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MacFarlane ER, Donaldson PJ, Grey AC. UV light and the ocular lens: a review of exposure models and resulting biomolecular changes. FRONTIERS IN OPHTHALMOLOGY 2024; 4:1414483. [PMID: 39301012 PMCID: PMC11410779 DOI: 10.3389/fopht.2024.1414483] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/09/2024] [Accepted: 08/12/2024] [Indexed: 09/22/2024]
Abstract
UV light is known to cause damage to biomolecules in living tissue. Tissues of the eye that play highly specialised roles in forming our sense of sight are uniquely exposed to light of all wavelengths. While these tissues have evolved protective mechanisms to resist damage from UV wavelengths, prolonged exposure is thought to lead to pathological changes. In the lens, UV light exposure is a risk factor for the development of cataract, which is a condition that is characterised by opacity that impairs its function as a focusing element in the eye. Cataract can affect spatially distinct regions of the lens. Age-related nuclear cataract is the most prevalent form of cataract and is strongly associated with oxidative stress and a decrease in the antioxidant capacity of the central lens region. Since UV light can generate reactive oxygen species to induce oxidative stress, its effects on lens structure, transparency, and biochemistry have been extensively investigated in animal models in order to better understand human cataract aetiology. A review of the different light exposure models and the advances in mechanistic understanding gained from these models is presented.
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Affiliation(s)
- Emily R MacFarlane
- Department of Physiology, School of Medical Sciences, New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand
| | - Paul J Donaldson
- Department of Physiology, School of Medical Sciences, New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand
| | - Angus C Grey
- Department of Physiology, School of Medical Sciences, New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand
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2
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Carreño M, Pires MF, Woodcock SR, Brzoska T, Ghosh S, Salvatore SR, Chang F, Khoo NKH, Dunn M, Connors N, Yuan S, Straub AC, Wendell SG, Kato GJ, Freeman BA, Ofori-Acquah SF, Sundd P, Schopfer FJ, Vitturi DA. Immunomodulatory actions of a kynurenine-derived endogenous electrophile. SCIENCE ADVANCES 2022; 8:eabm9138. [PMID: 35767602 PMCID: PMC9242454 DOI: 10.1126/sciadv.abm9138] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Accepted: 05/11/2022] [Indexed: 06/15/2023]
Abstract
The up-regulation of kynurenine metabolism induces immunomodulatory responses via incompletely understood mechanisms. We report that increases in cellular and systemic kynurenine levels yield the electrophilic derivative kynurenine-carboxyketoalkene (Kyn-CKA), as evidenced by the accumulation of thiol conjugates and saturated metabolites. Kyn-CKA induces NFE2 like bZIP transcription factor 2- and aryl hydrocarbon receptor-regulated genes and inhibits nuclear factor κB- and NLR family pyrin domain containing 3-dependent proinflammatory signaling. Sickle cell disease (SCD) is a hereditary hemolytic condition characterized by basal inflammation and recurrent vaso-occlusive crises. Both transgenic SCD mice and patients with SCD exhibit increased kynurenine and Kyn-CKA metabolite levels. Plasma hemin and kynurenine concentrations are positively correlated, indicating that Kyn-CKA synthesis in SCD is up-regulated during pathogenic vascular stress. Administration of Kyn-CKA abrogated pulmonary microvasculature occlusion in SCD mice, an important factor in lung injury development. These findings demonstrate that the up-regulation of kynurenine synthesis and its metabolism to Kyn-CKA is an adaptive response that attenuates inflammation and protects tissues.
