Objective:To investigate the anti-senescence effect of 3-bromo-4,5-dihydroxybenzaldehyde (BDB) from Polysiphonia morrowii Harvey in human dermal fibroblasts (HDF). Methods:HDF were subjected to treatment of BDB and then treated with hydrogen peroxide (H2O2) to induce premature senescence. Senescence-associated β-galactosidase (SA-β-gal) activity in HDF was determined using the SA-β-gal staining method. Intracellular reactive oxygen species (ROS) production was measured using the 2',7'-dichlorodihydrofluorescein diacetate assay. Western blotting assay was performed to assess the level of antioxidant enzyme glutathione peroxidase 1 (GPX1). In addition, intracellular collagen and collagenase contents were analyzed using the respective ELISA kits. Elastase activity in HDF supernatants was measured from p-nitroaniline release and normalized using total protein content. Results:Treatment of HDF with H2O2 increased the activity of SA-β-gal, but BDB pre-treatment resulted in the reduction of SA-β-gal activity. Moreover, BDB significantly reduced H2O2-induced intracellular ROS production. BDB also markedly increased the level of GPX1, which was inhibited by 400 μM of H2O2. Furthermore, in in vitro study, BDB significantly increased intracellular collagen content and decreased matrix metalloproteinase-1 and elastase activities in HDF. Conclusions:Our results demonstrate that BDB shows anti-senescence and anti-wrinkle activities in vitro.