(2-羟丙基)-β-环糊精

描述

环糊精是由6、7或8个吡喃葡萄糖单元组成的环状低聚糖，通常分别称为α-、β-或γ-环糊精。这些化合物具有刚性环形结构，使其成为天然的络合剂。这些化合物的相邻吡喃葡萄糖单元的C2-和C3-羟基之间易于形成分子内氢键，使其独特结构具有稳定性。该分子具有圆环形状，其C2-和C3-羟基位于较大开口端周围，反应性更强的C6-羟基排列在较小开口端周围。与氢键合C2-和C3-羟基相对的C6-羟基排列迫使氧键在空腔内紧密靠近，产生一个富电子的疏水内部。该疏水性空腔的大小是形成环糊精的吡喃葡萄糖单元数

应用

由于 HBC 和药物形成络合物，因此在水溶液中亲脂性药物的溶解度随着羟丙基-β-环糊精 (HBC) 的浓度线性增加。该客体-主体型络合物形成于药物和 HBC 的非极性腔之间，可引起增溶溶解。溶液可冻干生成易溶的粉末。对兔和小鼠无毒。

适用性

原理

制备说明

溶液可在4°C下储存数月。固体应在室温下密封保存。

外形

Description

Cyclodextrins are cyclic oligosaccharides consisting of 6, 7, or 8 glucopyranose units, usually referred to as α-, β-, or γ-cyclodextrins, respectively. These compounds have rigid doughnut-shaped structures making them natural complexing agents. The unique structures of these compounds owe their stability to intramolecular hydrogen bonding between the C2- and C3-hydroxyl groups of neighboring glucopyranose units. The molecule takes on the shape of a torus with the C2- and C3-hydroxyls located around the larger opening and the more reactive C6-hydroxyl aligned around the smaller opening. The arrangement of C6-hydroxyls opposite the hydrogen bonded C2- and C3-hydroxyls forces the oxygen bonds into close proximity within the cavity, leading to an electron rich, hydrophobic interior. The size of this hydrophobic cavity is a function of the number of glucopyranose units forming the cyclodextrin.The solubility of natural cyclodextrins is very poor. In the late 1960′s, it was discovered that chemical substitutions at the 2, 3, and 6 hydroxyl sites would greatly increase solubility. Most chemically modified cyclodextrins are able to achieve a 50% (w/v) concentration in water.Cavity size is the major determinant as to which cyclodextrin is used in complexation. The cavity diameter of β-cyclodextrins or β-glucopyranose unit compounds is well-suited for use with molecules the size of hormones, vitamins and many compounds frequently used in tissue and cell culture applications. For this reason, β-cyclodextrin is most commonly used as a complexing agent.The solubility of lipophilic drugs increases linearly with the concentration of hydroxypropyl-β-cyclodextrin (HBC) in aqueous solution because of the complex between HBC and the drug. This guest-host type complex is formed between the drug and the non-polar cavity in the HBC that results in enhanced solubility. Solutions may be lyophilized to produce freely soluble powders. Non-toxic in rabbits and mice.