New Triterpenic Saponins from the Aerial Parts of Medicago arabica (L.) Huds (original) (raw)

2009, Journal of Agricultural and Food Chemistry

The reinvestigation of saponin composition from Medicago arabica from Italy allowed the detection of nineteen (1-19) saponins. All of them were purified by reverse-phase chromatography and their structures elucidated by spectroscopic and spectrometric (1D and 2D NMR; ESI-MS/MS) and chemical methods. Fourteen were known saponins, previously found in other plants including other Medicago species. They have been identified as glycosides of oleanolic acid, 2 ,3 -dihydroxyolean-12-en-28-oic acid, hederagenin, bayogenin and soyasapogenol B. Five saponins, identified as 3-O-[-R-L-arabinopyranosyl(1f2)--Dglucuronopyranosyl]-30-O--D-glucopyranosyl 2 ,3 ,30-trihydroxyolean-12-en-28-oic acid (1), 3-O-[R-Larabinopyranosyl(1f2)--D-glucuronopyranosyl]-30-O-[ -D-glucopyranosyl] 3 ,30-dihydroxyolean-12-en-28-oic acid (2), 3-O-[ -D-glucuronopyranosyl]-30-O-[R-L-arabinopyranosyl(1f2)--D-glucopyranosyl] 2 ,3 ,30trihydroxyolean-12-en-28-oic acid (3), 3-O-[ -D-glucuronopyranosyl]-30-O-[R-L-arabinopyranosyl(1f2)--D-glucopyranosyl] 3 ,30-dihydroxyolean-12-en-28-oic acid (4) and 3-O-[ -D-glucuronopyranosyl]-30-O-[ -D-glucopyranosyl] 2 ,3 ,30-trihydroxyolean-12-en-28-oic acid (5), are reported here as new natural compounds. These new saponins, possessing a hydroxy group at the 30-methyl position of the triterpenic skeleton, have never been previously found in the genus Medicago.