A new mechanism for oxidation of epigallocatechin and production of benzotropolone pigments
作者:Yosuke Matsuo、Takashi Tanaka、Isao Kouno
DOI:10.1016/j.tet.2006.03.021
日期:2006.5
Proepitheaflagallin was decomposed on heating to give epitheaflagallin and hydroxytheaflavin. The former is a known black tea pigment and the latter is a new pigment with 1′,2′,3′-trihydroxy-3,4-benzotropolone moiety. The results revealed a new mechanism for the production of these pigments from epigallocatechin.
(-)-表没食子儿茶素的酶促氧化产生了两个新的醌二聚体,脱氢theasinensin C和proepitheaflagallin。脱氢茶黄素C具有水合的环己烯酮结构,其氧化还原歧化反应可产生红茶多酚,茶黄素C和E,以及半乳糖基乌龙茶素。基于通过与邻苯二胺缩合制备的喹喔啉衍生物的光谱数据,确定前叶前鞭毛蛋白的结构。加热后将前鞭毛蛋白分解,得到表皮鞭毛蛋白和羟基茶黄素。前者是一种已知的红茶颜料,而后者是一种具有1',2',3'-三羟基-3,4-苯并噻吩酮部分的新颜料。结果揭示了由表没食子儿茶素生产这些颜料的新机理。