Cyclodextrin
Introduction
Cyclodextrins are a group of compounds made from sugar molecules bound together in a ring (cyclic oligosaccharides). They are produced from starch by means of enzymatic conversion. They are used in food, pharmaceutical, drug delivery, and chemical industries, as well as agriculture and environmental engineering.
Structure and Properties
Cyclodextrins are composed of 5 or more D-glucopyranose units linked 1->4, as in amylose (a fragment of starch). The largest cyclodextrin contains 32 1,4-anhydroglucopyranoside units, while as a poorly characterized mixture, at least 150-membered cyclic oligosaccharides are also known. Typical cyclodextrins contain a number of glucose monomers ranging from six to eight units in a ring, creating a cone shape:
- α-Cyclodextrin: 6 glucose units - β-Cyclodextrin: 7 glucose units - γ-Cyclodextrin: 8 glucose units
The interior cavity of cyclodextrin is hydrophobic, allowing the "host" to form inclusion compounds with various "guest" molecules. This feature allows cyclodextrins to form complexes with hydrophobic compounds such as lipids, cholesterol, and various types of drugs, leading to various applications in food, pharmaceutical and chemical industries.
Production
Cyclodextrins are produced from starch by enzymatic conversion. They can be obtained from various sources of starch, including potatoes, corn, and wheat. The enzymatic process involves the use of a transferase enzyme, which breaks the starch molecule and rearranges it to form the cyclic structure of cyclodextrin.
Applications
Cyclodextrins have been used in a host of FDA-approved and marketed products. They can be found in a variety of applications, from food and pharmaceuticals to environmental engineering.
Food Industry
In the food industry, cyclodextrins are primarily used to improve the solubility and stability of flavoring agents. They can also be used to remove cholesterol from dairy products and to increase the bioavailability of vitamins.
Pharmaceutical Industry
In the pharmaceutical industry, cyclodextrins have been used to improve the solubility and bioavailability of drugs. They can also be used to stabilize drugs, improve the taste of bitter drugs, and to control drug release. Cyclodextrins can also be used in nasal and ocular drug delivery.
Environmental Engineering
In environmental engineering, cyclodextrins are used to enhance the bioremediation of hydrophobic pollutants. They can form complexes with pollutants, enhancing their solubility and thus their availability for microbial degradation.
Safety and Toxicity
Cyclodextrins are generally considered safe for use in food and pharmaceuticals. However, they can cause gastrointestinal upset if consumed in large amounts. They are not absorbed from the gastrointestinal tract and are therefore not systemically available.