Isolation and NMR Spectral Assignments of 18-Glycyrrhetinic acid-3-O-D-glucuronide and 18-Glycyrrhetinic acid

Two olenane triterpenes, 18β-glycyrrhetinic acid-3-O-β-D-glucuronide and 18β-glycyrrhetinic acid were obtained from the acid hydrolysis of 18β-glycyrrhetinic acid-3-O-β-D-glucuronopyranosyl-(1→2)-βD-glucuronide (Glycyrrhizic acid or Glycyrrhizin), a triterpene glucuronide isolated from the commercial extract of the roots of Glycyrrhia glabra. The complete 1 H and 13 C NMR assignments of the two triterpenes 18βglycyrrhetinic acid-3-O-β-D-glucuronide and 18β-glycyrrhetinic acid were achieved on the basis of extensive 1D and 2D NMR ( 1 H and 13 C, COSY, HSQC, and HMBC) as well as mass spectral data.