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Affiliation(s)
- Mara Carreño
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Maria F. Pires
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Steven R. Woodcock
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Tomasz Brzoska
- Pittsburgh Heart, Lung and Blood Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, PA, USA
- Division of Hematology/Oncology, Department of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
| | - Samit Ghosh
- Pittsburgh Heart, Lung and Blood Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, PA, USA
- Division of Hematology/Oncology, Department of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
| | - Sonia R. Salvatore
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Fei Chang
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Nicholas K. H. Khoo
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA, USA
- Pittsburgh Liver Research Center, University of Pittsburgh, Pittsburgh, PA, USA
| | - Matthew Dunn
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Nora Connors
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Shuai Yuan
- Pittsburgh Heart, Lung and Blood Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, PA, USA
| | - Adam C. Straub
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA, USA
- Pittsburgh Heart, Lung and Blood Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, PA, USA
- Center for Microvascular Research, University of Pittsburgh, Pittsburgh, PA, USA
| | - Stacy G. Wendell
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA, USA
- Pittsburgh Liver Research Center, University of Pittsburgh, Pittsburgh, PA, USA
| | | | - Bruce A. Freeman
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Solomon F. Ofori-Acquah
- Pittsburgh Heart, Lung and Blood Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, PA, USA
- Division of Hematology/Oncology, Department of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
- School of Biomedical and Allied Health Sciences, University of Ghana, Accra, Ghana
| | - Prithu Sundd
- Pittsburgh Heart, Lung and Blood Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, PA, USA
- Division of Hematology/Oncology, Department of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA
| | - Francisco J. Schopfer
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA, USA
- Pittsburgh Heart, Lung and Blood Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, PA, USA
- Pittsburgh Liver Research Center, University of Pittsburgh, Pittsburgh, PA, USA
| | - Dario A. Vitturi
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA, USA
- Pittsburgh Heart, Lung and Blood Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, PA, USA
- Center for Critical Care Nephrology, University of Pittsburgh, Pittsburgh, PA, USA
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Anderson K, Eastabrook AS, Sperry J. One-pot oxidative hydrolysis-oxidative cleavage of 7-borylindoles enables access to o-amidophenols and 4-acylbenzoxazoles. Chem Commun (Camb) 2020; 56:3559-3562. [PMID: 32104796 DOI: 10.1039/c9cc09807k] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
7-Borylindoles undergo a one-pot oxidative-hydrolysis of the arylboronate and oxidative cleavage of the indole C2-C3 double bond to afford o-amidophenol derivatives. Subsequent cyclisation delivers benzoxazoles bearing an acyl group at C4, a substitution pattern common to fungal-derived benzoxazole alkaloids. Using 7-borylindoles as substrates to access functionalised o-amidophenols circumvents the difficult preparation of these compounds from arenes, streamlining access to substituted 4-acylbenzoxazoles in the process.
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Affiliation(s)
- Kirsty Anderson
- School of Chemical Sciences, University of Auckland, 23 Symonds Street, Auckland, New Zealand.
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4
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Study of Anopheles gambiae 3-hydroxykynurenine transaminase activity and inhibition by LC-MS/MS method. J Pharm Biomed Anal 2019; 173:154-161. [DOI: 10.1016/j.jpba.2019.05.025] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2019] [Revised: 05/08/2019] [Accepted: 05/12/2019] [Indexed: 12/17/2022]
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5
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Bright Green Biofluorescence in Sharks Derives from Bromo-Kynurenine Metabolism. iScience 2019; 19:1291-1336. [PMID: 31402257 PMCID: PMC6831821 DOI: 10.1016/j.isci.2019.07.019] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2019] [Revised: 06/26/2019] [Accepted: 07/12/2019] [Indexed: 02/06/2023] Open
Abstract
