Cyclodextrins

Abstract

Cyclodextrins (CDs) were first isolated in 1891 as degradation products of starch from a medium of Bacillus amylobacter. They are cyclic water-soluble, nonreducing, macrocycle carbohydrate polymers constructed from (1-4)-linked d-glucopyranose units (naturally occurring, and formed by 6, 7, and 8 glucose units), in a ring formation and present a toroidal, hollow, truncated cone shape. Their most important property is the ability to establish specific interactions molecular encapsulation with various types of molecules through the formation of non-covalently bonded entities, either in the solid phase or in aqueous solution, taking up a whole molecule, or some part of it, into their cavities. This process in part mimics the clock and key mechanism of enzyme catalysis. Complexation may cause changes in physicochemical properties of the guest molecule (e.g., solubility, stability, kinetics and bioavailability, toxicity). Their negligible cytotoxic effects promoted them to the GRAS list and led them to be widely used in many industrial products and technologies.