Theoretical study of global and local reactivities of coumarin and its hydroxylated derivatives

Coumarins are bioactive substances of the benzo-α-pyrone family, which have shown antioxidant, antiviral, anti-inflammatory and antitumor activities, among others. 7-Hydroxycoumarin and 6,7-dihydroxycoumarin (esculetin) are two coumarin derivatives that have been reported to exhibit antitumor activity, but the action mechanism underlying this activity remains unknown. In this work, to elucidate this mechanism, a theoretical study of the local and global electronic reactivity properties of a series of hydroxylated and dihydroxylated coumarin derivatives with possible antitumor action is performed using Density Functional Theory in aqueous solution. The substitution by one or two hydroxyl groups in the benzene ring of coumarin produces better charge-donor than charge-acceptor compounds. All the studied compounds are generally stable in water and exhibit permanent polarization in the solvent. With one hydroxyl substitution, 7-hydroxycoumarin is the most polar and polarizable derivative, whereas 5,7-dihydroxycoumarin is the most polar and polarizable compound with two hydroxyl substitutions. 5,7-Dihydroxycoumarin is suggested to possess antitumor activity. © 2016 Wiley Periodicals, Inc.