Neuroprotective and neurotrophic effects of quinic acids from Aster scaber in PC12 cells

Aster scaber T. (Asteraceae) has been used to treat bruises, snakebite, headache, and dizziness in traditional Chinese medicine. In the present study, the neuroprotective effect of four quinic acid derivatives from A. scaber on amyloid Abeta-induced PC12 cell toxicity was investigated. When cells were treated with quinic acid derivatives prior to Abeta, cell toxicity was significantly diminished. Among quinic acid derivatives, (-)4,5-dicaffeoyl quinic acid (1) gave the highest protection against Abeta-induced cell toxicity. In addition, the neurotrophic effects of compounds were evaluated by microscopically monitoring their potency to induce neurite outgrowth in PC12 cells. Four quinic acid derivatives from A. scaber promoted neurite outgrowth in PC12 cells. Interestingly, a novel quinic acid, (-)3,5-dicaffeoyl-muco-quinic acid (2) was more effective than the other compounds in promoting neurite outgrowth. Unlike nerve growth factor, the withdrawal of quinic acids did not result in any significant decrease in cell viability. The results suggest that quinic acid derivatives from A. scaber might potentially be used as a therapeutic agent in Alzheimer disease.