Characterization of Isoorientin and Paeoniflorin as Botanical Glucocorticoid Receptor Modulators from White Peony and Chasteberry

Background/Objectives: Botanical supplements are increasingly investigated for their potential to address women’s health concerns. Compounds that modulate progesterone receptor (PR) signaling may help manage gynecologic disorders such as endometriosis, uterine hyperplasia, and preterm birth. Because PR ligands often cross-react with the glucocorticoid receptor (GR), this study examined two botanical compounds, paeoniflorin from Paeonia lactiflora (white peony root) and isoorientin from Vitex agnus-castus (chasteberry), that were identified as modulators of GR or PR signaling. Methods: Luciferase reporter assays were performed in OVCAR5, Ishikawa PR-B, and T47D A1-2 cells to evaluate GR and PR signaling. GR target gene expression was measured by qPCR. A receptor binding assay and computational docking were used to assess interaction with GR. Adipogenesis was evaluated in 3T3-L1 cells using Oil Red O staining and FABP4 protein expression by Western blot. Results: Paeoniflorin and isoorientin inhibited dexamethasone-induced GR signaling in OVCAR5 and Ishikawa PR-B cells. In T47D A1-2 cells, a variant of T47D engineered to express GR, both compounds blocked luciferase induction stimulated by progesterone; this effect was not observed in the parental line that expresses PR but lacks GR. In OVCAR5 cells, paeoniflorin or isoorientin combined with dexamethasone downregulated GILZ and DUSP1/MKP1 mRNA. Isoorientin directly bound GR, and computational analysis supported potential binding poses. Both compounds also reduced lipid accumulation during 3T3-L1 adipocyte differentiation and decreased FABP4 expression, consistent with GR antagonist activity and reduced adipogenesis. Conclusions: These findings identify paeoniflorin and isoorientin as botanical modulators that suppress GR signaling and limit GR-dependent adipogenic responses across multiple cell-based models under controlled in vitro conditions.