Simultaneous Determination of Baicalin, Wogonoside, Baicalein, Wogonin, Berberine, Coptisine, Palmatine, Jateorrhizine and Glycyrrhizin in Kampo Medicines by Ion-Pair High-Performance Liquid Chromatography

An ion-pair high-performance liquid chromatographic method for the simultaneous determination of four flavonoids, namely baicalin, wogonoside, baicalein and wogonin, and four berberine-type alkaloids, namely berberine, coptisine, palmatine and jateorrhizine, and glycyrrhizin in Kampo medicines is described. The analysis can be accomplished within 30 min with a Wakosil-II 5C18 HG column by linear gradient elution using a mobile phase containing aqueous phosphoric acid, sodium dodecyl sulfate and acetonitrile at a flow-rate of 1.0 ml·min-1, a thermostatic oven at 45°C, and detection at 265nm. The method was applied to quantifying these components in three Kampo decoctions : Oren-gedoku-to, San'o-shashin-to and Hange-shashin-to. The decoctions were diluted with 65% methanol at the final stage because a large quantity of precipitate, mainly from baicalin and berberine, was formed. The within-day relative standard deviations were less than 2.02% (n=10). The recoveries of these compounds were 90.3-102%. The detection limits of these compounds were 0.02-1.96 μM per injection (5 μl).