Vitamin K epoxide reductase complex (VKORC1)
Among the various pharmacological effects of coumarin and its derivatives, the anticoagulant effect is the most well-studied. As early as the 1970s, Bell et al. proposed that anticoagulant drugs such as coumarin exert anticoagulant effects by inhibiting the reduction of vitamin K 2,3-epoxide (KO) to the hydrogen quinine form of vitamin K. of. Later, it was discovered that coumarin drugs such as warfarin inhibit the activity of the key enzyme for KO reduction. This key enzyme is vitamin K epoxide reductase (VKOR).

There are currently three coumarin anticoagulant drugs on the market, namely warfarin potassium, warfarin sodium and Phenprocoumon, all of which were launched earlier. Among them, the clinical trials of warfarin sodium are more detailed. The results of 6 clinical studies showed that warfarin sodium was significantly (p<0.05) better than placebo, dipyridamole/aspirin and pentoxifylline/aspirin in preventing systemic thrombosis.

DNA gyrase B subunit (gyrB)
During the process of DNA replication, the negative supercoil created by DNA gyrase can stabilize the separation of DNA and prevent excessive and non-template double-stranded coiling to ensure the smooth progress of DNA replication. As a result, antibacterial drugs targeting gyrase: quinolones and coumarins have been developed. Quinolones act on the A subunit of gyrase, while coumarins act on the B subunit of gyrase.

The only gyrB inhibitor currently on the market is the coumarin drug novobiocin sodium. The drug has antibacterial activity against Gram-positive bacteria such as Staphylococcus aureus (including methicillin-resistant strains) and other staphylococci; Enterococcus faecalis is often resistant, while Enterococcus faecium may be susceptible. It is sensitive to Gram-negative bacteria including Haemophilus influenzae, Neisseria spp., and some Proteus species, but most Enterobacteriaceae are resistant to it. Novobiocin is mainly a bacteriostatic agent, but it also has a bactericidal effect on sensitive bacteria at high concentrations. Novobiocin can inhibit DNA helicase and can also clear plasmids, but it is easy to develop drug resistance in vitro or during treatment. Although novobiocin can be used alone or in combination with other drugs such as rifampicin and fusidate to treat infections caused by Staphylococcus aureus and other sensitive bacteria, novobiocin has now been largely used due to problems with drug resistance and toxicity. replaced by other drugs. Novobiocin is a highly effective sensitizer, and related hypersensitivity reactions include rash, fever, and pruritus. More severe cases may include Stevens-Johnson syndrome and pneumonia. Jaundice and liver damage can also occur, but jaundice is mainly caused by the yellow metabolites of the drug and partly by hyperbilirubinemia. Other adverse reactions include eosinophilia, leukopenia, thrombocytopenia, agranulocytosis, and hemolytic anemia; gastrointestinal reactions are common.

Photosensitizers
Another major use of coumarins on the market is as a treatment for psoriasis and vitiligo. Methoxsalen and trimethasalen, approved by the U.S. Food and Drug Administration (FDA) in 1954, were both developed by Valeant. As psoralens, they can be used as photosensitizers in photochemotherapy or PUVA therapy. In addition, methoxsalen can also be selectively used for atopic dermatitis, polymorphic light eruption, T-cell lymphoma (such as mycosis fungoides), etc. In a PUVA therapy study of 41 patients with psoriasis, the use of methoxsalen 25 mg/m2 according to the body surface level of the patients could make their blood drug concentrations more consistent and relatively reduce the risk of obesity due to the patient’s body fat. The potential for overdose or under-medication due to differences.

Transforming growth factor beta 1 (TGF-beta 1)
Transforming growth factor-β (TGF-β) was identified in 1978 by DeLarco and Todaro from the culture medium of mouse sarcoma virus cell lines. It was named transforming growth factor because of its cell transformation properties. TGF-β is an important cytokine in organisms and has a variety of biological effects, including embryonic development, wound healing, chemotaxis, and cell cycle regulation. Studies have found that TGF-β can stimulate tissue fibrosis and extracellular matrix deposition, disrupt immune function, stimulate angiogenesis and promote epithelial-to-mesenchymal transition.

The coumarin amide derivative nicousamide is a Phase II clinical drug intended for the treatment of renal dysfunction, including diabetic nephropathy and hypertensive nephropathy. Studies have shown that nicousamide inhibits or slows down the progression of renal fibrosis by inhibiting the phosphorylation of TGF-β receptor and its downstream proteins.