CUTANEOUS PHOTOTOXICITY OF TETRACYCLINE ANTIBIOTICS: GENERATION OF FREE RADICALS and SINGLET OXYGEN DURING PHOTOLYSIS AS MEASURED BY SPIN-TRAPPING and THE PHOSPHORESCENCE OF SINGLET MOLECULAR OXYGEN

AbstractThe electronically excited molecular oxygen (singlet oxygen, [1]O[2]) can be detrimental to cells in several ways, although recent reports indicate that it may play a role as an intercellular signal in eukaryotes. Here we present evidence that [1]O[2], generated by thermodissociation of disodium 3,3(1,4-naphthylidene) diproprionate endoperoxide, activates transcription of genes of the soxRS regulon, and that this induction is paralleled by induction of a soxS::lacZ operon fusion. The inductions were dependent on a functional soxR gene. These data imply that protective responses, such as induction of the soxRS regulon, may be triggered by diverse environmental oxidative stresses, and that [1]O[2] may also function as a signal molecule in prokaryotes.

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Generation of singlet oxygen (1O2) from hydrogen peroxide decomposition by in situ generated hypervalent iodoarene reagents

Pure and Applied Chemistry ◽

10.1515/pac-2013-0812 ◽

2014 ◽

Vol 86 (6) ◽

pp. 945-952 ◽

Cited By ~ 1

Author(s):

Erbay Kalay ◽

Hamdullah Kılıç ◽

Mustafa Catir ◽

Murat Cakici ◽

Cavit Kazaz

Keyword(s):

Hydrogen Peroxide ◽

Singlet Oxygen ◽

Molecular Oxygen ◽

Singlet Molecular Oxygen ◽

Hydrogen Peroxide Decomposition ◽

Co Catalyst ◽

Peroxide Decomposition ◽

Novel Method

AbstractA novel method for the production of singlet oxygen from H2O2 was developed. A combination of iodoarene (ArI), methyltrioxorhenium (MTO), and H2O2 in the presence of pyridine as the co-catalyst efficiently produced singlet molecular oxygen (1O2) under biphasic conditions. The existence of 1O2 was demonstrated by trapping experiments with aromatic dienes, 1,3-cyclodienes, and alkenes. The mechanism of 1O2 production from the iodoarene/MTO/35 % H2O2 system and the reaction scope was also discussed.

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Singlet oxygen in the environmental sciences. IX. Product distribution from reactions of singlet molecular oxygen in the gas phase

Journal of the American Chemical Society ◽

10.1021/ja00727a006 ◽

1970 ◽

Vol 92 (24) ◽

pp. 7042-7044 ◽

Cited By ~ 1

Author(s):

James N. Pitts ◽

W. S. Gleason ◽

Ionel. Rosenthal

Keyword(s):

Singlet Oxygen ◽

Gas Phase ◽

Molecular Oxygen ◽

Product Distribution ◽

Environmental Sciences ◽

Singlet Molecular Oxygen

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Carotenoids, tocopherols and thiols as biological singlet molecular oxygen quenchers

Biochemical Society Transactions ◽

10.1042/bst0181054 ◽

1990 ◽

Vol 18 (6) ◽

pp. 1054-1056 ◽

Cited By ~ 182

Author(s):

PAOLO Di MASCIO ◽

THOMAS P. A. DEVASAGAYAM ◽

STEPHAN KAISER ◽

HELMUT SIES

Keyword(s):

Singlet Oxygen ◽

Molecular Oxygen ◽

Rate Constants ◽

Protective Action ◽

Biological Tissues ◽

Oxygen Quenching ◽

Quenching Rate ◽

Singlet Molecular Oxygen ◽

Singlet Oxygen Quenching ◽

Β Carotene

Singlet molecular oxygen (1O2) has been shown to be generated in biological systems and is capable of damaging proteins, lipids and DNA. The ability of some biological antioxidants to quench 1O2 was studied by using singlet oxygen generated by the thermodissociation of the endoperoxide of 3,3′-(1,4-naphthylidene) dipropionate (NDPO2). The carotenoid lycopene was the most efficient 1O2 quencher (kq + kr = 31 × 109m-1s-1). Tocopherols and thiols were less effective. The singlet oxygen quenching ability decreased in the following order: lycopene, γ-carotene, astaxanthin, canthaxanthin, α-carotene, β-carotene, bixin, zeaxanthin, lutein, bilirubin, biliverdin, tocopherols and thiols. However, the compounds with low quenching rate constants occur at higher levels in biological tissues. Thus, carotenoids and tocopherols may contribute almost equally to the protection of tissues against the deleterious effects of 1O2. The quenching abilities of carotenoids and tocopherols were mainly due to physical quenching. In case of some thiols chemical quenching also plays a significant role. Carotenoids and tocopherols have been reported to exert a protective action against some types of cancer.

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