Chemistry of singlet oxygen. XI. Cis-trans isomerization of carotenoids by single oxygen and a probable quenching mechanism

1970 ◽  
Vol 92 (17) ◽  
pp. 5218-5219 ◽  
Author(s):  
Christopher S. Foote ◽  
Yew C. Chang ◽  
Robert W. Denny
Keyword(s):  
Singlet Oxygen ◽  
Quenching Mechanism ◽  
Trans Isomerization ◽  
Single Oxygen

The Photophysical Properties of Pyropheophorbide-a in Different Laser Light and PDT Efficiency for Eca-109 Cell In Vitro

2011 ◽  
Vol 393-395 ◽  
pp. 1029-1032
Author(s):  
Hui Jing Mao ◽  
Zhi Long Chen ◽  
Ying Ye
Keyword(s):  
Singlet Oxygen ◽  
Laser Light ◽  
Photophysical Properties ◽  
Oxygen Probe ◽  
Oxygen Production ◽  
Light Power ◽  
Oxygen Generation ◽  
Pyropheophorbide A ◽  
Single Oxygen

Pyropheophorbid-a (PyroPheo) is one of the well-known photosensitizers which can be useful for future clinical applications. This work is aimed to compare and measure generation rates of single oxygen through activation of pyropheophorbide-a by four different wavelength, and observe the sensitivity of pyropheophorbide-a mediated photodynamic therapy for eca-109 cell. Methods: UV-vis spectrophotometrics was used to measure decrease of singlet oxygen probe 9,10-dimethylanthracene(DPBF) so as to evaluate singlet oxygen production generation. The Eca-109 cells were were exposed to light (650nm) with a constant light power of 200mW/cm2, at a distance of 5cm, for 25 to 200 seconds. The results were measured by MTT assay. Results: pyropheophorbide-a in DMF solution irradiation by different light power can produce singlet oxygen quickly. Comparison of single oxygen generation rate has proved that photodynamic effect at 532nm is fastest, followed by 650nm, 635nm, 690nm which has correlation with absorbance of pyropheophorbide-a. The survival rate of cells dropped after irradiation by light what was significantly different from other groups. Conclusion: pyropheophorbide-a is an excellent photosensitizer and prooxidant. Through activated by different wavelength it could be apply to different disease

Modulation of emission and singlet oxygen photosensitisation in live cells utilising bioorthogonal phosphorogenic probes and protein tag technology

2020 ◽  
Vol 56 (45) ◽  
pp. 6074-6077 ◽  
Author(s):  
Peter Kam-Keung Leung ◽  
Kenneth Kam-Wing Lo
Keyword(s):  
Singlet Oxygen ◽  
Live Cells ◽  
Protein Tag ◽  
Single Oxygen

We developed a strategy to exploit the bioorthogonal reactivity and phosphorogenic property of iridium(iii) polypyridine nitrone complexes and SNAP-tag protein for the modulation of emission and single oxygen photosensitisation in live cells.

Single oxygen generation sensitized by spiro(dipyridinogermole)(dithienogermole)s

2016 ◽  
Vol 45 (39) ◽  
pp. 15679-15683 ◽  
Author(s):  
J. Ohshita ◽  
Yuya Hayashi ◽  
Kazuya Murakami ◽  
Toshiaki Enoki ◽  
Yousuke Ooyama
Keyword(s):  
Singlet Oxygen ◽  
Oxygen Generation ◽  
Single Oxygen

Three spiro(dipyridinogermole)(dithienogermole) derivatives (1–3), including newly prepared spiro(dipyridinogermole)[di(2-pyridyl)dithienogermole] (3), were examined as photosensitizers for singlet oxygen (1O2) generation in dichloromethane–methanol.

