Kurt, Ahmet Arif; Ibrahim, Bashar; Çınar, Harun; Atsü, Ayşe Nilhan; Bursalıoğlu, Ertuğrul Osman; Bayır, İsmail; Özmen, Özlem; Aslan, İsmail

Hypericum perforatum L. (H.P.), a plant renowned for its wound-healing properties, was investigated for antioxidant/antimicrobial efficacy, toxicological safety, and in vivo wound-healing effects in this research to develop and characterize novel nanoemulsion hydrogel (NG) formulations. NG were prepared via emulsion diffusion–solvent evaporation and polymer hydration using Cremophor RH40 and Ultrez 21/30. A D-optimal design optimized oil/surfactant ratios, considering particle size, PDI, and drug loading. Antioxidant activity was tested via DPPH, ABTS+, and FRAP. Toxicological assessment followed HET-CAM (ICH-endorsed) and ICCVAM guidelines. The optimized NG-2 (NE-HPM-10 + U30 0.5%) demonstrated stable and pseudoplastic flow, with a particle size of 174.8 nm, PDI of 0.274, zeta potential of −23.3 mV, and 99.83% drug loading. Release followed the Korsmeyer–Peppas model. H.P. macerates/NEs showed potent antioxidant activity (DPPH IC50: 28.4 µg/mL; FRAP: 1.8 mmol, Fe2+/g: 0.3703 ± 0.041 mM TE/g). Antimicrobial effects against methicillin-resistant S. aureus (MIC: 12.5 µg/mL) and E. coli (MIC: 25 µg/mL) were significant. Stability studies showed no degradation. HET-CAM tests confirmed biocompatibility. Histopathology revealed accelerated re-epithelialization/collagen synthesis, with upregulated TGF-β1. The NG-2 formulation demonstrated robust antioxidant, antimicrobial, and wound-healing efficacy. Enhanced antibacterial activity and biocompatibility highlight its therapeutic potential. Clinical/pathological evaluations validated tissue regeneration without adverse effects, positioning H.P.-based nanoemulsions as promising for advanced wound care.