Quantitative analysis of triterpene saponins by HPTLC with scanning densitometry

Abstract

Triterpene saponins (glycosides) are used as active compounds in many drugs [ 1]. Methods used for the quantitative determination of triterpene saponins are based mostly on their hydrolysis followed by the analysis of aglycons, which is usually performed by titrometric and (less fiequently) spectrophotomettic techniques [2 5]. These methods, involving decomposition of saponin molecules, have a number of disadvantages. The analytical procedures are time-consuming and do not ensure quantitative evaluation of the ratio of individual saponins in complex saponin-containing preparations. In most cases, however, the analysis of saponins is restricted to their qualitative assessment by TLC the most accessible and simple chromatographic procedure [69]. Unfortunately, the use of TLC for the quantitative determination of components is hindered by the lack of scanning optical densitometers to provide for the proper processing of the chromatograms. Below we report on the results of a quantitative TLC determination of some triterpene saponins oleanolic acid derivativesin drug preparations and tinctures of medicinal plants.