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Abstract
Endogenous photosensitizers play a critical role in both beneficial and harmful light-induced transformations in biological systems. Understanding their mode of action is essential for advancing fields such as photomedicine, photoredox catalysis, environmental science, and the development of sun care products. This review offers a comprehensive analysis of endogenous photosensitizers in human skin, investigating the connections between their electronic excitation and the subsequent activation or damage of organic biomolecules. We gather the physicochemical and photochemical properties of key endogenous photosensitizers and examine the relationships between their chemical reactivity, location within the skin, and the primary biochemical events following solar radiation exposure, along with their influence on skin physiology and pathology. An important take-home message of this review is that photosensitization allows visible light and UV-A radiation to have large effects on skin. The analysis presented here unveils potential causes for the continuous increase in global skin cancer cases and emphasizes the limitations of current sun protection approaches.
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Affiliation(s)
- Erick L Bastos
- Department of Fundamental Chemistry, Institute of Chemistry, University of São Paulo, 05508-000 São Paulo, São Paulo, Brazil
| | - Frank H Quina
- Department of Fundamental Chemistry, Institute of Chemistry, University of São Paulo, 05508-000 São Paulo, São Paulo, Brazil
- Department of Chemical Engineering, Polytechnic School, University of São Paulo, 05508-000 São Paulo, São Paulo, Brazil
| | - Maurício S Baptista
- Department of Biochemistry, Institute of Chemistry, University of São Paulo, 05508-000 São Paulo, São Paulo, Brazil
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Jiang Y, Liu D, Rotella ME, Deng G, Liu Z, Chen W, Zhang H, Kozlowski MC, Walsh PJ, Yang X. Net-1,2-Hydrogen Atom Transfer of Amidyl Radicals: Toward the Synthesis of 1,2-Diamine Derivatives. J Am Chem Soc 2023; 145:16045-16057. [PMID: 37441806 PMCID: PMC10411589 DOI: 10.1021/jacs.3c04376] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/15/2023]
Abstract
Hydrogen atom transfer (HAT) processes are among the most useful approaches for the selective construction of C(sp3)-C(sp3) bonds. 1,5-HAT with heteroatom-centered radicals (O•, N•) have been well established and are favored relative to other 1,n-HAT processes. In comparison, net 1,2-HAT processes have been observed infrequently. Herein, the first amidyl radicalls are reported that preferentially undergo a net 1,2-HAT over 1,5-HAT. Beginning with single electron transfer from 2-azaallyl anions to N-alkyl N-aryloxy amides, the latter generate amidyl radicals. The amidyl radical undergoes a net-1,2-HAT to generate a C-centered radical that participates in an intermolecular radical-radical coupling with the 2-azaallyl radical to generate 1,2-diamine derivatives. Mechanistic and EPR experiments point to radical intermediates. Density functional theory calculations provide support for a base-assisted, stepwise-1,2-HAT process. It is proposed that the generation of amidyl radicals under basic conditions can be greatly expanded to access α-amino C-centered radicals that will serve as valuable synthetic intermediates.
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Affiliation(s)
- Yonggang Jiang
- Key Laboratory of Medicinal Chemistry for Natural Resource, Ministry of Education; Yunnan Provincial Center for Research & Development of Natural Products; School of Pharmacy, Yunnan University, Kunming, 650500, P. R. China
| | - Dongxiang Liu
- Key Laboratory of Medicinal Chemistry for Natural Resource, Ministry of Education; Yunnan Provincial Center for Research & Development of Natural Products; School of Pharmacy, Yunnan University, Kunming, 650500, P. R. China
| | - Madeline E. Rotella
- Roy and Diana Vagelos Laboratories, Penn/Merck Laboratory for High-Throughput Experimentation, Department of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia, Pennsylvania, 19104, United States
| | - Guogang Deng
- Key Laboratory of Medicinal Chemistry for Natural Resource, Ministry of Education; Yunnan Provincial Center for Research & Development of Natural Products; School of Pharmacy, Yunnan University, Kunming, 650500, P. R. China
| | - Zhengfen Liu
- Key Laboratory of Medicinal Chemistry for Natural Resource, Ministry of Education; Yunnan Provincial Center for Research & Development of Natural Products; School of Pharmacy, Yunnan University, Kunming, 650500, P. R. China
| | - Wen Chen
- Key Laboratory of Medicinal Chemistry for Natural Resource, Ministry of Education; Yunnan Provincial Center for Research & Development of Natural Products; School of Pharmacy, Yunnan University, Kunming, 650500, P. R. China
| | - Hongbin Zhang
- Key Laboratory of Medicinal Chemistry for Natural Resource, Ministry of Education; Yunnan Provincial Center for Research & Development of Natural Products; School of Pharmacy, Yunnan University, Kunming, 650500, P. R. China
| | - Marisa C. Kozlowski
- Roy and Diana Vagelos Laboratories, Penn/Merck Laboratory for High-Throughput Experimentation, Department of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia, Pennsylvania, 19104, United States
| | - Patrick J. Walsh
- Roy and Diana Vagelos Laboratories, Penn/Merck Laboratory for High-Throughput Experimentation, Department of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia, Pennsylvania, 19104, United States
| | - Xiaodong Yang
- Key Laboratory of Medicinal Chemistry for Natural Resource, Ministry of Education; Yunnan Provincial Center for Research & Development of Natural Products; School of Pharmacy, Yunnan University, Kunming, 650500, P. R. China
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Radiolysis Studies of Oxidation and Nitration of Tyrosine and Some Other Biological Targets by Peroxynitrite-Derived Radicals. Int J Mol Sci 2022; 23:ijms23031797. [PMID: 35163717 PMCID: PMC8836854 DOI: 10.3390/ijms23031797] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2022] [Revised: 01/31/2022] [Accepted: 02/02/2022] [Indexed: 01/27/2023] Open
Abstract
The widespread interest in free radicals in biology extends far beyond the effects of ionizing radiation, with recent attention largely focusing on reactions of free radicals derived from peroxynitrite (i.e., hydroxyl, nitrogen dioxide, and carbonate radicals). These radicals can easily be generated individually by reactions of radiolytically-produced radicals in aqueous solutions and their reactions can be monitored either in real time or by analysis of products. This review first describes the general principles of selective radical generation by radiolysis, the yields of individual species, the advantages and limitations of either pulsed or continuous radiolysis, and the quantitation of oxidizing power of radicals by electrode potentials. Some key reactions of peroxynitrite-derived radicals with potential biological targets are then discussed, including the characterization of reactions of tyrosine with a model alkoxyl radical, reactions of tyrosyl radicals with nitric oxide, and routes to nitrotyrosine formation. This is followed by a brief outline of studies involving the reactions of peroxynitrite-derived radicals with lipoic acid/dihydrolipoic acid, hydrogen sulphide, and the metal chelator desferrioxamine. For biological diagnostic probes such as ‘spin traps’ to be used with confidence, their reactivities with radical species have to be characterized, and the application of radiolysis methods in this context is also illustrated.
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