Chemical profiling of rosemary essential oil (Rosmarinus officinalis): 1,8-cineole encapsulation via cyclodextrins, characterization, and evaluation of biological activities, cytotoxicity, and sperm protective capacity

Essential oils, as secondary metabolites, are extensively studied for their health benefits and therapeutic applications. This study investigates the chemical composition of Rosmarinus officinalis essential oil, identifying its major compounds using gas chromatography–mass spectrometry (GC–MS). The analysis revealed that 1,8-cineole (45.78%) was the predominant compound, followed by α-pinene (13.36%), camphor (8.93%), and (E)-Caryophyllene (4.86%), with other minor constituents such as β-pinene (4.58%) and camphene (4. 03%). Phase solubility diagrams were constructed to assess the solubility of 1,8-cineole, and its encapsulation in HP-β-CD was achieved, yielding a stability constant of 16.53 M⁻¹. The formation of the inclusion complex was confirmed by TGA and FTIR analyses. The 1,8 cineole/HP-β-CD inclusion complex showed enhanced free radical scavenging activity in the DPPH assay, especially at 300 µg/mL, where it reached 96.98%, compared to the lower activity (81.18%) observed for free 1,8- cineole. Moreover, it exhibited a protective effect on sperm motility after 48 h of cryopreservation, although 1,8-cineole-HP-β-CD showed cytotoxicity towards red blood cells as indicated by a hemolysis rate of 21.64%. These findings emphasize the valuable components of Rosmarinus officinalis essential oil, particularly in its encapsulated form, highlighting its potential for medicinal applications.