Eupatilin with PPARα agonistic effects inhibits TNFα-induced MMP signaling in HaCaT cells

Eupatilin (5,7-dihydroxy-3,4,6-trimethoxyflavone) is a flavonoid compound exhibiting several beneficial biological activities, including neuroprotection, anti-cancer, antinociception, chondroprotection, anti-oxidation, and anti-inflammation. Our previous study demonstrated that eupatilin specifically activates peroxisome proliferator-activated receptor alpha (PPARα) through direct binding. The PPAR subfamily includes ligand-dependent transcription factors that consist of three isotypes: PPARα, PPARβ/δ, and PPARγ. All isotypes are involved in inflammation, epidermal proliferation/differentiation and skin barrier function. Among them, PPARα regulates lipid and glucose metabolism and skin homeostasis. In this study, we confirm that the ability of eupatilin as a PPARα activator significantly inhibited tumor necrosis factor-alpha (TNFα)-induced matrix metalloproteinase (MMP)-2/-9 expression and proteolytic activity in HaCaT human epidermal keratinocytes. Furthermore, we found that eupatilin subsequently suppressed IκBα phosphorylation, blocked NF-κB p65 nuclear translocation and down-regulated MAPK/AP-1 signaling via PPARα activation. Taken together, our data suggest that eupatilin inhibits TNFα-induced MMP-2/-9 expression by suppressing NF-κB and MAPK⁄AP-1 pathways via PPARα. Our findings suggest the usefulness of eupatilin for preventing skin aging.