Gutierrez P L, Biswal S, Nardino R, Biswal N
Cancer Res. 1986 Nov;46(11):5779-85.
To analyze the mode of action of diaziquone [AZQ] on DNA, we examined the activity of two AZQ analogues and N,N',N"-triethylenethiophosphoramide on three forms [supercoiled (Form I), open circular (Form II), and linear (Form III)] of PM-2 DNA. The AZQ analogues contained chlorine atoms which substituted either the carbethoxyamino groups or the aziridine groups of the parent compound. N,N',N"-triethylenethiophosphoramide is a triaziridine compound containing pentavalent phosphorus instead of a quinone group. We found that only when reduced with sodium borohydride did AZQ change the topology of the three forms of PM-2 DNA by introducing mainly single strand breaks. The AZQ analogue containing only aziridines (RQ2) was active in both its oxidized and its reduced forms, while the analogue containing only the carbethoxyamino groups (RQ14) or N,N',N"-triethylenethiophosphoramide were not active in either form. Under similar experimental conditions, Adriamycin alone altered the electrophoretic mobility of PM-2 DNA, while borohydride reduced Adriamycin did not. By using electron spin resonance spectroscopy, we showed that dihydrodiaziquone (AZQH2) oxidizes to the semiquinone in the presence of oxygen. Although AZQH2 was active against DNA, it was not active against cellular DNA synthesis as measured by [3H]thymidine incorporation into exponentially growing HEp-2 cells. However, AZQ alone prevented [3H]thymidine incorporation into HEp-2 cells. We found that HEp-2 cells have the ability to reduce AZQ to its free radical anion, but AZQH2 does not autoxidize to the free radical in the presence of cells. The reductive ability of HEp-2 cells may be responsible in part for preventing the oxidation of AZQH2 to the free radical. We found that under our conditions (1-h incubations) the aziridines are essential for the activity of aziridinyl quinones against PM-2 DNA and that in the case of AZQ the hydroquinone is also required.
为分析重氮醌[AZQ]对DNA的作用模式，我们检测了两种AZQ类似物以及氮芥对PM-2 DNA的三种形式[超螺旋（形式I）、开环（形式II）和线性（形式III）]的活性。AZQ类似物含有氯原子，这些氯原子取代了母体化合物的乙氧羰基氨基或氮丙啶基团。氮芥是一种含五价磷而非醌基的三氮丙啶化合物。我们发现，只有在用硼氢化钠还原时，AZQ才会通过主要引入单链断裂来改变PM-2 DNA三种形式的拓扑结构。仅含氮丙啶的AZQ类似物（RQ2）在氧化态和还原态均有活性，而仅含乙氧羰基氨基的类似物（RQ14）或氮芥在两种形式下均无活性。在相似的实验条件下，单独的阿霉素会改变PM-2 DNA的电泳迁移率，而硼氢化钠还原后的阿霉素则不会。通过电子自旋共振光谱法，我们表明二氢重氮醌（AZQH2）在有氧存在时会氧化为半醌。尽管AZQH2对DNA有活性，但通过将[3H]胸苷掺入指数生长的HEp-2细胞来测定，它对细胞DNA合成无活性。然而，单独的AZQ可阻止[3H]胸苷掺入HEp-2细胞。我们发现HEp-2细胞有能力将AZQ还原为其自由基阴离子，但AZQH2在细胞存在时不会自氧化为自由基。HEp-2细胞的还原能力可能部分负责防止AZQH2氧化为自由基。我们发现，在我们的条件下（1小时孵育），氮丙啶对于氮丙啶基醌对PM-2 DNA的活性至关重要，并且就AZQ而言，对苯二酚也是必需的。
