Protocatechuic acid promotes the neuronal differentiation and facilitates survival of phenotypes differentiated from cultured neural stem and progenitor cells

Protocatechuic acid (PCA), a phenolic compound isolated from the kernels of Alpinia (A.) oxyphylla, plays crucial roles in the proliferation and neuroprotection of cultured neural stem and progenitor cells (NS/PCs) in our previous study. However, whether PCA modulates the differentiation of NS/PCs has remained to be elucidated. In this study, we show that PCA can promote the neuronal differentiation combined with fetal bovine serum (FBS) in vitro, although it cannot initiate the differentiation of NS/PCs by itself. Moreover, PCA is able to induce neuronal maturation and efficiently promote neurite outgrowth. On the other hand, PCA facilitates survival of phenotypes differentiated from cultured NS/PCs, which was associated with an increased percentage of the cellular viability and a decreased percentage of cells undergoing apoptosis under differentiation conditions. In addition, PCA-induced survival is also mediated with the activating of endogenous antioxidant enzymes. These results suggest that PCA may serve as a useful reference for future studies in designing stem cell strategies to promote brain recovery and repair in neurodegenerative diseases.