Ethyl biscoumacetate is a

vitamin K Vitamin K is a family of structurally similar, fat-soluble vitamers found in foods and marketed as dietary supplements. The human body requires vitamin K for post-translational modification, post-synthesis modification of certain proteins ...

antagonist.

References

* The Merck Index, 12th Edition. 3818 Coumarin drugs Ethyl esters {{blood-drug-stub