Theabrownin in Black Tea Suppresses UVB-induced Matrix Metalloproteinase-1 Expression in HaCaT Keratinocytes

Theabrownin is a heterogeneous polyphenolic compound, obtained from fermented dark teas, with many bioactive functions. However, the role of theabrownin in skin photoaging remains unclear. In this study, we investigated whether theabrownin modulates ultraviolet B (UVB)-induced matrix metalloprotease-1 (MMP-1) expression in HaCaT keratinocytes. Theabrownin exerted antioxidant properties, which resulted in scavenging of intracellular reactive oxygen species generated by UVB irradiation in HaCaT cells. Consequently, theabrownin inhibited UVB-induced extracellular signal-regulated kinase, p38, and c-Jun N-terminal kinase phosphorylation, which are activated by oxidative stress. Theabrownin also suppressed the downstream signaling pathway of mitogen-activated protein kinase and the nuclear accumulation of activator protein-1, which is an essential transcription factor for UVB-stimulated MMP-1 expression. Based on these results, we conclude that theabrownin can serve as a novel anti-photoaging compound for the skin.