Spirocyclohexadienone‐Type Neolignans with Neuroprotective and Neurite Outgrowth Enhancing Activities from Magnolia liliiflora

Three rare spirocyclohexadienone‐type neolignans, magnoflorins A–C (1–3), and three known analogs (4–6), were isolated from the leaves of Magnolia liliiflora. Magnoflorin D (4) was obtained from natural resources for the first time. The chemical structures and absolute configurations of 1–4 were elucidated through detailed analysis of HR‐ESI‐MS, IR, 1H, 13C, and 2D NMR, and ECD experiments. The absolute configuration of 5 were characterized by X‐ray crystallography in present study. Moreover, compounds 4 and 5 displayed moderate neuroprotective activity against corticosterone‐induced PC12 cells injury at 20 μM with cell viability of 71.5±0.99 % and 73.0±1.42 %, respectively, compared to the model group with 60.83±0.93 %. Compound 6 could enhance neurite outgrowth of nerve growth factor (NGF)‐induced PC12 cells at 10 μM with the differentiation rate of 11.98 %, compared with 20.49 % of 50 ng/ml NGF.