Singlet oxygen reactions in aqueous solution. Physical and chemical quenching rate constants of crocin and related carotenoids

1987 ◽  
Vol 28 (36) ◽  
pp. 4221-4224 ◽  
Author(s):  
Paolo Manitto ◽  
Giovanna Speranza ◽  
Diego Monti ◽  
Paola Gramatica
Keyword(s):  
Aqueous Solution ◽  
Singlet Oxygen ◽  
Rate Constants ◽  
Quenching Rate ◽  
Physical And Chemical

Carotenoids, tocopherols and thiols as biological singlet molecular oxygen quenchers

1990 ◽  
Vol 18 (6) ◽  
pp. 1054-1056 ◽  
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.

A physical and chemical investigation of the nature and properties of the species formed in the Hg(63P1)–CO system

1970 ◽  
Vol 48 (9) ◽  
pp. 1420-1431 ◽  
Author(s):  
G. London ◽  
A. C. Vikis ◽  
D. J. Le Roy
Keyword(s):  
Carbon Monoxide ◽  
Rate Constants ◽  
Chemical Investigation ◽  
Enhancement Effect ◽  
Quenching Rate ◽  
Physical Measurements ◽  
Quenching Process ◽  
Excimer Formation ◽  
Physical And Chemical

An investigation of the Hg(63P1)–CO system by physical measurements (emission, pressure studies) relevant to the reported Hg*CO species have yielded no additional evidence of its formation.Chemical experiments on the decomposition of ethylene and H2 are in accord with formation of a long lived (> 10−5 s) species. The relative quenching rate constants of the species by C2H4, H2, and CO are 1:0.10–0.18:0.023, respectively.The reliability of the "carbon monoxide effect" as a criterion for distinguishing the nature of the quenching process is discussed in the light of a CO enhancement effect (~ 30%) observed in the Hg(63P1) photosensitized decomposition of hydrogen in the presence of CO and at conditions of incomplete quenching. An alternative to Hg*CO excimer formation is also discussed. This approach is based on the possible formation of Hg(63P0) atoms in quantities in excess of those currently accepted, when Hg–CO mixtures are irradiated with 2537 Å light.

scholarly journals Singlet Oxygen in a Cell: Spatially Dependent Lifetimes and Quenching Rate Constants

2009 ◽  
Vol 131 (1) ◽  
pp. 332-340 ◽  
Author(s):  
Marina K. Kuimova ◽  
Gokhan Yahioglu ◽  
Peter R. Ogilby
Keyword(s):  
Singlet Oxygen ◽  
Rate Constants ◽  
Quenching Rate ◽  
A Cell

scholarly journals Comparison of Antioxidant Properties of Dehydrolutein with Lutein and Zeaxanthin, and their Effects on Retinal Pigment Epithelial Cells

2021 ◽  
Author(s):  
Malgorzata Rozanowska ◽  
Barbara Czuba-Pelech ◽  
John T. Landrum ◽  
Bartosz Rozanowski
Keyword(s):  
Singlet Oxygen ◽  
Rate Constants ◽  
Retinal Pigment ◽  
Antioxidant Properties ◽  
Retinal Pigment Epithelial Cells ◽  
Oxygen Quenching ◽  
Quenching Rate ◽  
Photosensitized Oxidation ◽  
Singlet Oxygen Quenching ◽  
Cell Extracts

Dehydrolutein accumulates in substantial concentrations in the retina. The aim of this study was to compare antioxidant properties of dehydrolutein with other retinal carotenoids, lutein and zeaxanthin, and their effects on ARPE-19 cells. The time-resolved detection of characteristic singlet oxygen phosphorescence was used to compare the singlet oxygen quenching rate constants of dehydrolutein, lutein, and zeaxanthin. The effects of these carotenoids on photosensitized oxidation were tested in liposomes, where photooxidation was induced by light in the presence of photosensitizers, and monitored by oximetry. To compare the uptake of dehydrolutein, lutein, and zeaxanthin, ARPE-19 cells were incubated with carotenoids for up to 19 days, and carotenoid contents were determined by spectrophotometry in cell extracts. To investigate the effects of carotenoids on phototocytotoxicity, cells were exposed to light in the presence of rose bengal or all-trans-retinal. The results demonstrate that the rate constants for singlet oxygen quenching are 0.77x1010, 0.55x1010, and 1.23x1010 M-1s-1 for dehydrolutein, lutein and zeaxanthin, respectively. Overall, dehydrolutein is similar to lutein or zeaxanthin in protection of lipids against photosensitized oxidation. ARPE-19 cells accumulate substantial amounts of both zeaxanthin and lutein but no detectable amounts of dehydrolutein. Cells pre-incubated with carotenoids are equally susceptible to photosensitized damage as cells without carotenoids. Carotenoids provided to cells together with the extracellular photosensitizers offer partial protection against photodamage. In conclusion, the antioxidant properties of dehydrolutein are similar to lutein and zeaxanthin. The mechanism responsible for its lack of accumulation in ARPE-19 cells deserves further investigation.

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