Hyperuralone A (1),a polycyclic polyprenylated acylphloroglucinolpossessing an unprecedented tetracyclo-[5.3.1.14,9.04,11]-dodecane core, was characterized from Hypericumuralumtogether with hyperuralone B (2), a congenerwith another complex caged skeleton. Their structures were determinedby extensive spectroscopic analysis and ECD calculations. A plausiblebiosynthetic pathway of their intriguing architectures via intramolecularDiels–Alder reactions was also proposed. Compound 1exhibited obviously cytotoxic activities against five human cancercell lines in vitro(IC504.6–14.4μM). [ABSTRACT FROM AUTHOR]