Integrating Ultrahigh‐Performance Liquid Chromatography–Mass Spectrometry and Network Pharmacology: Systematic Identification and Quantification of Bioactive Components in Erdong–Yangxin Oral Liquid, An Antidepressant Herbal Formulation

Erdong-Yangxin oral liquid (EYOL) is a traditional Chinese medicine (TCM) prescription that demonstrates clinical efficacy in treating depression, yet its comprehensive chemical profile and quality-control markers remain insufficiently studied. This study aimed to systematically characterize its chemical composition and establish a robust method for quality assessment. First, ultrahigh-performance liquid chromatography (UHPLC)-linear ion trap quadrupole-Orbitrap mass spectrometry enabled the tentative identification of 149 compounds, primarily iridoid glycosides, flavonoids, and saponins. Subsequently, network pharmacology analysis predicted several components, such as dioscin, calycosin, and ruscogenin, as potential bioactive candidates based on their target network associations. To quantitatively assess key constituents, a novel method based on UHPLC-tandem mass spectrometry was established and fully validated for 15 components selected by integrating network pharmacology predictions, phytochemical characteristics, and pharmacopoeia references. Quantitative results revealed catalpol as the predominant component, followed by rehmannioside D, lobetyolin, dioscin, and calycosin-7-O-β-d-glucoside. The study establishes a comprehensive chemical basis for EYOL and a reliable quantitative approach for its quality control, facilitating further research into its pharmacodynamic material basis.