Figure 1. Main Site of Action of Fluoropyrimidine Chemotherapeutic Agents. Thymidylate Synthase catalyses the reductive methylation of dUMP (deoxyuridine monophosphate) which is subsequently converted to deoxythymidine triphosphate (dTTP) in DNA synthesis. FH4, Tetrahydrofolate; FH2, Dihydrofolate; CH2FH4, Methylene Tetrahydrofolate; dUMP, Deoxyuridine Monophosphate; TMP, Thymidine Monophosphate; TTP, Thymidine Triphosphate; 5FdUMP, 5-Fluorodeoxyuridine Monophosphate; 5DFCR, 5'Deoxy-5-Fluorocytidine; 5DFUR, 5 Deoxy-5-Fluorouridine; 5-FUMP, 5-Fluorouridine-5-Monophosphate; 5-FUDP, 5-Fluorouridine-5-Diphosphate; 5-FUTP, 5-Fluorouridine-5-Triphosphate, FdURD, 5- Fluoro-2-deoxyuridine.
Figure 2. Sites of Action of Pemetrexed. Actions of pemetrexed on purine and pyrimidine pathways in DNA synthesis. dUMP, Deoxyuridine Monophosphate; TMP, Thymidine Monophosphate; CH2FH2, Methylenetetrahydrofolate; CHOFH4, 10-Formyltetrahydrofolate; FH2, Dihydrofolate; FH4, Tetrahydrofolate; DHFR, Dihydrofolate Reductase; GARFT, Glycinamide Ribonucleotide Formyl Transferase.
Figure 3. Mode of Action of Gemcitabine. Gemcitabine has different sites of action as a chemotherapeutic agent. CDP, Cytidine Diphosphate; dCTP, Deoxycytidine Triphosphate; FdUMP, Fluorodeoxyuridine Monophosphate; AICAR, Aminoimidazole Carboxamide Ribonucleotide Transformylase.
Figure 4. Actions of Chemotherapeutic Agents on Arachidonic Acid Pathways. Metabolic Pathways of Arachidonic Acid and the Actions of Cyclooxygenase and Lipooxygenase Inhibitors, and Leukotriene Receptor Antagonists. COX, Cyclooxygenase; LOX, Lipooxygenase; 5-HPETE, 5S hydroperoxyeicosatetraenoic acid; 12-HETE, 12S Hydroeicosatetranoic acid; PG, Prostaglandin I2/E2/D2/F2; TXB2, Thromboxane B2