leading to the inhibition of DNA synthesis, ..
inhibition of the synthesis of new dna ..
Folic acid, heterocyclic bases and nucleotides are the building blocks for DNA and are made naturally within the cells. Agents under this category block one or other step in the formation of nucleotides, not permitting the synthesis of DNA and RNA in turn stopping the process of replication. Examples of drugs in this class include methotrexate (Abitrexate®), fluorouracil (Adrucil®),hydroxyurea (Hydrea®) and mercaptopurine (Purinethol®).
Effects of semicarbazide on DNA, RNA and protein …
The anticancer effects of thiosemicarbazones were once solely attributed to the inhibition of ribonucleotide reductase, an enzyme involved in the rate-limiting step of DNA synthesis. However, the mechanism behind this inhibition was initially not described. The ability of thiosemicarbazones to chelate metal ions has now been recognized as a major factor in their antiproliferative effects. The more reasonable explanation for the higher activity by the metal-thiosemicarbazone complexes when compared to free ligands passes through the prevalence of the diffusive mechanism over the active transport mechanism across the membranes. The chelation of the metal ion by the most polar regions of the ligands (the donor atoms) allows an easier uptake by the cell. In vivo analysis indicates that some thiosemicarbazones show potential as chemotherapeutic agents. However, future study is warranted.