An enhanced SPR fluidic system for high-efficiency ligand fishing from traditional Chinese medicines.

Surface plasmon resonance (SPR) is a sensitive, label-free method for measuring biomolecular interactions, widely used in drug discovery, including fishing active components from traditional Chinese medicine (TCM). However, classical SPR systems encounter limitations when dealing with the complexity of TCM, specifically regarding high-throughput processing and distinguishing substances with different binding kinetics. To overcome these challenges, we constructed an upgraded fluidic system (UFS) on the SPR platform, integrating a customized ligand fishing sensor chip, an optimized sample flow path, and a selectable recovery mode. By screening for tumor necrosis factor receptor 1 (TNFR1) ligands, we identified esculetin as a direct binding component. In SH-SY5Y cells, esculetin targets TNFR1, reducing endogenous ligand binding and decreasing caspase-3 activity, thereby inhibiting apoptosis. The UFS system significantly enhances screening efficiency for complex natural compounds. This study provides the first evidence that esculetin directly interacts with TNFR1 via a novel anti-apoptotic mechanism, complementing its known anti-inflammatory effects and offering a valuable tool for TCM research.