Dihydrofolic acid plays a crucial role in the synthesis of nucleic acids and amino acids, making it essential for cell growth and division. It is a key intermediate in the folate metabolic pathway, where it is converted into tetrahydrofolic acid, a coenzyme necessary for the production of purines, thymidylate, and certain amino acids like methionine. This process is vital for DNA and RNA synthesis, particularly in rapidly dividing cells such as those in bone marrow and the immune system.

In the medical field, dihydrofolic acid is significant because it is the target of several antifolate drugs, including methotrexate and trimethoprim. These drugs inhibit the enzyme dihydrofolate reductase, which converts dihydrofolic acid to tetrahydrofolic acid. By blocking this conversion, antifolate drugs disrupt DNA synthesis and cell proliferation, making them effective in treating conditions like cancer, bacterial infections, and autoimmune diseases.

Additionally, understanding the role of dihydrofolic acid has led to advancements in nutritional science, particularly in addressing folate deficiency, which can lead to anemia and developmental issues. Supplementation with folic acid, a precursor to dihydrofolic acid, is commonly recommended to prevent such deficiencies, especially during pregnancy to reduce the risk of neural tube defects in developing fetuses.