Goeptar A R, Te Koppele J M, Lamme E K, Piqué J M, Vermeulen N P
Leiden/Amsterdam Center for Drug Research, Division of Molecular Toxicology, Vrije Universiteit, The Netherlands.
Mol Pharmacol. 1993 Dec;44(6):1267-77.
The role of cytochrome P450 (CYP) in the one-electron reductive bioactivation of Adriamycin (ADR) (doxorubicin) was investigated in subcellular fractions of the rat liver. The rate of one-electron reduction of ADR to its semiquinone free radical (ADRSQ), measured by ESR, was 5-fold greater with phenobarbital (PB)-induced (PB microsomes) than with beta-naphthoflavone (beta NF)-induced (beta NF microsomes) rat liver microsomes under anaerobic conditions. ADRSQ formation was inhibited by SK&F 525-A and metyrapone (MP) in PB microsomes but was not significantly inhibited in beta NF microsomes. Under aerobic conditions, the formation of ADRSQ from ADR was diminished in microsomal incubations and concomitant reduction of molecular oxygen occurred instead. Whereas ADR-induced H2O2 formation in PB microsomes was strongly inhibited by SK&F 525-A and MP, only a slight inhibition was observed with 2-ethylnylnaphthalene and 1-ethynylpyrene in beta NF microsomes. In addition, MP produced strong inhibition of ADR-stimulated lipid peroxidation in PB microsomes, compared with beta NF microsomes. The idea that CYP2B1 was involved in the one-electron reduction of ADR in PB microsomes and in reconstituted systems of purified CYP2B1 and purified NADPH-CYP reductase (RED) under anaerobic conditions could be concluded from inhibition studies using SK&F 525-A and antibodies (KO1) against CYP2B enzymes. Moreover, it was calculated from reconstitution experiments using varying amounts of purified CYP2B1 and purified RED that the contribution of CYP2B1 to the one-electron reduction of ADR was similar to that of RED alone.
在大鼠肝脏亚细胞组分中研究了细胞色素P450（CYP）在阿霉素（ADR，多柔比星）单电子还原生物活化中的作用。在厌氧条件下，通过电子顺磁共振（ESR）测量，苯巴比妥（PB）诱导的（PB微粒体）大鼠肝脏微粒体将ADR单电子还原为其半醌自由基（ADRSQ）的速率比β-萘黄酮（βNF）诱导的（βNF微粒体）大鼠肝脏微粒体快5倍。SK&F 525-A和甲吡酮（MP）可抑制PB微粒体中ADRSQ的形成，但对βNF微粒体中ADRSQ的形成无明显抑制作用。在有氧条件下，微粒体孵育中ADR形成ADRSQ的过程减少，取而代之的是分子氧的伴随还原。虽然SK&F 525-A和MP强烈抑制PB微粒体中ADR诱导的H2O2形成，但在βNF微粒体中，2-乙基萘和1-乙炔基芘仅产生轻微抑制作用。此外，与βNF微粒体相比，MP对PB微粒体中ADR刺激的脂质过氧化有强烈抑制作用。使用SK&F 525-A和针对CYP2B酶的抗体（KO1）进行的抑制研究可以得出结论，即在厌氧条件下，CYP2B1参与了PB微粒体中ADR的单电子还原以及纯化的CYP2B1和纯化的NADPH-CYP还原酶（RED）的重组系统。此外，通过使用不同量的纯化CYP2B1和纯化RED进行的重组实验计算得出，CYP2B1对ADR单电子还原的贡献与单独的RED相似。
