Liu Zhang-Bin, Matsuo Yosuke, Saito Yoshinori, Huang Yong-Lin, Li Dian-Peng, Tanaka Takashi
Department of Natural Product Chemistry, Graduate School of Biomedical Sciences, Nagasaki University, 1-14 Bunkyo-machi, Nagasaki 852-8521, Japan.
Guangxi Key Laboratory of Functional Phytochemicals Research and Utilization, Guangxi Institute of Botany, Guilin 541006, China.
Molecules. 2023 Jan 27;28(3):1246. doi: 10.3390/molecules28031246.
The identification of unstable metabolites of ellagitannins having ortho-quinone structures or reactive carbonyl groups is important to clarify the biosynthesis and degradation of ellagitannins. Our previous studies on the degradation of vescalagin, a major ellagitannin of oak young leaves, suggested that the initial step of the degradation is regioselective oxidation to generate a putative quinone intermediate. However, this intermediate has not been identified yet. In this study, young leaves of were extracted with 80% acetonitrile containing 1,2-phenylenediamine to trap unstable ortho-quinone metabolites, and subsequent chromatographic separation afforded a phenazine derivative of the elusive quinone intermediate of vescalagin. In addition, phenylenediamine adducts of liquidambin and dehydroascorbic acid were obtained, which is significant because liquidambin is a possible biogenetic precursor of C-glycosidic ellagitannins and ascorbic acid participates in the production of another C-glycosidic ellagitannin in matured oak leaves.
鉴定具有邻醌结构或活性羰基的鞣花单宁不稳定代谢产物对于阐明鞣花单宁的生物合成和降解过程至关重要。我们之前对橡木幼叶中主要鞣花单宁——紫铆因降解的研究表明，降解的第一步是区域选择性氧化以生成一种假定的醌中间体。然而，这种中间体尚未被鉴定出来。在本研究中，用含有1,2 - 苯二胺的80%乙腈提取橡木幼叶以捕获不稳定的邻醌代谢产物，随后的色谱分离得到了紫铆因难以捉摸的醌中间体的吩嗪衍生物。此外，还获得了异栗木鞣质和脱氢抗坏血酸的苯二胺加合物，这具有重要意义，因为异栗木鞣质可能是C - 糖苷鞣花单宁的生物合成前体，而抗坏血酸参与成熟橡木叶中另一种C - 糖苷鞣花单宁的生成。
