Unlocking the Bioactive Potential of Rosemary Hydrosol: A Comparative Study of Essential Oil and Hydrosol Properties

*The rosemary essential oil (REO) and hydrosol were obtained through hydrodistillation of the aerial parts of fresh rosemary collected from Da Lat, Vietnam. The distillation process lasted for 4 hours. A separating funnel separated the oil phase (REO) from the aqueous phase (RHD). The essential oils were then dried using anhydrous sodium sulfate (Na2SO4). The essential oil suspended in hydrosol was isolated by liquid-liquid extraction using diethyl ether, and the ether was evaporated to yield the hydrosol-essential oil (RHD-EO).
*The chemical composition of REO and RHD-EO was analyzed using a GC-MS system. The GC-MS system consisted of an Agilent 8890 gas chromatograph equipped with an Agilent 5977B mass spectrometer and a 30 m x 0.250 mm x 0.25 μm HP-5MS capillary column. Mass spectrometry analysis was performed at 70 eV ionization. Compounds were identified by comparing the components' mass spectra with standard references in the NIST 2020 library, and the relative percentage of each compound was calculated using peak area normalization.
*The antibacterial activity of both REO and RHD-EO was tested using two Gram-positive bacterial strains: Staphylococcus aureus ATCC 13709 and Propionibacterium acnes BCRC10723. The inhibition zone was measured to determine antibacterial activity.
*The ABTS radical scavenging assay assessed the antioxidant capacity of both REO and RHD-EO.
*The anti-inflammatory activity of REO and RHD-EO was evaluated by measuring nitric oxide (NO) production in RAW 264.7 macrophage cells using the Griess reagent method. The nitrite concentration (NO2-) was measured using the Griess reagent system at 540 nm. The inhibition of NO production was calculated by comparing the absorbance with that of the positive control (NG-Methyl-L-arginine acetate).
*The cytotoxicity of REO and RHD-EO was evaluated using the MTT assay.