Characterization of Flavonoid Subgroups and Hydroxy Substitution by HPLC-MS/MS

Abstract

HPLC-DAD coupled with mass spectrometry in the positive ionization mode was applied to study the fragmentation of twelve selected flavonoids. Compounds belonging to all the major subgroups found in common plants, i.e. flavonols, flavones, dihydroflavonols, flavanones and flavanols were studied. Compound standards were injected into the spectrometer and produced characteristic mass spectra. The fragmentation of each compound was studied and it was shown that the dehydration and carbon monoxide losses from the [M+H] + ion by the members of each subgroup produced specific fragments, thus allowing the characterization of the flavonoid subgroups. Moreover, fragments resulting from fission of the C-rings are specific of each subgroup and revealed the substitution pattern of A-and B-rings. In order to verify the identifying efficiency of the positive ionization mode through these characteristic fragmentations, the unknown flavonoids of an Origanum vulgare diethyl ether extract were separated with the HPLC system and the major peaks were successfully identified with the mass spectrometer.

Strategies for differentiation of isobaric flavonoids using liquid chromatography coupled to electrospray ionization mass spectrometry

“…The MRM transitions monitored with method 1 which are listed in Table 1 were chosen to match losses and fragmentations of free aglycones, based on m/z values observed upon fragmentation of standards combined with literature values reported by others. [24,25] MS/MS spectra, with monitored m/z values, of the free aglycones and their corresponding structure are shown in Figure S1 and Figure 2 respectively. The flavonoids in Table 1 are grouped based on nominal mass of the positive ion, starting with m/z 271 followed by 287, 291, 301, 303, 317 and 331.…”

Isolation and Characterization of Flavones from Artemisia monosperma

“…The antioxidant activity of flavonoids is related to their structure especially the hydroxy substitution of the aromatic A and B rings and the substitution pattern of the C-ring. 34 We report the isolation and characterization of nine flavones from the methanolic extract of A. monosperma; four of which are reported for the first time from this plant. The five previously reported flavones from Artemisia monosperma are eupatilin, 17 circimaritin, cirsilineol, jaceosidin and hispidulin.…”

“…20 The data of 1 H-NMR, UV and mass obtained for the different flavones match those reported in the literature. 20,[34][35][36][37][38][39][40][41] The two acetophenone derivatives are of importance because of the potential of their anti -oxidative and anti-inflammatory effects of acetophenones. …”

Antiulcer activity of the chloroform extract ofBauhinia purpurealeaf

“…Our HPLC profiling of CEBP also supported the presence of flavonoid-types of compounds wherein two of the major peaks (peak 5 and peak 6) detected at 330 nm in the chromatogram were found to have UV spectra of 324 nm and 296-343 nm, respectively. According to Tsimogiannis et al (2007) flavonoids can be divided into five major subgroups (e.g., flavonols, flavones, dihydroflavonols, flavanonols and flavanones), whereby the UV-Vis spectra of flavonoids falls within two absorbance bands, labelled as Band A and Band B. Band A, which represents flavones or flavonols, lies in the range of 310-350 nm or 350-385, respectively, while Band B, which falls between 250 and 290 nm, is much the same in all the aforementioned flavonoid subgroups.…”