Figure 2. Neuroprotective effects of quercetin on neurotoxic-induced injury and mitochondria parameters in PC12 cells via PINK1 and Parkin mitophagy pathway. (A) Effects of different concentration of 6-OHDA on PC12 cells viability. (B) After pretreated with different concentration of quercetin (1, 10, 20, 50, 100 μM), the cells were incubated with 6-OHDA (150 μM) and different concentration of quercetin for 24 h. Cell viability assessed using the CCK8 assay. Data are expressed as mean ± SEM. n = 5–6 wells for each group. *P < 0.05 compared to the control. Evaluation of mitochondria function parameters, such as mitochondria contents (C), mitochondria ROS (D), and mitochondria membrane potential (E). (F) Changes of Tyrosine Hydroxylase (TH), a-synuclein and mitophagy proteins (PINK1 and Parkin) in HeLa cells with or without quercetin treatment. (G–J) Quantification of (F). (K) Cell viability assessed using the CCK8 assay with or without Pink1 and Parkin siRNA treatment. (L) The protein levels of TH and a-synuclein in different groups. Data are expressed as mean ± SEM. *P < 0.05 compared to the designated control (ANOVA followed by Dunnett's multiple-comparison post hoc tests).