New Bis‐sesquiterpenoids From the Lindera glauca With Anti‐inflammatory Activity by Inhibiting the Lipopolysaccharide‐induced Expression of Inducible Nitric Oxide Synthase

ABSTRACT Three new sesquiterpenoid dimers linderasesquiterpenoids A–C ( 1–3 ) and three known compounds 4–6 were co‐isolated from the Lindera glauca . Their structures were elucidated based on spectroscopic methods and electronic circular dichroism calculations. Among them, linderasesquiterpenoid A ( 1 ) featuring the rare [4, 9] ring system was the first example of sesquiterpenoid dimers, and also the sesquiterpenoid dimers components were first found in this plant. Meanwhile, linderasesquiterpenoid A ( 1 ) exhibited stronger anti‐inflammatory activity against lipopolysaccharide‐induced nitric oxide (NO) production in RAW 264.7 cells with a 50% inhibitory concentration (IC 50 ) value of 11.0 µM than positive control (indomethacin, IC 50 24.1 µM). Further studies demonstrated that linderasesquiterpenoids A ( 1 ) significantly suppressed the protein expression of the enzyme inducible NO synthase, but did not affect the enzyme cyclooxygenase‐2.