Lindenane Sesquiterpenoid Hetero‐ or Homo‐Dimers From Sarcandra glabra and Their Anti‐Neuroinflammatory Activities

ABSTRACT Eighteen lindenane sesquiterpenoid dimers, including three previously undescribed hetero‐ or homo‐dimers ( 1–3 ), were isolated from the whole plant of Sarcandra glabra . Their structures were elucidated by High‐resolution electrospray ionization mass spectrometry, one‐ and two‐dimensional nuclear magnetic resonance, quantum chemical calculations, and electronic circular dichroism calculations. Notably, compound 1 is a rare hetero‐dimer formed by [4 + 2] cycloaddition of a eudesmane and a lindenane sesquiterpene, via C‐15−C‐9′, C‐6−C‐8′, and C‐11−C‐7′ linkages. Compound 2 features a unique epoxide structural motif. All compounds were evaluated for their inhibitory effect on nitric oxide (NO) production induced by lipopolysaccharide (LPS) in BV‐2 cells. The inhibitory effects of all isolates on LPS‐induced NO production in BV‐2 cells were evaluated. Thirteen compounds, excluding 3 , 5 , 13 , 15 , and 16 , exhibited IC 50 values ranging from 0.15 to 6.29 µM. Furthermore, compound 1 dose‐dependently inhibited the release of NO in BV‐2 cells by suppressing the expression of induced NO synthase, cyclooxygenase‐2, and MYD88 proteins.