Chlorahupetenes A–D, Four Eudesmane-Type Sesquiterpenoid Dimer Enantiomers with Two Unusual Carbon Skeletons from Chloranthus henryi Var. hupehensis

Abstract

(+)- 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.

Structurally Diverse Sesquiterpenoids from Chloranthus henryi var. hupehensis and Their Anti‐inflammatory Activities

“…The results showed that the experimental and calculated spectra for the (4 S ,5 R ,10 R ) ‐ 10 were in good agreement. [ 5‐6 ] Accordingly, the structure of 10 was established as shown in Figure 1.…”

“…The results (Figure 5D) showed that the calculated ECD curve was consistent with the experimental spectrum, which confirmed the above relative structure and assignment of the 1 S ,5 S ,10 S absolute configuration of 11 . [ 5‐6 ]…”

“…Natural products are an invaluable source of anti‐inflammatory molecules, and are drawing extensive attention from organic chemists. [ 1‐5 ]…”

“…Chloranthus is a plant genus that has produced diverse sesquiterpenoids compound classes, sesquiterpenoid dimers, and acylamide with a broad spectrum of bioactivities. [ 5‐9 ] Certain species have for a long time been used as Traditional Chinese Medicines to treat painful joints, fractures, and arthritis among other diseases caused by inflammation. [ 10 ]…”

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“…hupehensis , have undescribed polycyclic skeletons. 15 Possible biosynthetic routes to the chlorahupetenes have been presented. It is proposed that the biosynthetic pathways to the polycyclic abietane diterpenoid dimers biseupyiheoid A 20 and bisfischoid C 21 , from Euphorbia fischeriana , involve intramolecular Diels–Alder cycloadditions with different coupling patterns.…”