Modified Eremophilanes from and Their Neuroprotective Activities.

The new modified eremophilanes hastatusins A-K (-) and 13 known compounds (-) were isolated from . The structures of - were elucidated based on spectroscopic data analysis and comparison with literature data. The absolute configurations of compounds and were defined by single-crystal X-ray diffraction analysis, and the other new compounds were assigned based on ECD data. This work is the first report of the crystal structure of an 8,9--eremophilanolide () with two lactone units. The enantiomers of were separated by chiral-phase HPLC, and the absolute configurations of (-)- and (+)- were established via experimental and calculated ECD data. The new compounds represent four unusual skeletons: a modified 8,9--eremophilane featuring a rare 6,9;8,12-dilactone moiety (), a furanoeremophilane-type skeleton (-, ), a rare C -eremophilane-type skeleton (, ), and a modified eremophilane lactone-type skeleton (). All isolates were assayed for their neuroprotective effects against HO-induced SH-SY5Y cell injury, and compounds -, , , and exhibited activities even at a low concentration of 1 μM. Compounds -, , , , , , and also showed notable effects at 10 and 100 μM.