Seven pairs of new enantiomeric sesquiterpenoids from Curcuma phaeocaulis.

Seven pairs of new enantiomeric sesquiterpenoids, (+)/(-)-phaeocauline A - G [(+)/(-)-1-7], were isolated from the rhizomes of Curcuma phaeocaulis by chiral HPLC separation. Their structures, including absolute configurations, were determined by spectroscopic analyses and ECD data. The isolates were assessed for vasorelaxant, anti-platelet aggregative, and neuroprotective activities. Enantiomers (+)-1 and (-)-1 showed similar activity against abnormal platelet aggregation induced by arachidonic acid, while their C-4 epimers (+)-2 and (-)-2 were inactive, which indicated that those effects were stereoselective, but not enantioselective. Compounds (+)/(-)-3-5 exhibited vasorelaxant effects against KCl-induced contraction of rat aortic rings.