Discovering new natural products directly from crude extracts by HPLC-SPE-NMR: Chinane diterpenes in Harpagophytum procumbens

HPLC-SPE-NMR experiments with crude extracts of Harpagophytum procumbens allowed the rapid identification of novel, unstable chinane-type tricyclic diterpenes (1 and 2), along with numerous other constituents. Dramatic sensitivity gains achieved with this novel hyphenated technique establish a new paradigm in natural products research: rapid and rigorous structure determination of multiple extract components, including minor components, without preparative-scale isolation. © 2006 American Chemical Society and American Society of Pharmacognosy.