The results showed that procyanidin dimers and the procyanidin trimer C1 upregulated expression of the Nrf2 protein, promoted the accumulation of Nrf2 in the nucleus, and upregulated expression of the phase II detoxification enzymes NQO1 and HO-1, which are downstream of the Nrf2/ARE pathway, in the PC12 cell model of PD. This evidence concerns the gene HMOX1 and Parkinson disease.