Singlet oxygen sensitisation by excited state DNA

Bishop, Steven M.; Malone, Mark E.; Phillips, David; Parker, Anthony W.; Symons, M. C. R.

doi:10.1039/c39940000871

Cited by 46 publications

(48 citation statements)

References 6 publications

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“…4). In addition, it has been reported that in aerated solutions this product can be formed through a singlet oxygen reaction [31,32]. Herein, the formation of the Fapy products was observed in the presence of well-known electron scavengers (H 3 O þ , N 2 O), strongly suggesting that the guanine radical cation is one of their possible reactive precursors.…”

Section: Low Intensity 254 Nm Radiation Of the Guanine Monomersmentioning

confidence: 87%

Formamidopyrimidines as major products in the low- and high-intensity UV irradiation of guanine derivatives

Crespo‐Hernández

Arce

2004

Journal of Photochemistry and Photobiology B: Biology

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Section: Low Intensity 254 Nm Radiation Of the Guanine Monomersmentioning

confidence: 87%

Formamidopyrimidines as major products in the low- and high-intensity UV irradiation of guanine derivatives

Crespo‐Hernández

Arce

2004

Journal of Photochemistry and Photobiology B: Biology

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“…10 À3 in aqueous solution (Table 5). Bishop et al [139] measured a singlet oxygen yield of 0.030 AE 0.005 for adenine in acetonitrile after 248 nm nanosecond laser excitation by detecting singlet oxygen emission decay signals at 1,270 nm. However, for guanine and guanosine 5 0 -monophosphate, the authors were unable to detect singlet oxygen emission quantifiably in deuterated water, and estimated the yield to be lower than 0.005 (Table 6).…”

Section: Adenine and Guanine Monomersmentioning

confidence: 99%

“…Interestingly, low yields of the triplet state and of singlet oxygen have been reported in the adenine and guanine monomers [98,139], even though the population of their 1 nπ* and 3 ππ* states has not been detected in solution [89,[140][141][142]. Nikogosyan and co-workers [98] used two-step laser excitation to high-lying electronic states and kinetic modeling to estimate triplet yields in adenine and guanine of ca.…”

Section: Adenine and Guanine Monomersmentioning

confidence: 99%

Photochemistry of Nucleic Acid Bases and Their Thio- and Aza-Analogues in Solution

Pollum

Martínez‐Fernández

Crespo‐Hernández

2014

Topics in Current Chemistry

114

200

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The steady-state and time-resolved photochemistry of the natural nucleic acid bases and their sulfur- and nitrogen-substituted analogues in solution is reviewed. Emphasis is given to the experimental studies performed over the last 3-5 years that showcase topical areas of scientific inquiry and those that require further scrutiny. Significant progress has been made toward mapping the radiative and nonradiative decay pathways of nucleic acid bases. There is a consensus that ultrafast internal conversion to the ground state is the primary relaxation pathway in the nucleic acid bases, whereas the mechanism of this relaxation and the level of participation of the (1)πσ*, (1) nπ*, and (3)ππ* states are still matters of debate. Although impressive research has been performed in recent years, the microscopic mechanism(s) by which the nucleic acid bases dissipate excess vibrational energy to their environment, and the role of the N-glycosidic group in this and in other nonradiative decay pathways, are still poorly understood. The simple replacement of a single atom in a nucleobase with a sulfur or nitrogen atom severely restricts access to the conical intersections responsible for the intrinsic internal conversion pathways to the ground state in the nucleic acid bases. It also enhances access to ultrafast and efficient inter-system crossing pathways that populate the triplet manifold in yields close to unity. Determining the coupled nuclear and electronic pathways responsible for the significantly different photochemistry in these nucleic acid base analogues serves as a convenient platform to examine the current state of knowledge regarding the photodynamic properties of the DNA and RNA bases from both experimental and computational perspectives. Further investigations should also aid in forecasting the prospective use of sulfur- and nitrogen-substituted base analogues in photochemotherapeutic applications.

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“…However, in the isolated DNA, 2 0 -deoxyguanosine (dGuo) (6) absorbs UV radiation generating triplet state of purine bases which may react with molecular oxygen ( 3 O 2 ) yielding O 2 ( 1 D g ). This species oxidizes DNA giving rise mainly 7 (Bishop et al, 1994;Mohammad and Morrison, 1996).…”

Section: Introductionmentioning

confidence: 99%