This was a review of how coumarin compounds—both natural and synthetic—work in the body, focusing mainly on their anticoagulant (blood-thinning) properties used in prescription drugs like warfarin. The research examined how these compounds interact with vitamin K and outlined their chemical structures, but didn't test new skincare applications or provide data on topical vitamin K effectiveness for cosmetic purposes.

This was a literature review that synthesized existing research on coumarin chemistry and medical uses, rather than a new experimental study testing ingredients on skin.

Funding not disclosed in abstract