Synthesis and acetylcholinesterase inhibitory activities of tabersonine derivatives

Tabersonine, the main alkaloid in Voacanga seeds, was used as a lead compound to semi-synthesize tabersonine derivatives. In total, 13 compounds, containing 10 novel tabersonine derivatives, were synthesized by introducing substituent groups R-1-R-5. The acetylcholinesterase (AChE) inhibitory activities of tabersnonine derivatives were evaluated using Ellman's method. Among them, compound (7) showed the highest AChE inhibitory activity with the IC50 value was 5.32 mu M. The substituent groups R-1-R-5 showed different influences on the AChE inhibitory activities of tabersonine derivatives. The AChE inhibitory activities of tabersonine derivatives increased with the introduction of group R-1 and/or combined groups R-3, R-4, while decreased with the introduction of group R-5. And the group R-2 showed no significant influence on the AChE inhibitory activities of tabersonine derivatives. (C) 2015 Phytochemical Society of Europe. Published by Elsevier B.V. All rights reserved.