Estimation of cyclodextrin affinity to steroids

Abstract

A nonlinear spectrometric method for determination of the stability constant (Ks) for cyclodextrin complex with steroid was developed. The method is based on calculation of the parameters of competitive cyclodextrin complexation by simultaneous fitting of two types of curves. Those of the first type are the dependencies of absorbance of methyl orange solution on the cyclodextrin concentration, the second type being the absorption curves of displacement of the dye, by steroid, from the cyclodextrin complex. With the method proposed, Ks values were calculated with standard deviation less than 10%. This method is validated by determination of Ks values using the phase-solubility technique. For neutral steroid molecules, the effect of pH on Ks was found to be insignificant. Ks values for the cyclodextrin-dye complex were determined for randomly methylated beta-cyclodextrin, 2-hydroxypropyl-beta-cyclodextrin, carboxymethyl-beta-cyclodextrin and sulfobutylether-beta-cyclodextrin. More hydrophobic steroids were characterised by higher Ks values. Anionic beta-cyclodextrins showed high affinity for the steroids studied. Simple equipment and sufficient computing allowed recommendation of the method for express estimation of cyclodextrin's affinity for hydrophobic substrates.

Methyl-β-cyclodextrin alters growth, activity and cell envelope features of sterol-transforming mycobacteria

“…Sterol oxidation products [i.e. AD(D)] can cross the CW by the similar reverse pathway and, once outside the cells, can interact with MCD, forming soluble inclusion complexes (Khomutov et al, 2002). Natural or chemically modified CDs can interact with cells by means of their complexing ability and/or their surface activity.…”

Inclusion of chrysin in β-cyclodextrin nanocavity and its effect on antioxidant potential of chrysin: A spectroscopic and molecular modeling approach

“…It is a typical toroid with hydrophilic outer surface and a hydrophobic central cavity. Cyclodextrins (CDs) have been used extensively as additives to increase the solubility of poorly water-soluble organic compounds, by the formation of an inclusion complex between the host cyclodextrin molecule and the guest molecule [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34]. Such noncovalent associations can actually improve the guest's water solubility, bioavailability, stability and can regulate their release as well.…”

Laccase‐mediated oxidation of steroid alcohols in the presence of methylated β‐cyclodextrin: from inhibition to selective synthesis

“…For determination of stability constant (K) of the host-guest complex of mCD with steroids, the nonlinear spectrometric method was used as described earlier. 37 Parameters of competitive mCD complexation were calculated by simultaneous fitting of two types of curves. Those of the first type were the dependencies of absorbance of methyl orange (MetOr) solution on mCD concentration.…”