Hypatulins A and B, Meroterpenes from <i>Hypericum patulum</i>

Two novel prenylated benzophenone related meroterpenes, hypatulins A (<b>1</b>) and B (<b>2</b>), were isolated from the leaves of <i>Hypericum patulum</i>. The structures of <b>1</b> and <b>2</b> were assigned by spectroscopic analysis, chemical conversion, and calculations of the ECD (electron circular dichroism) spectra. Hypatulin A (<b>1</b>) had a unique densely substituted tricyclic octahydro-1,5-methanopentalene core, while hypatulin B (<b>2</b>) possessed a bicyclo­[3.2.1]­octane moiety. Hypatulin A (<b>1</b>) exhibited antimicrobacterial activity against <i>Bacillus subtilis</i>. A possible biogenetic pathway of the new meroterpenes <b>1</b> and <b>2</b> from a prenylated benzophenone was presented.