NMR-Guided Isolation of Anti-inflammatory Carabranolides from the Fruits of Carpesium abrotanoidesL.

Carabranolides present characteristic NMR resonances for the cyclopropane moiety, which distinctly differ from those of other compounds and were used for an NMR-guided isolation in this study. As a result, 11 undescribed carabranolides (1–11), along with five known ones (12–16), were isolated from the fruits of Carpesium abrotanoidesL. Compounds 1–11are new esters of carabrol at C-4 with different carboxylic acids. Their structures were elucidated by HRESIMS and NMR spectroscopic data analysis. The biological evaluation showed that compounds 2–4, 15, and 16exhibited significant inhibitory activity against LPS-induced NO release with an IC50value of 5.6–9.1 μM and dose-dependently decreased iNOS protein expression in RAW264.7 cells.