In vitro evaluation of the antioxidant potential and molecular docking study of the anti-inflammatory activity of apigenin-7- O -glucuronide from Matricaria pubescens targeting Hck kinase

Apigenin-7-O-glucuronide, a major circulating metabolite of the dietary flavonoid apigenin, was isolated for the first time from Matricaria pubescens and structurally confirmed by NMR and HR-ESI-MS analyses, highlighting the originality of this work. The compound exhibited moderate antioxidant activity in DPPH (IC50 = 73 ± 4.1 µg/mL) and FRAP (IC50 = 22.53 ± 5.57 µg/mL) assays, although less potent than ascorbic acid. Comprehensive in silico analyses revealed favorable human safety profiles but low oral bioavailability due to its high polarity (TPSA = 187.12 Å2) and P-glycoprotein-mediated efflux. Metabolic site prediction suggested susceptibility to β-glucuronidase-mediated hydrolysis, which could release active apigenin in target tissues. Bioactivity profiling highlighted strong anti-inflammatory potential (Pa > 0.97), prompting molecular investigation of its interaction with hematopoietic cell kinase (Hck), a myeloid-specific Src-family kinase involved in inflammation. Molecular docking demonstrated that apigenin-7-O-glucuronide binds the ATP-binding site of Hck (PDB: 2HCK) with higher affinity (ΔG = –9.16 kcal/mol; Ki = 194.6 nM) than quercetin, forming five hydrogen bonds and stabilizing the autoinhibited conformation. A 100-ns molecular dynamics simulation further confirmed the stability of the complex, with low RMSD fluctuations and persistent key interactions throughout the simulation. These findings support apigenin-7-O-glucuronide as a promising peripheral anti-inflammatory agent acting through selective Hck inhibition, despite its limited systemic absorption, and provide the first report of this metabolite from M. pubescens.