Phospholipids as antioxidants - preparation and characterization of phosphatidylethanolamine complexes with selected sugar-reductons

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The use of α-tocopherol as natural antioxidant in food is always the first choice. In a mixture of lecithin, L-ascorbic acid and α-tocopherol, phosphatidylethanolamine as component of lecithin thermally forms with L-ascorbic acid a covalently linked condensate, which is responsible for the extremely high antioxidat effect of the ternary mixture. The stabilizing effect is based on a synergistic mechanism, that depends on the regeneration of oxidatively degraded α-tocopherol by the phosphatidyl-ascorbic acid (1st application phase). However, the exact chemical structure of the condensate has not yet been determined since it can also be present as a dimer, which deranges preparative separation and structural elucidation.The aim of the follow-up application is firstly to elucidate of the chemical structure(s) of the phosphatidyl-ascorbic acid complexe. In analogy to the reaction of L-ascorbic acid and its antioxidant activity, reductones from the Maillard reaction (D-glucosone, furaneol, norfuranol and reductic acid) in combination with phosphatidylethanolamine and α-tocopherol are to be investigated for their antioxidant activity. The activation of the antioxidant properties by phosphatidylethanolamine combined with an α-tocopherol regeneration (synergistic effect) has already been shown for D-glucosone. It occurs with D-glucose as well, but surprisingly it is much greater with D-glucuronic acid-γ-lactone. Since the synergistic effect only occurs in a mixture together with phosphatidylethanolamine (in some cases even without α-tocopherol), the reactions behind, and the involved products are to be elucidated. We assume that the Amadori compounds of the phosphatidylethanolamine to be the key intermediats, characterized by higher stability compared to phosphatidyl-ascorbic acid.