HEC-Based Emulgels as Vehicles for NaDES Extracts: Safety, Efficacy, and Sensory Evaluation

Natural deep eutectic solvent (NaDES) extracts exhibit substantial bioactive potential, including antioxidant, UV-protective, and enzyme-inhibitory activities, owing to their rich phytochemical composition. However, their incorporation into appropriate dermal delivery systems is essential to maximize their efficacy. Our previous studies identified emulgels as innovative and effective vehicles for NaDES extracts of green tea and bilberry leaves. In the present study, the in vivo performance of hydroxyethyl cellulose (HEC)-based emulgels containing 12% (w/w) NaDES extracts was evaluated. Formulations stabilized with cetearyl olivate/sorbitan olivate (5%) were compared with those stabilized using cetearyl alcohol/cetearyl glucoside (6%) in a study involving 25 healthy volunteers. Over a 28-day application period, key biophysical skin parameters, including skin pH, transepidermal water loss (TEWL), erythema index (EI), skin capacitance (EC), melanin index (MI), and friction coefficient (F), were monitored. Additionally, a 24 h skin safety assessment and a sensory evaluation were conducted. Both formulations demonstrated excellent safety profiles, with no signs of irritation observed during the 24 h safety study. The emulgels stabilized with cetearyl olivate/sorbitan olivate produced significant improvements in skin biophysical parameters. Skin barrier recovery, indicated by a reduction in TEWL, was achieved within two weeks, while enhanced skin hydration was maintained throughout the study period. Sensory evaluation further demonstrated superior spreadability of the olivate-based formulations. Overall, these findings confirm that HEC-based emulgels are promising dermal delivery systems for NaDES extracts, combining excellent safety, efficacy, and favorable sensory properties.