Enantiomeric 8,4'-type oxyneolignans from the root barks of Ailanthus altissima (Mill.) Swingle and their neuroprotective effects against HO-induced SH-SY5Y cells injury.

Ailanthus altissima Swingle is a deciduous tree, belonging to the Simaroubaceae family. Phytochemical investigation of the root barks of A. altissima showed the presence of eight pairs of enantiomeric 8,4'-type oxyneolignans (1a/1b-8a/8b) including nine undescribed compounds (1b, 2a, 3a/3b, 4a/4b, 5b, 7b, 8a). Their structures were elucidated by comprehensive spectroscopic analyses, and their absolute configurations were determined by comparison of the experimental and quantum chemical calculations of electronic circular dichroism (ECD) curves. In addition, their neuroprotective effects against HO-induced oxidative stress in human neuroblastoma SH-SY5Y cells were investigated. Among them, 4a, 4b, and 8b exhibited moderate neuroprotective activity.