Synthesis of Betulin Dibenzoate and Diphthalate

Levdanskii, V. A.; Левданский, А.В.; Кузнецов, Б. Н.

doi:10.1007/s10600-017-1976-5

Cited by 13 publications

(4 citation statements)

References 4 publications

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“…The ester betulin derivatives were synthesized as described in [38–40]. Solutions of 10 mM disodium tetraborate decahydrate with pH 9.18 with the addition of 0–10 mM HP‐β‐CD were used as BGEs.…”

Section: Methodsmentioning

confidence: 99%

Determining binding constants for 1:1 and 1:2 inclusion complexes of ester betulin derivatives with (2‐hydroxypropyl)‐β‐cyclodextrin by affinity capillary electrophoresis

2020

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The complexation of ester betulin derivatives with (2‐hydroxypropyl)‐β‐cyclodextrin (HP‐β‐CD) was studied by mobility shift affinity CE. Electrophoretic mobility for triangular peaks was calculated using the parameter a1 of the Haarhoff–Van der Linde function instead of the peak top time. Dependences of the viscosity corrected electrophoretic mobility on HP‐β‐CD concentration were not described on the basis of only complexes with 1:1 stoichiometry due to the fact that these binding curves did not reach a plateau. However, the dependences were well described taking into account both 1:1 and 1:2 complexes. The presence of higher order equilibria was also revealed by x‐reciprocal plots. The values of apparent binding constant logarithm, obtained for the first time, for 1:1 and 1:2 HP‐β‐CD complexes of betulin 3,28‐diphthalate and betulin 3,28‐disuccinate with 95% confidence interval limits in brackets are the same within error and are equal to 4.85 (4.73–4.95), 8.56 (7.75–8.82), 4.92 (4.86–4.97), and 8.54 (8.23–8.72) at 25°C, respectively. These values for 1:1 and 1:2 HP‐β‐CD complexes of betulin 3,28‐disulfate at 25°C are 4.61 (4.57–4.64) and 7.11 (6.57–7.34), respectively. The binding constants for betulin 3,28‐disulfate agree with the previously obtained results from the separation in the thermostatted capillary segment.

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Section: Methodsmentioning

confidence: 99%

Determining binding constants for 1:1 and 1:2 inclusion complexes of ester betulin derivatives with (2‐hydroxypropyl)‐β‐cyclodextrin by affinity capillary electrophoresis

2020

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“…The ester betulin derivatives were synthesized as described in [13,37]. Stock solutions of the ester betulin derivatives at concentrations of about 0.5-1 g/L were prepared by dissolution of accurate weights in borate or phosphate BGEs or ethanol.…”

Section: Chemicalsmentioning

confidence: 99%

Evaluation of the effect of background electrolyte composition and independence of parameters in determining binding constants of betulin derivatives to β‐ and dimethyl‐β‐cyclodextrins by affinity capillary electrophoresis

Sursyakova

Levdansky

Rubaylo

2022

J of Separation Science

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The values of the apparent binding constants for β-cyclodextrin complexes of betulin derivatives determined by mobility shift affinity capillary electrophoresis were found to be independent of the composition of the two background electrolytes used (tetraborate buffer, pH 9.18, and phosphate buffer, pH 8.00, both of them with 20 mM ionic strength). It has been found that if there is not a constant plateau on the binding curve then four independent parameters can be determined: binding constants (also referred to as stability, association, or formation constants) and ionic mobilities of 1:1 and 1:2 complexes. However, at least 10-12 data points in the binding curve should be used to reliably estimate the parameters. For the first time, the apparent binding constants for complexes of ester betulin derivatives with dimethyl-β-cyclodextrin have been determined by mobility shift affinity capillary electrophoresis. The logarithms of the constants for 1:1 and 1:2 complexes at 25 • C for betulin 3,28-diphthalate with a 95% confidence interval are 4. 98 (4.95-5.01) and 7.52 (7.26-7.68); for betulin 3,28-disulfate, the values are 4.97 (4.89-5.03) and 8.24 (6.82-8.52). It has been found that betulin 3,28-disuccinate forms only a 1:1 complex and the binding constant logarithm is 5.25 ± 0.02.

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“…The ester betulin derivatives were synthesized as described in [31][32][33]. Stock solutions of ester betulin derivatives at concentrations of 1 or 4-5 g/L were prepared by dissolution a According to data from literature [34], tetraborate ions in diluted solutions are fully decomposed by hydrolysis as follows:…”

Section: Chemicals and Calculation Detailsmentioning

confidence: 99%

Electrophoretic mobility of ester betulin derivatives and their complexation with γ‐cyclodextrin studied by capillary electrophoresis in aqueous solutions at different pH values

2021

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In this article, capillary electrophoresis was used to measure the effective electrophoretic mobility of ester betulin derivatives as a pH function and to study their complexation with γ-cyclodextrin (γ-CD). The electrophoretic mobility of betulin 3,28-diphthalate (DPhB) and 3,28-disuccinate (DScB) changed unusually with decreasing pH: instead of decreasing, it first increased and then decreased. This fact as well as the turbidity of sample solutions at pH from 2.5 to 6, broadening of electrophoretic peaks and a decrease in the surface tension of the solutions indicates that these betulin derivatives, being amphiphilic compounds and weak acids, exist as micelles in aqueous solutions at pH 6 and below. The inclusion complexation of betulin derivatives with γ-CD at pH 9.18 and 4.5 was studied by mobility shift affinity capillary electrophoresis. At pH 9.18, the apparent binding (stability) constant logarithms for 1:1 γ-CD complexes of DPhB, betulin 3,28-disulfate (DSB) and DScB with 95% confidence interval limits were equal to 7. 44 ± 0.02, 7.09 (7.01-7.19), and 6.97 (6.87-7.08) at 25°C, respectively. At pH 4.5, the binding constant for the DSB complex was slightly lower, while the micelle formation did not allow determining the exact values of the constants for the DPhB and DScB complexes.

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Synthesis of Betulin Dibenzoate and Diphthalate

Cited by 13 publications

References 4 publications

Determining binding constants for 1:1 and 1:2 inclusion complexes of ester betulin derivatives with (2‐hydroxypropyl)‐β‐cyclodextrin by affinity capillary electrophoresis

Determining binding constants for 1:1 and 1:2 inclusion complexes of ester betulin derivatives with (2‐hydroxypropyl)‐β‐cyclodextrin by affinity capillary electrophoresis

Evaluation of the effect of background electrolyte composition and independence of parameters in determining binding constants of betulin derivatives to β‐ and dimethyl‐β‐cyclodextrins by affinity capillary electrophoresis

Electrophoretic mobility of ester betulin derivatives and their complexation with γ‐cyclodextrin studied by capillary electrophoresis in aqueous solutions at different pH values

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