Folinic Acid (calcium salt)

Folinic Acid (calcium salt) (CAS No.: 1492-18-8) is a metabolically active, reduced folate derivative that functions as a key cofactor in one-carbon transfer reactions essential for nucleotide biosynthesis and epigenetic regulation. As a formylated tetrahydrofolate analog, it is readily absorbed in biological systems and extensively converted in the liver to other folate cofactors that participate in thymidylate and purine synthesis, thereby supporting DNA replication and repair. Mechanistically, folinic acid bypasses dihydrofolate reductase inhibition and replenishes intracellular folate pools, enabling restoration of one-carbon metabolism and modulation of gene expression through effects on methylation pathways. It is widely used in biomedical research as a rescue agent to mitigate antifolate-induced cytotoxicity, particularly in methotrexate-based regimens, and as a biochemical modulator to enhance the efficacy of fluoropyrimidine drugs such as 5-fluorouracil by stabilizing ternary complexes with thymidylate synthase. In vitro, its functional activity is typically observed through modulation of cell proliferation and nucleotide synthesis pathways at concentrations ranging from nanomolar to micromolar levels, depending on cellular context and folate status. In experimental models, folinic acid is frequently applied in studies of cancer biology, antifolate resistance, and metabolic disorders, with dosing and exposure conditions tailored to specific assay systems and research objectives.