Mechanism of drugs interfering with nucleic acid metabolism

Interfere with nucleic acid metabolism

The drugs that inhibit nucleic acid synthesis mainly include quinolones, pyrimethamine and rifampicin, sulfonamides and their synergists. Quinolones are effective inhibitors of nucleic acid synthesis, which inhibit DNA gyrase and topoisomerase IV, inhibit DNA replication of sensitive bacteria and lead to bacterial death. Sulfonamides are analogues of p-aminobenzoic acid (PABA), which can compete with dihydropterin synthase and hinder dihydrogen. Synthesis of folic acid; Trimethoprim inhibits the dihydrofolate reductase of bacteria (5000 times stronger than dihydropterin synthase in mammals) and prevents the synthesis of tetrahydrofolate. The combination of them can inhibit dihydropterin synthase and dihydrofolate reductase in turn, thus playing a dual role of blocking and enhancing antibacterial effect. Rifampicin can inhibit DNA-dependent RNA polymerase in bacteria and hinder mRNA synthesis. Nucleic acid analogues such as zidovudine, acyclovir, cytarabine and other essential enzymes inhibit viral DNA synthesis and terminate viral nucleic acid replication.