Trans-cinnamic acid attenuates UVA-induced photoaging through inhibition of AP-1 activation and induction of Nrf2-mediated antioxidant genes in human skin fibroblasts

Excessive exposure to ultraviolet (UV) radiation from the sun, particularly UVA light is a primarily cause of premature skin aging or photoaging [1,2]. The long-wave UVA (320–400 nm) penetrates deeper into the skin than medium-wave UVB (280–320 nm), and it affects the deep dermis. Chronic UVA exposure triggers the production of intracellular reactive oxygen species (ROS), such as super oxide anion (O2–), singlet oxygen (1O2) and hydroxyl radials (OH) which then cause direct or indirect damage to cellular protein structures, lipid membranes and nucleic acids [3,4].