Riboflavin (VB2) photosensitized oxidation of 2′-deoxyguanosine-5′-monophosphate (dGMP) in aqueous solution: a transient intermediates study

Lu, Can‐Zhong; Wang, Lin; Wang, Wenfeng; Han, Zhewen; Yao, Side; Lin, Nianyun

doi:10.1039/a908492d

Cited by 110 publications

(118 citation statements)

References 36 publications

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“…McCall et al 4 have assumed that corneal cross-linking with Rf does not happen without carbonyl groups and singlet oxygen. This study used sodium azide to quench singlet oxygen selectively, but it has been reported before 9,25 that this salt is also able to quench Rf triplets, which is the primary cross-linking reactant. McCall et al 4 have also found that the mean maximum destructive tension for clinical Rf UV-A-treated shark and rabbit corneas was enhanced with heavy water (D 2 O) because, as they cited, enhancement of singlet oxygen's half-life in heavy water ranges from 6.8 to 12 times.…”

Section: Discussionmentioning

confidence: 99%

“…[25][26][27] Lu et al 9 and Gorner 10 have shown that the competing role of singlet oxygen in these processes is not completely excluded but that the reactive path via singlet oxygen would not be the primary reaction.…”

Section: Discussionmentioning

confidence: 99%

“…However, at low Rf concentrations, this pathway must be limited because, when Rf is illuminated anaerobically, its isoalloxazine ring becomes reduced 10 and in order to restore it, some amount of oxygen is required. 9 Furthermore, excess oxygen may be detrimental to the corneal cross-linking process because oxygen is able to inhibit free radical photopolymerization reactions by interacting with radical species to form chain-terminating peroxide molecules. 29 For example, with Table 1. increasing oxygen concentration, quantum yield of tryptophan photo-oxidation by Rf first increases and then decreases.…”

Section: Discussionmentioning

confidence: 99%

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Photochemical Kinetics of Corneal Cross-Linking with Riboflavin

Kamaev¹,

Friedman²,

Sherr³

et al. 2012

Invest. Ophthalmol. Vis. Sci.

272

270

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PURPOSE.To model the photochemical kinetics of corneal crosslinking with riboflavin (Rf) and confirm the model through measured oxygen concentration experiments under varying energy input conditions by UV-A irradiance and temperature modulation in ex vivo porcine cornea. METHODS.A theoretical model was developed to describe the corneal cross-linking photochemical kinetics of Rf. After instillation with drops of Rf solution in distilled water, deepithelialized porcine corneas were exposed to 365-nm ultraviolet light (UV-A) under varying irradiance and temperature. Oxygen concentration in the cornea at a known depth was monitored during UV-A illumination with a dissolved oxygen fiberoptic microsensor. Data from the oxygen experiments were used to confirm the model. RESULTS.On the basis of the known chemical reactions and diffusion rates of Rf and oxygen into the cornea, the authors developed a theoretical model consistent with corneal oxygen consumption experimental results during UV-A irradiation under different conditions. Oxygen concentration in the cornea is modulated by UV-A irradiance and temperature and quickly decreased at the beginning of UV-A exposure. The time-dependence of both Type-I and Type-II photochemical mechanisms in corneal cross-linking with Rf are discussed.CONCLUSIONS. Using a chemical kinetics modeling approach, the authors developed a simple model that is in agreement with their experimental results on oxygen consumption in the cornea during corneal cross-linking with Rf. It is suggested that the main photochemical kinetics mechanism is the direct interaction between Rf triplets and reactive groups of corneal proteins, which leads to the cross-linking of the proteins mainly through radical reactions. (Invest Ophthalmol Vis Sci.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Photochemical Kinetics of Corneal Cross-Linking with Riboflavin

Kamaev¹,

Friedman²,

Sherr³

et al. 2012

Invest. Ophthalmol. Vis. Sci.

272

270

View full text Add to dashboard Cite

show abstract

“…8. It is also possible an electron-transfer reaction from 3 RF* to 3 O 2 to form anion superoxide, but this reaction occurs with very low efficiency <0.1% (Lu et al, 2000).…”

Section: Quenching Of Electronically Excited Statesmentioning

confidence: 99%

Gum Arabic: More Than an Edible Emulsifier

Montenegro¹,

Boiero²,

Valle³

et al. 2012

Products and Applications of Biopolymers

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“…Some fluorophores conjugated DNA were reported to quench its fluorescence upon hybridization by photoinduced electron transfer accompanying DNA damage, such as irreversible electron transfer with guanine and/or DNA cleavage. 13,[25][26][27][40][41][42][43][44] These matters are greatly related to recent topics of DNA electron transfer, 45 but are too complicated to understood. Some researchers examined both forward and reverse electron transfer in the photoinduced electron transfer process, e.g.…”

Section: Several Dye-labeled Dna Probe and Its Quenching By Hybridizamentioning

confidence: 99%