Unravelling discolouration caused by iron-flavonoid interactions: Complexation, oxidation, and formation of networks

Exploring the Formation of Polymers with Anti-Amyloid Properties within the 2′3′-Dihydroxyflavone Autoxidation Process

“…The 2′3′-dihydroxyflavone autoxidation was confirmed in our study ( Figure 1 A), leading to the scarce amount of the initial compound and a variety of different end-products. These products were possibly formed during the processes of degradation, oxidation coupling and polymerization [ 30 , 33 , 34 ].…”

“…These findings indicate that the autoxidation of 2′,3′-dihydroxyflavone (pH 8.0) leads to the polymerization of intermediate products. The literature describes a potential pathway through the formation of quinone moiety in the B ring [ 30 , 33 ]. Such motifs are more likely to form when flavones possess the C2-C3 double bond and absence of 3-OH group.…”

“…The autoxidation of polyphenolic molecules can lead to multiple distinct products obtaining unique structures and features [ 28 , 29 ]. This process involves degradation, oxidative coupling [ 17 , 30 , 31 ], and polymerization [ 32 ]. A recent study shows that the browning of the epicatechin and epigallocatechin samples is related to the oxidative coupling where o-quinone intermediates participate [ 33 ].…”

“…In order to identify the inhibitory molecules in the flavone oxidation mixture, we selected oxidized 2′,3′-dihydroxyflavone, which has previously been shown to possess the highest inhibitory potential among number of tested flavones against Aβ aggregation [ 21 ]. The 2′,3′-dihydroxyflavone has a C2-C3 double bond catechol moiety and the absence of 3-hydroxyl group that should favor the stabilization of the o-quinone and the oxidation coupling [ 30 ]. In this work, we show that the 2′,3′-dihydroxyflavone oxidation products range from small degradation to large oligomeric molecular compounds.…”

Transition metal cations catalyze16O/18O exchange of catechol motifs with H218O

“…Although the above described 16 O/ 18 O exchange may provide an interesting new approach for production of stable 18 O-labeled catechols, Fe(III) has been reported to induce oxidative degradation of various catechols. 28 Therefore, we simultaneously determined the labeling yield and recovery of all eight catechol derivatives, shown in Fig. 1, at various time points, using high resolution RP-UHPLC-PDA-ESI-MS. As can be observed from Table 1, complete (i.e., 100% doubly labeled compound) or near-to-complete labeling (i.e., >90% doubly labeled compound) was obtained for catechol, 4-chlorocatechol, 4-methylcatechol, 3,4-DHBA and dopamine with high (i.e., >69%) to very high (i.e., >95%) recoveries.…”