Anti-inflammatory Meroterpenoids from <i>Baeckea frutescens</i>

Abstract

Frutescones H–R ( 1 – 11 ), new sesqui- or monoterpene-based meroterpenoids, were isolated from the aerial parts of Baeckea frutescens . Their structures and absolute configurations were established by means of spectroscopic analyses (HRESIMS, 1D and 2D NMR, and ECD), as well as single-crystal X-ray crystallography of 1, (−)- 7, and 9 . The anti-inflammatory activities of all isolates were evaluated by measuring their inhibitory effects on NO production in LPS-stimulated RAW 264.7 macrophages, and the structure–activity relationships of 1 – 11 are also discussed. Compound 8 exhibited anti-inflammatory activity with an IC 50 value of 0.36 μM, which might be related to the regulation of the NF-κB signaling pathway via the suppression of p65 nuclear translocation and the consequent decrease of IL-6 and TNF-α.