In Salvia miltiorrhiza, phenolic acids possess protective properties against amyloid β-induced cytotoxicity, and tanshinones act as acetylcholinesterase inhibitors.

Radix Salvia miltiorrhiza (RSM), a traditional Chinese medicinal herb, has been alleged to possess therapeutic effects against senile dementia, also known as Alzheimer's disease (AD). However, the effects of the major components in RSM on cytotoxicity induced by amyloid-β peptide (Aβ) and on acetylcholinesterase activity have not been studied in depth to date. In this report, the effects of RSM aqueous/ethanol extracts, total polyphenols, total tanshinones and 3 phenolic compounds against toxicity mediated by Aβ(25-35) were tested with PC-12 cells. The results showed that Aβ(25-35)-induced cytotoxicity was revised by RSM aqueous/ethanol extracts and total polyphenols and that danshensu and salvianolic acid B could protect PC-12 cells by blocking Aβ(25-35)-induced Ca(2+)-intake, lactate dehydrogenase release, cell viability decrease and apoptosis. In addition, the activities of RSM extracts and relevant constituents in their inhibition of acetylcholinesterase were investigated using rat brain homogenates as an enzyme resource. Galanthamine hydrobromide, an accepted acetylcholinesterase inhibitor, was employed as a positive control agent. Our preliminary studies demonstrated that RSM ethanol extract, total tanshinones, tanshinone I and dihydrotanshinone I had remarkable inhibition effects on acetylcholinesterase in vitro. These findings suggest that both tanshinones and polyphenols in RSM are the active constituents responsible for the beneficial effects of this herb in AD treatment.