Comprehensive spectroscopic investigation of alpha-onocerin.

A detailed NMR and MS analysis of alpha-onocerin was performed in order to provide precise phytochemical reference for structure identification and quality control of this analytical lead compound from Ononis spinosa the roots of which are widely used as a diuretic drug. Unambiguous 1H- and 13C-NMR assignments revealed that the linkage of two subunits were confirmed to possess identical stereochemistries in this triterpenoid.