1st International Conference on Chemo and BioInformatics, ICCBIKG 2021, (408-409)
AUTHOR(S) / АУТОР(И): Ilija Cvijetić, Miljan Bigović, Petar Ristivojević, Maja Vitorović-Todorović, Mire Zloh, Dušanka Milojković-Opsenica,
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ABSTRACT / САЖЕТАК:
Recent experimental study identified eight potent antioxidants in German beers, including isoxanthohumol, (R)- and (S)-adhumulone, cis– and trans-iso-adhumulone, cis– and trans-iso- n-humulone, and desdimetyhyl-octahydro-iso-cohumulone.
To provide insights into the structural basis of their radical scavenging activity, we calculated the thermodynamic feasibility of two common antioxidant mechanisms, hydrogen atom transfer (HAT) and single electron transfer followed by proton transfer (SET-PT), using the density functional theory (DFT) with B3LYP/6-311g++(2d,2p) method in the gas phase and implicit solvation model of water. The calculated bond dissociation enthalpies (BDEs) and ionization potential (IP) of all compounds were compared with the corresponding values for resveratrol, a highly potent antioxidant found in red wine.
The fully reduced humulone isomer, desdimetyhyl-octahydro-iso-cohumulone, could scavenge free radicals via HAT as revealed by BDEs 5.1 and 23.9 kJ/mol lower than the values for resveratrol in gas phase and water, respectively. Furthermore, the enolic –OH group was identified as the pharmacophoric hotspot for the interaction of humulones with the reactive free radicals. The HAT potency of this group is significantly reduced through the formation of strong intramolecular hydrogen bond (IHB) with the β-keto group. Moreover, the SET-PT mechanism was thermodynamically favorable for isoxanthohumol. These results strongly suggest higher antioxidant activity of beers with the increased content of the reduced forms of humulones and their isomers.
KEY WORDS / КЉУЧНЕ РЕЧИ:
Beer, humulones, isoxanthohumol, bond dissociation enthalpy, intramolecular hydrogen bonding
REFERENCES / ЛИТЕРАТУРА:
- Cvijetić, I., Bigović, M., Ristivojević, P., Vitorović-Todorović, M., Zloh, M., & Milojković-Opsenica, D. (2021), Structural Chemistry, doi:10.1007/s11224-021-01780-4;
- Ristivojević, P., Morlock, G. (2018) Food Chem 260:344–353.