Therapeutic Potential of Rosmarinus officinalis Extract on Endometriosis: Evidence from In Vitro Models

Natural therapeutic alternatives are increasingly explored in endometriosis, a highly prevalent gynecological disorder with limited therapeutic options. Rosmarinus officinalis (rosemary) has attracted increasing scientific interest due to its biological activity. This study aimed to characterize a hydroethanolic rosemary extract (RE) and evaluate its effects on key cellular processes involved in endometriosis pathophysiology. Major phenolic compounds in RE were quantified by RP-HPLC, and antioxidant activity was assessed using DPPH, ABTS, and FRAP assays. After RE treatment, cell viability (WST-1), migration (wound healing assay), cell cycle distribution (DAPI staining), apoptosis (Annexin V/PI), p21 and cyclin A expression (Western blot), and intracellular ROS levels (DCFH-DA) were evaluated in endometrial stromal (t-HESC, St-T1b) and endometriotic epithelial (12-Z) cells. Phytochemical analysis revealed rosmarinic acid (RA) at 4.2%, while carnosic acid (CA) and carnosol (CS) together accounted for 23.7% of the extract. RE reduced cell viability and cell migration in 12-Z and t-HESC cells (p < 0.05). S-phase accumulation with a concomitant reduction in the G1 phase was observed across all evaluated cell lines (p < 0.05), along with increased p21 and cyclin A expression in stromal cells (p < 0.05). RE induced cell death in both 12-Z (p < 0.05) and St-T1b cells (p < 0.0001). In t-HESC cells, RE reduced both basal and H₂O₂-induced ROS levels (p < 0.01). These findings indicate that RE modulates key mechanisms involved in endometriosis pathophysiology, supporting its multi-target therapeutic potential as a nutraceutical approach for endometriosis management.