Objective
Atherosclerotic cardiovascular disease poses a significant health challenge globally. Recent findings highlight the pivotal role of the endothelial-to-mesenchymal transition (EndMT) in atherosclerosis. Morin is a bioflavonoid mainly extracted from white mulberry, a traditional Chinese herbal medicine with anti-inflammatory and antioxidant properties. This study examines whether morin can alleviate atherosclerosis by suppressing EndMT and seeks to elucidate the underlying mechanism.
Methods
We induced an in vitro EndMT model in human umbilical vein endothelial cells (HUVECs) by stimulating the cells with transforming growth factor-β1 (TGF-β1) (10 ng/mL) for 48 h. The in vivo experiments were performed in an atherosclerosis model using apolipoprotein E (ApoE)–/– mice fed with a high-fat diet (HFD). Mice in the intervention group were given morin (50 mg/kg) orally for 4 weeks. Molecular docking and microscale thermophoresis were assayed to understand the interactions between morin and matrix metalloproteinase-9 (MMP-9).
Results
Morin inhibited the expression of EndMT markers in a dose-dependent manner in TGF-β1-treated HUVECs. Administering 50 μmol/L morin suppressed the upregulation of MMP-9 and Notch-1 signaling in TGF-β1-induced EndMT. Moreover, the overexpression of MMP-9 activated Notch-1 signaling, thereby reversing morin’s inhibitory effect on EndMT. In the HFD-induced atherosclerotic ApoE–/– mice, morin notably reduced aortic intimal hyperplasia and plaque formation by suppressing EndMT. Furthermore, morin demonstrated a strong binding affinity for MMP-9.
Conclusion
Morin acts as an MMP-9 inhibitor to disrupt EndMT in atherosclerosis by limiting the activation of Notch-1 signaling. This study underscores morin’s potential utility in the development of anti-atherosclerotic medication.

Key words: Morin, Endothelial-to-mesenchymal transition, Atherosclerosis, Traditional Chinese medicine, Matrix metalloproteinase-9