Coumarin is a benzopyrone found in many plants such as the Tonka bean and sweet woodruff. Coumarin is commonly used in perfumes and fabric conditioners for its sweet odor. Coumarin is a precursor in the synthesis of anticoagulants such as warfarin; coumarin inhibits vitamin K. Coumarin is clinically used to treat edema, as it stimulates macrophages to degrade extracellular albumen, allowing increased fluid reabsorption. Coumarin is also used in dyes and bio-imaging. Derivatives of coumarin exhibit immunomodulatory, anticancer, and antimicrobial activities.