Radiation-chemical transformations of coumarins in ethanolic solutions

• Coumarin, 4-hydroxycoumarin and warfarin oxidize α-hydroxyethyl radicals.
• Esculetin and fraxetin predominantly reduce α-hydroxyethyl radicals.
• Coumarins add α-hydroxyethyl radicals to the C=C bonds of the pyrone ring.
• Coumarins display antioxidant activity on radiation-induced oxidation of ethanol.

Effects of coumarin and its derivatives on product formation during radiolysis of deaerated and oxygenated ethanol were investigated. The data obtained in this study indicate that coumarin, 4-hydroxycoumarin and warfarin effectively oxidized α-hydroxyethyl radicals (α-HER), while esculetin and fraxetin predominantly reduced the above named intermediates. Coumarin, esculetin and fraxetin were able to add α-HER to the double carbon–carbon bond of the pyrone ring to form stable products with molecular masses exceeding those of the starting molecules. Coumarin, warfarin, esculetin and fraxetin were shown to display antioxidant activity during radiation-induced oxidation of ethanol.