Medicinal Chemistry Research

, Volume 27, Issue 6, pp 1589–1598 | Cite as

Spectroscopic investigation on the interaction characteristics and inhibitory activities between baicalin and acetylcholinesterase

  • Mingyan Sun
  • Ming Su
  • Hanwen Sun
Original Research


Restoring neurotransmitter acetylcholine (ACh) levels by inhibiting acetylcholinesterase (AChE) has become the primary treatment for the cognitive deficits of Alzheimer’s disease. The inhibitory effects of flavonoids on AChE have attracted great interest among researchers, but few reports have focused on the interaction characteristics of inhibitor with AChE. In this work, the interaction of inhibitor baicalin with AChE was studied for the first time by fluorescence spectroscopy coupled with UV spectroscopy and circular dichroism (CD) techniques under near physiological conditions. The fluorescence quenching rate constants and binding constants for baicalin‒AChE system were determined at different temperatures. The fluorescence quenching of AChE by baicalin is due to static quenching and energy transfer. The distance and the binding constant (Ka) between baicalin and AChE were estimated to be 2.85 nm and 9.772 × 104 L mol−1 at 298 K. The results of thermodynamic parameters, ΔH (−174.6 kJ mol−1), ΔS (−489.9 J mol−1 K−1) and ΔG (−28.61 ~ −23.71 kJ mol−1), indicated that van der Waals interaction and hydrogen bonding played a major role for baicalin‒AChE association. Synchronous fluorescence spectral change of AChE showed the binding sites mainly are focused on tryptophan moiety. Circular dichroism spectra showed that baicalin caused a secondary structure change of AChE. Synchronous fluorescence and three-dimensional fluorescence studies showed that the presence of baicalin could change the conformation of AChE during the binding process. Baicalin showed an obvious inhibitory activity, with 1.24 × 10−4 mol L−1 for 50% inhibition of AChE activity (IC50). The in intro studies suggest that the baicalin could decrease catalytic activity of AChE, it is helpful for restoring and rebalancing neurotransmitter ACh levels.


Fluorescence Baicalin Acetylcholinesterase Interaction characteristics Inhibitory activities 



This work was supported by the Science Foundation Office of Hebei Province, China (B2014201171).

Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflict of interest.


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© Springer Science+Business Media, LLC, part of Springer Nature 2018

Authors and Affiliations

  1. 1.Hebei College of Science and TechnologyBaodingChina
  2. 2.Key Laboratory of Analytical Science and Technology of Hebei ProvinceHebei UniversityBaodingChina

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