Interactions of Lycopodium alkaloids with acetylcholinesterase investigated by 1H NMR relaxation rate

In order to further understand the interaction processes between the Lycopodium alkaloids and acetylcholinesterase, the binding properties of N-acetyl huperzine A ( 1), huperzine B ( 2) and huperzine F ( 3) with Torpediniforms Nacline acetylcholinesterase (TnAchE) were investigated by 1H NMR methods. The nonselective, selective and double-selective spin-lattice relaxation rates were acquired in the absence and presence of TnAchE at a ratio of [ligand]/[protein] = 1:0.005. The selective relaxation rates show protons of 1–3 have dipole–dipole interaction with protons of TnAchE at the binding interface. The molecular rotational correlation time of bound ligands was calculated by double-selective relaxation rate at 298 K, which showed that 1–3 had high affinity with the protein. The results indicate that investigation of 1H NMR relaxation data is a useful method to locate the new Lycopodium alkaloids as AchE inhibitors.