol In Vitro 2009; 23:365-70. [DOI: 10.1016/j.tiv.2008.12.016] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2008] [Revised: 12/01/2008] [Accepted: 12/22/2008] [Indexed: 11/28/2022]
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7
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Accurate bond dissociation enthalpies of popular antioxidants predicted by the ONIOM-G3B3 method. ACTA ACUST UNITED AC 2007. [DOI: 10.1016/j.theochem.2007.03.012] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Goldstein S, Samuni A. Kinetics and mechanism of peroxyl radical reactions with nitroxides. J Phys Chem A 2007; 111:1066-72. [PMID: 17286360 DOI: 10.1021/jp0655975] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Cyclic nitroxides (>NO*) are stable radicals of diverse size, charge, lipophilicility, and cell permeability, which provide protection against oxidative stress via various mechanisms including SOD-mimic activity, oxidation of reduced transition metals and detoxification of oxygen- and nitrogen-centered radicals. However, there is no agreement regarding the reaction of nitroxides with peroxyl radicals, and many controversies in the literature exist. The question of whether nitroxides can protect by scavenging peroxyl radicals is important because peroxyl radicals are formed in biological systems. To further elucidate the mechanism(s) underlying the antioxidative effects of nitroxides, we studied by pulse radiolysis the reaction kinetics of piperidine, pyrrolidine, and oxazolidine nitroxides with several alkyl peroxyl radicals. It is demonstrated that nitroxides mainly reduce alkyl peroxyl radicals forming the respective oxoammonium cations (>N+=O). The most efficient scavenger of peroxyl radicals is 2,2,6,6-tetramethylpiperidine-N-oxyl (TPO), which has the lowest oxidation potential among the nitroxides tested in the present study. The rate constants of peroxyl reduction are in the order CH2(OH)OO*>CH3OO*>t-BuOO*, which correlate with the oxidation potential of these peroxyl radicals. The rate constants for TPO vary between 2.8x10(7) and 1.0x10(8) M-1 s-1 and for 3-carbamoylproxyl (3-CP) between 8.1x10(5) and 9.0x10(6) M-1 s-1. The efficacy of protection of nitroxides against inactivation of glucose oxidase caused by peroxyl radicals was studied. The results demonstrate a clear correlation between the kinetic features of the nitroxides and their ability to inhibit biological damage inflicted by peroxyl radicals.
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Affiliation(s)
- Sara Goldstein
- Department of Physical Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel.
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Gabbianelli R, Falcioni G, Lupidi G, Greci L, Damiani E. Fluorescence study on rat epithelial cells and liposomes exposed to aromatic nitroxides. Comp Biochem Physiol C Toxicol Pharmacol 2004; 137:355-62. [PMID: 15228954 DOI: 10.1016/j.cca.2004.03.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/06/2003] [Revised: 03/12/2004] [Accepted: 03/13/2004] [Indexed: 10/26/2022]
Abstract
This study was performed to evaluate the effects, if any, of aromatic nitroxides, namely, indolinic nitroxides, on membrane fluidity of rat epithelial cells using steady-state fluorescence. These nitroxides are being increasingly considered as new and versatile compounds to reduce oxidative stress in biological systems. Hence, the results obtained in this study will give more insights on the interaction of these compounds with biological structures which at present is lacking, especially in view of their possible application as antioxidant therapeutic agents. The probes DPH and Laurdan which give information on the hydrophobic and hydrophilic-hydrophobic regions of the membrane bilayer, respectively, showed that nitroxide 1 (1,2-dihydro-2-methyl-3H-indole-3-one-1-oxyl) significantly increases membrane fluidity, whereas the corresponding phenylimino nitroxide derivative 2 (1,2-dihydro-2-methyl-3H-indole-3-phenylimino-1-oxyl) leads to membrane rigidification. The aliphatic nitroxide TEMPO included in this study for comparison produced no modifications. Consequently, it appears that the structure of the heterocyclic rings (aromatic or aliphatic) and the substituents may affect membrane fluidity differently.
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Affiliation(s)
- Rosita Gabbianelli
- Dipartimento di Biologia M.C.A., Università di Camerino, Via Camerini, 2, 62032 Camerino, Italy.
