Hydrangenone, a New Isoprenoid with an Unprecedented Skeleton from <i>Salvia hydrangea</i>

Abstract

Hydrangenone, a new heptacyclic isoprenoid with a 6/7/6/5/5 membered carbon ring skeleton, was isolated from the aerial parts of <i>Salvia hydrangea.</i> The structure was established by extensive NMR spectroscopic methods. The relative and absolute configuration of <b>1</b> was assigned by NOESY and X-ray crystallographic analysis and by comparison of experimental and calculated electronic circular dichroism (ECD) spectra. Compound <b>1</b> showed in vitro antiplasmodial activity, with an IC₅₀ value of 1.4 μM against <i>P. falciparum</i>. A plausible biosynthetic pathway of <b>1</b> was also proposed