Radical Scavenging Activity of Silymarin Encapsulated in Liposomal Vesicles: Impact of UV Irradiation and Lyophilization

The radical scavenging activity of silymarin-loaded liposomes after different technological processes (UV irradiation and lyophilization) was investigated using DPPH and ABTS assays. Using the DPPH method, the antioxidant capacity of pure silymarin was 84.03%, while it was lower after encapsulation in liposomes; it was 81.63% after the formulation, 81.15% after UV irradiation, and 79.85% after lyophilization. The anti-ABTS potential was 3.04 µmol Trolox equivalent (TE)/mL for silymarin, 1.68 µmol TE/mL after the liposome preparation, 1.52 µmol TE/mL after UV irradiation, and 2.02 µmol TE/mL after lyophilization. UV irradiation did not cause significant changes in the antioxidant potential of liposomes, while the ABTS scavenging activity was higher after lyophilization. Considering that the two used antioxidant assays are based on different reactions, the obtained data provide a good insight into the overall antioxidant activity of silymarin-loaded liposomes.