Meroterpenoids with bicyclic polyprenylated acylphloroglucinol scaffold and anti-inflammatory activity from Hypericum lancasteri

Twelve undescribed meroterpenoids possessing bicyclic polyprenylated acylphloroglucinol (BPAP) scaffold, (+/-)-lancasternoids A-D and lancasternoids E-H, together with fourteen known analogues, were isolated from Hypericum lancasteri (Hypericaceae) and structurally characterized. (+/-)-Lancasternoids A-D are the first examples of bicyclo[3.2.1]octane-type BPAP meroterpenoids present as enantiomeric pairs, while (+/-)-lancasternoids A-C incorporate an unprecedented 5-oxatetracyclo[7.5.1.04,9.01,11]pentadecane system. Lancasternoids E-H are two pairs of epimers with [3.3.1]-type BPAP scaffold. Some of the isolates showed inhibition in hypoxiainducible factor-1 alpha (HIF-1 alpha) responsive element (HRE) luciferase assay, and uraloidin A further decreased the lipopolysaccharide (LPS)-induced pro-inflammatory factor IL-1 beta expression level in RAW 264.7 cells.