An integrated research strategy based on "compound exogenous chemical substances-endogenous metabolites in disease": To explore the scientific basis of Modified Bazhen Yimu Gao in the treatment of primary dysmenorrhea.

Ethnopharmacological Relevance: Primary dysmenorrhea (PD) is a common gynecological disease in women, which affects about 45 %-95 % of women. It exerts significant negative effects on the quality of life, learning and work efficiency of women. Modified Bazhen Yimu Gao (MBYG), a proprietary Chinese medicine preparation, has a medication history of 15 years. It is demonstrated to be effective on the treatment of PD. However, its mechanisms of action and key pharmacological substances in the treatment of PD remain unclear.

Aim Of The Study: An integrated study was conducted from the aspects of exogenous chemical components and endogenous metabolites to reveal the mechanisms of action and key active ingredients of MBYG in the treatment of PD.

Materials And Methods: A PD rat model was established by the induction of estradiol benzoate combined with oxytocin. Thereafter, the blood-entering components in PD rats after MBYG treatment were analyzed via ultra performance liquid chromatography-quadrupole time-of-flight tandem mass spectrometry (UPLC-QTOF-MS/MS). On this basis, network pharmacology and metabolomics analyses were performed to identify the common pathways and targets of MBYG in the treatment of PD. Furthermore, Pearson correlation analysis between exogenous chemical components and endogenous metabolites was carried out to screen for potential active ingredients. Afterwards, based on the identified potential active ingredients, network pharmacological screening studies were implemented to obtain key targets and pathways. Through conducting Western blotting assay, rat uterine tissue samples were obtained to validate the top 3 target proteins with the highest degree values, and a "potential active ingredient-target-pathway" network was constructed to reveal the underlying mechanisms of action. Finally, molecular docking experiments were performed to dock potential pharmacological substances with 3 target proteins, so as to screen for key pharmacological substances.

Results: MBYG significantly improved the symptoms of PD rats, with high-dose MBYG outperforming the positive control drug ibuprofen. Its mechanisms of action involved down-regulating the targets of PTGS2, AVPR1A, and ALOX5 proteins in rat uterine tissues and affecting pathways such as arachidonic acid metabolism, the sphingolipid signaling pathway, vascular smooth muscle contraction, and the neurotrophin signaling pathway. Among the blood components, rosmarinic acid, sinapic acid, and apigenin were the key pharmacological substances of MBYG in the treatment of PD.

Conclusion: Upon the integrated research of exogenous chemical components and endogenous metabolites, this study verifies the mechanisms of action and identifies key active ingredients of MBYG in the multi-component, multi-target and multi-pathway regulation and treatment of PD, laying a basis for its rational clinical application.