Phytochemical profile of the aerial parts of Rehmannia glutinosa liboschitz var. purpurea Makino

Background: The roots of Rehmannia glutinosa (RG) or Rehmanniae Radix are a well-known medicinal material in the Oriental medicine, and its phytochemical profile has been extensively studied with more than 100 individual compounds from Rehmannia species. In contrast, bioactive components of the aerial part of the title plant are largely unknown as only several compounds reported up to date. Objective: The objective was to study on chemical constituents of the aerial parts of the title plant and evaluate the aerial parts as a supplementary source for Rehmanniae radix. Materials and Methods: Solvent extraction, partition, and column chromatography was used to separate individual compounds; spectroscopic data including nuclear magnetic resonance and mass spectrometry were analyzed to determine the chemical structure of the isolates. Results: Eight compounds including five ursane-type triterpenoids for the first time from RG (ursolic acid [1], pomolic acid [2], 2β-hydroxypomolic acid [3], asiatic acid [4] and 7β,24-dihydroxy ursolic acid [5]) and three main glycosides (ajugol [6], aucubin [8], and acteoside [7]) were characterized from the aerial parts of the title plant. Their structures were identified on the basis of spectroscopic data and comparison with those reported in the literature. Conclusion: The current study reveals various ursane triterpenes in the organic portion beside the main hydrophilic glycosides in the RG aerial parts. The occurrence of various ursane triterpenes contributed in part to phytochemical database and evidence of the biological activity associated with potential in use as a medicinal material of the RG leaves.