A Practical Quality Control Method for Saponins Without UV Absorption by UPLC-QDA

Abstract

Saponins are a class of important active ingredients. Analysis of saponin-containing herbal medicines is a major challenge for the quality control of medicinal herbs in companies. Taking the medicine Astragali radix (AR) as an example, it has been shown that the existing evaporative light scattering detection (ELSD) methods of astragaloside IV (AG IV) has the disadvantages of time-consuming sample preparation and low sensitivity. The universality of ELSD results in an inapplicable fingerprint with huge signals from primary compounds and smaller signals from saponins. The purpose of this study was to provide a practical and comprehensive method for the quality control of the astragalosides in AR. A simple sample preparation method with sonication extraction and ammonia hydrolyzation was established, which shortens the preparation time from around 2 days to less than 2 h. A UPLC-QDA method with the SIM mode was established for the quantification of AG IV in AR. Methanol extract was subjected to UPLC-QDA for fingerprinting analysis, and the common peaks were assigned simultaneously with the QDA. The results showed that with the newly established method, the preparation time for a set of samples was less than 90 min. The fingerprints can simultaneously detect both saponins and flavonoids in AR. This simple, rapid, and comprehensive UPLC-QDA method is suitable for quality assessment of RA and its products in companies, and also provides references for the quality control of other saponin ingredients without UV absorption.

Quality Markers for Astragali Radix and Its Products Based on Process Analysis

“…The sample preparation for the AG IV determination in the Chinese Pharmacopoeia (National Commission of Chinese Pharmacopoeia, 2015) (version 2015) involves reflux extraction, liquid-liquid separation with n-butanol, and liquidliquid separation with ammonia, which may take more than 2 days to complete per sample. Therefore, we optimized and established practical method for the determination of AG IV content in raw materials and pieces of AR (Zhao et al, 2018). This method replaces all of the time-consuming preparation steps with sonication extraction and ammonia hydrolysis, shortening the preparation time from around 2 days to less than 2 h. Sample preparation methods and analysis methods were optimized in this study for freeze-dried powder and formula granules of AR as described below.…”

“…Extraction and preparation of AR pieces was carried out as described in our previous study (Zhao et al, 2018). Each sample of freeze-dried powder and formula granules was accurately weighed, 0.3 and 0.5 g, respectively, placed in a 50 ml centrifuge tube.…”

“…One critical step for the sample preparation of AR in Chinese Pharmacopoeia was reverse extraction with ammonia (National Commission of Chinese Pharmacopoeia, 2015). The purpose of this step was to transform other saponins into AG IV (Zhao et al, 2018). As an important parameter, the amount of ammonia solution needed for the transformation of astragalosides into AG IV was investigated.…”

“…Therefore, the present quality analysis methods based on AG IV and CG as Q-markers of AR and its products should be reconsidered. Previous studies on AR, have identified the major small molecules and different quantification methods have been developed for AR and its products (Qi et al, 2006;Song et al, 2007;Qi et al, 2008;Song et al, 2008;Zhao et al, 2018). However, the stability of the levels of Q-makers during the whole manufacturing process and sample preparations were neglected.…”

A Systematic Review of Phytochemistry, Pharmacology and Pharmacokinetics on Astragali Radix: Implications for Astragali Radix as a Personalized Medicine

“…The studies on astragaloside IV (AS-IV) are more and more increasingly popular. A simple and fast quantification method for AS-IV has been established with ultra-performance liquid chromatography (UPLC-QDA) [47]. In addition, it has been confirmed that AS-IV is the main bioactive constituent among the Astragalus saponins, which has been reported to exert extensive pharmacological actions in various diseases [36].…”