Tetrahydrofolate is an important coenzyme for synthesizing purine nucleotides and pyrimidine deoxynucleotides in the body. As a folate reductase inhibitor, this product mainly inhibits dihydrofolate reductase and prevents dihydrofolate from being reduced to physiologically active tetrahydrofolate, thereby hindering the transfer of one-carbon groups in the biosynthesis of purine nucleotides and pyrimidine nucleotides, resulting in the inhibition of DNA biosynthesis. In addition, this product also has an inhibitory effect on thymic nucleotide synthetase, but its effect on inhibiting RNA and protein synthesis is weaker. This product mainly acts on the S phase of the cell cycle and is a cell cycle-specific drug. It also has a delaying effect on cells in the G1S phase, but has a weaker effect on cells in the G1 phase.

Estrogen drugs. This product is a derivative of estriol. Its pharmacological effects are similar to those of estradiol, but its biological activity is low, so its effect on endometrial proliferation is also weak. It is suitable for estrogen replacement therapy for perimenopausal women. The introduction of cyclopentyl ether at the 3rd position increases its lipophilicity, which is beneficial for intestinal absorption and storage in adipose tissue, and then slowly released to play a long-term effect. The introduction of acetylene at the 17th position enhances the estrogen activity.