Brodiosaponins A-F, six new polyhydroxylated steroidal saponins from the tubers of Brodiaea californica

The constituents of the tubers of Brodiaea californica have been analyzed as part of a systematic study of plants of the subfamily Allioideae in Liliaceae. Six new polyhydroxylated steroidal saponins designated as brodiosaponins A-F (1-6) were isolated, and their structures were elucidated on the basis of spectroscopic analysis, including 2D NMR techniques, and acid- and alkaline-catalyzed hydrolysis. The bisdesmosidic saponins, brodiosaponins D-F (4-6) contain 6-deoxy-D-gulopyranose, which has been shown for the first time as a saccharide component among the steroidal and triterpene saponins reported to date.