New Hyperforin Derivatives from Hypericum revolutum V AHL with Growth‐Inhibitory Activity against a Human Colon Carcinoma Cell Line

The crude petroleum‐ether extract of the root bark of Hypericum revolutum VAHL (Guttiferae) exhibited in vitro growth‐inhibitory activity against the Co‐115 human colon carcinoma cell line. Activity‐guided fractionation of this extract resulted in the isolation of two new hyperforin derivatives 1 and 2. The structure of 1 (hyperevolutin A) was established by X‐ray analysis as the 4‐hydroxy‐8‐exo‐methyl‐5,7‐exo‐bis(3‐methylbut‐2‐enyl)‐1‐(2‐methyl‐1‐oxopropyl)‐8‐endo‐(4‐methylpent‐3‐enyl)bicyclo[3.3.1]non‐3‐ene‐2,9‐dione. The structure of the homologue 2 was deduced by comparison of its UV and 1H‐ and 13C‐NMR spectra with those of 1.