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Boaro A, Ramos LD, Bastos EL, Bechara EJH, Bartoloni FH. Comparison of the mechanisms of DNA damage following photoexcitation and chemiexcitation. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY. B, BIOLOGY 2024; 262:113070. [PMID: 39657451 DOI: 10.1016/j.jphotobiol.2024.113070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2024] [Revised: 11/25/2024] [Accepted: 11/27/2024] [Indexed: 12/12/2024]
Abstract
In this review, we compare the mechanisms and consequences of electronic excitation of DNA via photon absorption or photosensitization, as well as by chemically induced generation of excited states. The absorption of UV radiation by DNA is known to produce cyclobutane pyrimidine dimers (CPDs) and thymine pyrimidone photoproducts. Photosensitizers are known to enable such transformations using UV-A and visible light by generating triplet species able to transfer energy to DNA. Conversely, chemiexcitation of DNA is a process related to the formation of high energy peroxides whose decomposition leads to triplet excited species. In practice, both photoexcitation and chemiexcitation produce reactive excited species able to promote some DNA nucleobases to their excited state. We discuss the effect of epigenetic methylation modifications of DNA and the role of endogenous and exogenous photosensitizers on the formation of DNA photoproducts via triplet-triplet energy transfer as well as oxidative DNA damages. The mechanisms of pathogenic pathway involving the generation of CPDs via chemiexcitation (namely dark CPDs, dCPDs) are discussed and compared with photoexcitation considering their spatiotemporal characteristics. Recognition of the multifaceted noxious effects of UV radiation opens new horizons for the development of effective electronically excited quenchers, thereby providing a crucial step toward mitigating DNA photodamage.
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Affiliation(s)
- Andreia Boaro
- Centro de Ciências Naturais e Humanas, Universidade Federal do ABC, Santo André, São Paulo, SP 09210-580, Brazil; Laboratorio de Genetica e Cardiologia Molecular, Instituto do Coracao (InCor), Hospital das Clinicas HCFMUSP, Faculdade de Medicina, Universidade de Sao Paulo, Sao Paulo, SP 05403-000, Brazil.
| | - Luiz Duarte Ramos
- Centro de Ciências Naturais e Humanas, Universidade Federal do ABC, Santo André, São Paulo, SP 09210-580, Brazil
| | - Erick Leite Bastos
- Centro de Ciências Naturais e Humanas, Universidade Federal do ABC, Santo André, São Paulo, SP 09210-580, Brazil; Departamento de Química Fundamental, Instituto de Química, Universidade de São Paulo, São Paulo, SP 05508-000, Brazil
| | | | - Fernando Heering Bartoloni
- Centro de Ciências Naturais e Humanas, Universidade Federal do ABC, Santo André, São Paulo, SP 09210-580, Brazil
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Blasco-Brusola A, Tamarit L, Navarrete-Miguel M, Roca-Sanjuán D, Miranda MA, Vayá I. Photolytic splitting of homodimeric quinone-derived oxetanes studied by ultrafast transient absorption spectroscopy and quantum chemistry. Phys Chem Chem Phys 2024; 26:13489-13496. [PMID: 38651219 DOI: 10.1039/d4cp00830h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/25/2024]
Abstract
The photoinduced cycloreversion of oxetane derivatives is of considerable biological interest since these compounds are involved in the photochemical formation and repair of the highly mutagenic pyrimidine (6-4) pyrimidone DNA photoproducts ((6-4)PPs). Previous reports have dealt with the photoreactivity of heterodimeric oxetanes composed mainly of benzophenone (BP) and thymine (Thy) or uracil (Ura) derivatives. However, these models are far from the non-isolable Thy〈º〉Thy dimers, which are the real precursors of (6-4)PPs. Thus, we have synthesized two chemically stable homodimeric oxetanes through the Paternò-Büchi reaction between two identical enone units, i.e. 1,4-benzoquinone (BQ) and 1,4-naphthoquinone (NQ), that led to formation of BQ-Ox and NQ-Ox, respectively. Their photoreactivity has been studied by means of steady-state photolysis and transient absorption spectroscopy from the femtosecond to the microsecond time scale. Thus, photolysis of BQ-Ox and NQ-Ox led to formation of the monomeric BQ or NQ, respectively, through ring opening in a "non-adiabatic" process. Accordingly, the transient absorption spectra of the triplet excited quinones (3BQ* and 3NQ*) were not observed as a result of direct photolysis of the quinone-derived oxetanes. In the case of NQ-Ox, a minor signal corresponding to 3NQ* was detected; its formation was ascribed to minor photodegradation of the oxetane during acquisitions of the spectra during the laser experiments. These results are supported by computational analyses based on density functional theory and multiconfigurational quantum chemistry (CASSCF/CASPT2); here, an accessible conical intersection between the ground and excited singlet states has been characterized as the main structure leading to deactivation of excited BQ-Ox or NQ-Ox. This behavior contrasts with those previously observed for heterodimeric thymine-derived oxetanes, where a certain degree of ring opening into the excited triplet state is observed.
