Coupling and Decoupling of Diverse Molecular Units in Glycosciences by Zbigniew J. Witczak & Roman Bielski

Author:Zbigniew J. Witczak & Roman Bielski
Language: eng
Format: epub
Publisher: Springer International Publishing, Cham

More recently, the biosynthesis of vitexin (17), isovitexin (18), orientin (31) and isoorientin (32) was accomplished by Hao and co-workers using Desmodium incanum root proteins, starting from the corresponding 2-hydroxyflavanones, the required substrates of C-glycosyltransferases existent in Desmodium spp. [21, 22]. As clarified in a previous report [29], Wessely–Moser isomerization is responsible for the interconversion between the corresponding 8-β-C- (45 and 46) and 6-β-C-glucosyl derivatives (49 and 50), as 2-hydroxyflavanones may exist in solution in either open chain or cyclized structures (Scheme 9). In spite of the consequent lack of regioselectivity, these intermediates afforded the respective flavones in overall excellent yields after acid-promoted chemical dehydration.

Scheme 9Reagents and conditions: a D. Incanum root protein, 100 mM HEPES, 2 mM DTT, pH 7.5, UDP-Glucose, 30 °C; b 1 M HCl (vitexin, 17, 44% and isovitexin, 18, 53%; orientin, 31, 43% and isoorientin, 32, 56%) [22, 29]

Download

Copyright Disclaimer:
This site does not store any files on its server. We only index and link to content provided by other sites. Please contact the content providers to delete copyright contents if any and email us, we'll remove relevant links or contents immediately.