Phloroglucinol protects skin cells from particulate matter 2.5-induced oxidative stress and apoptosis

Particulate matter 2.5 (PM_2.5) is an air pollutant that causes skin inflammation and aging. Phloroglucinol (PG) is a naturally occurring polyphenol with strong antioxidant potential that is widely used in pharmaceutical production. Information regarding the protective effect of PG against PM_2.5-induced cellular damage is lacking; therefore, this study evaluated the protective effect of PG against the detrimental effects of PM_2.5. PG reduced cellular reactive oxygen species levels in a dose-dependent manner. Furthermore, PG reduced PM_2.5-induced 8-hydroxydeoxyguanosine, protein carbonylation, 8-isoprostane, interleukin (IL)-6, and IL-1β levels. PG reduced PM_2.5-induced apoptosis by inhibiting the expression of pro-apoptotic proteins and mitochondrial membrane depolarization. PG restored PM_2.5-impaired nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase 1 (Ho-1) protein expression. Furthermore, PG reduced PM_2.5-induced mitogen-activated protein kinase pathway-related protein expression. Assessment of mouse skin tissue further confirmed that PG could restore PM_2.5-reduced Nrf2 and Ho-1 expression and reduce PM_2.5-induced thickening of the mouse epidermis. Overall, PG exhibited a strong potential to reduce PM_2.5-mediated skin cell damage by activating the antioxidant defense system.