Triterpene saponins from barrel medic (Medicago truncatula) aerial parts

Triterpene saponins from Medicago truncatula aerial parts have been separated and their structures determined by the extensive use of 1D- and 2D-NMR experiments including 1H-1H (DQF-COSY, 1D-TOCSY) and 1H-13C (HSQC, HMBC) spectroscopy along with ESIMS. Fifteen individual compounds were isolated that included seven medicagenic acid and eight zanhic acid glycosides. Additionally, two soyasapogenol B and soyasapogenol E glycosides were identified by MS/MS and TLC. Four medicagenic acid glycosides (5, 11, 12, 14) and eight zanhic acid glycosides (1-4, 6-9) are reported here for the first time. The common feature of M. truncatula aerial part saponins is the (1-->3) linkage between the two glucose units at C-3 of medicagenic and zanhic acids, which is different from that found in alfalfa (Medicago sativa), where this linkage was always (1-->2). This may suggest differences in glucosyltransferases between these two Medicago species.