Photoprotective actions of natural and synthetic melanins

被引:94
作者
Krol, ES [1 ]
Liebler, DC [1 ]
机构
[1] Univ Arizona, Coll Pharm, Dept Pharmacol & Toxicol, Tucson, AZ 85721 USA
关键词
D O I
10.1021/tx980114c
中图分类号
R914 [药物化学];
学科分类号
100701 ;
摘要
Melanins are thought to be important modulators of photochemistry in skin. Eumelanin, a black-brown pigment, is believed to protect against UV-induced photodamage, whereas pheomelanin, a red-Yellow pigment, is believed to possess photosensitizing properties. To investigate the hypothesized dichotomy of melanins as both photoprotectants and photosensitizers, we examined the effects of melanins on UV-induced liposomal lipid peroxidation. Sepia melanin, a representative eumelanin, and both red hail pheomelanin and synthetic pheomelanin were employed in these studies. Both eumelanin and pheomelanin inhibited UVA/B- and UVA-induced liposomal lipid peroxidation in a concentration-dependent manner as measured by inhibition of conjugated diene formation. No change in protective properties of the melanins was observed in the presence of saturating levels of O-2 during UVA irradiation, Pheomelanin irradiated with UVA/B or UVA induced superoxide-catalyzed reduction of nitroblue tetrazolium, whereas eumelanin did not. Melanins are known to bind various metals, and we examined the effect of iron on the photoproperties of melanins. Eumelanin complexed with Fe(III) did not inhibit UVA/B-induced lipid peroxidation, whereas pheomelanin complexed with Fe(III) stimulated UVA/B-induced lipid peroxidation. Thus, complexation with iron reversed the antioxidant effect of eumelanin anti converted pheomelanin into a prooxidant. Analysis of lipid peroxidation products indicated that the oxidation was mediated by free radicals rather than by singlet oxygen. These data indicate that both eumelanin and pheomelanin exert antioxidant effects against UV-induced lipid peroxidation but that the prooxidant activities of pheomelanin result from pheomelanin-metal complexation.
引用
收藏
页码:1434 / 1440
页数:7
相关论文
共 32 条
[1]   PHOTODEGRADATION OF PHAEOMELANIN - AN INVITRO MODEL [J].
AGIN, PP ;
SAYRE, RM ;
CHEDEKEL, MR .
PHOTOCHEMISTRY AND PHOTOBIOLOGY, 1980, 31 (04) :359-362
[2]  
Buege J A, 1978, Methods Enzymol, V52, P302
[3]   ROLE OF MELANIN AS A SCAVENGER OF ACTIVE OXYGEN SPECIES [J].
BUSTAMANTE, J ;
BREDESTON, L ;
MALANGA, G ;
MORDOH, J .
PIGMENT CELL RESEARCH, 1993, 6 (05) :348-353
[4]   PHOTODESTRUCTION OF PHEOMELANIN - ROLE OF OXYGEN [J].
CHEDEKEL, MR ;
SMITH, SK ;
POST, PW ;
POKORA, A ;
VESSELL, DL .
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, 1978, 75 (11) :5395-5399
[5]   PHOTODESTRUCTION OF PHAEOMELANIN [J].
CHEDEKEL, MR ;
POST, PW ;
DEIBEL, RM ;
KALUS, M .
PHOTOCHEMISTRY AND PHOTOBIOLOGY, 1977, 26 (06) :651-653
[6]   SUNLIGHT, MELANOGENESIS AND RADICALS IN THE SKIN [J].
CHEDEKEL, MR ;
ZEISE, L .
LIPIDS, 1988, 23 (06) :587-591
[7]   Melanins in physiological conditions protect against lipoperoxidation. A study on albino and pigmented Xenopus [J].
Corsaro, C ;
Scalia, M ;
Blanco, AR ;
Aiello, I ;
Sichel, G .
PIGMENT CELL RESEARCH, 1995, 8 (05) :279-282
[9]   INTERACTIONS OF MELANIN WITH METAL-IONS - ELECTRON-SPIN RESONANCE EVIDENCE FOR CHELATE COMPLEXES OF METAL-IONS WITH FREE-RADICALS [J].
FELIX, CC ;
HYDE, JS ;
SARNA, T ;
SEALY, RC .
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 1978, 100 (12) :3922-3926
[10]   MELANIN PHOTOREACTIONS IN AERATED MEDIA - ELECTRON-SPIN RESONANCE EVIDENCE FOR PRODUCTION OF SUPEROXIDE AND HYDROGEN-PEROXIDE [J].
FELIX, CC ;
HYDE, JS ;
SARNA, T ;
SEALY, RC .
BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS, 1978, 84 (02) :335-341