DNA Cleaving Drugs

There are a number of drugs that intercalate very specifically into DNA with one part of the molecule in a way that brings another part that is capable of creating free radicals into a position to abstract an H-atom from the sugar moiety, again 

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The DNA-cleaving anti-cancer drugs such as bleomycin and camptothecin are bound by what they later destroy (Section 4.0). 

Bleomycin binds to the minor groove of DNA. Once in the minor groove, it uses a bound iron atom to remove a hydrogen atom from DNA, the first step in cleaving DNA. This drug has been approved for the treatment of Hodgkin lymphoma. 

Enediynes hold substantial promise as anti cancer drugs because of their potency and selectivity Not only do they inhibit cell growth they have a greater tendency to kill cancer cells than they do normal cells The mechanism by which enediynes act involves novel chemistry unique to the C C—C=C—C C unit which leads to a species that cleaves DNA and halts tumor growth... 

II cleaves the two complementary strands of DNA four base pairs apart and the resulting 5 -phosphoryl groups become covalently linked to a pair of tyrosine groups, one in each half of the dimeric topoisomerase II enzyme. Several groups of drugs are known that selectively inhibit topoisomerases in bacteria (quino-lones) or mammalian cells (etoposide, tenoposide). Quinolones are used to treat bacterial infections inhibitors of mammalian topoisomerases are cytostatic drugs used for the treatment of cancer. 

A. Oseltamivir inhibits neuraminidase, an enzyme that cleaves neuraminic acid from oligosaccharides. Neuraminidase activity aids the movement of viral particles through neuraminic acid-rich respiratory secretions and is required for the release of progeny virions. Inhibition of viral DNA polymerase is the mechanism of action of nucleoside analogue antiviral drugs. Interferons do stimulate the JAK-STAT signaling pathway but do not stimulate proliferation of immune cells. Ribavirin inhibits GTP synthesis, and the antiretroviral protease inhibitors (e.g., ritonavir) inhibit HIV protease. 

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