(±)-hypermonanones A-G, seven pairs of monoterpenoid polyprenylated acylphloroglucinol enantiomers from Hypericum monanthemum.

Seven pairs of undescribed monoterpenoid polyprenylated acylphloroglucinol enantiomers [(±)-hypermonanones A-G (1-7)], together with three known analogues, were identified from the whole plant of Hypericum monanthemum Hook. The structures of these compounds were determined by analyses of their UV, HRESIMS, 1D/2D NMR spectroscopic data, and NMR calculations. The absolute configurations of these compounds were assigned by ECD calculations after chiral HPLC separation. Diverse monoterpene moieties were fused at C-3/C-4 of the dearomatized acylphloroglucinol core, which led to 3,4-dihydro-2H-pyran-integrated angular or linear type 6/6/6 tricyclic skeletons in 1-7. Compounds (-)-2 and (+)-2 exhibited significant NO inhibitory activity against LPS induced RAW264.7 cells with the IC values of 7.07 ± 1.02 μM and 11.39 ± 0.24 μM, respectively.