Saponin constituents of Achyranthes root

Achyranthes root is a crude drug used as diuretic, tonic and remedy for blood stasis. Characteristic oleanolic acid saponins with a dicarboxylic acid moiety have been isolated as one of the representative constituents of this crude drug. This review focuses on the triterpene saponin constituents, especially those with a characteristic dicarboxylic acid moiety, of A. bidentata and A. fauriei. Several groups isolated the saponins and different names were given to one compound in some cases. The names of the compounds are sorted out and the stereochemistry of the dicarboxylic acid moieties are summarized. HPLC analysis of the composition of the saponin constituents and the effect of processing and extraction conditions on the composition are reviewed. Biological activities of the saponin constituents are also summarized. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s11418-021-01591-1.