The most bioactive fraction of stir-fried Radix Paeoniae Alba regulating IL-6/STAT3 signaling pathway in allergic asthma mouse

Ethnopharmacological relevance: Radix Paeoniae Alba (RPA), a traditional Chinese medicine, has been used frequently in the treatment of asthma. Previous studies demonstrated the dichloromethane fraction of Stir-Frying RPA (FDCM) enhanced the effect of anti-allergic asthma compared with the dichloromethane fraction of RPA (DCM).Aim of the study: The significant increasing of Paeoniflorin (PF), ethyl gallate (EG), 1,2,3,4,6-pentagalloylglucose (PGG) had been observed in FDCM. This study aimed to investigate the effects and mechanisms of these com-pounds from FDCM in ovalbumin (OVA)-induced allergic asthma mouse model.Materials and methods: The significant difference contents compounds fraction (FB-40) and other fractions in FDCM were enriched by Medium Pressure Liquid Chromatography (MPLC). The pharmacodynamics was verified among all fractions in OVA-induced allergic asthma mice. Moreover, the drug dose dependence of FB-40 (0.42 mg/kg, 0.21 mg/kg, and 0.07 mg/kg), which were the most active fraction from FDCM for anti-allergic asthma, was explored. The expression of IL-6, p-STAT3, and STAT3 was analyzed by Western blot analysis. In addition, the main components of FB-40 were identified by UPLC with standards. Finally, the anti-inflammatory effects of the main components from FB-40 were detected by LPS-stimulated BEAS-2B cells using an Elisa assay.Results: The results showed that FB-40 was the most active fraction from FDCM, which could significantly improve the lung tissue pathological condition, and decrease the number of inflammatory cells in bron-choalveolar lavage fluid (BALF). It had greater pharmacological activity than its main component PF. FB-40 also showed dose dependence and regulated the IL-6/STAT3 signaling pathway in allergic asthma mice. Besides, PF, Albiflorin (AF), PGG, EG, and 1,2,3,6-Tetra-O-galloyl-0-D-glucose (TGG) from FB-40 were identified by UPLC with the standard. At last, in the LPS-induced BEAS-2B cell experiments, EG, PGG, 1,2,3,6-Tetra-O-galloyl-0-D-glucose (TGG) showed stronger inhibiting activities of cytokine than the monoterpenoid glycosides (PF and AF).Conclusion: The research proved that FB-40 was an active fraction in FDCM, which regulates IL-6/STAT3 Signaling Pathway to ameliorate allergic asthma. Gallic acids including TGG and PGG, and EG also play a role in the treatment of allergic asthma in FB-40.