New secoisolariciresinol derivatives from Lindera obtusiloba stems and their neuroprotective activities.

A methanolic extract of Lindera obtusiloba (Lauraceae) stems significantly attenuated glutamate-induced oxidative stress in HT22 hippocampal cells. Two new secoisolariciresinol derivatives, characterized as 9,9'- O-di-(E)-feruloyl-meso-5,5'-dimethoxysecoisolariciresinol (1) and 9,9'-O-di-(E)-sinapinoyl-meso-5,5'-dimethoxysecoisolariciresinol (2), were isolated, along with the known compound 9,9'-O-di-(E)-feruloyl-meso-secoisolariciresinol (3), from the methanolic extract of L. obtusiloba stems. Compounds 1, 2, and 3 showed neuroprotective effects on glutamate-induced toxicity in HT22 cells.