Baicalin protects human skin fibroblasts from ultraviolet A radiation-induced oxidative damage and apoptosis

Reactive oxygen species (ROS) are an important factor in the development of skin photodamage after ultraviolet A (UVA) radiation. A flavonoid antioxidant, baicalin, can selectively neutralize super-oxide anion (O-2(-)) while having no significant effect on (OH)-O-center dot. Fibroblasts are a key component of skin dermis. In the present study, we investigated the protective effects of baicalin on human skin fibroblasts (HSFs) under UVA induced oxidative stress. Fluorescence microscopy and flow cytometry were used to assay the intracellular O-2(-), NO, ROS concentrations and the mitochondrial membrane potential. Cell viability was determined using the Cell Counting Kit-8 (CCK-8). The concentrations of cellular MDA, SOD, GSH, T-AOC, and 8-oxo-dG were also measured. Cellular apoptosis was measured by flow cytometry and caspase-3 detection. The results revealed that UVA radiation could cause oxidative stress and apoptosis in HSFs. Interestingly, the use of baicalin after UVA radiation significantly reduced the level of intracellular O-2(-), NO, and ROS, stabilized the mitochondrial membrane potential, and attenuated production of MDA and 8-oxo-dG. These efficiently enhanced the antioxidative defense system and protected the HSFs from subsequent oxidative stress damage and apoptosis. In other words, baicalin decreased the excessive generation of intracellular ROS and NO, and elevated the cellular antioxidative defense, which eventually mitigate the UVA-induced apoptosis. Based on our results, baicalin may have applications in the treatment of skin photodamage caused by UVA irradiation.