Xanthine oxidase-catalyzed metabolism of 2-nitrofluorene, a carcinogenic air pollutant, in rat skin.
The reductive metabolism of 2-nitrofluorene, a carcinogenic air pollutant, in rat skin microsomes and cytosol was investigated. 2-Nitrofluorene was reduced to the corresponding amine by the microsomes with NADPH and by the cytosol with 2-hydroxypyrimidine or 4-hydroxypyrimidine under anaerobic conditions. The cytosolic activity was much higher than that of skin microsomes. The 2- or 4-hydroxypyrimidine-linked nitroreductase activity was inhibited by oxypurinol and (+/-)-8-(3-methoxy-4-phenylsulfinylphenyl) pyrazolo[1,5-a]-1,3,5-triazine-4(1H)-one (BOF-4272), inhibitors of xanthine oxidase, but not by menadione, chlorpromazine and isovanillin, inhibitors of aldehyde oxidase. When skin cytosol was applied to a DEAE-cellulose column, the fractions containing xanthine oxidase exhibited a marked 2-hydroxypyrimidine-linked nitroreductase activity. In contrast, the aldehyde oxidase fraction showed little activity. Nitroreductase fractions obtained by ion exchange chromatography showed a band in Western blotting analysis using anti-rat xanthine oxidase. Moreover, the xanthine oxidase fraction exhibited a significant nitroreductase activity in the presence of 2-hydroxypyrimidine, 4-hydroxypyrimidine or hypoxanthine, and these activities were inhibited by inhibitors of xanthine oxidase. These results indicated that reduction of 2-nitrofluorene in the skin was mainly catalyzed by xanthine oxidase.
Ueda
Osamu
O
Graduate School of Biomedical Sciences, Hiroshima University, Kasumi 1-2-3, Minami-ku, Hiroshima 734-8551, Japan.
Kitamura
Shigeyuki
S
Ohashi
Koji
K
Sugihara
Kazumi
K
Ohta
Shigeru
S
D000393:Air Pollutants / Q000378:metabolism* / Q000506:poisoning; D000818:Animals; D015153:Blotting, Western / Q000379:methods; D002848:Chromatography, DEAE-Cellulose / Q000295:instrumentation / Q000379:methods; D002851:Chromatography, High Pressure Liquid / Q000295:instrumentation / Q000379:methods; D003600:Cytosol / Q000378:metabolism; D004347:Drug Interactions; D005449:Fluorenes / Q000378:metabolism* / Q000506:poisoning; D066298:In Vitro Techniques; D008297:Male; D008861:Microsomes / Q000378:metabolism; D010084:Oxidation-Reduction; D051381:Rats; D017207:Rats, Sprague-Dawley; D012867:Skin / Q000201:enzymology*; D013997:Time Factors; D014969:Xanthine Oxidase / Q000378:metabolism*
D000393:Air Pollutants; D005449:Fluorenes; C019499:2-nitrofluorene; C012177:2-aminofluorene; D014969:Xanthine Oxidase