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Fedeli D, Damiani E, Greci L, Littarru GP, Falcioni G. Nitroxide radicals protect against DNA damage in rat epithelial cells induced by nitric oxide, nitroxyl anion and peroxynitrite. Mutat Res 2003; 535:117-25. [PMID: 12581529 DOI: 10.1016/s1383-5718(02)00296-6] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In order to gain more knowledge on the antioxidant role of nitroxide radicals, in this study we investigate their possible protective action against DNA damage induced by nitric oxide (NO) and reactive nitrogen oxide species deriving from it, namely nitroxyl anion (NO(-)) and peroxynitrite (ONOO(-)). Rat trachea epithelial cells were exposed under aerobic conditions to (1) NO generated by 150 microM S-nitrosoglutathione monoethyl ester (GSNO-MEE), (2) NO(-) generated by 200 microM Angeli's salt (Na(2)N(2)O(3)) (3) ONOO(-) generated by 1mM SIN-1 (3-morpholino-sydnonimine) and (4) 100 microM synthesized ONOO(-), in the absence and presence of 5 microM of two indolinonic nitroxides synthesized by us and the piperidine nitroxide TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl). DNA damage was assessed using the comet assay-a rapid and sensitive, single-cell gel electrophoresis technique used to detect primary DNA damage in individual cells. The parameter tail moment, used as an index of DNA damage, showed that in all cases the nitroxides remarkably inhibited DNA strand breaks induced by the different nitrogen oxide species. All three nitroxides protect to the same extent, except in the case of synthesized peroxynitrite where the aromatic nitroxides 1 and 2 are more efficient than TEMPO. These findings are consistent with the antioxidant character of nitroxide compounds and give additional information on the potential implications for their use as therapeutic agents.
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Affiliation(s)
- Donatella Fedeli
- Dipartimento di Biologia MCA, Università degli Studi di Camerino, Via Camerini 2, I-62032 (MC), Camerino, Italy
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11
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Shimakawa S, Yoshida Y, Niki E. Antioxidant action of a lipophilic nitroxyl radical, cyclohexane-1-spiro-2'-(4'-oxyimidazolidine-1'-oxyl) -5'-spiro-1"-cyclohexane, against lipid peroxidation under hypoxic conditions. Lipids 2003; 38:225-31. [PMID: 12784862 DOI: 10.1007/s11745-003-1055-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Nitroxyl radicals are known to act as radical scavenging antioxidants. In the present study, a lipophilic nitroxyl radical, cyclohexane-1-spiro-2'-(4'-oxyimidazolidine-1'-oxyl)-5'-spiro-1"-cyclohexane (nitroxyl radical I) was synthesized and its antioxidant capacity was assessed in comparison with a hydrophilic nitroxyl radical, 4-hydroxy-2,2,6,6-tetra-methylpiperidine-N-oxyl (Tempol). Both nitroxyl radical I and Tempol inhibited methyl linoleate oxidation induced by free radicals, and the efficacy increased with decreasing partial pressure of oxygen, the effect being more pronounced for nitroxyl radical I than Tempol. Their hydroxylamines inhibited lipid peroxidation more effectively than their corresponding parent nitroxyl radicals. In liposomal membranes, a synergistic effect was observed in the combination of nitroxyl radical I with ascorbic acid, whereas only an additive effect was observed between Tempol and ascorbic acid. The present study suggests that nitroxyl radical I and its hydroxylamine may act as potent antioxidants, especially in combination with ascorbic acid under hypoxic conditions.
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Affiliation(s)
- Shuichi Shimakawa
- Human Stress Signal Research Center (HSSRC), National Institute of Advanced Industrial Science and Technology (AIST), Japan, Midorigaoka, Ikeda, Osaka 563-8577, Japan
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12
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Damiani E, Castagna R, Greci L. The effects of derivatives of the nitroxide tempol on UVA-mediated in vitro lipid and protein oxidation. Free Radic Biol Med 2002; 33:128-36. [PMID: 12086690 DOI: 10.1016/s0891-5849(02)00876-6] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Derivatives of tetramethylpiperidines are extensively employed in polymers to prevent photooxidation, and their stabilizing effect is attributed to the activity of the nitroxide radical derived from the parent amine. In this study, we examined the photoprotective effect of a commercial polymer photostabilizer, HALS-1, its corresponding nitroxide, bis(2,2,6,6-tetramethyl-piperidine-1-oxyl-4-yl)sebacate (TINO), and two derivatives of the piperidine nitroxide TEMPOL, 2,2,6,6-tetramethyl-piperidin-4-acetyloxy-1-oxyl (TEMP2) and 2,2,6,6-tetramethyl-piperidin-4-octanoyloxy-1-oxyl (TEMP8) synthesized by us, in liposomes exposed to ultraviolet A (UVA) radiation. For comparison, the UVA-absorber, 4-tert-butyl-4'-methoxydibenzoylmethane (Parsol 1789) used in many suncream formulations, was also included. The nitroxide TINO resulted extremely efficient at inhibiting aldehydic breakdown products deriving from 30 min exposure of liposomes to UVA and the protection was dose-dependent (10-100 microM). The corresponding amine HALS-1 was the least efficient while protection increased in the order: TEMP2 < Parsol 1789 < TEMP 8. HALS-1, TINO, and the two TEMPOL derivatives were also tested in a simple protein system consisting of bovine serum albumin (BSA) exposed to UVA. In this case, these compounds did not inhibit nor enhance UVA-mediated protein carbonyl formation in BSA. The differences in protection between the compounds are discussed in relation to their chemical reactivity, UVA-absorbing capacities, and their molecular structure. Overall, the results obtained envisage the potential use of nitroxide compounds as topical antioxidants.