Although in recent years there has been an increased awareness of the widespread nature of biofluorescence in the marine environment, the diversity of the molecules responsible for this luminescent phenotype has been mostly limited to green fluorescent proteins (GFPs), GFP-like proteins, and fluorescent fatty acid-binding proteins (FABPs). In the present study, we describe a previously undescribed group of brominated tryptophan-kynurenine small molecule metabolites responsible for the green biofluorescence in two species of sharks and provide their structural, antimicrobial, and spectral characterization. Multi-scale fluorescence microscopy studies guided the discovery of metabolites that were differentially produced in fluorescent versus non-fluorescent skin, as well as the species-specific structural details of their unusual light-guiding denticles. Overall, this study provides the detailed description of a family of small molecules responsible for marine biofluorescence and opens new questions related to their roles in central nervous system signaling, resilience to microbial infections, and photoprotection. We describe a new form of biofluorescence from the skin of catsharks Bromo-tryptophan-kynurenines are biofluorescent and show antimicrobial activities Specific dermal denticles in the chain catshark act as optical light-guides This study opens questions related to biological function of shark fluorescence
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Demarais NJ, Donaldson PJ, Grey AC. Age-related spatial differences of human lens UV filters revealed by negative ion mode MALDI imaging mass spectrometry. Exp Eye Res 2019; 184:146-151. [PMID: 31004573 DOI: 10.1016/j.exer.2019.04.016] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Revised: 04/08/2019] [Accepted: 04/16/2019] [Indexed: 01/01/2023]
Abstract
Tryptophan-derived UV filters are predominantly found in the lenses of primates and humans. While protective against UV radiation, aging alters the complement and spatial distributions of human lens UV filters, and a role for UV filters has been suggested in age-related cataract formation. To establish how the spatial distributions of UV filters change in normal human lens aging, matrix assisted laser desorption/ionisation-imaging mass spectrometry (MALDI-IMS) was utilised to map the locations and relative abundance of multiple UV filters simultaneously. Frozen human lenses were cryosectioned axially, and the 20 μm-thick sections coated with MALDI matrix via robotic sprayer and analysed using negative ion mode MALDI-Fourier transform-ion cyclotron resonance MS. While signal for many UV filters was detected throughout the lenses, signal intensity was generally highest in the central (embryonic) nucleus and decreased uniformly in outer (foetal, juvenile, adult) nuclear and cortical regions, and many UV filter signals declined with age. In contrast, two antioxidant-conjugated UV filters (Cys-3-OHKG and GSH-3-OHKG) were restricted to the lens nucleus and their relative signal increased with increasing lens age. The enhanced spatial resolution of MALDI-IMS over manual trephine dissection techniques and its multiplex capability allowed the spatial relationships between lens UV filters to be established and explored in relation to aging. Together these results confirmed that the complement of UV filters in each lens is dynamic and undergoes significant age-related changes. In the future, this information could be used to compare with other lens biomolecule changes to better understand the lens aging process and age-related cataract formation.
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Affiliation(s)
- Nicholas J Demarais
- School of Biological Sciences, University of Auckland, Auckland, New Zealand
| | - Paul J Donaldson
- Department of Physiology, School of Medical Sciences, University of Auckland, Auckland, New Zealand
| | - Angus C Grey
- Department of Physiology, School of Medical Sciences, University of Auckland, Auckland, New Zealand.
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7
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Sherin PS, Tsentalovich YP, Vauthey E, Benassi E. Ultrafast excited state decay of natural UV filters: from intermolecular hydrogen bonds to a conical intersection. Phys Chem Chem Phys 2018; 20:15074-15085. [DOI: 10.1039/c8cp02183j] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
An unsaturated bond in the side chain leads to the ultrafast decay of the excited statesviaa conical intersection independent of solvent properties.
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Affiliation(s)
- Peter S. Sherin
- International Tomography Center SB RAS
- Novosibirsk
- Russia
- Novosibirsk State University
- Novosibirsk
| | - Yuri P. Tsentalovich
- International Tomography Center SB RAS
- Novosibirsk
- Russia
- Novosibirsk State University
- Novosibirsk
| | - Eric Vauthey
- Department of Physical Chemistry
- University of Geneva
- Geneva
- Switzerland
| | - Enrico Benassi
- Novosibirsk State University
- Novosibirsk
- Russia
- School of Science and Technology
- Nazarbayev University
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Sormacheva ED, Sherin PS, Tsentalovich YP. Dimerization and oxidation of tryptophan in UV-A photolysis sensitized by kynurenic acid. Free Radic Biol Med 2017; 113:372-384. [PMID: 29024806 DOI: 10.1016/j.freeradbiomed.2017.10.007] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Revised: 10/04/2017] [Accepted: 10/05/2017] [Indexed: 11/24/2022]
