Figure 8. Hypothetic mechanism of luteolin in preventing 6-OHDA-induced apoptosis in PC12 cells.

6-OHDA is rapidly oxidized to generate H₂O₂ and p-quinone. Both agents activate stress response pathways, p53, Nrf2-ARE and eIF2α-ATF4-CHOP, in PC12 cells. Luteolin can directly scavenge intracellular ROS over-production and decreases the transcription of genes involved in these three pathways. The activation of caspase-3 and cell cycle arrest are subsequently attenuated and cell viability is restored.