3371-27-5Relevant articles and documents
Oxidation and epimerization of epigallocatechin in banana fruits
Tanaka, Takashi,Kondou, Kouhei,Kouno, Isao
, p. 311 - 316 (2000)
To examine the metabolism of proanthocyanidins in banana fruit, (-)- epigallocatechin was treated with the homogenate of the fruit flesh to yield (-)-gallocatechin and an oxidation product, 1-(3,4,5-trihydroxyphenyl)-3- (2,4,6-trihydroxyphenyl)-2-hydroxy-
Enzymatic oxidation of gallocatechin and epigallocatechin: Effects of C-ring configuration on the reaction products
Matsuo, Yosuke,Yamada, Yuko,Tanaka, Takashi,Kouno, Isao
, p. 3054 - 3061 (2008)
Tea leaf is rich in pyrogallol-type catechins, and their oxidation is important in the generation of black tea polyphenols. In the present study, the enzymatic oxidation of three pyrogallol-type catechins, (+)- and (-)-gallocatechins and (-)-epigallocatechin, was compared. The reactions yielded unstable quinone products, which were trapped as condensation products with o-phenylenediamine. The oxidation of (+)-gallocatechin proceeded very slowly compared to the reaction of (-)-epigallocatechin, and yielded a proepitheaflagallin-type dimer as the major product, though oxidation of (-)-epigallocatechin gave predominantly dehydrotheasinensin C. The cis-configuration of the C-3 hydroxyl group and the B-ring of (-)-epigallocatechin was apparently crucial for rapid and selective production of dehydrotheasinensin C. Oxidation of (-)-gallocatechin proceeded in a manner similar to that of (+)-gallocatechin, and produced an enantiomer of the (+)-gallocatechin product. The results suggest that enzymes catalyze oxidation of the pyrogallol B-ring to the o-quinone, with subsequent non-enzymatic coupling reactions proceed under highly steric control.
Mechanism of oolongtheanin formation via three intermediates
Hirose, Sayumi,Kamatari, Yuji O.,Yanase, Emiko
supporting information, (2020/01/24)
To clarify the mechanism of oolongtheanin formation, the oxidations of (?)-epigallocatechin and (?)-epigallocatechin gallate were investigated, and key intermediates were isolated. These intermediates were determined to be dehydrotheasinensins and pro-oolongtheanins, which we have reported previously, and one novel intermediate. Based on the chemical structures of these intermediates, a mechanism was proposed for oolongtheanin formation from catechins, and confirmed by NMR and GC–MS analysis.
Enantioselective total syntheses of (+)-gallocatechin, (-)- epigallocatechin, and 8-C-ascorbyl-(-)-epigallocatechin
Lin, Guang,Chang, Le,Liu, Yongxiang,Xiang, Zheng,Chen, Jiahua,Yang, Zhen
supporting information, p. 700 - 704 (2013/05/09)
Reading the tea leaves: The enatioselective total syntheses of 8-C-ascorbyl-(-)-epigallocatechin was accomplished by CuII-mediated oxidative coupling of ascorbic acid and (-)-epigallocatechin as a key step. Also, the asymmetric total syntheses of tea-leaf extracts (+)-gallocatechin and (-)-epigallocatechin were achieved by Au-catalyzed intramolecular cycliarylation of the precursor epoxide and Sharpless dihydroxylation. Copyright