New triterpenic saponins from the aerial parts of Medicago arabica (L.) huds.
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, 2beta,3beta-dihydroxyolean-12-en-28-oic acid, hederagenin, bayogenin and soyasapogenol B. Five saponins, identified as 3-O-[-alpha-L-arabinopyranosyl(1-->2)-beta-D-glucuronopyranosyl]-30-O-beta-D-glucopyranosyl 2beta,3beta,30-trihydroxyolean-12-en-28-oic acid (1), 3-O-[alpha-L-arabinopyranosyl(1-->2)-beta-D-glucuronopyranosyl]-30-O-[beta-D-glucopyranosyl] 3beta,30-dihydroxyolean-12-en-28-oic acid (2), 3-O-[beta-D-glucuronopyranosyl]-30-O-[alpha-L-arabinopyranosyl(1-->2)-beta-d-glucopyranosyl] 2beta,3beta,30-trihydroxyolean-12-en-28-oic acid (3), 3-O-[beta-D-glucuronopyranosyl]-30-O-[alpha-L-arabinopyranosyl(1-->2)-beta-D-glucopyranosyl] 3beta,30-dihydroxyolean-12-en-28-oic acid (4) and 3-O-[beta-D-glucuronopyranosyl]-30-O-[beta-D-glucopyranosyl] 2beta,3beta,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.
Tava
Aldo
A
CRA-FLC Centro di Ricerca per le Produzioni Foraggere e Lattiero Casearie, Viale Piacenza 29, 26900 Lodi, Italy. aldo.tava@entecra.it
Mella
Mariella
M
Avato
Pinarosa
P
Biazzi
Elisa
E
Pecetti
Luciano
L
Bialy
Zbigniew
Z
Jurzysta
Marian
M
D002851:Chromatography, High Pressure Liquid; D008401:Gas Chromatography-Mass Spectrometry; D009682:Magnetic Resonance Spectroscopy; D029902:Medicago / Q000737:chemistry*; D018515:Plant Leaves / Q000737:chemistry; D012503:Saponins / Q000032:analysis*; D021241:Spectrometry, Mass, Electrospray Ionization; D053719:Tandem Mass Spectrometry; D014315:Triterpenes / Q000032:analysis*
D012503:Saponins; D014315:Triterpenes