Hypericin and Its Photodynamic Action

Durán, Nelsón; Song, Pill‐Soon

doi:10.1111/j.1751-1097.1986.tb05646.x

Cited by 270 publications

(179 citation statements)

References 50 publications

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“…These have been the subject of several reviews [1][2][3][4][5] and have been referred to in detail in our previous work. One of the most interesting photophysical processes that these molecules execute is excited-state proton or H atom transfer, both intramolecular [6][7][8][9][10][11][12][13][14][15][16][17][18][19] and intermolecular.…”

Section: Introductionmentioning

confidence: 99%

Excited-State Intramolecular H Atom Transfer of Hypericin and Hypocrellin A Investigated by Fluorescence Upconversion

et al. 1999

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The excited-state intramolecular H atom transfer reaction occurring in hypericin and hypocrellin A is investigated by means of the fluorescence upconversion technique in a variety of solvents. Rising components of ∼10 ps, attributable to intramolecular H atom transfer, are clearly observed in the fluorescence upconversion traces of both hypericin and hypocrellin A. The amplitude of the rising component is emission wavelength dependent and occurs on the blue edge of the emission spectra. Neither in hypericin nor in hypocrellin A does this fluorescent component exhibit a deuterium isotope effect. This result identifies it with the ∼10 ps component, also lacking a deuterium isotope effect, observed in hypericin in transient absorption measurements monitoring stimulated emission. The clear and complementary observation in fluorescence of the ∼10 ps component in both hypericin and hypocrellin A is a crucial link in refining a unified model of the hypericin and hypocrellin photophysics that we first proposed in J. Phys The excited-state intramolecular H atom transfer reaction occurring in hypericin and hypocrellin A is investigated by means of the fluorescence upconversion technique in a variety of solvents. Rising components of ∼10 ps, attributable to intramolecular H atom transfer, are clearly observed in the fluorescence upconversion traces of both hypericin and hypocrellin A. The amplitude of the rising component is emission wavelength dependent and occurs on the blue edge of the emission spectra. Neither in hypericin nor in hypocrellin A does this fluorescent component exhibit a deuterium isotope effect. This result identifies it with the ∼10 ps component, also lacking a deuterium isotope effect, observed in hypericin in transient absorption measurements monitoring stimulated emission. The clear and complementary observation in fluorescence of the ∼10 ps component in both hypericin and hypocrellin A is a crucial link in refining a unified model of the hypericin and hypocrellin photophysics that we first proposed in

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Section: Introductionmentioning

confidence: 99%

Excited-State Intramolecular H Atom Transfer of Hypericin and Hypocrellin A Investigated by Fluorescence Upconversion

et al. 1999

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“…[1][2][3][4][5] We have argued that they also present a fascinating system with which to study excited-state intramolecular H-atom transfer. [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] Hypericin executes an intramolecular excited-state H-atom transfer in ∼10 ps.…”

Section: Introductionmentioning

confidence: 99%

Coupling of Large-Amplitude Side Chain Motions to the Excited-State H-Atom Transfer of Perylene Quinones: Application of Theory and Experiment to Calphostin C

et al. 2001

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The excited-state intramolecular H-atom transfer reactions of hypocrellins B and A are compared with those of calphostin C. On the basis of the results of transient absorption measurements and ab initio quantum mechanical calculations, it is concluded that large-amplitude conformational changes are coupled to the Hatom transfer in calphostin C, just as they are in hypocrellins A and B. The calculations on this very large molecule with a very complex ground electronic state potential energy surface were made possible by the use of highly scalable electronic structure theory codes on large parallel computers. Disciplines Chemistry CommentsReprinted (adapted) The excited-state intramolecular H-atom transfer reactions of hypocrellins B and A are compared with those of calphostin C. On the basis of the results of transient absorption measurements and ab initio quantum mechanical calculations, it is concluded that large-amplitude conformational changes are coupled to the H-atom transfer in calphostin C, just as they are in hypocrellins A and B. The calculations on this very large molecule with a very complex ground electronic state potential energy surface were made possible by the use of highly scalable electronic structure theory codes on large parallel computers.

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“…4). Duran and Song (47) showed that photoactivation of hypericin in the presence of oxygen leads to the generation of superoxide anion radicals and singlet oxygen (1O2). It is generally accepted that 1O2 plays a major role in the biological activity of hypericin.…”

Section: Discussionmentioning

confidence: 99%

Erythropoietin inhibits apoptosis induced by photodynamic therapy in ovarian cancer cells

Solár

Kovaľ

Mikeš

et al. 2008

Molecular Cancer Therapeutics

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Recombinant human erythropoietin is widely used to treat anemia associated with cancer and with the myelosuppressive effects of chemotherapy, particularly platinumbased regimens. Erythropoietin is the principal regulator of erythroid cell proliferation, differentiation, and apoptosis. Recently, the antiapoptotic and proliferative effects of erythropoietin on nonhematopoietic cells were also established. We now show the effect of erythropoietin treatment on the response of A2780 and SKOV3 ovarian carcinoma cell lines to photodynamic therapy (PDT) using hypericin. SKOV3 exhibited an increased resistance to hypericin when cells were treated with erythropoietin. This resistance was reversed by treatment of SKOV3 cells with the specific Janus kinase 2 kinase inhibitor AG490 or the tyrosine kinase inhibitor genistein. These results support a role for the specific erythropoietin-induced Janus kinase 2/STAT signal transduction pathway in PDT resistance. Evidence of erythropoietin signaling was obtained by the demonstration of Akt phosphorylation in both A2780 and SKOV3 cells. Erythropoietin-treated SKOV3 cells exhibited decreased apoptosis induced by hypericin, an effect that was blocked by the phosphoinositide 3-kinase/Akt inhibitor wortmannin. These results may have important implications for ovarian cancer patients undergoing PDT and receiving erythropoietin.

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Hypericin and Its Photodynamic Action

Cited by 270 publications

References 50 publications

Excited-State Intramolecular H Atom Transfer of Hypericin and Hypocrellin A Investigated by Fluorescence Upconversion

Excited-State Intramolecular H Atom Transfer of Hypericin and Hypocrellin A Investigated by Fluorescence Upconversion

Coupling of Large-Amplitude Side Chain Motions to the Excited-State H-Atom Transfer of Perylene Quinones: Application of Theory and Experiment to Calphostin C

Erythropoietin inhibits apoptosis induced by photodynamic therapy in ovarian cancer cells

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