Abstract
Photoinduced generation of radicals in the eye lens may play an important role in the modification of proteins leading to their coloration, aggregation, and insolubilization. The radicals can be formed via the reactions of photoexcited endogenous chromophores of the human lens with lens proteins, in particular with tryptophan residues. In the present work we studied the reactions induced by UV-A (315-400nm) light between kynurenic acid (KNA), an effective photosensitizer present in the human lens, and N-acetyl-L-tryptophan (NTrpH) under aerobic and anaerobic conditions. Our results show that the reaction mechanism strongly depends on the presence of oxygen in solution. Under aerobic conditions, the generation of singlet oxygen is the major channel of the effective NTrpH oxidation. In argon-bubbled solutions, the quenching of triplet KNA by NTrpH results in the formation of KNA•- and NTrp• radicals. Under laser pulse irradiation, when the radical concentration is high, the main pathway of the radical decay is the back electron transfer with the restoration of initial reagents. Other reactions include (i) the radical combination yielding NTrp dimers and (ii) the oxygen atom transfer from KNA•- to NTrp• with the formation of oxidized NTrp species and deoxygenated KNA products. In continuous-wave photolysis, even trace amounts of molecular oxygen are sufficient to oxidize the majority of KNA•- radicals with the rate constant of (2.0 ± 0.2) × 109M-1s-1, leading to the restoration of KNA and the formation of superoxide radical O2•-. The latter reacts with NTrp• via either the radical combination to form oxidized NTrp (minor pathway), or the electron transfer to restore NTrpH in the ground state (major pathway). As the result, the quantum yields of the starting compound decomposition under continuous-wave anaerobic photolysis are rather low: 1.6% for NTrpH and 0.02% for KNA. The photolysis of KNA with alpha-crystallin yields the same deoxygenated KNA products as the photolysis of KNA with NTrpH, indicating the similarity of the photolysis mechanisms. Thus, inside the eye lens KNA can sensitize both protein photooxidation and protein covalent cross-linking with the minor self-degradation. This may play an important role in the lens protein modifications during the normal aging and cataract development.
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Affiliation(s)
- Ekaterina D Sormacheva
- International Tomography Center SB RAS, Institutskaya str. 3A, 630090 Novosibisrk, Russia
| | - Peter S Sherin
- International Tomography Center SB RAS, Institutskaya str. 3A, 630090 Novosibisrk, Russia; Novosibirsk State University, Pirogova str. 2, 630090 Novosibisrk, Russia.
| | - Yuri P Tsentalovich
- International Tomography Center SB RAS, Institutskaya str. 3A, 630090 Novosibisrk, Russia; Novosibirsk State University, Pirogova str. 2, 630090 Novosibisrk, Russia
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9
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Tsentalovich YP, Verkhovod TD, Yanshole VV, Kiryutin AS, Yanshole LV, Fursova AZ, Stepakov DA, Novoselov VP, Sagdeev RZ. Metabolomic composition of normal aged and cataractous human lenses. Exp Eye Res 2015; 134:15-23. [PMID: 25773987 DOI: 10.1016/j.exer.2015.03.008] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2015] [Revised: 03/06/2015] [Accepted: 03/11/2015] [Indexed: 10/23/2022]
Abstract
Quantitative metabolomic profiles of normal and cataractous human lenses were obtained with the combined use of high-frequency nuclear magnetic resonance (NMR) and high-performance liquid chromatography with high-resolution mass-spectrometric detection (LC-MS) methods. The concentration of more than fifty metabolites in the lens cortex and nucleus has been determined. For the majority of metabolites, their concentrations in the lens cortex and nucleus are similar, which confirms low metabolic activity in the lens core. The difference between the metabolite levels in the cortex and nucleus of the normal lens is observed for antioxidants and UV filters, which demonstrates the activity of redox processes in the lens. A huge difference is found between the metabolomic compositions of normal and age-matched cataractous lenses: the concentrations of almost all metabolites in the normal lens are higher than in the cataractous one. The most pronounced difference is observed for compounds playing a key role in the lens cell protection and metabolic activity, including antioxidants, UV filters, and osmolytes. The results obtained imply that the development of the age-related cataracts might originate from the metabolic dysfunction of the lens epithelial cells.
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Affiliation(s)
- Yuri P Tsentalovich
- International Tomography Center SB RAS, Institutskaya 3a, Novosibirsk 630090, Russia; Novosibirsk State University, Pirogova 2, Novosibirsk 630090, Russia.
