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 (CuKα 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 IC50 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 IC50 values of 4.60 ± 1.05 μM, 3.17 ± 0.66 μM, and 1.57 ± 0.27 μM, respectively.

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