Formation d’oxygène singulet <sup>1</sup>Δ<sub>g</sub> photosensibilisée par l’hypericine caractérisation et étude du mécanisme par spectroscopie laser

Jardon, Pierre; Lazortchak, Nélia; Gautron, R.

doi:10.1051/jcp/1987841141

Cited by 52 publications

(19 citation statements)

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“…Both mechanisms have been observed in in virro studies (Heitz, Knox et al, 1987). The singlet oxygen quantum yield has been determined and is quite large, 0.74 (Jardon et al, 1986(Jardon et al, , 1987. A value such as this usually indicates an efficient intersystem crossing mechanism, common for aromatic ketones, involving conformational changes (difficult in the expectedly rigid hypericin structure) or aggregation (Turro, 1978).…”

Section: Introductionmentioning

confidence: 91%

Resonance Raman and Surface‐enhanced Resonance Raman Spectroscopy of Hypericin

Raser¹,

Kolaczkowski²,

Cotton³

1992

Photochem & Photobiology

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Hypericin has been found to exhibit a variety of photodynamic effects. To correlate biological activity with molecular structure, complete physical characterization of hypericin is required. The vibrational spectrum has been determined and resonance Raman and surface enhanced resonance Raman scattering spectra are reported. In addition, the Raman spectrum of a model compound has been studied to facilitate assignment of the vibrational modes of hypericin.

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Section: Introductionmentioning

confidence: 91%

Resonance Raman and Surface‐enhanced Resonance Raman Spectroscopy of Hypericin

Raser¹,

Kolaczkowski²,

Cotton³

1992

Photochem & Photobiology

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“…Since hypericin is a photoactive molecule its activity is significantly augmented by exposure to light (13,14 ). Photosensitizing properties of hypericin could be explained by means of type I mechanism involving the superoxide anion and hypericinium ion formation and type II mechanism which includes the formation of singlet oxygen as a primary oxidizer via energy transfer from the excited triplet state of hypericin towards the ground state of molecular oxygen (15)(16)(17)(18)(19). As hypericin antiviral activity was observed even for the low oxygen concentration (20) and with regards to the low quantum yield of the singlet oxygen generation from the excited hypericin (21 ), Petrich and coworkers proposed an alternative origin for the photoinduced virucidal activity linked to its ability to produce a photogenerated pH drop through an intramolecular proton transfer in the excited state of the molecule probably preceding an acidification (22).…”

Section: Introductionmentioning

confidence: 99%

Sequence Specific Interaction of the Photoactive Drug Hypericin Depends on the Structural Arrangement and the Stability of the Structure Containing its Specific 5′AG3′ Target: A Resonance Raman Spectroscopy Study

Kočišová

Chinsky²,

Miškovský³

1999

Journal of Biomolecular Structure and Dynamics

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The resonance Raman spectra of three oligonucleotides with different lengths containing a specific 5'AG3' target doublet for hypericin - a potent antiretroviral and anticancer photoactive agent, and their 1:1 and 1:2 (oligonucleotide: hypericin) complexes are reported. It is shown that the structural arrangement of the oligonucleotides, their structural stability and the local structural arrangement around the 5'AG3' hypericin target, are the factors which determine the formation of a stable, specifically bounded DNA-hypericin complexes.

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“…Stern-Volmer plots for fluorescence quenching of hypericin(9) and stentorin (O) by 1,4-benzoquinone. Regression lines are also reported.…”

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confidence: 99%

Electron Transfer Quenching and Photoinduced EPR of Hypericin and the Ciliate Photoreceptor Stentorin

et al. 1997

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Time-correlated single photon counting was used to observe dynamic quenching of the hypericin and stentorin excited singlet states. The fluorescence quenching data for hypericin and stentorin were interpreted in terms of electron transfer. The observed correlation between free energy change of electron transfer and quenching rate constant suggests that quenching proceeds via electron transfer from hypericin and stentorin to the quenchers. EPR spectra for hypericin, stentorin, and stentorin chromoprotein demonstrated that free radical formation was initiated or enhanced by visible light and that similar radical species were produced in each sample. Furthermore, the EPR signal for stentorin was significantly enhanced by 1,4-benzoquinone, but the overall shape and g-value was unchanged. We suggest that electron transfer in the excited state of these chromophores results in the formation of a cation radical. This electron transfer is a rapid and efficient pathway for deactivation of hypericin and stentorin excited singlet states and should be considered when discussing the photoreactivity of hypericin as a photodynamic agent and of stentorin as the Stentor coeruleus photoreceptor.

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Formation d’oxygène singulet ¹Δ_g photosensibilisée par l’hypericine caractérisation et étude du mécanisme par spectroscopie laser

Cited by 52 publications

References 0 publications

Resonance Raman and Surface‐enhanced Resonance Raman Spectroscopy of Hypericin

Resonance Raman and Surface‐enhanced Resonance Raman Spectroscopy of Hypericin

Sequence Specific Interaction of the Photoactive Drug Hypericin Depends on the Structural Arrangement and the Stability of the Structure Containing its Specific 5′AG3′ Target: A Resonance Raman Spectroscopy Study

Electron Transfer Quenching and Photoinduced EPR of Hypericin and the Ciliate Photoreceptor Stentorin

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Formation d’oxygène singulet 1Δg photosensibilisée par l’hypericine caractérisation et étude du mécanisme par spectroscopie laser

Cited by 52 publications

References 0 publications

Resonance Raman and Surface‐enhanced Resonance Raman Spectroscopy of Hypericin

Resonance Raman and Surface‐enhanced Resonance Raman Spectroscopy of Hypericin

Sequence Specific Interaction of the Photoactive Drug Hypericin Depends on the Structural Arrangement and the Stability of the Structure Containing its Specific 5′AG3′ Target: A Resonance Raman Spectroscopy Study

Electron Transfer Quenching and Photoinduced EPR of Hypericin and the Ciliate Photoreceptor Stentorin

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Formation d’oxygène singulet ¹Δ_g photosensibilisée par l’hypericine caractérisation et étude du mécanisme par spectroscopie laser