| | - Timofey D Verkhovod
- International Tomography Center SB RAS, Institutskaya 3a, Novosibirsk 630090, Russia
| | - Vadim V Yanshole
- International Tomography Center SB RAS, Institutskaya 3a, Novosibirsk 630090, Russia; Novosibirsk State University, Pirogova 2, Novosibirsk 630090, Russia
| | - Alexey S Kiryutin
- International Tomography Center SB RAS, Institutskaya 3a, Novosibirsk 630090, Russia
| | - Lyudmila V Yanshole
- International Tomography Center SB RAS, Institutskaya 3a, Novosibirsk 630090, Russia; Novosibirsk State University, Pirogova 2, Novosibirsk 630090, Russia
| | - Anjella Zh Fursova
- Novosibirsk State Regional Clinical Hospital, Nemirovicha-Danchenko 130, Novosibirsk 630087, Russia
| | - Denis A Stepakov
- Novosibirsk Regional Clinical Bureau of Forensic Medical Examination, Nemirovicha-Danchenko 134, Novosibirsk 630087, Russia
| | - Vladimir P Novoselov
- Novosibirsk Regional Clinical Bureau of Forensic Medical Examination, Nemirovicha-Danchenko 134, Novosibirsk 630087, Russia
| | - Renad Z Sagdeev
- International Tomography Center SB RAS, Institutskaya 3a, Novosibirsk 630090, Russia; Novosibirsk State University, Pirogova 2, Novosibirsk 630090, Russia
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10
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Calvet A, Li B, Ryder AG. A rapid fluorescence based method for the quantitative analysis of cell culture media photo-degradation. Anal Chim Acta 2014; 807:111-9. [DOI: 10.1016/j.aca.2013.11.028] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2013] [Revised: 10/31/2013] [Accepted: 11/14/2013] [Indexed: 10/26/2022]
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Tsentalovich YP, Yanshole VV, Polienko YF, Morozov SV, Grigor’ev IA. Deactivation of Excited States of Kynurenine Covalently Linked to Nitroxides. Photochem Photobiol 2010; 87:22-31. [DOI: 10.1111/j.1751-1097.2010.00841.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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12
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Antioxidative properties of nitroxyl radicals and hydroxyamines in reactions with triplet and deaminated kynurenine. Russ Chem Bull 2010. [DOI: 10.1007/s11172-010-0046-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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13
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Kopylova LV, Snytnikova OA, Chernyak EI, Morozov SV, Forbes MDE, Tsentalovich YP. Kinetics and mechanism of thermal decomposition of kynurenines and biomolecular conjugates: ramifications for the modification of mammalian eye lens proteins. Org Biomol Chem 2009; 7:2958-66. [PMID: 19582306 DOI: 10.1039/b903196k] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Thermal degradation reactions of kynurenine (KN), 3-hydroxykynurenine (3OHKN), and several adducts of KN, to amino acids and reduced glutathione (GSH) have been studied at physiological temperature. These compounds are all implicated in age-related mammalian eye lens cataract formation at the molecular level. The main reaction pathway for both KN and 3OHKN is deamination via beta-elimination to carboxyketoalkenes CKA and 3OHCKA. These reactions show a weak pH dependence below pH values of approximately 8, and a strong pH dependence above this value. The 3OHKN structure deaminates at a faster rate than KN. A mechanism for the deamination reaction is proposed, involving an aryl carbonyl enol/enolate ion, that is strongly supported by the structural, kinetic, and pH data. The degradation of Lys, His, Cys and GSH adducts of the CKA moieties was also studied. The Lys adduct was found to be relatively stable over 200 h at 37 degrees C, while significant degradation was observed for the other adducts. The results are discussed in terms of known post-translational modification reactions of the lens proteins and compared to incubation studies involving KN and related compounds in the presence of proteins.
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Affiliation(s)
- Lyudmila V Kopylova
- International Tomography Center SB RAS, Institutskaya 3a, Novosibirsk, 630090, Russia
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Tolstoluzhsky NV, Gorobets NY, Kolos NN, Desenko SM. Efficient ytterbium triflate catalyzed microwave-assisted synthesis of 3-acylacrylic acid building blocks. ACTA ACUST UNITED AC 2008; 10:893-6. [PMID: 18715040 DOI: 10.1021/cc800103f] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The derivatives of 4-(hetero)aryl-4-oxobut-2-enoic acid are useful as building blocks in the synthesis of biologically active compounds. An efficient general protocol for the synthesis of these building blocks was developed. This method combines microwave assistance and ytterbium triflate catalyst and allows the fast preparation of the target acids starting from different (hetero)aromatic ketones and glyoxylic acid monohydrate giving pure products in 52-75% isolated yields.
