Photophysical properties of biologically important molecules related to proximity effects: psoralens

Lai, Ting Ing; Lim, B. T.; Lim, E. C.

doi:10.1021/ja00390a039

Cited by 106 publications

(71 citation statements)

References 2 publications

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“…Compounds KC1 and KC2 have the weakest fluorescence. The experimental fluorescence properties of 8-MOP at room temperature agreed with those published [5]. The band maxima in the fluorescence spectra of all compounds underwent a short-wavelength shift and the fluorescence quantum yields increased as the temperature was lowered.…”

supporting

confidence: 85%

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Luminescence characteristics of new substituted coumarins

et al. 2009

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supporting

confidence: 85%

“…The standard was 8-MOP. Its fluorescence quantum yield at room temperature in ethanol was 0.0013 [5]; at 77 K, 0.013 [6,7]. The phosphorescence quantum yield of 8-MOP at 77 K in ethanol was 0.17 [6].…”

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confidence: 96%

Luminescence characteristics of new substituted coumarins

et al. 2009

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“…31,32 This behavior was attributed to the proximity effect. [11][12][13][14]52 However, this effect cannot account for the increase of the IC rate constant in protic solvents found here with KN. H-bonding is known to lead to an increase of the n,π* transition energy, and to a decrease of the of π,π* transition energy, 53 thus to a larger n,π*-π,π* energy gap.…”

Section: Discussionmentioning

confidence: 65%

Ultrafast Excited-State Dynamics of Kynurenine, a UV Filter of the Human Eye

et al. 2009

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The excited-state dynamics of kynurenine (KN) has been examined in various solvents by femtosecondresolved optical spectroscopy. The lifetime of the S 1 state of KN amounts to 30 ps in aqueous solutions, increases by more than 1 order of magnitude in alcohols, and exceeds 1 ns in aprotic solvents such as DMSO and DMF, internal conversion (IC) being shown to be the main deactivation channel. The IC rate constant is pH independent but increases with temperature with an activation energy of about 7 kJ/mol in all solvents studied. The dependence on the solvent proticity together with the observation of a substantial isotope effect indicates that hydrogen bonds are involved in the rapid nonradiative deactivation of KN in water. These results give new insight into the efficiency of KN as a UV filter and its role in cataractogenesis.

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“…If the two lowest singlet states of different nature, 1 (n,p*) and 1 (p,p*) are very close each other, an increase of the n,p* energy causes an increase in the energy gap and a decrease in the vibronic interaction between them. The magnitude of the energy gap controls the value of the IC rate constant (proximity effect) as was discussed in detail by Lai et al [13]. When the two states are close each other, the vibronic interaction is large and the singlet decays mainly through the internal conversion (quinolones in acetonitrile, f F negligible).…”

mentioning

confidence: 98%

Photophysical and Phototoxic Properties of the Antibacterial Fluoroquinolones Levofloxacin and Moxifloxacin

Viola

Facciolo

Canton

et al. 2004

Chemistry & Biodiversity

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Two antibacterial fluoroquinolones, levofloxacin and moxifloxacin, were investigated to evaluate their photophysical properties and to explore the mechanism of their phototoxicity. Photophysical experiments were carried out in aqueous solution by stationary and time-resolved fluorimetry, and by laser flash photolysis, to obtain information on the various decay pathways of the excited states of the drugs and on transient species formed upon irradiation. The results obtained show that levofloxacin is able to photosensitize red blood cell lysis in an oxygen-independent way and induce a high decrease in cell viability after UVA irradiation, although to a lesser degree than the racemic mixture ofloxacin. Moxifloxacin, which is an 8-MeO-substituted fluoroquinolone, is less phototoxic than the other compounds. Cellular phototoxicity was inhibited by the addition of superoxide dismutase, catalase, and free radical and hydroxyl radical scavengers (BHA, GSH, mannitol, and DMTU), indicating the involvement of superoxide anion and/or a radical mechanism in their cytotoxicity. A good correlation was observed between lipid peroxidation, protein photodamage, and cellular phototoxicity, indicating that test compounds exert their toxic effects mainly in the cellular membrane. Experiments carried out on pBR322 DNA show that these derivatives do not significantly photocleave DNA directly, but single-strand breaks were evidenced after treatment of photosensitized DNA by two base-excision-repair enzymes, and Endo III.

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Photophysical properties of biologically important molecules related to proximity effects: psoralens

Cited by 106 publications

References 2 publications

Luminescence characteristics of new substituted coumarins

Luminescence characteristics of new substituted coumarins

Ultrafast Excited-State Dynamics of Kynurenine, a UV Filter of the Human Eye

Photophysical and Phototoxic Properties of the Antibacterial Fluoroquinolones Levofloxacin and Moxifloxacin

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