to be more efficient than β-cyclodextrin. The water-soluble MβCD is known to form soluble inclusion complexes with cholesterol, thereby enhancing its solubility in aqueous solution. MβCD is employed for the preparation of cholesterol-free products: the bulky and hydrophobic cholesterol molecule is easily lodged inside cyclodextrin rings. MβCD is also employed in research to disrupt lipid rafts by removing cholesterol from membranes. Due to the covalent attachment of thiol groups to cyclodextrins high mucoadhesive properties can be introduced as these thiolated oligomers (thiomers) are capable of forming disulfide bonds with cysteine-rich subdomains of mucus glycoproteins. The gastrointestinal and ocular residence time of thiolated cyclodextrins is therefore substantially prolonged. Research In supramolecular chemistry, cyclodextrins are precursors to mechanically interlocked molecular architectures, such as rotaxanes and catenanes. Illustrative, α-cyclodextrin form second-sphere coordination complex with tetrabromoaurate anion ([AuBr4]-). β-Cyclodextrin complexes with certain carotenoid food colorants have been shown to intensify color, increase water solubility and improve light stability. Complexes formed between β-cyclodextrin and adamantane derivatives have been used to make self-healing materials, such as hydrogels and low-friction surfaces. History Cyclodextrins, as they are known today, were called "cellulosine" when first described by A. Villiers in 1891. Soon after, F. Schardinger identified the three naturally occurring cyclodextrins -α, -β, and -γ. These compounds were therefore referred to as "Schardinger sugars". For 25 years, between 1911 and 1935, Hans Pringsheim in Germany was the leading researcher in this area, demonstrating that cyclodextrins formed stable aqueous complexes with many other chemicals. By the mid-1970s, each of the natural cyclodextrins had been structurally and chemically characterized and many more complexes had been studied. Since the 1970s, extensive work has been conducted by Szejtli and others exploring encapsulation by cyclodextrins and their derivatives for industrial and pharmacologic applications. Among the processes used for complexation, the kneading process seems to be one of the best. Safety Cyclodextrins are of wide interest in part because they appear nontoxic in animal studies. The LD50 (oral, rats) is on the order of grams per kilogram. Nevertheless, attempts to use β-Cyclodextrin for the prevention of atherosclerosis, age-related lipofuscin accumulation and obesity encounter an obstacle in the form of damage to the auditory nerve and nephrotoxic effect. References Oligosaccharides Starch Macrocycles Chelating agents E-number additives