(2-Hydroxypropyl)-beta-cyclodextrin

General description.
Cyclodextrin is a cyclic oligosaccharide composed of 6, 7 or 8 glucopyranose units, usually called α -, β -, or γ-cyclodextrin, respectively. These compounds have a rigid ring structure, making them natural complexing agents. The stability of the unique structures of these compounds is due to the intramolecular hydrogen bonds between the C2-and C3-hydroxyl groups of the adjacent glucopyranose units. The molecule is ring-shaped, in which C2-and C3-hydroxyl groups are located around the larger opening, while the more reactive C6-hydroxyl group is arranged around the smaller opening. The relative arrangement of C6-hydroxyl and hydrogen-bonded C2-and C3-hydroxyl groups forces the oxygen cavity to be bonded to the adjacent position, resulting in an electron-rich hydrophobic interior. The size of the hydrophobic cavity is a function of the number of glucopyranose units forming cyclodextrins. Natural cyclodextrins have very low solubility. In the late 1960s, it was found that the chemical substitution at hydroxyl sites No. 3 and 6 could greatly improve the solubility. Most chemically modified cyclodextrins can reach a concentration of 50% (w / w) in water. The size of the cavity is the main determinant of which kind of cyclodextrin is used for complexation. The cavity diameters of β-cyclodextrin or β-glucopyranose unit compounds are very suitable for hormones, vitamins and many compound-sized molecules commonly used in tissue and cell culture applications. For this reason, β-cyclodextrin is the most commonly used complexing agent.

Application.
Because HBC forms a complex with the drug, the solubility of lipophilic drugs in aqueous solution increases linearly with the concentration of hydroxypropyl-β-cyclodextrin (HBC). The guest-host complex is formed between the drug and the non-polar cavity of HBC, which can cause solubilization. The solution can be freeze-dried to form a soluble powder. It is not toxic to rabbits and mice.

(2-hydroxypropyl)-β-cyclodextrin has been used to explore its effect on cholesterol homeostasis; ignition process and hippocampal electrogram analysis in mice; and improvement of adverse pre-pulse suppression (PPI) in mice.