Anti-Parkinson's disease activity of phenolic acids from Eucommia ulmoides Oliver leaf extracts and its autophagy activation mechanism


Although Parkinson’s disease (PD) is the second most common neurodegenerative disorder, the preventative or therapeutic agents for the treatment of PD are limited. Eucommia ulmoides Oliver (EuO) is widely used as traditional herb to treat various diseases. EuO bark extracts have been reported to possess anti-PD activity. Here, we investigated whether extracts of EuO leaves (EEuOL) also have therapeutic effect on PD since similar components and clinical application have been found between barks and leaves of this tree. We identified the chemical composition of EEuOL by HPLC-Q-TOF-MS and tested the anti-PD effect of EEuOL using zebrafish PD model. As a result, 28 compounds including 3 phenolic acids, 7 flavonoids, and 9 iridoids were identified. EEuOL significantly reversed the loss of dopaminergic neurons and neural vasculature as well as reduced the numbers of apoptotic cells in the zebrafish brain in a concentration-dependent manner. Moreover, EEuOL relieved locomotor impairments in MPTP-modeled PD zebrafish. We also investigated the underlying mechanism and found that EEuOL may activate autophagy, contributing to α-synuclein degradation, therefore alleviate PD-like symptoms. Molecular docking simulation implied the interaction between autophagy regulators (Pink1, Beclin1, Ulk2, and Atg5) and phenolic acids of EEuOL, affirming the involvement of autophagy in EEuOL-exerted anti-PD action. The overall results indicated the anti-PD effect of EEuOL, opening a possibility to use the extract in PD treatment.


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