Thermodynamic study of pH and sodium chloride impact on gemcitabine binding to cucurbit[7]uril in aqueous solutions.
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| Title: | Thermodynamic study of pH and sodium chloride impact on gemcitabine binding to cucurbit[7]uril in aqueous solutions. |
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| Authors: | Buczkowski, Adam1 (AUTHOR) adam.buczkowski@chemia.uni.lodz.pl |
| Source: | Journal of Molecular Liquids. Jan2022, Vol. 345, pN.PAG-N.PAG. 1p. |
| Subjects: | Cucurbituril, Salt, Excipients, Aqueous solutions, Gemcitabine, Binding constant |
| Abstract: | [Display omitted] • ITC and ESI MS show the impact of counter-ions on Q[7]-Gem complexation. • Acidification of the solution facilitates binding of Gem to Q[7]. • Increasing NaCl concentration, decreased the binding constant of Gem-Q[7] complex. • Binding enthalpy Gem-Q[7] is less favorable at high NaCl concentration. • Entropic factor confirms hindering effect of the association of Na+ with Q[7]. In solutions of pH < 5, cucurbit[7]uril (Q[7]) spontaneously includes a molecule of the anticancer drug gemcitabine within its cavity, forming a supramolecular complex. The results of ITC calorimetric studies of the gemcitabine cation (Gem) complexation with the Q[7] macrocycle in 20 mM aqueous HCOOH–HCOONa buffer mixtures with pH ranging from 5 to 2, indicate that the acidification of the solution facilitates binding of the drug by cucurbit[7]uril. In mixtures with a fixed pH = 4 and an increasing concentration of sodium chloride (10–4000 mM), the binding constant of Gem by Q[7] decreases rapidly, as is the absolute value of the binding enthalpy. This phenomenon illustrates the hindering effect of the association of sodium cations with Q[7] portals on gemcitabine binding, which is confirmed by ESI MS measurements. However, gemcitabine is still efficiently bound by cucurbit[7]uril (l o g K ≥ 3) in aqueous 10 – 250 mM sodium chloride solutions. The Q[7] macrocycle may therefore be used as a stabilizing agent for this drug in pharmaceutical formulations. [ABSTRACT FROM AUTHOR] |
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| Database: | Engineering Source |
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