Differentiation between isomeric acacetin‐6‐C‐(6″‐O‐malonyl)glucoside and acacetin‐8‐C‐(6″‐O‐malonyl)glucoside by using low‐energy CID mass spectra

Abstract

Differentiation between isomeric acacetin-6-C-(6 -O-malonyl)glucoside and acacetin-8-C-(6 -O-malonyl)glucoside by using low-energy CID mass spectra Flavonoid conjugates constitute a very diversified group of plant secondary metabolites. These compounds reveal various type of biological activity. 1,2 Mass spectrometric techniques have been successfully used for the structural elucidation of flavonoid C-glycosides for more than 25 years. First, the flavonoid C-glycosides were analysed as permethyl ethers using electron ionization. 3 -5 The use of so-called 'soft' ionization techniques allows the analysis of underivatized compounds. 6,7 Fragmentation pathways of protonated and/or deprotonated molecules of C-glycosidic flavonoids obtained with collision-induced dissociation (CID) tandem mass spectrometric (MS/MS) techniques enabled important structural information to be obtained about different substitution patterns of sugars in this class of compounds. 8 -12 Acylation of the sugar moiety in the molecules of C-and O-flavonoid glycosides is a common modification occurring in plant cells. Mass spectrometric techniques have also been applied to the analysis of this kind of flavonoid conjugates. Substitutions of aliphatic and aromatic acids in both C-and O-glycosides were reported. Acyl-C-glucosyl flavonoids esterified with sinapic, ferulic and p-coumaric acids, and less often with acetic acid, have already been isolated as pure compounds from the plant material (Cucumis

Glucose–sulfate conjugates as a new phase II metabolite formed by aquatic crustaceans

“…The fragment with m/z 97 was considered to be the sulfate moiety. On the other hand, those at m/z 259 and m/z 289 were considered to be the common fragments of glycoconjugates [18,19]. Our results of LC/ESI-MS/MS analysis and deconjugation indicated that peak-f was the glucose-sulfate conjugate of 1-hydroxypyrene.…”

“…On the other hand, Stroomberg et al [18] determined the structure of a conjugation metabolite of pyrene formed by isopods (Porcellio scaber) and collembolans (Folsomia candida) as pyrene-1-O-(6"-O-malonyl)-glucoside, which is the first reported conjugate formed by animals. On the other hand, malonyl-glycosides are well-known conjugation products formed by plants [19][20][21][22][23][24]. Glucose conjugates formed by various plants are often further conjugated by malonic acid or pentosyl units of hemicellulose, such as apiose or xylose, and form glucose-malonate or glucose-pentosyls [19][20][21][22][23][24].…”

“…On the other hand, malonyl-glycosides are well-known conjugation products formed by plants [19][20][21][22][23][24]. Glucose conjugates formed by various plants are often further conjugated by malonic acid or pentosyl units of hemicellulose, such as apiose or xylose, and form glucose-malonate or glucose-pentosyls [19][20][21][22][23][24]. Day and Saunders [23] demonstrated roles of these additional conjugation processes as signals of sequestration of phase-2 metabolites in the plant cell (phase-3 processes for plants).…”

New features on the fragmentation and differentiation of C‐glycosidic flavone isomers by positive electrospray ionization and triple quadrupole mass spectrometry

“…C-8)-apigenin. 20,21 Also, the success of proposed rules to differentiate C-isomers is relatively limited to the particular type of instrument and experimental conditions of the spectra used to generate those guidelines. So it is advisable to obtain ones own rules and guidelines in other types of instruments.…”

Effect of Aquilegia vulgaris (L.) ethyl ether extract on liver antioxidant defense system in rats

“…We have isolated and identified several flavonoids [6][7][8][9] and phenolic acids [10,11] in the aerial parts of the plant as well as alkaloids in roots [12]. The predominant compound was 4'-methoxy-5,7-dihydroxyflavone 6-C-glucopyranoside (isocytisoside) [6].…”