Characterization of non‐covalent complexes of rutin with cyclodextrins by electrospray ionization tandem mass spectrometry

Abstract

Electrospray ionization tandem mass spectrometry (ESI-MS(n)) and the phase solubility method were used to characterize the gas-phase and solution-phase non-covalent complexes between rutin (R) and alpha-, beta- and gamma-cyclodextrins (CDs). The direct correlation between mass spectrometric results and solution-phase behavior is thus revealed. The order of the 1 : 1 association constants (K(c)) of the complexes between R and the three CDs in solution calculated from solubility diagrams is in good agreement with the order of their relative peak intensities and relative collision-induced dissociation (CID) energies of the complexes under the same ESI-MS(n) condition in both the positive and negative ion modes. Not only the binding stoichiometry but also the relative stabilities and even binding sites of the CD-R complexes can be elucidated by ESI-MS(n). The diagnostic fragmentation of CD-R complexes, with a significant contribution of covalent fragmentation of rutin leaving the quercetin (Q) moiety attached to the CDs, provides convincing evidence for the formation of inclusion complexes between R and CDs. The diagnostic fragment ions can be partly confirmed by the complexes between Q and CDs. The gas-phase stability order of the deprotonated CD-R complexes is beta-CD-R > alpha-CD-R > gamma-CD/R; beta-CD seems to bind R more strongly than the other CDs.

Mass spectrometric decompositions of cationized β-cyclodextrin

“…[18][19][20][21][22][23] Many papers were also devoted to the mass spectrometry of cyclodextrin complexes with organic compounds. [24][25][26][27][28][29][30][31][32][33][34] However, to the best of our knowledge, the mass spectrometric fragmentation pathways of cyclodextrins cationized by divalent metals have not been reported yet. Recently, Kurokawa et al have obtained a b-cyclodextrin-CuCl 2 complex in condensed phase.…”

Mass spectrometric investigations of α‐ and β‐cyclodextrin complexes with ortho‐, meta‐ and para‐coumaric acids by negative mode electrospray ionization

“…Mass spectrometry plays an increasingly important role as a probe of size, composition and structure of non‐covalent bonding and inclusion complexes, and as a quantitative detector of components of host, guest and non‐covalently bound complexes in solution 7. Negative ion electrospray ionization mass spectrometry (ESI‐MS) has been used intensively to investigate non‐covalent complexes including complexes between CDs and various acidic organic compounds such as sulfonated azo dyestuffs and organic carboxylic acids 8–11, 13, 14. Some studies have reported the consistency of structures of complexes in solutions and in gas‐phase ionic forms,8–11 while Cunniff and Vouros report that β ‐CD‐amino acid (aryl‐ and alkyl‐substituted) complex ions detected by positive ion ESI‐MS are electrostatic adducts and not proper inclusion complexes 12.…”

Investigation of heptakis(2,6‐di‐O‐methyl)‐β‐cyclodextrin inclusion complexes with flavonoid glycosides by electrospray ionization mass spectrometry

“…This paper continues our work on the detection and analysis of non‐covalent complexes of CDs with active components from Traditional Chinese Medicine (TCM) by means of ESI‐MS 16–18. Previous work17 has demonstrated the formation of the non‐covalent complexes between rutin and native CDs and characterized them in the gas phase by tandem mass spectrometry (MS/MS). In this study, ESI‐MS was employed to study inclusion complexes of DM‐ β ‐CD with the three quercetin O ‐glycosides (quercitrin (Qr), hyperoside (Hr) and rutin (R)) shown in Scheme .…”