Vicinal Diol Sesquiterpenes from Cinnamomum migao with Neuroprotective Effects in PC12 Cells

In the ongoing search for new vicinal diol natural products, four new (Migaones A-D, 1-4) and four known (5-8) vicinal diol sesquiterpenoids were isolated from the branches and leaves of Cinnamomum migao. Their structures were unequivocally determined by comprehensive spectroscopic analyses (HRESIMS, 1D, and 2D NMR), single-crystal X-ray diffraction, electronic circular dichroism calculations, and comparison with existing literature data. All compounds isolated from C. migao possess vicinal diol structural units except compound 2. The newly isolated compounds (1-4) were evaluated for their neuroprotective activity using the PC12 cell injury model induced by N-methyl-daspartate acid (NMDA) and compounds 1-2 showing moderate neuroprotective activity against NMDA-induced neurotoxicity. Furthermore, molecular docking studies indicated that the most active compound 2 binds to the active site of the NMDA receptor via hydrogen bonds and hydrophobic interactions.