Flavonol Triglycosides from the Leaves of Silphium Albiflorum

Abstract

In the course of chemotaxonomic studies of the genus Silphium two new and six known flavonol glycosides were isolated from the leaves of S. albiflorum. The structures of the new flavonoids were established by spectral analysis (1 H NMR, 13 C NMR, HMQC, HMBC, ROESY, TOCSY, MS) as isorhamnetin 3-O-α-L-rhamnosyl (1´˝→6˝)-O-β-D-galactopyranoside 7-O-β-Dapiofuranoside (1) and quercetin 3-O-α-L-rhamnosyl (1´˝→6˝)-O-β-D-galactopyranoside 7-O-β-D-apiofuranoside (2). LC-MS and LC-MS n (with post-column manganese complexation) were applied to elucidate the structures of some of the studied compounds.

An investigation of the homolytic saccharide cleavage of deprotonated flavonol 3‐O‐glycosides in a quadrupole ion trap mass spectrometer

“…Kaempferol 3‐ O ‐rutinoside exhibits the lowest amount of radical cleavage of all the 3‐ O ‐glycosides, while kaempferol 3‐ O ‐glucoside and kaempferol 3‐ O ‐galactoside exhibit the highest. (Kaempferol 3‐ O ‐galactoside was not available as a purified standard and therefore, not included in Table 1, but it was noted during an LC‐MS analysis of a Silphium albiflorum extract to behave similar to kaempferol 3‐ O ‐glucoside 17…”

“…These commercial flavonoid glycoside standards were dissolved in methanol at a concentration of 10 µ M and were directly infused into the mass spectrometer with a flow rate of 5 µl/min. Kaempferol 3‐ O ‐galactoside is not commercially available, but was identified as a component in an extract from the Asteraceae plant family 17. The spectra from this compound were taken during the course of LC‐MS experiments.…”

“…In addition, we explore the implications of prominent radical cleavage ions for the identification of the aglycon portion of flavonoid glycosides. In the past we have used MS n of deprotonated flavonoid O ‐glycosides to identify the aglycon portions,14–17 but this is much more difficult in cases where large amounts of homolytic cleavage are observed. Here we document the second‐generation product ions observed from the fragmentation of the initial [Y 0 ] − and [Y 0 − H] −• ions with an emphasis on the potential impediments to structural identification.…”

Absorption, metabolism and excretion of flavanones from single portions of orange fruit and juice and effects of anthropometric variables and contraceptive pill use on flavanone excretion

“…The fragmentation patterns of the [Co(II) (flavonoid glucuronide–H) (4,7-dpphen) 2 ] + complexes are highly indicative of the position of the glucuronic acid moieties, as demonstrated in a recent study ( 29 ) . Similar types of metal complexes have been used recently to identify flavonoid glycosides in various plant extracts ( 30 , 31 ) . Methanol (7·5 ml) was added to 2·5 ml samples of urine for protein precipitation.…”

The Flavonoids and Phenolic Acids of the Genus Silphium and Their Chemosystematic Value

“…Our research group conducted one of the first investigations of flavonoids from Silphium perfoliatum, which resulted in the discovery of two apiose-containing kaempferol triosides and nine known flavonoids [10]. Two additional, novel apiose-containing and six known flavonol glycosides were later isolated from S. albiflorum and were further characterized through LC-MS with postcolumn manganese complexation [25].…”