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

α-生育酚作为天然抗氧化剂在食品中的应用一直是首选。在卵磷脂、L-抗坏血酸和α-生育酚的混合物中，作为卵磷脂组分的磷脂酰乙醇胺与L-抗坏血酸热形成共价连接的缩合物，这是三元混合物具有极高抗氧化效果的原因。稳定作用基于协同机制，这取决于磷脂酰-抗坏血酸对氧化降解的α-生育酚的再生（第1个应用阶段）。然而，由于其也可以作为二聚体存在，因此尚未确定缩合物的确切化学结构，这扰乱了制备分离和结构解析。与L-抗坏血酸的反应及其抗氧化活性类似，将研究来自美拉德反应的还原酮（D-葡糖醛酮、呋喃酮、去甲呋喃醇和还原酸）与磷脂酰乙醇胺和α-生育酚组合的抗氧化活性。已证明磷脂酰乙醇胺与α-生育酚再生（协同效应）结合可激活D-葡萄糖酮的抗氧化特性。它也发生在D-葡萄糖中，但令人惊讶的是，它在D-葡萄糖醛酸-γ-内酯中的作用要大得多。由于协同效应仅发生在与磷脂酰乙醇胺的混合物中（在某些情况下甚至不含α-生育酚），因此后面的反应和涉及的产物有待阐明。我们假设磷脂酰乙醇胺的Amadori化合物是关键中间体，其特征在于与磷脂酰抗坏血酸相比具有更高的稳定性。

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.