Investigations of anthralin free radicals in model systems and in skin of hairless mice.
The antipsoriatic compound anthralin (1.8-dihydroxy-9-anthrone) is converted in skin into several oxidized products, including persistent free radicals that are not well characterized. Anthralin oxidation was investigated by electron spin resonance spectroscopy in a biological system and in a chemical system. Free radical formation in the skin of hairless mice is reduced by the antioxidant tocopherol. The data indicate that tocopherol acts by interfering with free radical formation rather than by scavenging persistent anthralin radicals directly. The skin radicals do not correspond to 10-anthranyl, the initial paramagnetic anthralin oxidation product. Similar radicals obtained in skin are formed by anthralin exposed to ultraviolet light or alkaline solution and by mitochondria and microsomes. The pertinent skin radical is attributed to products derived from anthralin dark structures, the final oxidation products of anthralin. It is suggested that resonance stabilized, paramagnetic polycyclic hydrocarbons are the compounds detected. Their stability and low reactivity indicate a low potential for cutaneous irritation and tumor promotion. Reactive oxygen species, which have been reported to be formed concomitantly during oxidation of anthralin, and the initially formed highly reactive 10-anthranyl radical are more potent candidates for mediating tumor promotion and inflammation.
Fuchs
J
J
Department of Physiology and Anatomy, University of California Berkeley, CA 94720.
Packer
L
L
D000818:Animals; D000875:Anthralin / Q000032:analysis*; D004578:Electron Spin Resonance Spectroscopy; D005260:Female; D005609:Free Radicals; D051379:Mice; D008812:Mice, Hairless; D012867:Skin / Q000032:analysis*
D005609:Free Radicals; D000875:Anthralin