Dibenzocyclooctadiene lignans from Kadsura polysperma and their antineurodegenerative activities.

Eleven new dibenzocyclooctadiene lignans, polysperlignans A-K (1-11), and eight known analogues (12-19) were isolated from the stems of Kadsura polysperma. Their structures and absolute configurations were established using a combination of MS, NMR, CD, and single-crystal X-ray diffraction techniques. Selected compounds were evaluated for activity against β-amyloid- or hydrogen peroxide-induced neurotoxicity on PC12 cells, and 1, 2, 4, 5, 13, and 16 showed statistically significant neuroprotective effects in these in vitro assays.