The primary target of Coumachlor is vitamin K epoxide reductase (VKOR), a key enzyme in the vitamin K cycle. It acts as a vitamin K antagonist, inhibiting VKOR and preventing the reduction of vitamin K 2,3-epoxide to reduced vitamin K. This depletes reduced vitamin K, which is essential for gamma-carboxylation of clotting factors II, VII, IX, and X. As a result, these clotting factors remain inactive, leading to impaired coagulation and fatal hemorrhage. Coumachlor is a first-generation anticoagulant requiring multiple feedings to achieve lethal effects.

In vitro, Coumachlor inhibits VKOR activity in liver microsomes. It is a first-generation anticoagulant that requires multiple feedings to achieve lethal effects. The compound is used as a reference standard for VKOR inhibition assays and in forensic toxicology for method development. Its anticoagulant activity is measured by prothrombin time (PT) prolongation in plasma. Specific IC50 values for VKOR inhibition are reported in the literature.

In vivo, Coumachlor is an anticoagulant rodenticide used for rodent control. It requires multiple feedings to achieve lethal anticoagulation. The compound causes internal hemorrhage and death. It is toxic to non-target species. Coumachlor is primarily used in research settings for studying VKOR resistance mechanisms and for forensic toxicology. Specific published in vivo efficacy data, including LD50 values and time to death, are reported in the literature.

The VKOR inhibition assay uses liver microsomes incubated with vitamin K 2,3-epoxide and NADH in reaction buffer. Coumachlor is added at serial dilutions. The conversion of vitamin K epoxide to reduced vitamin K is measured by HPLC or spectrophotometry. IC50 values are calculated from dose-response curves. Prothrombin time (PT) is measured in plasma samples from treated animals using standard coagulation assays.

For cell-based assays, hepatocytes are cultured and treated with Coumachlor. VKOR activity is measured in cell lysates using vitamin K epoxide as substrate. Clotting factor synthesis is assessed by measuring gamma-carboxylated prothrombin (PIVKA-II) by ELISA. Cell viability is evaluated using standard reagents. The compound is typically tested at concentrations ranging from 0.1 to 100 µM.

In vivo studies with Coumachlor employ rodent models (rats, mice). The compound is formulated in bait carriers and administered orally. Doses are selected based on LD50 values. Key readouts include mortality, prothrombin time, and internal bleeding assessed by necropsy. The compound requires multiple feedings to achieve lethal anticoagulation. Due to toxicity, in vivo studies are conducted with appropriate safety precautions.

Interactions
The following drugs may enhance the response to Coumafuryl or indanedione derivatives: alcohol (acute poisoning), allopurinol, aminosalicylic acid, amiodarone, anabolic steroids, chloral hydrate, chloramphenicol, cimetidine, clofibrate, trimethoprim-sulfamethoxazole, danazol, dexthylexin sodium, diazoxide, diflunisal, disulfiram, erythromycin, ethacrynic acid, fenoprofen calcium, glucagon, ibuprofen, indomethacin, influenza vaccine, isoniazid, meclofenamic acid, mefenamic acid, methylthiouracil, metronidazole, miconazole, nalidixic acid, neomycin (oral), pentoxifylline, phenylbutazone, propoxyphene, propylthiouracil, quinidine, quinine. Salicylates, streptokinase, sulfinpyrazone, sulfonamides, sulindac, tetracyclines, thiazide diuretics, thyroid medications, tricyclic antidepressants, urokinase, vitamin E. /Coumafuryls and Indanedione Derivatives/
The following drugs...may...reduce...the response to Coumafuryl or indanedione derivatives: alcohol (chronic alcoholism), barbiturates, carbamazepine, corticosteroids, adrenocorticotropic hormone, ethylclofenac, glutamine, griseofulvin, mercaptopurine, methylquinone, estrogen-containing oral contraceptives, rifampin, spironolactone, vitamin K. /Coumafuryls and Indanedione Derivatives/

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Non-human toxicity values
LD50: Rat (Norwegian albino rat) oral administration 900.0 mg/kg

[1]. Comparison of the Anticoagulant Action of 3-(α-p-chlorphenyl-β-aeetylethyl)-4-hydroxycoumarin (Coumachlor) and Dicoumarol in Chicks and Rats. Acta Pharmacologica et Toxicologica. April 1953.

