Synthesis of tropolone derivatives and evaluation of their in vitro neuroprotective activity.

beta-Thujaplicin (hinokitiol or 2-hydroxy-4-isopropyl-2,4,6-cycloheptatrien-1-one), a natural tropolone, shows numerous activities while its synthetic analogues were found to exhibit anticancer and anti-ischemic activity. However, the ability of tropolone derivatives to protect neuronal cells from oxidative stress-induced cell damage has not been studied so far. As an ongoing effort toward highly effective antioxidants with potential neuroprotective activity, we have synthesized 7-substituted derivatives of beta-thujaplicin and its methoxy analogue. The substituents were heterocycles (piperazine, morpholine) or heteroaromatics (triazoles, pyridine). Only the piperazine derivatives of beta-thujaplicin were able to protect HT22 hippocampal neurons from oxidative stress-induced cell death.