Bioassay and NMR-HSQC-Guided Isolation and Identification of Phthalide Dimers with Anti-Inflammatory Activity from the Rhizomes of <i>Angelica sinensis</i>

Under the guidance of a bioactivity-guided approach and HSQC characteristic signals, nine pairs of phthalic dimers, angesilides A-I (<b>1</b>-<b>9</b>), with complex polycyclic skeletons featuring bridged, fused, and spiro ring systems were discovered from the rhizomes of <i>Angelica sinensis</i>. Their structures and absolute configurations were established by comprehensive spectroscopic methods, X-ray diffraction analysis, and chiral separation. Plausible biosynthetic pathway for <b>1</b>-<b>9</b> was proposed. Moreover, the anti-inflammatory activities of all isolates were evaluated in lipopolysaccharide (LPS) stimulated mouse leukemia cells of monocyte macrophages (RAW = 264.7). Among them, compound <b>9</b> showed a remarkable inhibitory activity with IC₅₀ values of 425 nM and could significantly decrease IL-1β and IL-6 transcription levels. Interestingly, (+)-<b>9</b> has superior NO inhibitory activity compared to that of (-)-<b>9</b>, which was verified by further molecular docking analysis. The findings provide new insights into <i>A. sinensis</i> as a functional food or for the development of new anti-inflammatory drug candidates.