Geniposide, a Principal Component of Gardeniae Fructus, Protects Skin from Diesel Exhaust Particulate Matter-Induced Oxidative Damage

Gardeniae Fructus (GF) is the fruit of Gardenia jasminoides Ellis and is traditionally prescribed to treat pyogenic infections and skin ulcers. This study investigated the protective effects of GF and the underlying mechanism responsible for these effects on diesel exhaust particulate matter- (DEP-) induced skin damage. The protective effects of an ethanolic extract of GF (GFE) and its constituents (geniposidic acid, gardenoside, geniposide, chlorogenic acid, and genipin) were examined by analyzing reactive oxygen species (ROS) production, apoptosis, and tight junction (TJ) protein expression in HaCaT cells. Treatment with GFE dose-dependently inhibited intracellular ROS production and apoptosis by regulating the protein expressions of Bax, Bcl-2, and cytochrome C in DEP-stimulated (100 μg/ml) HaCaT cells. Mechanistic studies revealed that the protective effects of GFE were related to its activation of Nrf2 and HO-1 signaling in HaCaT cells. Geniposide, a main constituent of GFE, enhanced the expression of occludin in DEP-stimulated HaCaT cells. Furthermore, topical application of geniposide reduced the expressions of 8-OHdG and Bax and increased the expression of occludin in the dorsal skin lesions of DEP-stimulated mice. Gardeniae Fructus and its main component geniposide are potential candidates for the repair of DEP-induced skin damage due to their antioxidant and antiapoptotic activities.