Abstract
Carascynol A, an unprecedented 4/9/8 ring system hybrid with a peroxide bridge, was characterized from Hypericum ascyron. The architecture contains a caryophyllane-type moiety and a C(6) unit derived from polyprenylated acylphloroglucinols. Its structure and absolute configuration were determined by comprehensive spectroscopic and X-ray diffraction data. Biologically, compound 1 inhibited cell proliferation in LoVo, SW480, and HCT116 cell lines (IC(50) = 12.30-24.57 µM).