In conclusion, procyanidins (monomers, dimers, and one trimer) from grape seeds with different structures may be useful in the prevention of PD by activating the Nrf2/ARE pathway and its downstream detoxification (NQO1, HO-1) and antioxidant enzymes (GSH-Px, CAT, and SOD) (Figure 11). Here, HMOX1 is linked to Parkinson disease.