[2]. 16th International Congress of Endocrinology/96th Annual Meeting and Exposition of the Endocrine Society (ICE/ENDO), Chicago, Illinois, USA-June 21-24, 2014. Drugs of the Future v. 39, n. 9 (2014) : 0661.

Coumachlor is a hydroxyCoumafuryl. Mechanism of Action 4-HydroxyCoumafuryl derivatives and indanedione (also known as oral anticoagulants) are both vitamin K antagonists. Their use as rodenticides works by inhibiting vitamin K-dependent steps in the synthesis of various blood coagulation factors. Vitamin K-dependent proteins involved in the coagulation cascade (Figure 1) include procoagulant factors II (prothrombin), VII (prothrombin convertase), IX (Christmas factor), and X (Stuart-Proll factor), as well as coagulation inhibitory proteins C and S. All of these proteins are synthesized in the liver. Before being released into the bloodstream, various precursor proteins undergo numerous (intracellular) post-translational modifications. Vitamin K acts as a coenzyme in one of these modifications, specifically by carboxylating 10-12 glutamate residues at a specific site to generate γ-carboxyglutamate (Gla). The presence of these Gla residues is crucial for the procoagulant activity of various coagulation factors. Vitamin K hydroquinone (KH2) is an active coenzyme that is oxidized to vitamin K 2,3-epoxide (KO), providing the energy required for the carboxylation reaction. Subsequently, this epoxide is recycled through two reduction steps catalyzed by KO reductase (Figure 2). KO reductase is the target of Coumafuryl anticoagulants. Inhibition of KO reductase by Coumafuryl anticoagulants leads to rapid depletion of KH2, effectively preventing the formation of Gla residues. This results in the accumulation of uncarboxylated clotting factor precursors in the liver. In some cases, these precursor proteins are further processed without carboxylation and (depending on the species) may appear in the bloodstream. At this point, the uncarboxylated protein is called a decarboxylated clotting factor. Normal clotting factors circulate as proenzymes, which can only be activated after limited proteolytic degradation to participate in the coagulation cascade. Decarboxylated clotting factors do not have procoagulant activity (i.e., cannot be activated) and cannot be converted into active proenzymes by the action of vitamin K. While high levels of circulating decarboxylation clotting factors can be detected in humans receiving anticoagulation therapy, these levels are negligible in rats and mice treated with warfarin. /Anticoagulant rodenticide/
Similar to warfarin, it delays the effect on prothrombin levels and blood clotting, ultimately leading to bleeding death.

C19H15CLO4

342.77

342.065

81-82-3

54682651

Colorless, crystalline solid
Crystals

1.4±0.1 g/cm3

543.1±50.0 °C at 760 mmHg

168-170 °C(lit.)

282.3±30.1 °C

0.0±1.5 mmHg at 25°C

1.641

4.01

1

4

4

24

534

0

O=C1C(C(CC(C)=O)C2C=CC(Cl)=CC=2)=C(O)C2C(=CC=CC=2)O1

DEKWZWCFHUABHE-UHFFFAOYSA-N

InChI=1S/C19H15ClO4/c1-11(21)10-15(12-6-8-13(20)9-7-12)17-18(22)14-4-2-3-5-16(14)24-19(17)23/h2-9,15,22H,10H2,1H3

3-[1-(4-chlorophenyl)-3-oxobutyl]-4-hydroxychromen-2-one

G 23133; G-23133; Coumachlor

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

DMSO: ~25 mg/mL (~72.9 mM; with ultrasonication)

Solubility in Formulation 1: ≥ 2.5 mg/mL (7.29 mM) (saturation unknown) in 10% DMSO + 40% PEG300 + 5% Tween-80 + 45% Saline (add these co-solvents sequentially from left to right, and one by one), Clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of DMSO stock solution (25.0 mg/mL) to 400 μL of PEG300 and mix well; then add 50 μL of Tween-80 and mix well; finally add 450 μL of physiological saline and adjust the volume to 1 mL.
Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution.

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Solubility in Formulation 2: ≥ 2.5 mg/mL (7.29 mM) (saturation unknown) in 10% DMSO + 90% Corn Oil (add these co-solvents sequentially from left to right, and one by one), Clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of DMSO stock solution (25.0 mg/mL) to 900 μL of corn oil and mix well.

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 (Please use freshly prepared in vivo formulations for optimal results.)