Tactfully improve the antioxidant activity of 2′-hydroxychalcone with the strategy of substituent, solvent and intramolecular hydrogen bond effects

Role of the Solvent and Intramolecular Hydrogen Bonds in the Antioxidative Mechanism of Prenylisoflavone from Leaves of Vatairea guianensis

“…Therefore, interactions such as intramolecular HB can influence the thermodynamic and reactive properties of the molecule. There are several initiatives in this direction. − In the gas phase, for example, these interactions vary from 8.37 to 62.76 kJ/mol, which demands special attention once the values of ΔBDE, discussed above, generally exhibit the same order of magnitude of HB formation. − For example, from Table in aqueous solution, it is possible to see that the BDE for the molecule S10c (334 kJ/mol) is slightly lower than that calculated for the radical S11c (336 kJ/mol), suggesting that S10 is the best antioxidant compound. However, if the OH···OCH 3 HB structure is not allowed as in the S11′c molecule, a BDE value of 331 kJ/mol is obtained.…”

Computational Chemistry Strategies to Investigate the Antioxidant Activity of Flavonoids—An Overview

“…The IHBs are present in the most stable conformation of flavonoids. It reduces the antioxidant activity of hydrogen-bond donors (such as the 5-OH, 3-OH and 3′-OH groups in flavonoids) and enhances the antioxidant activity of hydrogen-bond acceptors (such as the 4′-OH group) [ 163 , 186 ], which is considered crucial for scavenging free radicals by flavonoids [ 33 , 78 , 187 ]. Moreover, it is closely connected to the ESIPT mechanism.…”

“… The basic skeleton of the subclasses to which the investigated compounds belong, along with the number of compounds in each subclass that have been studied over the past five years [ 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 ...…”

“… The methods employed in the past five years to investigate the electronic structure of flavonoids, along with the proportion of each method used [ 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 , …”

Antioxidant mechanisms and products of four 4′,5,7-trihydroxyflavonoids with different structural types

“…They usually have 4′,5,7-OHs as antioxidant sites and scavenge free radicals through hydrogen atom transfer (HAT), single electron transfer followed by proton transfer (SET-PT), and sequential proton loss electron transfer (SPLET) mechanisms. 7 Under the three mechanisms, hydroxyl is oxidized by free radicals to an unstable phenoxy radical intermediate; the intermediate can form stable radical adducts to terminate the free-radical-chain reaction. The covalent linkage is essentially a radical adduct formation (RAF) or radical coupling reaction.…”