Analysis of astragalosides I, II and IV in some Egyptian Astragalus species and Astragalus dietary supplements using high-performance liquid chromatography/evaporative light scattering detector and non-parametric regression

Introduction GenuTsAstragalusL. is characterised by the presence of cycloartane saponins which have wide biological activities such as antioxidant, immunomodulating, hepatoprotective and anti-inflammatory activities. From these cycloartane saponins are astragalosides I, II and IV which have been regarded as the most important active constituents inAstragalusspecies. Objectives This work describes the quantitative analysis of astragalosides I, II and IV in some EgyptianAstragalusspecies andAstragalusdietary supplements in a single run by high-performance liquid chromatography/evaporative light scattering detector (HPLC/ELSD) using gradient elution. Methodology The method of quantitation adopted in this study is the standard addition method. First and second derivative treatment of the data was performed, and the study presents comparison between two statistical regression methods for handling data; parametric and non-parametric regression methods. Results Derivative treatment of the chromatographic response data gives improved quantitation of the chromatographic signals. Non-parametric regression of the data using Theil's method is advantageous over the usual least squares method as it assumes that errors could occur in bothx- andy-directions and they might not be normally distributed. In addition, it could effectively circumvent any outlier data points. Conclusion Due to the simplicity and the good accuracy and reproducibility of the suggested methods, they could be used for analysis and quality control ofAstragalusspecies andAstragalusdietary supplements.