Low stimulation of NADH oxidation and oxygen consumption by 5-iminodaunorubicin and its derivatives

NADH oxidation and oxygen consumption mediated by 5-iminodaunorubicin and its derivatives have been studied. Experiments were carried out using two enzyme system: microsomes isolated from rat liver and cytochrome c-reductase. All 5-iminoanthracyclines examined were relatively poor electron transfer mediators. In addition, 5-imino-derivatives of daunorubicin modified at sugar moiety were less effective in stimulating NADH oxidation and oxygen radical production than 5-iminodaunorubicin itself. This may be due to the additive effect of 5-imino structure and the presence of bulky substituents at sugar moiety, which might make the compounds poor enzyme substrates.