Broccoli Sprout Extract Suppresses Particulate-Matter-Induced Matrix-Metalloproteinase (MMP)-1 and Cyclooxygenase (COX)-2 Expression in Human Keratinocytes by Direct Targeting of p38 MAP Kinase

Background/Objectives: Particulate matter (PM) is an environmental pollutant that negatively affects human health, particularly skin health. In this study, we investigated the inhibitory effects of broccoli sprout extract (BSE) on PM-induced skin aging and inflammation in human keratinocytes. Methods: HaCaT keratinocytes were pretreated with BSE before exposure to PM. Cell viability was assessed using the MTT assay. The expression of skin aging and inflammation markers (MMP-1, COX-2, IL-6) was measured using Western blot, ELISA, and qRT-PCR. Reactive oxygen species levels were determined using the DCF-DA assay. Kinase assays and pull-down assays were conducted to investigate the interaction between BSE and p38 alpha MAPK. Results: Our findings demonstrate that BSE effectively suppressed the expression of MMP-1, COX-2, and IL-6-critical skin aging and inflammation markers-by inhibiting p38 MAPK activity. BSE binds directly to p38 alpha without competing with ATP, thereby selectively inhibiting its activity and downstream signaling pathways, including MSK1/2, AP-1, and NF-kappa B. Conclusions: These results suggest that BSE is a potential functional ingredient in skincare products to mitigate PM-induced skin damage.