Neuroprotective Lignans from the Fruits of Schisandra bicolor var. tuberculata

Nine new lignans (1–9) and ten known analogues (10–19) were isolated from the fruits of Schisandra bicolor var. tuberculata. The structures of compounds 1–9 were established on the basis of spectroscopic data analysis. The absolute configuration of compound 1 was determined by single-crystal X-ray diffraction analysis with Cu Kα irradiation techniques, and the absolute configurations of compounds 2–9 were deduced by comparing their experimental ECD spectra and optical rotations with those of compound 1 or similar compounds. All isolates were evaluated for their neuroprotective activities against CoCl₂, H₂O₂, and Aβ_25–35-induced SH-SY5Y cell injury, and were found to exhibit different degrees of neuroprotective effects. At a low concentration of 3.2 nM, compounds 3, 8, 9, and 14–19 in CoCl₂-induced, compounds 7, 8, 13, 17, and 18 in H₂O₂-induced, and compounds 2, 6, 7, 9, 10, and 12–19 in Aβ_25–35-induced SH-SY5Y cell injury models, showed statistically significant neuroprotective activities, when compared with each negative control group.