*Article* **Neuroprotective Effects of B-Type Cinnamon Procyanidin Oligomers on MPP<sup>+</sup> -Induced Apoptosis in a Cell Culture Model of Parkinson's Disease**

**Qi Xu 1,2,†, Ziyu Chen 2,†, Borong Zhu <sup>3</sup> , Yiming Li <sup>3</sup> , Manju B. Reddy <sup>4</sup> , Huilin Liu <sup>1</sup> , Guodong Dang <sup>1</sup> , Qi Jia 3,\* and Xiaojun Wu 2,\***


**Abstract:** Cinnamon procyanidin oligomers (CPOs) are water-soluble components extracted from cinnamon. This study aims to explore the neuroprotection of B-type CPO (CPO-B) against 1-methyl-4-phenylpyridinium (MPP<sup>+</sup> )-mediated cytotoxicity and the molecular mechanisms underlying its protection. The results demonstrated that CPO-B showed protection by increasing cell viability, attenuating an intracellular level of reactive oxygen species, downregulating cleaved caspase-3 expression, and upregulating the Bcl-2/Bax ratio. Moreover, CPO-B completely blocked the dephosphorylation of extracellular, signal-regulated kinase 1 and 2 (Erk1/2) caused by MPP<sup>+</sup> . Treatment with an Erk1/2 inhibitor, SCH772984, significantly abolished the neuroprotection of CPO-B against MPP<sup>+</sup> . Taken together, we demonstrate that CPO-B from cinnamon bark provided protection against MPP<sup>+</sup> in cultured SH-SY5Y cells, and the potential mechanisms may be attributed to its ability to modulate the dysregulation between pro-apoptotic and anti-apoptotic proteins through the Erk1/2 signaling pathway. Our findings suggest that the addition of cinnamon to food or supplements might benefit patients with PD.

**Keywords:** Parkinson's disease; CPO-B; MPP<sup>+</sup> ; Erk1/2; neuroprotection
