Discovery and characterization of baicalin as potent PGAM1 ligand with anti-myocardial fibrosis effects

Objective Myocardial fibrosis drives the progression of various cardiovascular diseases and causes heart failure and death, largely due to the activation and myofibroblastic differentiation of cardiac fibroblasts. Phosphoglycerate mutase 1 (PGAM1) interacts with actin alpha 2, smooth muscle (ACTA2) to regulate myocardial fibrosis, and disrupting this interaction can alleviate fibrotic lesions. However, novel natural product-derived PGAM1 ligands targeting this axis remain unidentified. To address this gap, this study aimed to screen and identify novel PGAM1 ligands from a natural product library for potential anti-fibrotic application. Methods Drug affinity responsive target stability (DARTS) and in silico screening were used to identify promising ligand in Carthami Flos . Cellular thermal shift assay (CETSA), DARTS, molecular dynamics simulation and bio-layer interferometry assays were performed for target identification. Furthermore, the cardioprotective effects against myocardial fibrosis were assessed in transforming growth factor- β 1 (TGF- β 1)-induced cardiac fibroblasts and in mouse transverse aortic constriction (TAC) or isoproterenol-induced fibrosis models. Western blotting, quantitative real-time polymerase chain reaction, immunoprecipitation and immunofluorescent were performed to confirm the antifibrosis mechanism of baicalin. Results Firstly, various natural products were screened via DARTS assay and Carthami Flos was identified as a target pool for molecular docking. Then, in silico screening assay identified baicalin as a novel ligand. In addition, baicalin could directly bind to the PGAM1 protein with a equilibrium dissociation constant (KD) value of 34.6 μmol/L. Molecular dynamics simulation revealed that baicalin and PGAM1 interactions were stable. These findings indicate that PGAM1 is a direct pharmacological target of baicalin. Furthermore, molecular mechanism exploration reveals that baicalin exerts anti-myocardial fibrosis effects by inhibiting the activation of fibroblasts, the interaction between PGAM1 and ACTA2. Finally, the anti-myocardial fibrosis effect of baicalin was verified in vivo . Conclusion These findings suggest that baicalin is a novel PGAM1 templates for developing new therapeutics against myocardial fibrosis.