Comprehensive SummaryIn this study, 27 new sesquiterpenoids: twenty monomers and seven dimers, with diverse structures, along with one known chlorajaponilide F (25) were isolated from the aerial parts of Chloranthus henryi var. hupehensis. Structurally, chlorahupetolides A (1) and B (2), two eudesmane‐type merosesquiterpenoids with an undescribed C18 carbon framework, and chlorahupetene E (18) are the first example of dimers comprising two eudesmane sesquiterpenoids bridged by a four‐membered ring in the Chloranthus. Their structures were characterized by nuclear magnetic resonance (NMR), electronic circular dichroism (ECD), and X‐ray diffraction analysis. In the RAW264.7 macrophages model of inflammation induced by LPS, compounds 12, 18, and 25 significantly reduced NO production in a dose dependent manner and without cytotoxicity. The mRNA expression of COX‐2 was considerably inhibited by treatments with compounds 12, 18, and 25.

(+)- and (−)-Chlorahupetenes A (1a and 1b), B (2a and 2b), C (3a and 3b), and D (4a and 4b), four unique enantiomeric pairs of eudesmane-type sesquiterpenoid dimers with two new carbon skeletons, were isolated from the aerial parts of Chloranthus henryi var. hupehensis. Compounds 1 and 2 possess an unprecedented 6/6/5/6/6 pentacyclic carbon skeleton with a new dimerization pattern of two eudesmane-type sesquiterpenoids. Compounds 3 and 4, which are fused with two eudesmane-type sesquiterpenoids via an unprecedented five-membered O-heterocyclic ring, represent a new 6/6/5/5/6/6/5 heptacyclic ring system. The structures of the compounds were determined through spectroscopic data and X-ray crystallography. Compounds 1a–3b significantly inhibited NO production with IC50 values ranging from 9.62 to 12.91 μM. Moreover, compounds 1b and 3a suppressed the production of a proinflammatory mediator (TNF-α) and enzyme expression (iNOS) at the mRNA level.