Oregano (Origanum vulgar subsp. viride) Essential Oil: Extraction, Preparation, Characterization, and Encapsulation by Chitosan-Carbomer Nanoparticles for Biomedical Application

Background: Plant essential oils (EOs) as natural agents have broad activities, including antibacterial, antifungal, antiviral, insecticidal, and repel activities because of their chemical compositions. Objectives: The objective of this study was to increase the stability of Origanum vulgar subsp. viride EOs by encapsulation in chitosan-carbomer nanoparticles by ionic gelation method. Methods: The EOs from dried leaves of O. vulgar subsp. viride were extracted by hydro-distillation method, and EO components were determined by gas chromatography-mass spectrometry (GC-MS). Besides, OEO-loaded chitosan (CS) nano-capsules were prepared using the ionic gelation method. The molecular structure and morphology of nanoparticles were characterized by Fourier Transform-Infrared (FTIR) and scanning electron microscopy (SEM), respectively. The encapsulation efficiency (EE), loading capacity (LC) of the OEO-loaded CS nanoparticles, and their release profiles were determined using UV/Vis spectrophotometry. Results: The major components of OEO were thymol (20.53%), 4-terpinenol (20.28%), and γ-terpinene (12.22%). The percentages of EE and LC of OEO ranged from 99.25 ± 0.74 to 93.84 ± 0.71 and 38.02 ± 0.18 to 66.73 ± 0.51, respectively, with increasing the OEO to chitosan ratio from 1:0.01 to 1:0.04 W/V. The nanoparticles were regular, uniform, and spherical in shape with an average size of 134 to 181 nm, which were dispersed throughout the solution. The zeta potential values for blank chitosan nanoparticles (CSNPs) and OEO-loaded CSNPs were +23.4 and +38.5 mV, respectively. Conclusions: The results confirmed the suitability of the CS-carbomer complex for OEO- CSNPs formation. It is recommended to evaluate the antimicrobial, insecticidal and insect repel activities of developed OEO nanoparticles in laboratory and field studies.