Cloning of a Novel O-Methyltransferase from Camellia sinensis and Synthesis of O-Methylated EGCG and Evaluation of their Bioactivity

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• 作者：Masanobu Kirita ; Daiki Honma ; Yoshihisa Tanaka ; Shinya Usui ; Toshihiko Shoji ; Manabu Sami ; Toyokazu Yokota ; Motoyuki Tagashira ; Atsuya Muranaka ; Masanobu Uchiyama ; Tomomasa Kanda ; Mari Maeda-Yamamoto
• 刊名：Journal of Agricultural and Food Chemistry
• 出版年：2010
• 出版时间：June 23, 2010
• 年：2010
• 卷：58
• 期：12
• 页码：7196-7201
• 全文大小：759K
• 年卷期：v.58,no.12(June 23, 2010)
• ISSN：1520-5118

文摘

The gene of a novel O-methyltransferase was isolated from tea cultivars (Camellia sinensis L.). Using the recombinant enzyme, O-methylated (−)-epigallocatechin-3-O-gallate (EGCG) in all cases were synthesized. EGCG and the synthesized O-methylated EGCGs including (−)-epigallocatechin-3-O-(3-O-methyl)-gallate (EGCG3′′Me), (−)-epigallocatechin-3-O- (4-O-methyl)-gallate(EGCG4′′Me), (−)-epigallocatechin-3-O-(3,5-O-dimethyl)-gallate (EGCG3′′,5′′diMe), and (−)-3-O-methyl-epigallocatechin-3-O-(3,5-O-dimethyl)-gallate (EGCG3′,3′′,5′′triMe) were assayed using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assay and antibacterial activity. EGCG was the most effective of the O-methylated EGCGs. The antiallergic effects of EGCG and the other O-methylated EGCGs were measured by conducting histamine release assays using bone marrow-derived mouse mast cells, and the order of potency was EGCG3′,3′′,5′′triMe = EGCG3′′,5′′diMe > EGCG3′′Me > EGCG. These results indicated that reducing the number of hydroxyl groups decreases the effectiveness of DPPH radical scavenging and antibacterial activity. In contrast, the inhibition of histamine release was potentiated by an increase in the number of methyl groups in EGCG, especially in the galloyl moiety.