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. Keywords: Barrel medic; Medicago truncatula; triterpene saponins