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Affiliation(s)
- Elisabetta Damiani
- Dipartimento di Scienze dei Materiali e della Terra, Università di Ancona, Ancona, Italy.
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Zhang HY, Wang LF. Theoretical elucidation on structure-antioxidant activity relationships for indolinonic hydroxylamines. Bioorg Med Chem Lett 2002; 12:225-7. [PMID: 11755360 DOI: 10.1016/s0960-894x(01)00724-7] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Indolinonic hydroxylamines (IH), representing a new type of antioxidants, are comparative to alpha-tocopherol to protect lipids from oxidation. To elucidate the structure-activity relationship for IH, B3LYP/6-31G(d, p) method was employed to calculate the O-H bond dissociation enthalpy (BDE), a theoretical parameter to characterize the free radical scavenging activity. By constructing several model molecules, it was revealed that hydroxylamine was the key structural factor for this type of antioxidants, and substituents had little effect on the O-H BDE. If the =NR of IH was substituted by =O, its activity got lower.
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Affiliation(s)
- Hong-Yu Zhang
- Laboratory for Computational Biology, Shandong Provincial Research Center for Bioinformatic Engineering and Technique, Shandong University of Technology, Zibo 255091, PR China.
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Kocherginsky NM, Grishchenko AB, Osipov AN, Koh SN. Nitroxide radicals. Controlled release from and transport through biomimetic and hollow fibre membranes. Free Radic Res 2001; 34:263-83. [PMID: 11264901 DOI: 10.1080/10715760100300241] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Stable nitroxide radicals have found wide applications in chemistry and biology and they have some potential applications in medicine due to their antioxidant properties. Nitrocellulose filters impregnated with lipid-like substances are used as an imitation of biomembranes and could be used as a controlled drug release vehicle, while experiments with hollow fibres can be useful in the modelling of a drug delivery via blood vessels. This paper describes mechanisms of the nitroxide transport in four different model systems, i.e. a) exit of nitroxide into aqueous solution from porous nitrocellulose filters, impregnated with organic solvents, b) transport of nitroxides through the impregnated membrane from one into another aqueous solution, c) transport of nitroxides from bulk phase of organic solvents through the impregnated membrane into aqueous phase with ascorbic acid, and d) transport of nitroxides from liquid organic phase into aqueous solution through porous hollow fibres. The results are analysed in terms of mass transfer resistance of a membrane, organic and aqueous phase, based on nitroxide diffusion and distribution coefficients. Ascorbic acid reduced nitroxides in water and enhanced the rate of their transfer due to the decrease of transport resistance of unstirred aqueous layers. It is demonstrated that in the case of biomembranes the rate limiting step could be the transport through unstirred aqueous layers and membrane/water interface.
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Affiliation(s)
- N M Kocherginsky
- National University of Singapore, Department of Chemical & Environmental Engineering, 10 Kent Ridge Crescent, Singapore 119260
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15
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Damiani E, Kalinska B, Canapa A, Canestrari S, Wozniak M, Olmo E, Greci L. The effects of nitroxide radicals on oxidative DNA damage. Free Radic Biol Med 2000; 28:1257-65. [PMID: 10889456 DOI: 10.1016/s0891-5849(00)00242-2] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The indolinonic and quinolinic aromatic nitroxides synthesized by us are a novel class of biological antioxidants, which afford a good degree of protection against free radical-induced oxidation in different lipid and protein systems. To further our understanding of their antioxidant behavior, we thought it essential to have more information on their effects on DNA exposed to free radicals. Here, we report on the results obtained after exposure of plasmid DNA and calf thymus DNA to peroxyl radicals generated by the water-soluble radical initiator, 2,2'-azobis(2-amidinopropane)dihydrochloride (AAPH), and the protective effects of the aromatic nitroxides and their hydroxylamines, using a simple in vitro assay for DNA damage. In addition, we also tested for the potential of these nitroxides to inhibit hydroxyl radical-mediated DNA damage inflicted by Fenton-type reactions using copper and iron ions. The commercial aliphatic nitroxides 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO), 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPOL), and bis(2,2, 6,6-tetramethyl-1-oxyl-piperidin-4-yl)sebacate (TINUVIN 770) were included for comparison. The results show that the majority of compounds tested protect: (i) both plasmid DNA and calf thymus DNA against AAPH-mediated oxidative damage in a concentration-dependent fashion (1-0.1 mM), (ii) both Fe(II) and Cu(I) induced DNA oxidative damage. However, all compounds failed to protect DNA against damage inflicted by the presence of the transition metals in combination with H(2)O(2). The differences in protection between the compounds are discussed in relation to their molecular structure and chemical reactivity.
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Affiliation(s)
- E Damiani
- Dipartimento di Scienze dei Materiali e della Terra, Via Brecce Bianche, Università, I-60131, Ancona, Italy.
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