Screening and determination for potential acetylcholinesterase inhibitory constituents from ginseng stem–leaf saponins using ultrafiltration (UF)-LC-ESI-MS2

Abstract

Introduction: Previous studies have demonstrated that several ginsenosides have remarkable inhibitory effect on acetylcholinesterase (AChE). In the present study, ginseng stem–leaf saponins (GSLS) can improve learning and memory of Alzheimer's disease patients. However, much comprehensive information regarding AChE inhibition of GSLS and its metabolites is yet unknown. Objective: The present study aims to screen and determine the potential of AChE inhibitors (AChEIs) from GSLS. Methodology: The active fraction of the GSLS detected in vitro AChE inhibition assays was selected as a starting material for the screening of the potential of AChEIs using ultrafiltration liquid chromatography coupled to electrospray ionisation tandem mass spectrometry (UF-LC-ESI-MS2). Results: The results showed that 31 ginsenosides were identified with analysis using rapid resolution liquid chromatography with a diode array detector combined with electrospray ionisation tandem mass spectrometry (RRLC-DAD-ESI-MS2) from the active fraction, and there are 27 compounds with AChE binding activity. Among them, 11 ginsenosides were evaluated and confirmed using in vitro enzymatic assay, and ginsenosides F1, Rd, Rk3, 20(S)-Rg3, F2 and Rb2 were found to possess strong AChE inhibitory activities. Conclusion: The proposed UF-LC-ESI-MS2 method was a powerful tool for the discovery of AChEIs from traditional Chinese medicine (TCM).