Cahill A, Jenkins T C, White I N
MRC Toxicology Laboratories, Carshalton, Surrey, U.K.
Biochem Pharmacol. 1993 Jan 26;45(2):321-9. doi: 10.1016/0006-2952(93)90067-7.
Purified DT-diaphorase [NAD(P)H (quinone acceptor) oxidoreductase (EC.1.6.99.2)] from Walker cells was used to investigate the reductive metabolism of 3-amino-1,2,4-benzotriazine-1,4-dioxide (SR 4233) under aerobic and anaerobic conditions. In the presence of NADPH, under aerobic conditions, HPLC analysis showed the four-electron reduction product 3-amino-1,2,4-benzotriazine (SR 4330) was the major reaction product. In contrast, anaerobically, the 2-electron reduction product 3-amino-1,2,4-benzotriazine-1-oxide (SR 4317) was the predominant metabolite. Anaerobic reduction of SR 4233 to the known metabolites SR 4317 and SR 4330, catalyzed by DT-diaphorase, was 3-fold higher than reduction under aerobic conditions. Anaerobically, approximately half of the substrate utilized could not be accounted for by the formation of known products. Aerobically, the majority of the SR 4233 lost could be accounted for by its conversion to SR 4317 and SR 4330. In Walker cells incubated with SR 4233 anaerobically, SR 4317 was the major metabolite formed. Dicoumarol (100 microM) had little effect on the rate of formation of this metabolite in this cell line or in a rat liver epithelial derived (JBJ) cell line. Dicoumarol did however partially reduce the induction of unscheduled DNA synthesis caused by SR 4233 in Walker cells but not in JB1 cells, suggesting the action of dicoumarol may be specific to Walker cells. It is concluded that DT-diaphorase plays only a minor role in the overall reduction of SR 4233 in the two cell lines studied.
用从沃克细胞中纯化得到的DT-黄递酶[NAD(P)H(醌受体)氧化还原酶(EC.1.6.99.2)]来研究3-氨基-1,2,4-苯并三嗪-1,4-二氧化物(SR 4233)在需氧和厌氧条件下的还原代谢。在有NADPH存在的情况下，需氧条件下，高效液相色谱分析显示四电子还原产物3-氨基-1,2,4-苯并三嗪(SR 4330)是主要反应产物。相比之下，在厌氧条件下，双电子还原产物3-氨基-1,2,4-苯并三嗪-1-氧化物(SR 4317)是主要代谢物。由DT-黄递酶催化的SR 4233厌氧还原为已知代谢物SR 4317和SR 4330的反应，比需氧条件下的还原反应高3倍。在厌氧条件下，大约一半利用的底物无法通过已知产物的形成来解释。在需氧条件下，损失的大部分SR 4233可通过其转化为SR 4317和SR 4330来解释。在厌氧条件下用SR 4233孵育的沃克细胞中，SR 4317是形成的主要代谢物。双香豆素(100微摩尔)对该细胞系或大鼠肝上皮衍生的(JBJ)细胞系中这种代谢物的形成速率几乎没有影响。然而，双香豆素确实部分降低了SR 4233在沃克细胞中而非JB1细胞中引起的非程序性DNA合成的诱导，这表明双香豆素的作用可能对沃克细胞具有特异性。得出的结论是，在所研究的两种细胞系中，DT-黄递酶在SR 4233的整体还原中仅起次要作用。
