Bioactivity-Guided Separation of Anti-Cholinesterase Alkaloids from (Miq.) Miq. Ex Havil Based on HSCCC Coupled with Molecular Docking.

As an important source of cholinesterase inhibitors, alkaloids in natural products have high potential value in terms of exerting pharmacological activities. In this study, a strategy for targeted preparation of cholinesterase inhibitors in (Miq.) Miq. ex Havil (UR) by high-speed counter-current chromatography was provided. In the method, a two-phase polar solvent system composed of ethyl acetate/-butanol/water (1:4:5, //) was used, which isolated five alkaloids from the UR extract for the first time. All alkaloids were identified by HR-ESI-MS and NMR as 7--javaniside (), vincosamide (), strictosamide (), cadambine (), and 3α-dihydrocadambine (). The poorly resolved compounds and were separated by preparative HPLC (prep-HPLC). Among them, compounds , , and were firstly obtained from UR. The purity of these plant isolates was 98.8%, 98.7%, 99.2%, 95.7%, and 98.5%, respectively. Compounds - exhibited an inhibitory effect on acetyl-cholinesterase and butyryl-cholinesterase with an IC from 1.47 to 23.24 µg/mL and 1.01 to 18.24 µg/mL. Molecular docking and inhibitory activities indicated that compound showed stronger inhibitory activity on acetyl-cholinesterase and butyryl-cholinesterase.