In this study, the cellular protective effect of isoquercitrin against H2O2 and rose bengal-indued HaCaT cell damage was investigated. The ethosome and elastic liposome for enhanced transdermal delivery were prepared. Particle size, loading efficiency and cumulative permeated amounts of them were evaluated. Isoquercitrin didn't show any characteristic cytotoxicity at 50 µM. When HaCaT cells were treated with 5 mM H2O2 and 25 µM rose bengal, isoquercitrin protected the cells against the oxidative damage in a concentration dependent manner (6.25 ~ 50 µM). The size of 0.03 % isoquercitrin loaded ethosome was 222.85 nm and the loading efficiency was 82.26 %. The ethosome loaded with 0.03 % isoquercitrin was stable and maintained the constant particle size for 2 weeks after being prepared. The ethosome exhibited more enhanced skin permeability than general liposome and ethanol solution. The optimal ratio of lipid to surfactant of 0.1 % isoquercitrin loaded elastic liposomes was observed to be 89 : 5 through evaluating particle size (341.2 nm), deformability index (59.89), loading efficiency (54.3 %), and skin permeability (54.4 %).

In this study, the cellular protective effects on HaCaT cells and human erythrocytes and antioxidative effects of P. tricuspidata stem extracts were investigated. The ethyl acetate (50 µ g/mL) and aglycone fraction (25 µ g/mL) of P. tricuspidata stem extracts doesn't show any characteristics of cytotoxicity. When HaCaT cells were treated with 10 mM H2O2 and 30 µ M rose bengal, the ethyl acetate (6.25 ∼ 50 µ g/mL) and aglycone (6.25 ∼ 25 µ g/mL) fraction protected the cells against the oxidative damage in a concentration dependent manner. The P. tricuspidata stem extracts showed more prominent cellular protective effect than (+)-α-tocopherol, known as lipid antioxidant at 10 µ g/mL. The ethylacetate fraction of P. tricuspidata stem extracts (18.5 µ g/mL) showed more free radical (1,1-diphenyl-2-picrylhydrazyl, DPPH) scavenging activity (FSC550). Reactive oxygen species (ROS) scavenging activity (OSC50) of P. tricuspidata stem extracts on ROS generated in Fe 3+ -EDTA/H2O2 system was investigated using the luminol-dependent chemiluminescence assay. The ethyl acetate (1.72 µ g/mL) and the aglycone fraction (1.53 µ g/mL) showed similar ROS scavenging activity of L-ascorbic acid (1.50 µ g/mL). These results indicate that extract/fractions of P. tricuspidata stem extracts can function as natural cytoprotective agents and antioxidants in biological systems, particularly skin exposed to UV radiation by protecting cellular membrane against ROS.