Quercetin displacement caused by sodium dodecyl sulphate on inclusion complex quercetin-beta cyclodextrin in an acid environment

The global formation constants of two inclusion complexes formed from quercetin (QH5) and beta-cyclodextrin (beta CD) in ClO4-0.1 M pH 4.7 were calculated with the support of Stability Quotients from Absorbance Data (SQUAD), in addition, the effect of sodium dodecyl sulphate (SDS) on these complexes was studied. The molar ratios of the inclusion complexes formed QH5-beta CD were 1:1 and 1:2 with log beta values of 2.06 +/- 0.22 and 3.69 +/- 0.13 M-1 respectively. With measurements of surface tension and fluorescence, the critical micellar concen-tration (CMC) value of the SDS was calculated in the absence and presence of beta CD resulting in an increase with the concentration of beta CD, as a consequence of the formation of an inclusion complex beta CD-SDS with log K of 3.589 +/- 0.059 M-1. From the fluorescence results, the breakdown of the complex Q-beta CD is inferred due to the interaction with the SDS causing its inclusion in the beta CD cavity and displacement of the QH5. Finally, with the UV-vis spectrophotometric data it is shown that the formation of a ternary complex does not take place, as stated in some studies.

Automated summary

In this study, the global formation constants of two inclusion complexes formed by quercetin (QH5) and beta-cyclodextrin (beta CD) were calculated using SQUAD. The effect of sodium dodecyl sulphate (SDS) on these complexes was also investigated. The results showed the formation of 1:1 and 1:2 molar ratio inclusion complexes with log beta values of 2.06 +/- 0.22 and 3.69 +/- 0.13 M-1, respectively. The presence of beta CD increased the critical micellar concentration (CMC) of SDS, indicating the formation of an inclusion complex beta CD-SDS. The fluorescence results suggested the breakdown of the Q-beta CD complex due to interaction with SDS.