Isolation From the Flowers of Dryandra praemorsa of a Flavonol Glycoside That Reacts With β-Lectins

Abstract

A flavonol glycoside has been isolated from aqueous extracts of the flowers of Dryandra praemorsa (Proteaceae) that inhibits the reaction between β-lectins and the Yariv 'artificial antigens'. The flavonol is myricetin; the sugars are galactose (~ 90 %) and glucose (~ 10 %). The material analyses as a myricetin hexoside monohydrate, thus appearing to be a mixture of two components that have not been separated. The optical rotation is consistent with a β-configuration; experiments with compounds of known structure show that inhibitory activity is characteristic of flavonols glycosylated in the 3-position. Hyperin (the 3-β-D-galactopyranoside of the pentahydroxyflavone, quercetin) and the related quercitrin and rutin are somewhat less inhibitory but can be used to demonstrate the general characteristics of the inhibition with compounds of known structure. The inhibitory material can be attached to agarose to give a column packing that shows some capacity to bind β-lectins.