Structurally Diverse Polymethylated Phloroglucinol Meroterpenoids from Baeckea frutescens

Abstract Phytochemical investigation of the MeOH extract of twigs and leaves of Baeckea frutescens led to the isolation of seven new polymethylated phloroglucinol meroterpenoids (PPMs), named baeckfrutones M–S (1–7). Their structures and absolute configurations were determined by spectroscopic analyses, chiral-phase HPLC analysis, and electronic circular dichroism (ECD) calculations. PPM 1 is a novel meroterpenoid possessing a 6/6/5/3 tetracyclic skeleton in PPMs, whereas 3 and 4 are the first hydroxytasmanone type phloroglucinol-monoterpene hybrids. (+)-2 and 7 displayed potent anti-inflammatory activity with IC50 values of 20.86 ± 0.60 and 36.21 ± 1.18 μΜ, respectively. Graphical Abstrac