MAPT and Alzheimer disease: In summary, our results demonstrated that rhynchophylline and isorhynchophylline significantly decreased Aβ25–35-induced cell death, calcium overloading, and tau protein hyperphosphorylation in PC12 cells, suggesting that rhynchophylline and isorhynchophylline may be the major active ingredients of Uncaria  rhynchophylla  for the treatment of AD, and their neuroprotective effect may be mediated, at least in part, by inhibition of intracellular calcium overloading and tau protein hyperphosphorylation.