1. Identification of Unstable Ellagitannin Metabolites in the Leaves of Quercus dentata by Chemical Derivatization
- Author
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Zhang-Bin Liu, Yosuke Matsuo, Yoshinori Saito, Yong-Lin Huang, Dian-Peng Li, and Takashi Tanaka
- Subjects
vescalagin ,liquidambin ,ascorbic acid ,phenylenediamine ,oxidation ,intermediate ,Organic chemistry ,QD241-441 - Abstract
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 Quercus dentata 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.
- Published
- 2023
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