http://www.biosyn.com - Doxorubicin is an anthracycline antibiotic used in cancer chemotherapy, which is also being evaluated as an antiviral agent. Two different mechanisms have been proposed to explain doxorubicin anticancer activity, in one it intercalates into the DNA and disrupts the topoisomerase-II DNA repair, leading to DNA-strand breaks at certain sites which are specific for doxorubicin; in the other mechanism, the antibiotic generates free radicals that damage cell membranes, DNA and proteins.