A DFT study of antioxidant potential of a flavanone and isoflavanone by multiple free radical (H+/e-) mechanisms

Reactive oxygen species (ROS), reactive nitrogen species (RNS), and reactive sulfur species (RSS) are continuously obtained as a byproduct of various aerobic processes. Lower or moderate presence of these species has various health benefits. But, if the accumulation of these ROS, RNS and RSS are uncontrollable, they lead to major health defects like oxidative stress which plays a key role in various non-communicable diseases. To balance these reactions, non-enzymatic antioxidants such as secondary metabolites are promising choices because of their complex heterogeneous structures and charge-withdrawing functional groups. In this present work, the potential radical scavenging behavior of the two chosen biomaterials namely, Eriodictiol ER (5,7,3',4' tetrahydroxyflavanone) and Dalbergiodin DA (5,7,2',4' tetrahydroisoflavanone) are considered. The potential radical scavenging behavior of the chosen biomaterials is examined via quantum computations using thermodynamic mechanisms like H atom transfer (HAT), Sequential electron transfer-proton transfer (SETPT) and Sequential proton loss-electron transfer (SPLET) and their extended versions such as tetra H- atom transfer (teHAT), tetra Sequential electron transfer-proton transfer (teSETPT) and tetra Sequential proton loss-electron transfer (teSPLET). All the computations are analyzed by using density functional theory (DFT) by Minnesota functionals M06-2X/6-311 G(d,p) at the gas phase. The results reveal the potent antioxidant abilities of the investigated secondary metabolites. All four consecutive steps in the given mechanisms show gradually decreasing energy magnitudes compared to the same site at the previous steps. As per the obtained results, all four successive HAT mechanisms show profound results compared to the other two multiple scavenging mechanisms by their lower energy parameters.