Coumarin derivatives as promising xanthine oxidase inhibitors

Xanthine oxidase (XO) is an interesting target for the synergic treatment of several diseases. Coumarin scaffold plays an important role in the design of efficient and potent inhibitors. In the current work, twenty 3-arylcoumarins and eight 3-heteroarylcoumarins were evaluated for their ability to inhibit XO. Among all the candidates, 5,7-dihydroxy-3-(3'-hydroxyphenyl)coumarin (compound 20) proved to be the best inhibitor with an IC₅₀ of 2.13 μM, being 7-fold better than the reference compound, allopurinol (IC₅₀ = 14.75 μM). To deeply understand the potential of this compound, the inhibition mode was also evaluated. Compound 20 showed an uncompetitive profile of inhibition. Molecular docking studies were carried out to analyze the interaction of compound 20 with the studied enzyme. The binding mode involving residues different from the catalytic site of the binding pocket, is compatible to the observed uncompetitive inhibition. Compound 20 was not cytotoxic at its IC₅₀ value, as demonstrated by the viability of 99.1% in 3 T3 cells. Furthermore, pharmacokinetics and physicochemical properties were also calculated, which corroborated with the potential of the studied compounds as promising XO inhibitors.