Cellular activation of diaziquone [2,5-diaziridinyl-3,6-bis (carboethoxyamino)-1,4-benzoquinone] to its free radical species.

Human leukemic cell lines K562 and HL60, and the murine leukemic cell line L1210, reduce Diaziquone (AZQ) (NCS182986) to its free radical anion. With all cell lines, the free radical was observed immediately in both aerobic and anaerobic cell suspensions. The steady-state concentration of AZQ free radicals was approximately 1% of the total AZQ concentration. L1210 cells treated with azide reduced AZQ, but cells treated with diamide and N-ethylmaleimide did not. NADPH and L-cysteine reduced AZQ. The latter did so under anaerobic conditions; the former did so under both anaerobic and aerobic conditions.