DFT study on the quenching mechanism of singlet oxygen by lycopene

RSC Advances ◽  
2016 ◽  
Vol 6 (100) ◽  
pp. 98498-98505 ◽  
Author(s):  
Yingyuan Zhang ◽  
Yi Liu ◽  
Qingzhang Lv
Keyword(s):  
Dft Calculations ◽  
Singlet Oxygen ◽  
Dft Study ◽  
Quenching Mechanism

The quenching mechanism of singlet oxygen by lycopene is analyzed based on DFT calculations at the B3LYP/6-311+(d,p) level.

scholarly journals Induction of benzo[a]pyrene Mono-oxygenase in liver cell culture by the photochemical generation of active oxygen species. Evidence for the involvement of singlet oxygen and the formation of a stable inducing intermediate

1976 ◽  
Vol 158 (1) ◽  
pp. 109-117 ◽  
Author(s):  
A J Paine
Keyword(s):  
Singlet Oxygen ◽  
Culture Medium ◽  
Enzyme System ◽  
Active Oxygen Species ◽  
Active Oxygen ◽  
Oxygen Species ◽  
Photochemical Generation ◽  
Single Oxygen ◽  
Cytochrome P 450 ◽  
Stimulation Of

1. The photochemical generation of excited states of oxygen in liver cell culture by the mild ilumination of culture medium containing riboflavin, results in stimulation of benzo[a]pyrene 3-mono-oxygenase, a cytochrome P-450-linked mono-oxygenase. 2. The same large increase in mono-oxygenase activity was found when medium containing riboflavin was illuminated in the absence of cells and then stored in the dark for 24h before contact with the cells. From this it may be inferred that stimulation is due to the formation of a stable inducer in the culture medium. Further experiments indicate that the stable inducer is due to the photo-oxidation of an amino acid. 3. Evidence that singlet oxygen is responsible for initiating the stimulation of the mono-oxygenase is based on the use of molecules that scavenge particular active oxygen species. Of all the scavengers tested, only those that scavenge single oxygen inhibited the stimulation. 4. A hypothesis is developed to relate the stimulation of the mono-oxygenase by singlet oxygen in cultured cells to the regulation of the cytochrome P-450 enzyme system in vivo. It is suggested that single oxygen generation within cells may be a common factor linking the many structurally diverse inducers of the enzyme system.

Singlet Oxygen Quantum Yields of Different Photosensitizers in Polar Solvents and Micellar Solutions

1998 ◽  
Vol 02 (02) ◽  
pp. 145-158 ◽  
Author(s):  
WOLFGANG SPILLER ◽  
HOLGER KLIESCH ◽  
DIETER WÖHRLE ◽  
STEFFEN HACKBARTH ◽  
BEATE RÖDER ◽  
...  
Keyword(s):  
Singlet Oxygen ◽  
Micellar Solution ◽  
Quantum Yields ◽  
Side Reactions ◽  
Chemical Methods ◽  
Luminescence Method ◽  
Chain Reactions ◽  
Aqueous Micellar Solution ◽  
Photochemical Systems ◽  
Single Oxygen

The singlet oxygen luminescence method and the photochemical methods using 1,3-diphenylisobenzofuran ( DPBF ) or bilirubin ditaurate ( BDT ) as chemical quenchers were employed to determine the single oxygen quantum yields (ΦΔ) of different phthalocyanines and tris(2,2″-bipyridyl)ruthenium(II) dichloride in dimethylformamide ( DMF ) or aqueous micellar solution of 0.1 M CTAC (cetyltrimethylammonium chloride). Additionally, a perylenetetracarboxylic acid diimide derivative was examined in DMF . In a series of tetrasulfonated phthalocyanines ( PTS ) the following order was found: ZnPTS > GaPTS > AlPTS ≈ H 2 PTS > CoPTS . In general, the singlet oxygen quantum yields are higher in DMF than in 0.1 M CTAC/H 2 O . The results obtained with the photochemical systems are comparable with those obtained by the photophysical method. The photochemical DPBF method results in absolute values of ΦΔ. However, in micellar solution, chain reactions occur when DPBF is used as chemical quencher in the photo-oxidative process. This problem can be overcome by adding sodium thiosulphate which is able to destroy the endoperoxide initially formed. BDT can be used as quencher in different solvents to determine ΦΔ relative to a photosensitizer with known singlet oxygen quantum yield in the respective solvent. In comparison to the chemical methods the luminescence method exhibits the advantage that side reactions of the quencher are excluded. But normally the ΦΔ values obtained are relative to a reference, since absolute determinations need much larger efforts.

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