Protective effect of phenolic compounds on carbonyl-amine reactions produced by lipid-derived reactive carbonyls

- Phenolics protected amino acids against damage produced by epoxyalkenals.
- Flavonols and single m-diphenols were the most protective phenolics.
- The protection occurred via epoxyalkenal trapping by phenolics.
- Reaction of epoxyalkenals with phenolics was faster than with amino acids.
- Structure-activity relationship for assayed phenolics is discussed.

The degradation of phenylalanine initiated by 2-pentenal, 2,4-heptadienal, 4-oxo-2-pentenal, 4,5-epoxy-2-heptenal, or 4,5-epoxy-2-decenal in the presence of phenolic compounds was studied to determine the structure-activity relationship of phenolic compounds on the protection of amino compounds against modifications produced by lipid-derived carbonyls. The obtained results showed that flavan-3-ols were the most efficient phenolic compounds followed by single m-diphenols. The effectiveness of these compounds was found to be related to their ability to trap rapidly the carbonyl compound, avoiding in this way the reaction of the carbonyl compound with the amino acid. The ability of flavan-3-ols for this reaction is suggested to be related to the high electronic density existing in some of the aromatic carbons of their ring A. This is the first report showing that carbonyl-phenol reactions involving lipid-derived reactive carbonyls can be produced more rapidly than carbonyl-amine reactions, therefore providing a satisfactory protection of amino compounds.