gammacyclodextrin

Gamma-cyclodextrin (gamma-CD) is a cyclic oligosaccharide composed of eight D-glucopyranose units linked by α-1,4 glycosidic bonds, forming a torus-shaped molecule with a relatively hydrophobic interior and a hydrophilic exterior. This architecture enables gamma-CD to form inclusion complexes with various hydrophobic guest molecules, improving their solubility, stability, and sometimes taste or odor properties.

Gamma-CD is produced industrially by enzymatic conversion of starch using cyclodextrin glycosyltransferase (CGTase). The process yields a mixture of cyclodextrins (alpha-, beta-, and gamma-CD); gamma-CD can be enriched and purified by crystallization, membrane filtration, or chromatography.

Properties and applications: In aqueous solutions, gamma-CD is more soluble than beta-CD and can accommodate larger guest molecules due to its larger cavity. Because of its inclusion capability, gamma-CD is widely used as an excipient in pharmaceutical formulations to solubilize poorly water-soluble drugs, enhance physical stability, and mask unfavorable tastes or odors. It is also employed in the food, cosmetic, and fragrance industries for encapsulation of flavors, vitamins, and active ingredients, and for stabilization of volatile components or controlled release.

Safety: Cyclodextrins are generally regarded as safe excipients in many jurisdictions when used within approved concentrations, but regulatory status varies by country and application. Gamma-CD is typically well tolerated, with rare gastrointestinal effects at high doses.