In vitro platelet antiaggregatory properties of 4-methylcoumarins

► Antiaggregatory properties of 4-methylcoumarins were tested. ► Arachidonic acid, collagen or ADP was added for induction of aggregation. ► 5,7-Dihydroxy-4-methylcoumarins reached the activity of acetylsalicylic acid. ► Probable mechanism of action is competitive antagonism on thromboxane receptors and cyclooxygenase-1 inhibition.