Application of Methotrexatein the Treatment of Diseases

Methotrexate is an odorless yellow to orange-brown crystalline powder that is slightly soluble in diluted hydrochloric acid and insoluble in water, alcohol, chloroform, and ether. The chemical name of it is N-[4-[(2,4-diamino-6-pteridine) methyl]methylamino]benzoyl]-L-glutamic acid. It is used to treat cancer and rheumatoid arthritis. The is shown in fig. 1.

Fig. 1 Structure of methotrexate

Application in the treatment of diseases

• Cancer

Methotrexate, one of the earliest cancer chemotherapy agents, which is extensively used in the treatment of cancer, including breast cancer, leukemia, lung cancer, lymphoma, osteosarcoma and so on. The efficacy of methotrexate mainly due to its inhibitory effect on dihydrofolate reductase (DHFR)[1]. DHFR catalyzes the conversion of dihydrofolate to the active tetrahydrofolate that is needed for the synthesis of nucleoside thymidine. Nucleoside thymidine is critical for DNA synthesis. In other words, methotrexate can inhibit the synthesis of DNA in cancer cells.

• Rheumatoid arthritis

Rheumatoid arthritis is a long-term autoimmune disorder with symptoms usually involving swelling, stiffness, and pain in the joints. Stiffness and pain often worsen after rest. Rheumatoid arthritis may also affect other parts of the body, such as the skin, eyes, lungs, heart, nerves and blood. Methotrexate is one of the most effective and commonly used active pharmaceutical ingredients to treat rheumatoid arthritis and has been used for about three decades now[2]. In rheumatoid arthritis, methotrexate can inhibit aminoimidazole caboxamide ribonucleotide transformase (AICART), which blocks the metabolism of adenosine and guanine, leading to the accumulation of adenosine and guanine. Adenosine has an anti-inflammatory action, which is beneficial to inhibit the activation of T-cells, slow down the regulation of B-cells, increase the sensitivity of activated CD-95 T cells and repress the activity of methyltransferase. That's why methotrexate can relieve the symptoms of rheumatoid arthritis.