Comparison between HPLC and HPTLC-densitometry for the determination of harpagoside from Harpagophytum procumbens CO2-extracts

Carbon dioxide (CO2) extracts of the secondary roots of Harpagophytum procumbens were quantified by high performance liquid chromatography (HPLC) and high performance thin layer chromatography (HPTLC). An isocratic HPLC method was used for the quantification of the iridoid glucoside harpagoside at 278 nm. A HPTLC assay was developed for the determination of harpagoside after coloration at 509 nm. The diode array detection of both analytical assays were used to examine the purity of harpagoside peaks and compared with the standards, respectively. The assays provide good accuracy, reproducibility and selectivity for the quantitative analysis of harpagoside. The harpagoside contents of 15 different CO2-extracts were compared by HPLC and HPTLC-densitometry. The quantitative results of both analytical methods did not show any statistical significance between each other, although a trend to slightly lower mean values could be found for the HPTLC method. (c) 2004 Elsevier B.V. All rights reserved.