Bioactive Compounds from the Stems of Clausena lansium

In view of the significant neuroprotective effect of Clausena lansium, we continued to separate the n-butanol and the water extracts from the stems of C. lansium in order to find the leading compounds with significant activity. Two new phenolic glycosides, Clausenolside A–B (1–2), one new pair of phenolic enantiomers (3a, 3b), and two new monoterpenoids, clausenapene A–B (4–5), together with twelve known analogues (6–17) were isolated from the stems of C. lansium. Compounds 1–17 were obtained from C. lansium for the first time. Compounds 3a, 3b, 4, 16, and 17 showed strong or moderate potential neuroprotective effects on inhibited PC12 cell injury induced by okadaic acid, and compound 9 exhibited strong potential hepatoprotective activities. Their structures were elucidated on the basis of spectroscopic analyses, including UV, IR, NMR experiments, and electronic circular dichroism (ECD) spectra.