Antiradical Activity and Mechanism of Coumarin–Chalcone Hybrids: Theoretical Insights

Abstract

In view of the multifunctional features of coumarins and chalcones, coumarin–chalcone hybrids have attracted much attention in recent years. Herein, the free radical scavenging activities of a series of coumarin–chalcone hybrids were investigated using the density functional theory (DFT) method. Three main reaction mechanisms were explored: hydrogen atom transfer (HAT), electron transfer followed by proton transfer (SET-PT), and sequential proton loss electron transfer (SPLET). Thermodynamic descriptors associated with these mechanisms were calculated in the gas phase and solvents. The results demonstrate that the predicted antioxidant efficiencies are generally in accordance with the experimental results. HAT is proposed as the thermodynamically favored mechanism in the gas phase and nonpolar solution, while SPLET is preferred in polar media. Our results indicate that compound MPHCC possesses potential for inactivating free radicals via double HAT and double SPLET mechanisms depending upon the polarity of environment. In addition, the SPLHAT mechanism provides an alternative pathway to HAT and SPLET for radical scavenging by MPHCC and OPHCC. The results confirmed the crucial role of hydroxyl groups on the chalcone moiety in trapping radicals. 4′-OH in the catechol group is proposed as the primary target for radical attack.

Antioxidant Activity and Mechanism of Avenanthramides: Double H+/e– Processes and Role of the Catechol, Guaiacyl, and Carboxyl Groups

“…Different conformations in each case were analyzed to select the most stable structure. The B3LYP method has been successfully used in research on chalcones − and other phenolic compounds. ,− Furthermore, Michalik and co-workers recently demonstrated that the results obtained by both B3LYP and M06-2X methods provide similar general trends, although the absolute values are somewhat different from them.…”

Radical Scavenging Activity of Puerarin: A Theoretical Study

“…Frontier molecular orbitals (FMO) play important roles in the reactivities of molecules [29][30][31]. As shown in Figure 3, FMO orbitals are not distributed on the glycosyl group of puerarin, and the orbital shapes of puerarin and daidzein are similar, which indicates the glycosyl group unlikely participated in the reaction.…”

Photophysical properties and sensing mechanism of fluorescent coumarin–chalcone hybrid for biothiols: A theoretical study

“…According to our previous studies, [ 59,60,76 ] the s‐cis conformers of coumarin–chalcone are more stable than the s‐trans ones. Thus, in this study, only the s‐cis conformer was considered for the probe CCH .…”