Methylcyclodextrin

Methylcyclodextrin refers to derivatives of cyclodextrins in which one or more hydroxyl groups on the glucopyranose units are methylated. The most commonly used forms are methyl-β-cyclodextrin (MβCD) and randomly methylated β-cyclodextrin (RAMEB). Cyclodextrins are cyclic oligosaccharides that create a relatively hydrophobic inner cavity and a hydrophilic exterior, enabling them to form inclusion complexes with various hydrophobic guest molecules.

Methylation increases the water solubility of the parent cyclodextrin relative to native beta-cyclodextrin and can modify the cavity’s properties, affecting which molecules are accommodated and how strongly they bind. The degree and pattern of methylation influence solubility, binding affinity, and, in some contexts, toxicity or membrane interactions. Randomly methylated derivatives contain a mixture of substitution patterns, while permethylated or highly methylated derivatives have more uniform methylation.

Derivatives include randomly methylated cyclodextrins (such as RAMEB) and permethylated derivatives. They are prepared by methylating native cyclodextrins with reagents like dimethyl sulfate or methyl iodide under basic conditions, followed by purification to isolate specific products or mixtures.

Applications are broad: they solubilize poorly water-soluble drugs, stabilize flavors and fragrances, and form inclusion complexes for analytical extraction. In biological research, methyl-β-cyclodextrin is commonly used to extract cholesterol from cellular membranes and modulate membrane properties; derivatives are also used as pharmaceutical or cosmetic excipients to improve formulation stability and drug delivery.

Safety and handling depend on the specific derivative and exposure level; because methylated cyclodextrins can disrupt membranes or deplete cholesterol at high concentrations, appropriate dosing and formulation are essential in research and therapeutic contexts.