Cooperative binding and stabilization of the medicinal pigment curcumin by diamide linked γ-cyclodextrin dimers: A spectroscopic characterization

Takaaki Harada, Duc Truc Pham, Mandy H.M. Leung, Huy Tien Ngo, Stephen F. Lincoln, Christopher J. Easton, Tak W. Kee

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    71 Citations (Scopus)

    Abstract

    Diamide linked γ-cyclodextrin (γ-CD) dimers are used to capture curcumin and suppress its decomposition in water. In this study, succinamide and urea linked γ-CD dimers joined through the C6A carbon on each γ-CD are used. The γ-CD dimers, 66γCD2su and 66γCD2ur, show a remarkable ability to suppress the decomposition of curcumin and extend its half-life from less than 30 min to greater than 16 h. The 1:1 association of curcumin with 66γCD 2su and 66γCD2ur has high stability constants of 8.7 × 106 M-1 and 2.0 × 106 M -1, respectively. In addition, 2D 1H NOESY NMR results show specific hydrogen interactions in the association of curcumin with 66γCD2su and 66γCD2ur, consistent with the cooperative binding of curcumin by both γ-CD annuli of 66γCD 2su and 66γCD2ur. The interactions between curcumin in the linked γ-CD dimers and surfactant micelles were studied using fluorescence spectroscopy. While linked γ-CD dimer-bound curcumin has a negligible fluorescence quantum yield, a significant increase in fluorescence intensity (Φfl > 2%) in the presence of micelles suggests that curcumin is delivered to the micelle. The overall results indicate that the diamide linked γ-CD dimers are highly promising systems for curcumin delivery in vivo due to effective curcumin stabilization.

    Original languageEnglish
    Pages (from-to)1268-1274
    Number of pages7
    JournalJournal of Physical Chemistry B
    Volume115
    Issue number5
    DOIs
    Publication statusPublished - 10 Feb 2011

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