Chlorajaponols A–F, sesquiterpenoids from Chloranthus japonicus and their in vitro anti-inflammatory and anti-tumor activities

Two new eudesmane sesquiterpenoids, chlorajaponols A–B ( 1 – 2 ), two new guaiane sesquiterpenoids, chlorajaponols C–D ( 3 – 4 ), a new germacrane sesquiterpenoid, chlorajaponol E ( 5 ), and a new lindenane sesquiterpenoid, chlorajaponol F ( 6 ), along with 8 known sesquiterpenoids and 6 known disesquiterpenoids, were isolated from the whole plant of Chloranthus japonicus . Their structures were established by extensive analysis of NMR spectroscopic data in combination with mass spectrometry. The structures of compounds 1 – 4 were confirmed by single crystal X-ray diffraction (Cu K α radiation). The possible biogenetic pathways of compounds 1 – 6 were discussed. Chlorajaponol B ( 2 ) showed significant inhibition against nitric oxide (NO) release in LPS-induced RAW264.7 macrophages with the IC 50 value of 9.56 ± 0.71 μM, comparable to that of positive control amino guanidine (8.50 ± 0.35 μM). Shizukaol C ( 18 ) strongly suppressed the proliferation of three human tumor cell lines MGC803, HepG2, and HL-60 with IC 50 values of 4.60 ± 1.05 μM, 3.17 ± 0.66 μM, and 1.57 ± 0.27 μM, respectively.