Core Constituents of Caragana sinica Root for Rheumatoid Arthritis Treatment and the Potential Mechanism

[Image: see text] Purpose: As a traditional herb product, the root of Caragana sinica (Buc’hoz) Rehder (Chinese name: Jin Quegen [JQG]) has been widely used in folk medicines for rheumatoid arthritis (RA) treatment. However, which herbal constituents exert a core pharmacological role in RA treatment remains a great challenge due to the multiple phytochemical constituents, targets, and pathways. In this work, we aimed to use a new strategy to explore the core herbal constituents and potential mechanisms of JQG against RA for the first time. Methods: A successively partitioned extract of JQG, bioactive partition screening in vitro and in vivo, qualitative analysis, bioinformatic analysis, molecular docking, and mechanism validation were used in this study. The partitioned extract was used to obtain the bioactive partition, while in vitro anti-inflammatory effects and in vivo anti-arthritis effects in adjuvant-induced arthritis (AIA) rats were applied to screen the bioactive partition with the best efficacy. Qualitative analysis was used to identify bioactive constituents. Bioinformatic analysis was used to explore the potential mechanism for RA treatment. Molecular docking and immunofluorescence were used to validate the underlying mechanism. Results: After successively partitioning extract and bioactive partition screening, ethyl acetate extract (EAE) yielded the best anti-inflammatory effects in vitro and in vivo among JQG extracts. By ultra-performance liquid chromatography (UPLC) coupled with Orbitrap mass spectrometry, a total of 58 constituents were identified in EAE, and 17 constituents were regarded as the core constituents based on their oral bioavailability and drug-like properties. The nuclear factor kappa B (NF-κB) signal pathway was screened as the core pathway of core constituents for RA treatment based on bioinformatic analysis, and the core constituents showed good ligand–receptor binding activity to NF-κB P65. In vitro study demonstrated that EAE could significantly reduce NF-κB P65 transfer from the cytoplasm to the nucleus. Conclusion: Our study suggested that the therapeutic efficacy of JQG for RA treatment could be derived from negative regulation of the NF-κB pathway, and EAE of JQG could represent a promising herb product for RA treatment that deserves further development.