Cyclodextrin, also called amylopectin, is a kind of oligosaccharide formed by the action of glucosyltransferase on starch. which is a compound that are formed by cyclic linkage of 6 to 8 molecules of D-glucose using alpha -1 and 4 bonds. Composed by 6 molecule glucose is calledα- cyclodextrin(α-CD), composed by 7 molecule glucose is called β-cyclodextrin (β-CD), and composed by 8 molecule glucose is calledγ- cyclodextrin (γ-CD). There are also composed by 9 to 10 glucose molecules. Cyclodextrin is a crystal, with a cylindrical structure, in the upper part of the cylinder (wide mouth) link –OH, in the bottom of the cylinder (the throat side) connected with a CH2OH base, so, as a whole cyclodextrin molecule is hydrophilic and soluble in water, and accordingly, it is hydrophobic within the cyclodextrin (inside the cylinder). Since it is ring-shaped, it does not have a reducing end. The cyclodextrin has certain stability to the acid, and it is difficult for ordinary amylase to hydrolysis. Various cyclodextrins and iodine color reaction is different. Specific rotation and solubility are not the same. The solubility ofβ- cyclodextrin is the smallest, the most easy to crystallize, and the most easy to separate. Because of its molecular cavity has a cavity, the diameter between 7 ~ 10A °, and the attracting effect of the intermolecular van Edward force can cause some gas, liquid or solid molecules to enter the cavity path to form the inclusion compound. Therefore, when the formation of inclusion compounds with traditional Chinese medicine, it can play a role in improving drug properties, improve drug stability, reduce side effects, increase bioavailability and so on. Such as naoliqing tablets contains a lot of borneol and mint, which are melted into viscous liquid, so that tablets is not qualified. There is no common melting phenomenon after the use of β-CD, so as to make the tablet quality meet the requirements.
Cyclodextrin is also a surfactant, can be used for food, as a stabilizer, can eliminate and cover special smell; improve food tissue structure; reduce and remove the bitter taste; antioxidant; envelope flavor, make it less volatile, the lasting fragrance; envelope edible pigment, make its stability; enhance the foaming effect of protein and so on; can be used for aquatic products, animal products, ice cream, sauces, dairy products. According to the size of the cyclodextrin hole, it can coordinate the cation with the same ionic radius, which can be used as phase transfer catalyst, analytical reagent and medicine. The envelope function of cyclodextrin is also applied to the pesticide, reduce the decomposition of pesticide, improve the efficacy, and used as emulsifier, deodorant and preservative for cosmetics, detergent for washing powder, and has a certain medical effect on acne.