Introduction:
Nowadays, the therapeutic administration of essential oils is gaining high interest. For instance, oregano oil possesses remarkable effects, such as antioxidant, anti-inflammatory, antibacterial, antifungal and antiviral activity. However, it is characterized by low aqueous solubility, which makes its application difficult and compromises its effects. Loading the oil into nanoparticles is an appropriate strategy to improve its use. Nanogels prepared from natural polymers are considered alternative nanosized drug delivery systems capable of improving the characteristics of hydrophobic substances.
Methods:
Oregano oil was loaded into nanogels prepared from chitosan and albumin by emulsification. The nanogel system was physicochemically characterized via DLS, TEM, IR and XRD analysis. A dialysis method was applied to study its in vitro release. The antiviral activity of the nanoparticles loaded with oregano oil was tested on Betacoronavirus 1 (S379 Riems) using a direct treatment approach. The MTT dye assay was applied for measurement of the cell viability. The cytopathic effect was evaluated microscopically.
Results and Discussion:
The encapsulation efficiency of the oil in the nanogel particles was approx. 40%. The nanogels possessed a small mean diameter of 26 nm, a narrow size distribution and a positive zeta-potential (+20.6 mV). TEM confirmed their small size. The in vitro dissolution test showed that approx. 100% of the oil was released for 24 h. The IR and XRD analyses confirmed the successful entrapment of the oil. The nanoparticles showed more than 40% protection of the treated cells at concentrations between 15 and 30 µg/mL as compared to the non-treated virus-infected control.
Conclusions:
Nanogels prepared from the natural polymers chitosan and albumin could be considered appropriate carriers for the delivery of oregano oil. Their moderate activity against Betacoronavirus 1 could be a platform for further investigations of the pharmacodynamics and possible combinations with clinically applied chemotherapeutics.
