Flavonol Glycoside Content and Composition of Tea Infusions Made from Commercially Available Teas and Tea Products

Abstract

The composition and content of flavonol glycosides (FGs) have been measured in infusions of a range of black tea and black tea products. Tea contains a mixture of glycosides of quercetin, kaempferol, and myricetin and the total level of these glycosides, in infusions prepared in a normal domestic manner, for the leaf teas varied from 36.5 to 88.3 mg/L, although greater variation was observed for the tea products, from 7.0 to 428.1 mg/L. Altogether seven quercetin, five kaempferol, and two myricetin glycosides were detected; their relative amounts varied significantly in the different samples. The significance of these differences in relation to the bioavailability and potential bioactivity of these compounds is discussed. Keywords: Tea; flavonol; glycoside; HPLC; quercetin; kaempferol; myricetin