Essential oils (EOs) are complex mixtures of strongly active compounds, but very volatile and sensitive to light, oxygen, moisture and temperature. Loading inside nanostructures can be a strategy to stabilize them and use them in therapy [1]. In the present study, Melissa officinalis L. (Lamiaceae) essential oil was loaded inside glycerosomes (GS) at a concentration of 10 µL/mL and was evaluated for its anti-herpetic activity [2]. GS were prepared by the thin layer evaporation method and characterized by Light Scattering techniques, determining average diameter (about 60 nm), polydispersity index (⋍ 0.2) and ζ-potential (⋍ -30 mV). From the morphological observation by transmission electron microscope, GS appeared as small vesicles with several lamellae and a spherical shape. Moreover, the EO encapsulation efficiency inside the GS, in terms of citral and β-caryophyllene, obtained by HPLC-DAD, was ⋍63 % and ⋍76 % respectively and the EO release, by the dialysis bag method, was very low (⋍15% of citral) within 24h. The same instruments and analytical techniques were adopted to monitor the GS long-term stability until 4 months and no relevant changes were observed in the chemical-physical parameters. Successively, GS were tested with an in vitro antiviral assay against the HSV-1/strain vCLIDA61. From these studies, the antiviral activity of loaded-EO was found to be comparable to free-EO, for high concentrations of EO. Hence, at present, GS seems to be a promising tool in order to administer the EO and replace the conventional anti-herpetic drugs, when drug-resistance forms take place.
