Neuroprotective dibenzocyclooctadiene lignans from the stems of Kadsura coccinea

Phytochemical investigation of the stems of Kadsura coccinea led to the isolation of seven previously undescribed dibenzocyclooctadiene lignans, designated kadcoccinlignans A-G (1-7), together with eight known analogues (8-15). The structures of the new compounds were established by comprehensive spectroscopic analyses. All isolated compounds were evaluated for their neuroprotective effects against 6-hydroxydopamine (6-OHDA)-induced oxidative damage in PC12 cells. Among the tested compounds, 8, 13, and 15 exhibited significant neuroprotective activity at 50 μM, increasing cell viability by 27.26%, 26.74%, and 28.86%, respectively, without appreciable cytotoxicity. In addition, these compounds reduced intracellular reactive oxygen species (ROS) levels and restored superoxide dismutase (SOD) activity. Western blot analysis further demonstrated that compound 15 activated the Nrf2/HO-1 signaling pathway, thereby attenuating oxidative injury. These findings enrich the phytochemical profile of K. coccinea and support further investigation of dibenzocyclooctadiene lignans as potential neuroprotective agents.