Draft:Cyclodextran

Cyclodextran, also known as cyclic isomaltooligosaccharide (CI), is a non-reducing sugar derived from dextran. It is characterized by its cyclized structure and composition of alpha-1,6 bonds.

Comparison with cyclodextrin
Although CI shares the common constituent of glucose, its linkage pattern is distinct from that of another cyclic oligosaccharide, cyclodextrin (CD), which consists of alpha-1,4 bonds. The structures of 11 types of CIs, with glucose units ranging from seven to seventeen, have been determined. CI-10, in particular, has strong inclusion complex-forming ability. Four Bacillus strains and two Paenibacillus strains were identified as novel CI-producing bacteria. These strains mainly produced CI-10 to CI-12, but larger CIs up to CI-17 were also identified. While CIs with high molecular weights, incorporating more than eighteen glucose units, also exist, research predominantly focuses on CIs with seven to twelve glucose units (CI-7 to CI-12) due to their higher prevalence and relative ease of purification.

Initial discovery
CI was first discovered in 1993. In a liquid culture using dextran as a carbon source, the researchers noticed that a strain of bacteria isolated from soil produced and accumulated a substance different from linear isomaltooligosaccharides.

Natural occurrence
This substance, which was revealed to have a structure where 7 to 9 glucose molecules were connected in a circular fashion via alpha-1,6 bonds, was named cyclodextran. Given that dextran and isomaltooligosaccharides are naturally occurring, it was speculated that CI might also be a natural product. A trace amount of CI from CI-7 to CI-9 was confirmed when attempts were made to detect CI from brown sugar.

Industrial production
Two methods are used to produce CI: one uses sucrose as a raw material to produce and cyclize dextran, and the other involves production from starch. Commercially, sucrose is the preferred raw material. CI is produced by applying the enzyme CITase to this dextran. A product known as CI-Dextran mix, containing at least 13% CI by weight, is manufactured exclusively by Nissin Sugar Co., Ltd. This product is known for its ability to inhibit dental plaque formation. Additionally, research has shown that Paenibacillus sp. 598K produces cycloisomaltooligosaccharides (cyclodextrans:CIs) from starch even in the absence of dextran.

Inhibition of Glucosyltransferase (GTF)
CI specifically inhibits the activity of glucosyltransferase (GTF), a key enzyme in Streptococcus mutans, thereby suppressing the formation of glucan, a major component of dental plaque.

Mechanism of action
The inhibition mechanism of GTF is presumed to be competitive inhibition where CI binds to the active site of GTF, but the detailed inhibition mechanism remains a subject for future research.

Solubility enhancement
CI enhances the solubility of some difficult-to-dissolve substances. Research has shown that CI can form inclusion complexes with various hydrophobic compounds, enhancing their solubility and stability.

Chemical properties
One notable characteristic of CI is its lack of sweetness, indicating that it does not function as a sweetener. Due to its cyclic structure, CI has no terminal groups, and as a result, it does not exhibit reducing properties. CI is a sugar with strong stability against heat, acid, and alkali due to its cyclic structure. CI has high solubility in water and can dissolve in an equivalent or smaller amount of water.

Prevention of dental diseases
CI, a functional oligosaccharide, is suggested to potentially assist in the prevention of dental caries and periodontal disease. Studies have shown that CI inhibits the activity of glucosyltransferase (GTF), reducing glucan formation and thus dental plaque. This reduction in dental plaque formation is significant because dental plaque is a known contributor to dental caries and periodontal disease【5】【6】. A clinical trial demonstrated that consuming CI-Dextran mix significantly reduced plaque accumulation in healthy adults, with no adverse events observed【7】. Further research is being conducted to explore these effects in more detail【8】.

Potential applications
CI's unique mechanism of action inhibits the glucosyltransferase (GTF), leading to a suppression of plaque formation without exhibiting bactericidal effects, meaning it does not harm beneficial bacteria. This characteristic of CI allows it to remain effective even when consumed alongside sugars. Its potential use extends to food, cosmetics, and possibly even over-the-counter drugs. A key advantage of CI, compared to other similar substances, is its ability to inhibit plaque formation without disturbing the balance of the oral microbiota, even in the presence of sugars.