A multivariate analysis on the comparison of raw notoginseng (Sanqi) and its granule products by thin-layer chromatography and ultra-performance liquid chromatography

BACKGROUND Granule products produced from medicinal herbs are gaining popularity. However, there have been few studies comparing the quality or efficacy of granules with those of herbal formulations. This study aims to compare commercially available notoginseng (Sanqi in Chinese) in both raw and granule forms by thin layer chromatography (TLC) and ultra-performance liquid chromatography with photodiode array detection (UPLC-PDA) using multivariate analysis. METHODS Aqueous extracts of the raw herb (collected from six different sources in China) and granule products (purchased in China, Taiwan and Australia) were re-extracted with methanol to remove water-soluble excipients. Five compounds (ginsenosides Rg1, Rg2, Rd and Rb1 and notoginsenoside NR1) in the methanolic extracts were quantified by TLC and UPLC-PDA. Multivariate statistical analysis using hierarchical component analysis (HCA) and principal component analysis (PCA) was used to determine the similarities between the granule products and raw herbs. A 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) assay was used to measure the antioxidant capacities of the extracts. RESULTS HCA and PCA of the TLC analysis clustered the granule products into one group. By UPLC analysis, the raw herbs and two of the granule products (G7 and G12) were allocated into Group 1 and the rest of the granule products into Group 2. The contents of the five marker compounds in Group 1 were higher than Group 2 and also exhibited stronger ABTS activity (P = 0.005). By Pearson correlation, the contents of the five compounds in the samples were positively and significantly correlated to their antioxidant activities. CONCLUSIONS UPLC was more efficient than TLC for the simultaneous determination of the five major compounds in Sanqi products in terms of linearity, higher sensitivity and repeatability. The statistical analysis of the samples by HCA and PCA revealed that the contents of the marker compounds were significantly higher in the raw herb group than the granule group.