Doxorubicin structure-activity relationship

Anthracyclines are antitumor quinone containing antibiotics produced by different strains of Streptomyces. Some of them, such as adriamycin doxorubicin), and daunorubicin are broad spectrum antitumor compounds. They act by binding to DNA and interfering with DNA replication and gene transcription. Their limitations for clinical use are cardiac toxicity and drug resistance phenomena. Consequently, intense structure-activity relationship studies have been performed to improve the pharmacological profile as well as to enhance the affinity for DNA. In particular, a number of fluorinated anthracyclines have been prepared with introduction of fluorine atoms into D or A cycles, and into the aglycone side chain linked atC-14. ... 

A considerable amount of research has gone into elucidating the molecular mechanism of action of these antitumour quinones. While several mechanisms are possible, a single mechanism may not fully explain all of the observed cytotoxic effects. One of the objectives of the NCI and other studies elsewhere has been to determine if there were any structure-activity relationships within the major structural groups ranging from the simplest benzoquinones to the complex multiple heteroatom quinones. One of the main conclusions from these studies was that the most active compounds were mitomycin C, the 3,6-diaziridinylbenzoquinones with 2,5-alkylamino substituents, adriamycin (doxorubicin), daunomycin (daunorubicin) and AZQ (Figure 1). 

A complex array of properties contribute to the in vivo antitumor activity and toxicity of anthracyclines, including ability to bind DNA, accumulation in tissues (dbtribution), elimination, and metabolic fate of the drugs. In an effort to find anthracyclines with higher efficacy to toxicity ratios, more than 2000 analogs of daunombicin, doxorubicin, and other anthracyclines have been synthesized and tested (1). From these tests, some ivoad generalizations can he made concerning structure-activity relationships. 

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