Physical And Chemical Properties

Cavity size
Table shows the dimensions of the alpha, beta and gamma Cyclodextrins. Dimensions, in Angstroms, of the Cyclodextrins.

The more interaction that occurs between the walls of the Cyclodextrin and the guest molecule, the stronger is the binding.

Solubility of Cyclodextrins
This fundamental characteristic derives from the location of all free hydroxyl groups of each successive glucose unit on rims of this donut shape molecules.

Thermal stability
Peaks of differential Scanning Calorimetry shows that Cyclodextrins are heat stable.

Hygroscopicity
Cyclodextrins are not hygroscopic and remain a dry pourable powder at the equilibrium moisture (10 – 14 % water ) .

Chemical stability
Cyclodextrins undergo acid hydrolysis with strong acids such as hydrochloric or sulfuric acid. Weak acids, such as organic acids, do not hydrolyze cyclodextrins. However, hydrolysis with citric acid has been observed in case of beta Cyclodextrin. Bases do not hydrolyze Cyclodextrins.

Enzymatic stability
Cyclodextrins are hydrolyzed by Cyclodextrin glucosyltransferase. Glucoamylases and beta amylases do not hydrolyze cyclodextrins. Many alpha amylases will hydrolyze Cyclodextrins

Toxicology and metabolism
Alpha and beta Cyclodextrin are resistant to salivary and pancreatic amylases. As a result, they pass through the digestive system to the colon intact. Various other toxicological tests including dermal irritation, ocular irritation, inhalation, mutagenicity, Ames test, chromosomal aberration, and teratology have shown no adverse effects of b-Cyclodextrin. While GRAS petitions for use of b-Cyclodextrin are still pending at the Food and Drug Administration in the United States, it is already approved as an food additive in countries including West Germany, France, Japan, China, Hungary, Netherlands, Luxembourg, Belgium and Spain. Cyclodextrins are non-reducing.