生物活性

• 描述The biologically active form of folic acid is tetrahydrofolate which is essential for DNA synthesis. Tetrahydrofolate is oxidised to dihydrofolate during DNA synthesis and is regenerated to its active form by the enzyme dihydrofolate reductase. Inhibition of this enzyme prevents DNA synthesis and causes failure of cell renewal. This leads to breaks in epithelial surfaces resulting in oropharyngeal and intestinal ulceration. Methotrexate (MTX) is the most powerful antagonist to inhibit dihydrofolate reductase. Folinic acid is an analogue of tetrahydrofolate and so bypasses the dihydrofolate reductase block. It thus supplies the tetrahydrofolate compounds needed for DNA synthesis ^[3]. Treatment with folinic acid calcium pentahydrate (CF) could cause improved development in the heart and vessels in MTX-treated embryos, which proved that MTX induced the malformations by inhibiting dihydrofolate reductase (DHFR). The transcript levels of genes such as hand2, mef2a, mef2c, and flk-1 were reduced in MTX-treated embryos. Compared with the MTX-treated group, the transcript levels of hand2, mef2a, mef2c, and flk-1 were increased in the MTX + CF group ^[4]. Folinic Acid Calcium Pentahydrate may also be useful in the treatment of acute methotrexate overdose ^[3].

• 动物研究
  剂量	Mice: 7 mg/kg[3] (i.p.)
  给药途径	i.p.