Neuroprotective carbazole alkaloids from the stems and leaves of Clausena lenis

The investigation on the stems and leaves of Clausena lenis led to the isolation of a previously undescribed carbazole alkaloid, clausenalenine A (1), along with seven known analogues (2–8). The structure of 1 was elucidated based on comprehensive spectroscopic analyses and the known compounds were identified by comparisons with data reported in the literatures. All known compounds (2–8) were isolated from C. lenis for the first time. All isolated compounds were evaluated for their neuroprotective activities against 6-hydroxydopamine induced cell death in human neuroblastoma SH-SY5Y cells in vitro. Compounds 1–8 showed significant neuroprotective effects with EC50 values ranging from 0.68 to 18.76 μM.