EVALUATION OF TRIACETYLOLEANDOMYCIN, ALPHA-NAPHTHOFLAVONE AND DIETHYLDITHIOCARBAMATE AS SELECTIVE CHEMICAL PROBES FOR INHIBITION OF HUMAN CYTOCHROMES P450
EVALUATION OF TRIACETYLOLEANDOMYCIN, ALPHA-NAPHTHOFLAVONE AND DIETHYLDITHIOCARBAMATE AS SELECTIVE CHEMICAL PROBES FOR INHIBITION OF HUMAN CYTOCHROMES P450
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DOI：
10.1006/abbi.1994.1259
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发表时间：
1994-06-01
影响因子：
3.9
通讯作者：
WAXMAN, DJ
中科院分区：
文献类型：
--
作者：
CHANG, TKH;GONZALEZ, FJ;WAXMAN, DJ
许多化学物质，包括三乙酰莱兰霉素(TAO)、α-萘黄酮(ANF)和二乙基二硫代氨基甲酸酯(DDC)，被广泛用作个别人细胞色素P450(CYP)酶的抑制探针，尽管这些抑制剂的选择性尚未得到严格评估。在本研究中，我们利用最近在cDNA指导的人P450表达方面的最新进展，使用一组10个单独表达的人P450来直接评估TAO、ANF和DDC的P450形式的选择性。在已知与P450血红蛋白形成最大络合的实验条件下，TAO(20mU M)抑制表达的3A3、3A4和3A5的催化活性，而不影响CyPS 1A1、1A2、2A6、2B6、2C8、2C9和2E1的活性。ANF不仅对Cyps 1A1和1A2有抑制作用(IC50=0.4-0.5µM)，而且对Cyps 2C8和2C9也有同样的抑制作用。当ANF浓度增加到10 mU/M时，对细胞色素P450 2A6和细胞色素P450 2B6有抑制作用。虽然先前的研究表明DDC是一种选择性的CYP2E1抑制剂，但目前的研究表明，在抑制CYP2E1所需的浓度(与NADPH预先孵育时的IC50约为125 mU M)时，DDC也对Cyps 1A1、1A2、2A6、2B6、2C8、3A3和3A4产生抑制作用。然而，将DDC浓度降低到10 mU M时，对细胞色素P450的抑制作用明显增强，对细胞色素P450的抑制率分别为65%和50%，但对包括细胞色素P450 1在内的其他P450酶均无抑制作用。总体而言，这些结果证实：(A)TAO是人CYP3A亚家族的选择性抑制物；(B)ANF除了抑制CYP1A1和1A2外，还有效地抑制CYP2C8和CYP2C9；以及(C)DDC不能用作CYP2E1的诊断抑制探针。(C)1994年学术出版社。
A variety of chemicals, including triacetyloleandomycin (TAO), alpha-naphthoflavone (ANF), and diethyldithiocarbamate (DDC), are widely used as inhibitory probes for select individual human cytochrome P450 (CYP) enzymes, despite the fact that the selectivity of these inhibitors has not been rigorously evaluated. In the present study we take advantage of recent advances in cDNA-directed human P450 expression to evaluate directly the P450 form selectivity of TAO, ANF, and DDC, using a panel of 10 individual cDNA-expressed human P450s. Under experimental conditions known to yield maximal TAO complexation with P450 hemoproteins, TAO (20 mu M) inhibited the catalytic activity of expressed CYPs 3A3, 3A4, and 3A5, whereas it did not affect CYPs 1A1, 1A2, 2A6, 2B6, 2C8, 2C9, or 2E1 activity. ANF inhibited not only CYPs 1A1 and 1A2 (IC50 = 0.4-0.5 mu M), but it was also similarly effective against CYPs 2C8 and 2C9. Increasing the concentration of ANF to 10 mu M led to inhibition of CYP2A6 and CYP2B6. Although a previous study suggested that DDC is a selective inhibitor of CYP2E1, the present investigation shows that at concentrations required to inhibit CYP2E1 (IC50 approximate to 125 mu M when preincubated with NADPH), DDC also inhibited CYPs 1A1, 1A2, 2A6, 2B6, 2C8, 3A3, and 3A4. Decreasing the concentration of DDC to 10 mu M, however, led to inhibition of CYP2A6 (65% inhibition) and CYP2B6 (50% inhibition), but none of the other p450s examined, including CYP2E1. Overall, these results establish that (a) TAO is a selective inhibitor of the human CYP3A subfamily; (b) ANF potently inhibits CYP2C8 and CYP2C9, in addition to CYPs 1A1 and 1A2; and (c) DDC cannot be employed as a diagnostic inhibitory probe for CYP2E1. (C) 1994 Academic Press, Inc.