An LPS-Immobilized Affinity Screening Platform Identifies Lipopolysaccharide Binding Phytochemicals from Taraxacum mongolicum

Lipopolysaccharide (LPS) is a major component of the outer membrane of Gram-negative bacteria and a key factor involved in the induction of host inflammatory responses. In this study, an LPS-immobilized Ag@SiO2 affinity screening platform was established to enrich potential LPS-binding constituents from an extract of Taraxacum mongolicum, followed by identification and validation using high-resolution mass spectrometry, surface plasmon resonance (SPR), and antibacterial assays. Affinity enrichment coupled with mass spectrometric analysis resulted in the annotation of 14 candidate constituents, primarily phenolic acids and flavonoids. All six representative compounds exhibited detectable interactions with immobilized LPS. Among them, chlorogenic acid and cichoric acid showed relatively strong apparent affinities, with KD values of 7.42 × 10−9 and 2.63 × 10−8 M, respectively. Antibacterial assays indicated that these compounds generally exhibited limited direct growth-inhibitory effects against Escherichia coli and Shigella spp., with cichoric acid showing an MIC of 1024 μg/mL against both tested bacteria. These findings identify chlorogenic acid and cichoric acid as notable candidate LPS-binding constituents of T. mongolicum. This study provides a methodological basis for screening LPS-binding natural small molecules from complex plant extracts.