Stability of Cotinus coggygria Scop. Extract-Loaded Liposomes: The Impact of Storage on Physical and Antioxidant Properties

The stability of Cotinus coggygria extract-loaded liposomes (non-treated and UV-irradiated) was determined after 60 days through an investigation of the impact of storage on liposomal physical and antioxidant properties. The liposome size varied in a narrow range for 60 days; PDI was 0.273–0.313 (non-treated) and 0.829–0.911 (UV-irradiated). The zeta potential ranged from −28.2 to −29.6 mV (non-treated) and from −21.5 to −22.0 mV (UV-irradiated). The obtained liposomes with the extract neutralized 81.9% of free DPPH radicals before UV irradiation and 80.9% after irradiation. In the ABTS assay, UV irradiation also significantly reduced the antioxidant capacity, from 12.02 to 10.55 µmol Trolox equivalent (TE)/mL. The ABTS and DPPH radical scavenging activity of the UV-irradiated liposomes significantly decreased after the 60-day storage (8.93 µmol TE/mL and 75.4%, respectively), whereas in the non-treated sample, the mentioned drop in antioxidant capacity was not noticed. Liposomal formulations of C. coggygria extract can exhibit significant potential for further development as a functional food or dermo-cosmetic ingredient.