Occurrence of singlet oxygen oxygenation of oleic acid and linoleic acid in the skin of live mice
Department of Food Science, Graduate School of Nutrition and Bioscience, The University of Tokushima, Tokushima, Japan. Free Radical Research
(Impact Factor: 2.98).
04/2008; 42(3):197-204. DOI: 10.1080/10715760801948088
To assess the contribution of singlet molecular oxygen [O(2) ((1)Delta(g))] to lipid peroxidation in vivo, this study combined gas chromatography-mass spectrometry with thin layer chromatography to analyse peroxidized lipids in the skin of hairless mice. Hydroxyoctadecenoate isomers and unconjugated hydroxyoctadecadienoate isomers derived from peroxidized oleic acid and linoleic acid, respectively, which are specific to O(2) ((1)Delta(g))-dependent oxygenation, were detected in the skin of live mice under ordinary feeding conditions. Short-term ultraviolet A (UVA)-irradiation of the skin in vivo elevated levels of the unconjugated hydroxyoctadecadienoate isomers significantly, whereas the irradiation of skin homogenate in vitro increased levels of all isomers derived from both O(2) ((1)Delta(g)) and free radical-dependent oxygenation to a much greater extent. This is the first report to demonstrate the occurrence of O(2) ((1)Delta(g))-specific oxygenation of unsaturated fatty acids in living animals.
Available from: PubMed Central
- "O2 (1Δg) oxygenation-specific lipid hydroperoxide isomers appeared in the peroxidized phospholipids of mouse skin homogenate after irradiation with UVA light.(31) We recently developed a new method for the gas chromatography-mass spectrometry (GC-MS) analysis of esterified fatty acid hydroperoxides, and demonstrated that O2 (1Δg) oxygenation–specific hydroperoxides isomers accumulated in the skin lipids of hairless mice at higher levels due to the exposure of UVA.(32) These animal studies clearly indicated that O2 (1Δg) originating from type-II photosensitized oxidation participates in the oxidative stress and injury to the skin seen after chronic exposure to UVA. "
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ABSTRACT: Carotenoids are known to be potent quenchers of singlet molecular oxygen [O(2) ((1)Δ(g))]. Solar light-induced photooxidative stress causes skin photoaging by accelerating the generation of reactive oxygen species via photodynamic actions in which O(2) ((1)Δ(g)) can be generated by energy transfer from excited sensitizers. Thus, dietary carotenoids seem to participate in the prevention of photooxidative stress by accumulating as antioxidants in the skin. An in vivo study using hairless mice clarified that a O(2) ((1)Δ(g)) oxygenation-specific peroxidation product of cholesterol, cholesterol 5α-hydroperoxide, accumulates in skin lipids due to ultraviolet-A exposure. Matrix metalloproteinase-9, a metalloproteinase family enzyme responsible for the formation of wrinkles and sagging, was enhanced in the skin of ultraviolet-A -irradiated hairless mice. The activation of metalloproteinase-9 and the accumulation of 5α-hydroperoxide, as well as formation of wrinkles and sagging, were lowered in mice fed a β-carotene diet. These results strongly suggest that dietary β-carotene prevents the expression of metalloproteinase-9 (at least in part), by inhibiting the photodynamic action involving the formation of 5α-hydroperoxide in the skin. Intake of β-Carotene therefore appears to be helpful in slowing down ultraviolet-A -induced photoaging in human skin by acting as a O(2) ((1)Δ(g)) quencher.
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ABSTRACT: The activation of matrix metalloproteinase (MMP)-9 leading to the formation of wrinkle and sagging of skin is an essential step in the skin photoaging on exposure to ultraviolet A (UVA). This study attempted to elucidate the role of peroxidized cholesterol including cholesterol hydroperoxides (Chol-OOHs), primary products of lipid peroxidation in biomembranes, in MMP-9 activation and the effect of dietary beta-carotene in MMP-9 activation. Hairless mice were subjected to periodic UVA irradiation for 8 weeks. The amount of peroxidized cholesterol detected as total hydroxycholesterol in the skin was increased significantly by the exposure. The activity and protein level of MMP-9 were elevated with wrinkling and sagging formation. MMP-9 activity was also enhanced by the intracutaneous injection of Chol-OOHs into the mouse skin. Adding beta-carotene to the diet of the mice during the period of irradiation suppressed the activity and expression of MMP-9 as well as the wrinkling and sagging formation. The amount of cholesterol 5alpha-hydroperoxide, a singlet molecular oxygen oxygenation-specific peroxidized cholesterol, was significantly lowered by the addition of beta-carotene to the diet. These results strongly suggest that Chol-OOHs formed on exposure to UVA contribute to the expression of MMP-9, resulting in photoaging. Dietary beta-carotene prevents the expression of MMP-9, at least partly, by inhibiting photodynamic action involved in the formation of Chol-OOHs.
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ABSTRACT: Lipid peroxidation (LPO) has been shown to induce disturbance of membrane organization and functional loss and modification of proteins and DNA bases, and it has been implicated in the pathogenesis of various diseases. At the same time, LPO products have been shown to act as redox signaling mediators. Free and ester forms of both polyunsaturated fatty acids and cholesterol are important substrates for LPO in vivo and they are oxidized by both enzymatic and nonenzymatic mechanisms to give a variety of products. The results of numerous studies reported in the literatures show that the levels of LPO products in plasma of healthy human subjects are below 1 muM and that the molar ratios of LPO products to the respective parent lipids are below 1/1000, that is, below 0.1%. The levels of LPO products in human erythrocytes were found to be higher than those in plasma. Considerable levels of cholesterol oxidation products were observed. Although many LPO products exert cytotoxicity, sublethal concentrations of LPO products induce cellular adaptive responses and enhance tolerance against subsequent oxidative stress through upregulation of antioxidant compounds and enzymes. This adaptive response is observed not only for chemically reactive alpha,beta-unsaturated carbonyl compounds such as 4-hydroxy-2-nonenal and 15-deoxy-delta-12,14-prostaglandin J(2) but also for chemically stable compounds such as hydroxyoctadecadienoic acid, hydroxylcholesterol, and lysophosphatidylcholine. Such opposite dual functions of LPO products imply that LPO, and probably oxidative stress in general, may exert both deleterious and beneficial effects in vivo. LPO as well as reactive oxygen and nitrogen species has been shown to play an important role as a regulator of gene expression and cellular signaling messenger. In order to exert physiologically important functions as a regulator of gene expression and mediator of cellular signaling, the formation of LPO products must be strictly controlled and programmed. In contrast to LPO products by enzymatic oxidation, it appears difficult to regulate the formation of free radical-mediated LPO products. Even such unregulated LPO products may exert beneficial effects at low levels, but excessive unregulated LPO may lead to pathological disorders and diseases.
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