Flavonoids measuring total anthocyanins

Total flavonoid content. Quantitative analysis of flavonoids depends on the objective of the study. Colorimetric estimation of total flavonoid content is measured by the aluminum chloride colorimetric assay (Jia and others 1999 Chang and others 2002). The total flavonoid content measured in this way is normally expressed in equivalent values of a standard flavonoid, often catechin or quercetin equivalents. Not all subgroups of flavonoids can be quantified by colorimetric methods however, total anthocyanin content is determined using the pH-differentiation method (Boyles and others 1993). 

More recently, studies on the absorption of flavonoid glycosides typical of berries and grapes are reported. Lapidot et al. (1998) traced anthocyanins in human urine after the intake of 300 ml red wine, corresponding to 218 mg of anthocyanins. Totals of 1.5-5.1% of the anthocyanins were recovered in the urine within 12 h after wine consumption, two compounds were unchanged, whereas other compounds seemed to have undergone molecular modifications. The anthocyanin levels of the urine reached a peak within 6 h of consumption. Serafini et al. (1998) tested the effects of the intake of the nonalcoholic fraction of red or white wine on plasma antioxidant capacity, measured as total radical-trapping parameter (TRAP), and on... 

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