Effect of selenium on the interaction between daunorubicin and cardiac myosin

The interactions between selenium (sodium selenite), anthracycline antibiotics daunorubicin (DNR), and major contractile protein cardiac myosin (CM) were investigated. The results showed that the binding force between selenium and CM was 100 times stronger than that of DNR and CM. There was no marked influence on fluorescence intensity of DNR-CM at selenium concentrations of up to 20 μM. The co-administration of selenium (0.5-10.0 μg Se/ml) together with DNR resulted in a significant reduction in mice cardiotoxicity. However, selenium at the dose of 50.0 or 100.0 μg Se/ml afforded no obvious protection. The data indicate that selenium in the form of sodium selenite at appropriate dosage (<10.0 μg Se/ml) diminish the cardiac toxicity of DNR, potentially allowing the use of DNR at higher dosages in clinical cancer chemotherapy.