2,4-Alkadienal trapping by phenolics

Abstract

Phenolics can trap lipid-derived reactive carbonyls as a protective function that diminishes the broadcasting of the lipid oxidative damage to food macromolecules. In an attempt to clarify the trapping of 2,4-alkadienals by phenolics, this study analyzes the reactions of 2,4-hexadienal, 2,4-heptadienal, and 2,4-decadienal with 2-methylresorcinol. These reactions produced (E)-4-(alk-1-en-1-yl)-8-methyl-2,7-bis(prop-1-en-2-yloxy)chromanes, which were isolated and characterized by 1D and 2D NMR and MS. Carbonyl-phenol adduct formation was favored at pH > 7 and moderate temperatures (25-80 °C). Adducts were quantified and shown to be produced as a mixture of diastereomers. Diastereomers 2R,4S plus 2S,4R were formed to a higher extent than diastereomers 2R,4R plus 2S,4S under the different conditions assayed, although activation energies (E) for the formation of all of them was mostly the same (∼62 kJ·mol). These results show that phenolics can trap 2,4-alkadienals and provide the basis for the later detection of the formed adducts in food pro[ducts.

Phytochemical‐Rich Antioxidant Extracts of Vaccinium Vitis‐idaea L. Leaves Inhibit the Formation of Toxic Maillard Reaction Products in Food Models

“…Better inhibitory effect observed in case of AE, possessing weaker radical scavenging and total phenolic content than WE, may seem somewhat unexpected. According to our results and previously reported observations (Hidalgo & Zamora, ), it may be assumed that different effect of WE and AE on PhIP formation could be due to the different composition of phenolics: WE contained more hydroxycinnamic acids, proanthocyanidins, and flavonols than AE. The amounts of hydroxycinnamic acids as quinic, protocatechuic, chlorogenic, caffeic, and p ‐coumaric were in traces or even undetectable in AE.…”

Characterization of Carbonyl–Phenol Adducts Produced by Food Phenolic Trapping of 4-Hydroxy-2-hexenal and 4-Hydroxy-2-nonenal

“…Stabilization of adduct 4 occurs simply by forming the corresponding hemiacetal (6), analogous to that observed in reactions involving 2-alkenals 24 or 2,4-alkadienals. 25 The later acetylation of adduct 6 stabilizes the structure of the adduct and produces the adducts 2 isolated and characterized in this study. Curiously, acetylation only occurs in the phenolic hydroxyl group.…”

“…After this initial addition, the molecule is then stabilized by blocking the carbonyl group, usually by the formation of a hemiacetalic structure. This occurs in 2-alkenals, , 2,4-alkadienals, and 4-oxo-2-alkenals . As an exception, in 4,5-epoxy-2-alkenals, the reaction is initiated by the attack of the hydroxyl group of phenolic to the epoxide ring of lipid carbonyl because of the high reactivity of this three-membered ring …”

“…18 In addition, formation of these carbonyl-phenol adducts has been related to the protective function of some phenolics on the formation of heterocyclic aromatic amines and biogenic amines by carbonylamine reactions, 19,20 and the beneficial properties of polyphenolic-rich foods such as tea or coffee. 21 Although carbonyl-phenol reactions with different lipid-derived reactive carbonyls have been described, [22][23][24][25][26][27] the ability of phenolic compounds to trap and produce carbonyl-phenol adducts with 4-hydroxyalkenals has not been described. To the best of our knowledge, although several studies have shown that 4-hydroxy-2-nonenal (HNE) seems to be effectively trapped by phenolics, 28,29 neither the produced reaction has been described in detail nor the structure(s) of the formed adduct(s) has been unequivocally characterized.…”

“…Although carbonyl–phenol reactions with different lipid-derived reactive carbonyls have been described, − the ability of phenolic compounds to trap and produce carbonyl–phenol adducts with 4-hydroxyalkenals has not been described. To the best of our knowledge, although several studies have shown that 4-hydroxy-2-nonenal (HNE) seems to be effectively trapped by phenolics, , neither the produced reaction has been described in detail nor the structure(s) of the formed adduct(s) has been unequivocally characterized.…”