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Affiliation(s)
- Nikita V Tolstoluzhsky
- Department of Organic Chemistry, V. N. Karazin Kharkiv National University, Svobody Square, 4, Kharkiv 61077, Ukraine
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15
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Presbyopia. Emerging from a blur towards an understanding of the molecular basis for this most common eye condition. Exp Eye Res 2008; 88:241-7. [PMID: 18675268 DOI: 10.1016/j.exer.2008.07.003] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2008] [Revised: 07/04/2008] [Accepted: 07/08/2008] [Indexed: 11/24/2022]
Abstract
All people will be presbyopic by age 50, and we now understand something of the basis for this condition. It turns out to be a direct consequence of two features; first the design of the transparent lens and the way it must change shape to enable focussing by the human eye, and second the instability of proteins over a very long time period. The incremental changes that take place in the lens to render the central region inflexible by middle age and, as a consequence the person presbyopic, may also promote the subsequent development of cataract. Based on the most recent data, heat-induced denaturation of proteins in the lens appears to be a worthy topic for future investigation. Understanding such processes may allow us to glimpse the origin both of presbyopia and age-related nuclear cataract.
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16
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Snytnikova OA, Fursova AZ, Chernyak EI, Vasiliev VG, Morozov SV, Kolosova NG, Tsentalovich YP. Deaminated UV filter 3-hydroxykynurenine O-beta-D-glucoside is found in cataractous human lenses. Exp Eye Res 2008; 86:951-6. [PMID: 18436210 DOI: 10.1016/j.exer.2008.03.013] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2008] [Revised: 03/13/2008] [Accepted: 03/14/2008] [Indexed: 01/01/2023]
Abstract
Analysis of UV filter levels in 48 cataractous human lenses was performed with the use of HPLC. A new chromophore with the absorption maximum at 410nm and molecular mass of 369Da was detected and assigned as deaminated 3-hydroxykynurenine O-beta-D-glucoside (3OHCKAG). Cataractous lenses are characterized by the wide range of the UV filter concentrations and remarkably lower levels of UV filters and glutathione than published for the normal lenses. No correlation between the lens age and the level of UV filters has been found in cataractous lenses.
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Affiliation(s)
- Olga A Snytnikova
- Department of Multispin Coordination Compounds, International Tomography Center SB RAS, Institutskaya 3a, Novosibirsk 630090, Russian Federation
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Mizdrak J, Hains PG, Truscott RJW, Jamie JF, Davies MJ. Tryptophan-derived ultraviolet filter compounds covalently bound to lens proteins are photosensitizers of oxidative damage. Free Radic Biol Med 2008; 44:1108-19. [PMID: 18206985 DOI: 10.1016/j.freeradbiomed.2007.12.003] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/10/2007] [Revised: 12/07/2007] [Accepted: 12/07/2007] [Indexed: 11/22/2022]
Abstract
The human eye is chronically exposed to light of wavelengths >300 nm. In the young human lens, light of wavelength 300-400 nm is predominantly absorbed by the free Trp derivatives kynurenine (Kyn), 3-hydroxykynurenine (3OHKyn), and 3-hydroxykynurenine-O-beta-D-glucoside (3OHKynG). These ultraviolet (UV) filter compounds are poor photosensitizers. With age, the levels of the free UV filters in the lens decreases and those of protein-bound UV filters increases. The photochemical behavior of these protein-bound UV filters and their role in UV damage are poorly elucidated and are examined here. UVA illumination of protein-bound UV filters generated peroxides (principally H2O2) in a metabolite-, photolysis-time-, and wavelength-dependent manner. Unmodified proteins, free Trp metabolites, and Trp metabolites that do not bind to lens proteins gave low peroxide yields. Protein-bound 3OHKyn (principally at Cys residues) yielded more peroxide than comparable Kyn and 3OHKynG adducts. Studies using D2O and sodium azide implicated 1O2 as a key intermediate. Illumination of the protein-bound adducts also yielded protein-bound Tyr oxidation products (DOPA, di-tyrosine) and protein cross-links via alternative mechanisms. These data indicate that the covalent modification of lens proteins by Kyn derivatives yields photosensitizers that may enhance oxidation in older lenses and contribute to age-related nuclear cataract.
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Affiliation(s)
- Jasminka Mizdrak
- Department of Chemistry and Biomolecular Sciences, Macquarie University, Sydney, NSW 2109, Australia
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