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O-Galloyl-C-glycosylflavones from Pelargonium reniforme
Klaus Peter Latté1, Daneel Ferreira, M S Venkatraman
1Institut für Pharmazie, Pharmazeutische Biologie, Freie Universität Berlin, Konigin-Luise-Str. 2+4, Berlin 14195, Germany.
Abstract:
The unique series of C-2''-acylated C-glycosylflavones is extended by the discovery of the C-8-glucosyl derivatives 2''-O-galloylvitexin and 2''-O-galloylorientin and their C-6 analogues 2''-O-galloylisovitexin and 2''-O-galloylisoorientin, representing the first described O-galloyl-C-glycosylflavones. They are accompanied in the aerial parts of Pelargonium reniforme by the known non-galloylated parent analogues vitexin, orientin, isovitexin and isoorientin, as well as several known flavonoid-O-glycosides. The structures of these compounds were established from spectroscopic studies. Differentiation between C-glycosylation at C-6 and C-8 is discussed on the basis of the effects of dynamic rotational isomerism.