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Affiliation(s)
- Alejandro Blasco-Brusola
- Departamento de Química/Instituto de Tecnología Química UPV-CSIC, Universitat Politècnica de València, Camino de Vera s/n, València 46022, Spain.
| | - Lorena Tamarit
- Departamento de Química/Instituto de Tecnología Química UPV-CSIC, Universitat Politècnica de València, Camino de Vera s/n, València 46022, Spain.
| | - Miriam Navarrete-Miguel
- Instituto de Ciencia Molecular, Universitat de València, P.O. Box 22085, València 46071, Spain
| | - Daniel Roca-Sanjuán
- Instituto de Ciencia Molecular, Universitat de València, P.O. Box 22085, València 46071, Spain
| | - Miguel A Miranda
- Departamento de Química/Instituto de Tecnología Química UPV-CSIC, Universitat Politècnica de València, Camino de Vera s/n, València 46022, Spain.
| | - Ignacio Vayá
- Departamento de Química/Instituto de Tecnología Química UPV-CSIC, Universitat Politècnica de València, Camino de Vera s/n, València 46022, Spain.
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Shen Y, Zhang S, Su Y, Qu Z, Ren H. Controlling the repair mechanisms of oxetanes through functional group substitution. Phys Chem Chem Phys 2023; 25:14511-14519. [PMID: 37190991 DOI: 10.1039/d3cp01019h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Intersystem crossing (ISC) plays a key role in the photolysis processes of oxetanes formed by benzophenone (BP)-like and thymine structures. In this work, we systematically explored the photophysical processes of oxetanes and ring-splitting products and investigated the effect of substituents on the repair mechanisms of oxetanes. The regioselectivity of oxetanes (head-to-head, HH and head-to-tail, HT) and the electron-donating and electron-withdrawing substituents, including CH3, OCH3 and NO2, were considered. It was found that the substituents influence the ISC rates of these compounds more by changing their spin-orbit coupling (SOC) coefficients rather than energy gaps. The SOC coefficients of HH-oxetanes are more affected by these groups than HT-oxetanes and products, and they have greater ISC rates on the whole. Besides, the insertion of substituents can alter the radiative and nonradiative decay rates, thereby transforming the photoinduced cycloreversion mechanisms of oxetanes. The ring-splitting reactions of non-substituted oxetanes could occur via two pathways of singlet and triplet manifolds. Furthermore, oxetanes with NO2 at the X site have the largest ISC rates but hardly undergo repair processes, while the introduction of electron-donating substituents can effectively promote the repair of oxetanes. The singlet ring-splitting reactions of HH-oxetanes are more inclined to occur after introducing CH3 and OCH3 at two sites. However, HT-oxeatnes with CH3 are more likely to undergo triplet repair processes and OCH3-substituted structures tend to originate cycloreversion in the singlet manifolds. Moreover, the introduction of CH3 and OCH3 at the Y site rather than the X site can more significantly accelerate the repair processes of HH-oxetanes. Contrarily, HT-oxetanes with electron-donating groups at the X site exhibit faster repair rates than those at the Y site. We hope this work can provide valuable insights into BP-like drugs and photosensitive DNA repair.
