Ruptured organosilica nanocapsules immobilized acetylcholinesterase coupled with MnO2 nanozyme for screening inhibitors from Inula macrophylla.

Abnormal expression of acetylcholinesterase (AChE) causes Alzheimer's disease (AD). Inhibiting AChE is a common strategy for reducing the degradation of neurotransmitter acetylcholine, in order to treat early-stage AD. Therefore, it is crucial to screen and explore AChE inhibitors which are safer and cause fewer side effects. Our research is focused on establishing a platform of ruptured organosilica nanocapsules (RONs) immobilized AChE coupled with an MnO2-OPD colorimetric assay, which could monitor AChE activity and screen AChE inhibitors. The fabricated RONs immobilized AChE possessed excellent pH and thermal stability. Huperzine A was introduced into the established platform to evaluate the inhibition kinetics of the immobilized AChE, which promoted its application in the screening of AChE inhibitors. The satisfactory results of enzyme inhibition kinetics proved the feasibility and applicability of the established method. Thus, the proposed platform was applied to screen AChE inhibitors from 14 compounds isolated from Inula macrophylla, and β-cyclocostunolide (compound 4) demonstrated the best AChE inhibitory activity among these compounds. This work confirms the existence of chemical components that inhibit AChE activity in Inula macrophylla, and provides a new idea for the application of immobilized enzyme-nanozyme in the field of enzyme inhibitor screening.