Five rare dimeric sesquiterpenes exhibiting potential neuroprotection activity from Vladimiria souliei

Two rare C-32 sesquiterpene lactone dimers, vlasouliolides J-K (1-2), together with three C-30 sesquiterpene dimers, vlasoulioliones A-C (3-5), were isolated from Vladimiria souliei. Their chemical structures were elucidated by NMR and MS spectroscopic data. Among them, compounds 1, 3 and 5 were unambiguously established by Cu-Ka X-ray crystallographic analysis. Furthermore, compound 1 showed prominent neuroprotective effects against glutamate-induced neurotoxicity in PC-12 cells, with EC50 value of 2.11 +/- 0.35 mu M. And the leakage of LDH from glutamate-induced PC-12 was significantly reduced by compound 1 at concentration of 10 mu M.