Methyl-β-cyclodextrin

Methyl-β-cyclodextrin has been used:

• to study the effect of cholesterol depletion, from sperm membrane on sperm′s ability to undergo acrosome reaction.
• to determine the effect of caveolin overexpression and its loss on pro-survival and pro-growth signaling
• in conventional in vitro fertilization

Methyl-β-cyclodextrin (MβCD) is commonly applicable as an inhibitor and modifies cholesterol domains on the cellular surface. It causes depletion of cholesterol on the membrane. It is also known to prevent the action of cholera toxin, nitric oxide (NO) synthase and glucose transporter through internalization. This is observed in specific to lipid rafts and caveolae endocytosis. MβCD induces eflux as well as influx of cholesterol. It can affect cell viability as the genes regulating cholesterol levels are upregulated, due to decreased cholesterol level by the action of MβCD. It can be used to increase the solubility of non-polar substances such as fatty acids, lipids, vitamins and cholesterol for use in cell culture applications. Cavity size is the major determinant as to which cyclodextrin is used in complexation. The cavity diameter of β-cyclodextrins or β-glucopyranose unit compounds is well-suited for use with molecules the size of hormones, vitamins and many compounds frequently used in tissue and cell culture applications. For this reason, β-cyclodextrin is most commonly used as a complexing agent.

Methyl-β-cyclodextrin is a heptasaccharide, soluble in water, and has more affinity to cholesterol due to the presence of hydrophobic core. Cyclodextrins are cyclic oligosaccharides consisting of 6, 7, or 8 glucopyranose units, usually referred to as α-, β-, or γ-cyclodextrins, respectively. These compounds have rigid doughnut-shaped structures making them natural complexing agents. The unique structures of these compounds owe their stability to intramolecular hydrogen bonding between the C2- and C3-hydroxyl groups of neighboring glucopyranose units. The molecule takes on the shape of a torus with the C2- and C3-hydroxyls located around the larger opening and the more reactive C6-hydroxyl aligned around the smaller opening. The arrangement of C6-hydroxyls opposite the hydrogen bonded C2- and C3-hydroxyls forces the oxygen bonds into close proximity within the cavity, leading to an electron rich, hydrophobic interior. The size of this hydrophobic cavity is a function of the number of glucopyranose units forming the cyclodextrin.

The solubility of natural cyclodextrins is very poor. In the late 1960′s, it was discovered that chemical substitutions at the 2, 3, and 6 hydroxyl sites would greatly increase solubility. Most chemically modified cyclodextrins are able to achieve a 50% (w/v) concentration in water.

Solutions may be obtained by stirring 30 min at room temperature. Alternatively, sonication with cooling may be employed. Solutions may be stored for several months at 4°C. Solid should be stored tightly sealed at room temperature.