Yamaguchi T, Horio F, Hashizume T, Tanaka M, Ikeda S, Kakinuma A, Nakajima H
Department of Biochemical Genetics, Tokyo Medical and Dental University, Japan.
Biochem Biophys Res Commun. 1995 Sep 5;214(1):11-9. doi: 10.1006/bbrc.1995.2250.
We examined the possibility that bilirubin physiologically acts as an antioxidant by using scurvy-prone ODS-od/od rats treated with endotoxin (lipopolysaccharide: LPS). Recently, bilirubin oxidative metabolites were isolated from human urine and named biotripyrrin-a and biotripyrrin-b. The LPS injection markedly increased bilirubin oxidative metabolites in urine of rats fed an ascorbic acid-free diet. This increase was supressed by feeding an adequate amount of ascorbic acid, a physiological antioxidant. the concentrations of biotripyrrin-a and -b in urine collected 6.5-10 h after the LPS injection were lower in rats fed an ascorbic acid-supplemented diet than in rats fed an ascorbic acid-free diet. Moreover, feeding with ascorbic acid suppressed the elevation of hepatic mRNA level of heme oxygenase-1, the rate-limiting enzyme of bilirubin biosynthesis, in rats injected with LPS. These findings suggest that bilirubin is oxidized in rats treated with LPS and acts as a physiological antioxidant synergistically with ascorbic acid in vivo.
我们通过使用易患坏血病的经内毒素（脂多糖：LPS）处理的ODS-od/od大鼠，研究了胆红素在生理上作为抗氧化剂的可能性。最近，从人尿中分离出胆红素氧化代谢产物，并将其命名为生物三吡咯-a和生物三吡咯-b。注射LPS显著增加了喂食无抗坏血酸饮食的大鼠尿液中的胆红素氧化代谢产物。通过喂食适量的生理抗氧化剂抗坏血酸，这种增加受到抑制。在注射LPS后6.5 - 10小时收集的尿液中，喂食补充抗坏血酸饮食的大鼠的生物三吡咯-a和-b的浓度低于喂食无抗坏血酸饮食的大鼠。此外，喂食抗坏血酸抑制了注射LPS的大鼠中血红素加氧酶-1（胆红素生物合成的限速酶）的肝脏mRNA水平的升高。这些发现表明，在用LPS处理的大鼠中胆红素被氧化，并在体内与抗坏血酸协同作为生理抗氧化剂。
