Chemical Composition of Shallot (Allium ascalonicum Hort.)

Abstract

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.

Comparative Study on Phytochemical Variations in Japanese F₁ Varieties of Bulb Onions and South-East Asian Shallot Landraces

“…Differences in latitude may account for the differences in day length, light quality, UV radiation, and temperature. However, in agreement with the results of this research, it has been reported that shallots produce higher levels of flavonoids than bulb onions (Fattorusso et al, 2002;Leighton et al, 1992). In fact, shallots from Indonesia, which were cultivated near the equator and exposed to high UV radiation, produced the highest levels of flavonoids.…”

Characterization of the fraction components using 1D TOCSY and 1D ROESY experiments. Four new spirostane saponins from Agave brittoniana Trel. spp. Brachypus

“…The axial-axial couplings H-3/H-4 and H-4/H-5, and the axialequatorial relationship between H-2 and H-3 as the resonances of C-3 and C-5 led to the determination of a L-rhamnose unit with -configuration. 11,12 The nature of the sugar moiety for both the compounds was deduced from the 1D ROESY and HMBC spectra, in which two sequences could be observed. The proposed sequences are confirmed after obtaining the 1 H NMR of minor aliquots from the chromatographic process with different intensities of anomeric signals.…”

New furostanol saponins from Allium ascalonicum L.

“…3 -7 With regard to the saponin constituents of the Allium ascalonicum L., some steroidal saponins have been reported. 8 Further phytochemical analysis of the A. ascalonicum L. with attention to the steroidal glycoside constituents led to the isolation of two new furostanol saponins and two known furostanol saponins, dichotomin 9 and parisaponin I. 10 This paper reports the isolation and structural determination of two new furostanol saponins, compounds 1 and 2 ( Fig.…”