ive phenolic moieties of flavonoids. Contemplating the scope of this contribution, this precise structural modification will be addressed in the following section. 4. Oxidation of the Phenolic Moieties of Flavonoids and Its Consequences on Their Antioxidant Properties As currently pointed out, the oxidizability with the phenolic moieties of all flavonoids may be the basis for their capacity to either scavenge or lessen distinctive ROS. During such reactions, one (or extra) in the phenolic groups engages within a redox HDAC10 custom synthesis reaction exactly where either an electron or perhaps a hydrogen atom of a hydroxyl groups is transferred for the ROS, stabilizing these species [58,59]. The latter reaction, as described in extra detail beneath for quercetin, necessarily converts the flavonoid into a no cost radical intermediate, eventually giving location for the formation of an oxidized metabolite, or to a set of different metabolites. Within this mechanism, the ROS-scavenging action on the flavonoid would last as considerably time because it takes to oxidatively consume its redox-active phenolic groups. On the other hand, it remains to be observed if, just after undergoing such oxidation, the flavonoids that act via this direct antioxidant mechanism will necessarily drop their original antioxidant properties. The answer to this question was, for any long time, good. The cause for that was that in order to function as a straight acting antioxidant, the redox-active phenolic groups of a flavonoid involved in its ROS scavenging/reducing action want to exist in their decreased state. Consequently, if such groups have currently engaged within a reaction where they’ve been oxidatively consumed, it seems affordable to assume that the generated metabolite(s) will necessarily be devoid of the flavonoid’s original ROS scavenging/reducing potential. Similarly, this argument may be extended to these flavonoids whose original structures need to be preserved in an effort to inhibit the catalytic activity of ROS-generating enzymes and/or to chelating redox-active metals. Lately, on the other hand, some proof has emerged revealing that such contention requirements to be revised–at least for the ROS-scavenging and ROS-reducing capacity of particular flavonoids. In reality, in addressing the consequences that the oxidation of quercetin and that of thirteen other structurally associated flavonoids could bring on, with regards to their original ROS-scavenging (ORAC assay) and ROS-reducing (Folin iocalteu- and Fe-Triazine) properties, Atala et al. [53] reported that most of the mixtures of metabolites that resulted from such oxidations partially or largely conserved, rather than lost, the antioxidant properties of their precursors. These latter effects have been observed irrespective of the technique employed to induce their oxidative consumption (i.e., alkali-induced or mushroom tyrosinase-mediated)Antioxidants 2022, 11,8 ofand within the case from the alkali-exposed flavonoids, the oxidation mixtures of 9 with the 14 Leishmania Compound tested flavonoids (which included flavanols, flavonols, flavones and flavanones) exhibited ROS-scavenging remnant activities that have been higher than 70 , and that thirteen from the 14 tested flavonoids retained over 50 on the original Folin iocalteu-reducing properties. Whilst the referred to study did not establish the chemical identity on the metabolites in every oxidation mixture, the authors speculated that the oxidation process would not grossly alter these structural moieties that happen to be mainly accountable for the ROS-scavenging and/or redox-reducing properties of your flavonoids. Presu
