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.

中文翻译：

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亲和毛细管电泳法测定桦木醇酯衍生物与（2-羟丙基）-β-环糊精的 1:1 和 1:2 包合物的结合常数

通过迁移率迁移亲和 CE 研究了酯桦木脑衍生物与（2-羟丙基）-β-环糊精（HP-β-CD）的络合。三角峰的电泳迁移率是使用Haarhoff-Van der Linde 函数的参数a ₁而不是峰顶时间来计算的。由于这些结合曲线没有达到平台期，因此没有根据仅具有 1:1 化学计量的复合物描述粘度校正的电泳迁移率对 HP-β-CD 浓度的依赖性。然而，考虑到 1:1 和 1:2 复合物，这些依赖性得到了很好的描述。x也揭示了高阶均衡的存在- 互惠图。首次获得的 1:1 和 1:2 HP-β-CD 复合物 3,28-二邻苯二甲酸桦木酯和 3,28-二琥珀酸桦木酯的表观结合常数对数值，括号内为 95% 置信区间限制在误差范围内相同，在 25°C 时分别等于 4.85 (4.73–4.95)、8.56 (7.75–8.82)、4.92 (4.86–4.97) 和 8.54 (8.23–8.72)。25°C 下桦木脑 3,28-二硫酸盐的 1:1 和 1:2 HP-β-CD 复合物的这些值分别为 4.61 (4.57–4.64) 和 7.11 (6.57–7.34)。桦木醇 3,28-二硫酸盐的结合常数与先前在恒温毛细管段中分离得到的结果一致。