Investigation of Potential Targets for Bupleuri Radix in the Treatment of Subacute Thyroiditis

Objective: This study aimed to reveal the underlying mechanism of Radix Bupleuri in the treatment of subacute thyroiditis (SAT). Methods: Radix Bupleuri, a key herb in traditional Chinese medicine (TCM) for over two millennia, is widely used to treat exterior syndromes, dissipate heat, harmonize liver Qi, and invigorate Yang-Qi. It is also commonly prescribed for SAT. To understand its molecular mechanisms, we collected active components and their targets from databases such as TCMSP, SwissADME, and Swiss TargetPrediction. Radix Bupleuri SAT genes were sourced from GeneCards, OMIM, and DisGeNET databases. By analyzing these data sources together, we identified the relevant ingredients of Radix Bupleuri for treating SAT. Using Cytoscape 3.7.1 software, we selected core proteins to construct an ingredient-target-pathway network. Molecular docking and visualization were performed with AutoDock Vina and Discovery Studio tools, respectively. The stability of the binding model was confirmed through molecular dynamics (MD) simulation techniques. To further validate the causal relationship between CDK4 gene in the GWAS database and SAT in the FinnGen database, we conducted a two-sample Mendelian randomization analysis. Results: Through active ingredient-target network screening, 8 key active ingredients and 10 core targets were identified. The strongest binding was observed between cubebin/quercetin and CDK4 with a binding energy of ≤ -9.2 kcal·mol^-1, whereas isorhamnetin/quercetin showed stable binding with PIK3CA. The stability of cubebin binding with CDK4 was confirmed through MD simulation, indicating that CDK4 potentially modulates SAT by regulating cell cycle progression, cellular proliferation, immune responses, and inflammatory reactions. Conclusion: Radix Bupleuri may affect SAT by its action on CDK4, providing scientific basis for further clinical application of Radix Bupleuri in the treatment of SAT.