Chemical composition of shallot (Allium ascalonicum Hort.).
An extensive phytochemical analysis of the polar extracts from bulbs of shallot, Allium ascalonicum Hort., led to the isolation of two new furostanol saponins, named ascalonicoside A1/A2 (1a/1b) and ascalonicoside B (4), respectively, along with compounds 2a and 2b, most likely extraction artifacts. On the basis of 2D NMR and mass spectrometry data, the structures of the novel compounds were elucidated as furost-5(6)-en-3beta,22alpha-diol 1beta-O-beta-D-galactopyranosyl 26-O-[alpha-L-rhamnopyranosyl-(1-->2)-O-beta-D-glucopyranoside] (1a), its epimer at position 22 (1b), and furost-5(6),20(22)-dien-3beta-ol 1beta-O-beta-D-galactopyranosyl 26-O-[alpha-L-rhamnopyranosyl-(1-->2)-O-beta-D-glucopyranoside] (4). This is the first report of furostanol saponins in A. ascalonicum. High concentrations of quercetin, isorhamnetin, and their glycosides were also isolated and described.
Fattorusso
Ernesto
E
Dipartimento di Chimica delle Sostanze Naturali, Università di Napoli Federico II, Via D. Montesano 49, Italy.
Iorizzi
Maria
M
Lanzotti
Virginia
V
Taglialatela-Scafati
Orazio
O
D000490:Allium / Q000737:chemistry*; D044948:Flavonols; D006027:Glycosides / Q000032:analysis; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D015394:Molecular Structure; D010936:Plant Extracts / Q000737:chemistry*; D011794:Quercetin / Q000031:analogs & derivatives* / Q000032:analysis; D012503:Saponins / Q000032:analysis; D016339:Spectrometry, Mass, Fast Atom Bombardment
D044948:Flavonols; D006027:Glycosides; D010936:Plant Extracts; D012503:Saponins; C047368:3-methylquercetin; D011794:Quercetin