Protocatechuic Aldehyde Attenuates UVA-induced Photoaging in Human Dermal Fibroblast Cells by Suppressing MAPKs/AP-1 and NF-κB Signaling Pathways

Ultraviolet radiation (UV) is a major causative factor of DNA damage, inflammatory responses, reactive oxygen species (ROS) generation and a turnover of various cutaneous lesions resulting in skin photoaging. The purpose of this study is to investigate the protective effect of protocatechuic aldehyde (PA), which is a nature-derived compound, against UVA-induced photoaging by using human dermal fibroblast (HDF) cells. In this study, our results indicated that PA significantly reduced the levels of intracellular ROS, nitric oxide (NO), and prostaglandins-E(2) (PGE(2)) in UVA-irradiated HDF cells. It also inhibited the levels of cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) expression. Besides, PA significantly suppressed the expression of matrix metalloproteinases-1 (MMP-1) and pro-inflammatory cytokines and promoted collagen synthesis in the UVA-irradiated HDF cells. These events occurred through the regulation of activator protein 1 (AP-1), nuclear factor-κB (NF-κB), and p38 signaling pathways in UVA-irradiated HDF cells. Our findings suggest that PA enhances the protective effect of UVA-irradiated photoaging, which is associated with ROS scavenging, anti-wrinkle, and anti-inflammatory activities. Therefore, PA can be a potential candidate for the provision of a protective effect against UVA-stimulated photoaging in the pharmaceutical and cosmeceutical industries.