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

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).