Binding of the five multistate species of the anthocyanin analog 7-β-D-glucopyranosyloxy-4′-hydroxyflavylium to the β-cyclodextrin derivative captisol

Johan Mendoza, Nuno Basílio, Olivier Dangles, Nathalie Mora, Sheiraz Al Bittar, Fernando Pina

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)

Abstract

The host-guest chemistry of the anthocyanin analog 7-β-D-glucopyranosyloxy-4′-hydroxyflavylium (GHF) was studied in the presence of the β-cyclodextrin derivative captisol by stopped flow, UV–visible spectroscopy, flash photolysis, circular dichroism and isothermal titration calorimetry. The equilibrium and rate constants of the multistate of chemical species derived from the flavylium ion were calculated and compared with those in the absence of the host. A new procedure to obtain the host-guest association constants of the multistate (including the transient species) by superimposing the two energy level diagrams, in the presence and absence of the cyclodextrin, was developed. The results indicate that the magnitude of the association constants follows the order, trans-chalcone ≈ cis-chalcone ≈ hemiketal > quinoidal base > flavylium cation. The hydration equilibrium constant increases ca. 42 times in the presence of captisol as the hydration and dehydration rate constants respectively increases and decreases. The other equilibrium constants are modestly affected: the rate constants of ring closure and opening are significantly decreased in the complex and the isomerization rate constants increase in both directions. The quantum yield of the photochromic system in the presence of captisol is 0.3, i.e. 3 times higher than in the absence of the host.

Original languageEnglish
Pages (from-to)479-487
Number of pages9
JournalDyes and Pigments
Volume143
DOIs
Publication statusPublished - 1 Aug 2017

Keywords

  • Anthocyanin
  • Cyclodextrin
  • Flavylium
  • Host-guest
  • Multistate

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