FREE-RADICALS IN QUINONE-CONTAINING ANTITUMOR AGENTS - ELECTROCHEMICAL REDUCTION OF DIAZIQUONE (2,5-DIAZIRIDINE-3,6-BIS(CARBOETHOXYAMINO)-1,4-BENZOQUINONE) AND 2 ANALOGS

  • 1 January 1984
    • journal article
    • research article
    • Vol. 26  (3) , 582-586
Abstract
The one-electron electrochemical reduction of diaziquone was analyzed using ESR and compared to its enzymatic reduction. Two analogs were used to help the analysis. The analog contained Cl atoms which substituted either the carboethoxyamino groups or the aziridine groups of the parent compound. The diaziquone free radical produced electrochemically in dimethyl sulfoxide exhibited an 11-line ESR spectrum. The hyperfine couplings responsible for this spectrum were due to the aziridine nitrogens .**GRAPHIC**. and the imide hydrogens .**GRAPHIC**. and nitrogens .**GRAPHIC**. of the carboethoxyamino groups. The couplings had the following order of strength: .**GRAPHIC**. > .**GRAPHIC**. > .**GRAPHIC**. The nuclei responsible for the .**GRAPHIC**. and .**GRAPHIC**. coupling were magnetically inequivalent. Adding H2O to the dimethyl sulfoxide solution of electrochemically reduced diaziquone changed its 11-line ESR spectrum to a 5-line spectrum identical to that observed for enzymatically reduced diaziquone. The identity of this latter free radical was resolved. Electrochemically reduced free radicals of antitumor agents can be used to understand biologically reduced ones and thus explore drug activity-free radical structure relationships.

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