REDUCTIVE ACTIVATION OF POTENTIAL ANTITUMOR MITOSENE COMPOUNDS

The reductive activation of mitosene compounds was studied with cyclic voltammetry and HPLC analysis. Reduction of mitosenes, possessing goo d leaving groups at C-1 and C-10, was shown to result in loss of these groups pH 7.0 and 6.0. The loss of leaving groups from mitosenes occu rred faster at lower pH. Mitosenes without good leaving groups were fo und to be stable upon reduction. In the presence of acetoxy groups at C-1 and C-10, the C-10 site is the most reactive site upon reductive a ctivation. This is opposite to the case of mitomycin C, where the C-1 site is the first to react upon reduction. At pH 6.0 without reduction , acid degradation also caused the loss of leaving groups of mitosenes , although at a very slow rate. In contrast to reductive activation, u pon acid degradation of a diacetoxymitosene the C-1 group appeared to be lost faster. Electrochemical as well as dithionite reduction of a b ifunctional (diacetoxy) mitosene compound in the presence of calf thym us DNA at pH 5.5 resulted in the formation of DNA interstrand cross-li nks. Depending on activation method, this diacetoxymitosene was at lea st as efficient in DNA cross-linking as mitomycin C under comparable c onditions.