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Affiliation(s)
- Yan Shen
- School of Chemical Engineering, Sichuan University, Chengdu, 610065, China.
| | - Shaoqin Zhang
- Institute of Theoretical Chemistry, College of Chemistry, Jilin University, Changchun, 130023, China
| | - Yingli Su
- School of Chemical Engineering, Sichuan University, Chengdu, 610065, China.
| | - Zexing Qu
- Institute of Theoretical Chemistry, College of Chemistry, Jilin University, Changchun, 130023, China
| | - Haisheng Ren
- School of Chemical Engineering, Sichuan University, Chengdu, 610065, China.
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Su Y, Song G, Shen Y, Li X, Ren H. Mechanisms and energetics for hydrogen abstraction of thymine photosensitized by benzophenone from theoretical principles. Phys Chem Chem Phys 2023; 25:6467-6472. [PMID: 36779968 DOI: 10.1039/d2cp05481g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The significant role of hydrogen abstraction in chemistry and biology has inspired many theoretical works to link its practical phenomena and mechanistic properties. Here, the photophysical processes and hydrogen abstraction mechanisms of benzophenone (BZP) photosensitized thymine damage were systematically investigated from theoretical principles. It was found that the BZP photosensitizer upon UV irradiation undergoes vertical excitation, internal conversion, vibrational relaxation and intersystem crossing into a triplet excited state. Then the triplet BZP damages thymine by a hydrogen abstraction process. However, the reverse reaction easily occurs due to the lower reaction energy, which causes a low yield of hydrogen abstraction products. We hope this comprehensive work can provide a deeper understanding of photosensitive DNA damage from hydrogen abstraction.
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Affiliation(s)
- Yingli Su
- College of Chemical Engineering, Sichuan University, Chengdu, 610065, China.
| | - Guanlin Song
- College of Chemical Engineering, Sichuan University, Chengdu, 610065, China.
| | - Yan Shen
- College of Chemical Engineering, Sichuan University, Chengdu, 610065, China.
| | - Xiangyuan Li
- College of Chemical Engineering, Sichuan University, Chengdu, 610065, China.
| | - Haisheng Ren
- College of Chemical Engineering, Sichuan University, Chengdu, 610065, China.
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Blasco-Brusola A, Vayá I, Miranda MA. Regioselectivity in the adiabatic photocleavage of DNA-based oxetanes. Org Biomol Chem 2020; 18:9117-9123. [PMID: 33150924 DOI: 10.1039/d0ob01974g] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/25/2024]
Abstract
Direct absorption of UVB light by DNA may induce formation of cyclobutane pyrimidine dimers and pyrimidine-pyrimidone (6-4) photoproducts. The latter arise from the rearrangement of unstable oxetane intermediates, which have also been proposed to be the electron acceptor species in the photoenzymatic repair of this type of DNA damage. In the present work, direct photolysis of oxetanes composed of substituted uracil (Ura) or thymine (Thy) derivatives and benzophenone (BP) have been investigated by means of transient absorption spectroscopy from the femtosecond to the microsecond time-scales. The results showed that photoinduced oxetane cleavage takes place through an adiabatic process leading to the triplet excited BP and the ground state nucleobase. This process was markedly affected by the oxetane regiochemistry (head-to-head, HH, vs. head-to-tail, HT) and by the nucleobase substitution; it was nearly quantitative for all investigated HH-oxetanes while it became strongly influenced by the substitution at positions 1 and 5 for the HT-isomers. The obtained results clearly confirm the generality of the adiabatic photoinduced cleavage of BP/Ura or Thy oxetanes, as well as its dependence on the regiochemistry, supporting the involvement of triplet exciplexes. As a matter of fact, when formation of this species was favored by keeping together the Thy and BP units after splitting by means of a linear linker, a transient absorption at ∼400 nm, ascribed to the exciplex, was detected.
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Affiliation(s)
- Alejandro Blasco-Brusola
- Departamento de Química/Instituto de Tecnología Química UPV-CSIC, Universitat Politècnica de València, Camino de Vera s/n, 46022 València, Spain.
| | - Ignacio Vayá
- Departamento de Química/Instituto de Tecnología Química UPV-CSIC, Universitat Politècnica de València, Camino de Vera s/n, 46022 València, Spain.
| | - Miguel A Miranda
- Departamento de Química/Instituto de Tecnología Química UPV-CSIC, Universitat Politècnica de València, Camino de Vera s/n, 46022 València, Spain.
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