DFT study of the radical scavenging activity of isoxanthohumol, humulones (α-acids), and iso-α-acids from beer

Humulones and iso-humulones are potent natural antioxidants found in beer. In this study, density functional theory (DFT) method was applied for elucidating the structure-antioxidant activity relationship molecular mechanism of antioxidant eight bioactive humulones previously identified different beer samples: isoxanthohumol, (R)- (S)-adhumulone, cis- trans-iso-adhumulone, trans-iso-n-humulone, desdimethyl-octahydro-iso-cohumulone. The calculated bond dissociation enthalpies (BDEs) suggest that desdimethyl-octahydro-iso-cohumulone most compound with BDEs 5.1 23.9 kJ/mol lower compared to values resveratrol gas phase water, respectively. enolic –OH is reactive site hydrogen atom transfer (HAT). presence β-keto group respect diminishes HAT potency via formation a strong intramolecular bond. Another common mechanism, single electron followed by proton (SET-PT), only feasible isoxanthohumol. results study indicate correlation between increased products higher content reduced iso-α-acids.