Oxidative chemistry of the natural antioxidant hydroxytyrosol: hydrogen peroxide-dependent hydroxylation and hydroxyquinone/o-quinone coupling pathways
作者:Maria De Lucia、Lucia Panzella、Alessandro Pezzella、Alessandra Napolitano、Marco d'Ischia
DOI:10.1016/j.tet.2005.10.055
日期:2006.2
Similar oxidation of 4-methylcatechol gave, after the same work-up, the acetylated derivatives of 1,2,4-trihydroxy-5-methylbenzene (5) and the pentahydroxybiphenyl 6. Mechanistic experiments suggested that hydrogen peroxide affects the course of the oxidation of 1 by adding to the first formed o-quinone to give a hydroxyquinone intermediate. This could bring nucleophilic attack to the o-quinone of 1 to
在pH 7.4的磷酸盐缓冲液中用过氧化物酶/ H 2 O 2氧化天然抗氧化剂羟基酪醇(1)导致形成两种主要的可乙酸乙酯萃取的产物。这些可以通过还原和乙酰化后的制备TLC分离,并且通过2D NMR和MS分析鉴定为2-(2,4,5-三羟基苯基)乙醇(3)的四乙酰基衍生物和五羟基联苯4的七乙酰基衍生物。经过相同的后处理,4-甲基邻苯二酚的类似氧化反应得到1,2,4-三羟基-5-甲基苯的乙酰化衍生物(5)和五羟基联苯6。机械实验表明,过氧化氢的影响的氧化过程1通过向第一形成Ò -quinone,得到羟基醌中间体。这可能对1的邻醌产生亲核攻击,从而使二聚体4形成。这些结果揭示了4-烷基邻苯二酚的新型氧化途径,并为研究1的抗氧化作用机理提供了改进的化学基础。