During black tea production, catechins and their galloyl esters are enzymatically oxidized to generate a complex mixture of black tea polyphenols. The role of galloyl ester groups in this process has yet to be determined. Enzymatic oxidation of epicatechin 3-O-gallate (1) yielded two new oxidation products, theaflavate C and bistheaflavate A, along with theaflavate A (2), a known dimer of 1 generated by coupling of the B-ring with the galloyl group. Theaflavate C is a trimer of 1 and possesses two benzotropolone moieties generated by the oxidative coupling of the galloyl groups with the catechol B-rings. Bistheaflavate A was found to be a tetramer produced by intermolecular coupling of two benzotropolone moieties of 2. From the structures of the products, it was deduced that oxidative coupling of galloyl groups resulted in extension of the molecular size of the products in catechin oxidation.
雑誌名
Chemical & Pharmaceutical Bulletin
巻
55
号
12
ページ
1768 - 1772
発行年
2007-12
出版者
The Pharmaceutical Society of Japan
ISSN
00092363
EISSN
1347-5223
書誌レコードID
AA10885497
PubMed番号
18057757
DOI
10.1248/cpb.55.1768
著者版フラグ
publisher
関係URI
http://dx.doi.org/10.1248/cpb.55.1768
引用
Chemical & Pharmaceutical Bulletin v.55(12) p.1768-1772, 2007
Structures of Epicatechin Gallate Trimer and Tetramer Produced by Enzymatic Oxidation
CPBul55_1768.pdf
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