Background  Oxidative stress plays an important role in the pathogenesis of epidermal diseases. This study aimed to investigate the effects of quercetin on the anti-oxidative response and on mitochondrial protection in cultured normal human keratinocytes.
Methods  Cultured HaCaT cells were treated with different concentrations of H₂O₂ (0, 50, 100, 250, 500 μmol/L) for different periods of time (0.5, 1, 2, 4 hours) to establish an oxidative stress model. The cultured HaCaT cells were randomly assigned to control, H₂O₂, and quercetin+H₂O₂ groups. For the quercetin groups, the cells were treated with different concentrations of quercetin (0, 10, 25, 50 μmol/L) before exposure to H₂O₂. Morphological changes of the cells were observed under an inverted microscope and an electron microscope. The cell viability was detected by the MTT method. The cell apoptosis (AnnexinV/propidium iodide double stain) and mitochondrial membrane potential (ΔΨm) changes were detected by flow cytometry.
Results  An oxidative stress model of HaCaT cells was established under a suitable concentration (250 μmol/L) and treated time of H₂O₂ (2 hours). The cell viability and ΔΨm decreased in a concentration-dependent and time-dependent manner while the percentage of apoptotic cells significantly increased in the H₂O₂ groups compared with the control group (P <0.05). The cell viability and ΔΨm of the quercetin treated group increased (P <0.05) and the percentage of apoptotic cells decreased at concentrations of 1–50 μmol/L quercetin (P <0.01) compared with H₂O₂ treated group.
Conclusion  Quercetin can relieve the cell damage and apoptosis from H₂O₂ induced injury to HaCaT cells by anti-oxidation and mitochondrial protection.