Polymethylated Flavonols of Chrysosplenium americanum I. Identification and Enzymatic Synthesis
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چکیده
Polymethylated Flavonols, Identification, Enzymatic Synthesis, O-Methyltransferase, Chrysosplenium americanum, Saxifragaceae The major flavonoid constituents of Chrysosplenium americanum (Saxifragaceae) were identi fied by UV-, NMRand mass spectroscopy and the analysis of their hydrolytic products. They consisted of two 2'-0-/?-D-glucosides of partially methylated 2'-hydroxyquercetin and four 5'-0-/?-D-glucosides of partially methylated 6-hydroxyquercetin (quercetagetin). The O-methyltransferase system of this tissue can catalyse the stepwise O-methylation of quercetin, but not quercetagetin, to its 3,7,4'-triOMe-dervative. It is postulated that the latter compound may serve as a branching-point intermediate in the biosynthesis of the naturally occurring O-methylated flavonols of this tissue.
منابع مشابه
Role of Serine 286 in cosubstrate binding and catalysis of a flavonol O-methyltransferase.
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