Protective effect of 3-bromo-4,5-dihydroxybenzaldehyde against PM2.5-induced cell cycle arrest and autophagy in keratinocytes

Particulate matter 2.5 (PM_2.5) poses a serious threat to human health and is responsible for respiratory disorders, cardiovascular diseases, and skin disorders. 3-Bromo-4,5-dihydroxybenzaldehyde (3-BDB), abundant in marine red algae, exhibits anti-inflammatory, antioxidant, and antidiabetic activities. In this study, we investigated the protective mechanisms of 3-BDB against PM_2.5-induced cell cycle arrest and autophagy in human keratinocytes. Intracellular reactive oxygen species generation, DNA damage, cell cycle arrest, intracellular Ca²⁺ level, and autophagy activation were tested. 3-BDB was found to restore cell proliferation and viability which were reduced by PM_2.5. Furthermore, 3-BDB reduced PM_2.5-induced reactive oxygen species levels, DNA damage, and attenuated cell cycle arrest. Moreover, 3-BDB ameliorated the PM_2.5-induced increases in cellular Ca²⁺ level and autophagy activation. While PM_2.5 treatment reduced cell growth and viability, these were restored by the treatment with the autophagy inhibitor bafilomycin A1 or 3-BDB. The findings indicate that 3-BDB ameliorates skin cell death caused by PM_2.5 via inhibiting cell cycle arrest and autophagy. Hence, 3-BDB can be exploited as a preventive/therapeutic agent for PM_2.5-induced skin impairment.