dihidrofolátsav

Dihidrofolátsav, also known as dihydrofolic acid or DHFA, is a crucial intermediate in the metabolism of folic acid in living organisms. Folic acid, or vitamin B9, is essential for various biological processes, including DNA synthesis, repair, and methylation. Dihidrofolátsav is formed when folic acid is reduced by the enzyme dihydrofolate reductase (DHFR). This reduction step is vital because the subsequent form, tetrahydrofolate (THF), is the active coenzyme that carries one-carbon units necessary for the synthesis of purines and pyrimidines, the building blocks of DNA and RNA.

The pathway involving dihidrofolátsav is a target for several medications. For instance, methotrexate, a commonly used chemotherapy drug and immunosuppressant, works by inhibiting the enzyme DHFR. By blocking the conversion of dihidrofolátsav to THF, methotrexate disrupts DNA synthesis and rapidly dividing cells, such as cancer cells and immune cells. This inhibition effectively starves these cells of the necessary components for replication.

In bacteria, this pathway is also essential, and drugs like trimethoprim selectively inhibit bacterial DHFR, making it an effective antibiotic. The selective toxicity arises because mammalian DHFR is less sensitive to these drugs compared to bacterial DHFR. Therefore, dihidrofolátsav plays a central role in a metabolic pathway that is fundamental to life and is therapeutically exploited to treat a range of diseases.