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Bacteriochlorophyll derivatives: Phototoxicity, hyrophobicity & oxygen radicals production
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THE EFFECT OF ANTIOXIDANT SUPPLEMENTATION ON SKIN DAMAGE INDUCED BY UV-GENERATED FREE RADICALS
BACTERIOCHLOROPHYLL DERIVATIVES: PHOTOTOXICITY, HYROPHOBICITY & OXYGEN
Frank McArdle, Christopher A.G. Parslew, Catherine IA.
;;;lo;,
J. Jackson. Department Liverpool, L69 3GA, UK.
Price, Lesley E. Rhodes, Richard Jack, Peter S. Friedmann, Malcolm of Medicine, University of Liverpool,
Using a novel in viva system, we have previously described a complex pattern of changes in markers of free radical activity following ultraviolet light (UVB) exposure of human skin’. This system was used to examine the efF&ts of antioxidant supplementation on these markers, with the aim of providing information on the intake of antioxidants required to protect the skin from ti UVB-induced effects. Three groups of volunteers were supplemented for 8 weeks with either vitamin E (4OOmg/day), vitamin C (SOOmg/day), or p-carotene (1 Smg/day), and theii skin response to UVB compared before and after supplementation. Although supplementation with all three antioxidants reduced some markers of endogenous oxidative stress, including skin malonaldehyde content and oxidised to total glutathione ratios, they appear to have little effect on the UVBThese data do not induced oxidative processes measured. support an increase in the intake of these antioxidants to suppress W-induced oxidative stress. ‘F. McArdle, L.E. Rhodes, C.I.A. Jack, P.S. Freedmann, M.J. Jackson. Free radical Biology and Medicine (1998) 25(Sl) S102
OXYGEN
RADICALS PRODUCTION VokrntY.. We& L., Bmndis, .+, Mazor, O:, Hami, R:, Gross, S., Schreiber, 5.. Y. nnd A&hen
We:zmnnn lnshtute
ofSaence,
Rehouot 76100
Bacteriochlorophylls, substituted with I’d for the central Mg and peripherally modified, were found highly phototoxic in cultured cells (at nh4 concentrations) and tumor xenografts in mice using new strategies of photodynamic therapy. This study presents generation of reactive oxygen species (ROS) by hydrophobic and hydrophilic representatives of the new sensitizer’s class in aqueous and membrane-like environment. Applying Electron Spin Resonance spectroscopy and spin trapping we found that illumination (710-800nm) of a hydrophobic derivative in Triton X-100 or in phosphathidylcholine liposomes produces hydroxyl radicals and singlet oxygen in a time dependent manner with a carbon centered radical appearing with a slight delay. The hydrophilic derivative, examined in Buffered aqueous solution, generated mainly hydroxyl radical and a small amount of singlet oxygen. The photocytotoxicity of of this derivative in cell cultures was 10 times lower (LD50 = 300 nM) than that of the hydrophobic one (LD50 = lo-20 nM). However, the easier application of the first, provides an advantage for in viva application. The correlation between ROS production, senstitzer hydrophilicity and possible subcellular distribution of the new derivatives will be discussed.
’ 9
9
S129
1
) 400
1
THE EFFECT OF ANTIOXIDANT SUPPLEMENTATION ON SKIN DAMAGE INDUCED BY UV-GENERATED FREE RADICALS
BACTERIOCHLOROPHYLL DERIVATIVES: PHOTOTOXICITY, HYROPHOBICITY & OXYGEN
Frank McArdle, Christopher A.G. Parslew, Catherine IA.
;;;lo;,
J. Jackson. Department Liverpool, L69 3GA, UK.
Price, Lesley E. Rhodes, Richard Jack, Peter S. Friedmann, Malcolm of Medicine, University of Liverpool,
Using a novel in viva system, we have previously described a complex pattern of changes in markers of free radical activity following ultraviolet light (UVB) exposure of human skin’. This system was used to examine the efF&ts of antioxidant supplementation on these markers, with the aim of providing information on the intake of antioxidants required to protect the skin from ti UVB-induced effects. Three groups of volunteers were supplemented for 8 weeks with either vitamin E (4OOmg/day), vitamin C (SOOmg/day), or p-carotene (1 Smg/day), and theii skin response to UVB compared before and after supplementation. Although supplementation with all three antioxidants reduced some markers of endogenous oxidative stress, including skin malonaldehyde content and oxidised to total glutathione ratios, they appear to have little effect on the UVBThese data do not induced oxidative processes measured. support an increase in the intake of these antioxidants to suppress W-induced oxidative stress. ‘F. McArdle, L.E. Rhodes, C.I.A. Jack, P.S. Freedmann, M.J. Jackson. Free radical Biology and Medicine (1998) 25(Sl) S102
OXYGEN
RADICALS PRODUCTION VokrntY.. We& L., Bmndis, .+, Mazor, O:, Hami, R:, Gross, S., Schreiber, 5.. Y. nnd A&hen
We:zmnnn lnshtute
ofSaence,
Rehouot 76100
Bacteriochlorophylls, substituted with I’d for the central Mg and peripherally modified, were found highly phototoxic in cultured cells (at nh4 concentrations) and tumor xenografts in mice using new strategies of photodynamic therapy. This study presents generation of reactive oxygen species (ROS) by hydrophobic and hydrophilic representatives of the new sensitizer’s class in aqueous and membrane-like environment. Applying Electron Spin Resonance spectroscopy and spin trapping we found that illumination (710-800nm) of a hydrophobic derivative in Triton X-100 or in phosphathidylcholine liposomes produces hydroxyl radicals and singlet oxygen in a time dependent manner with a carbon centered radical appearing with a slight delay. The hydrophilic derivative, examined in Buffered aqueous solution, generated mainly hydroxyl radical and a small amount of singlet oxygen. The photocytotoxicity of of this derivative in cell cultures was 10 times lower (LD50 = 300 nM) than that of the hydrophobic one (LD50 = lo-20 nM). However, the easier application of the first, provides an advantage for in viva application. The correlation between ROS production, senstitzer hydrophilicity and possible subcellular distribution of the new derivatives will be discussed.
’ 9
9
S129