- Dimethyl sulfoxide (DMSO) is a highly polar, aprotic solvent that is widely used in chemical, pharmaceutical, and biological sciences due to its exceptional solvating capabilities.
- Its molecular structure, featuring a sulfur atom double-bonded to an oxygen atom and bonded to two methyl groups, allows it to dissolve both polar and nonpolar compounds, making it one of the most versatile solvents available.
- DMSO’s miscibility with water and a wide range of organic solvents enhances its utility in diverse applications, from organic synthesis to drug formulation and biochemical assays.
- In organic chemistry, DMSO is valued for its ability to stabilize reaction intermediates and facilitate reactions involving polar transition states, such as SN2 reactions, oxidations, and certain types of coupling reactions. It is frequently used as the solvent in oxidizing systems like the Swern oxidation, where it activates reagents under mild conditions without introducing water. Its high dielectric constant and ability to solvate cations and anions make it particularly effective for conducting reactions involving ionic species or where strong nucleophiles are involved.
- In pharmaceutical research and development, DMSO is commonly used to dissolve poorly water-soluble compounds for in vitro and in vivo testing. Its compatibility with biological systems at low concentrations allows researchers to prepare concentrated stock solutions of drug candidates or biochemical modulators, which can then be diluted into aqueous media. This is particularly useful for dose-response experiments in cell culture, enzyme kinetics, and molecular biology applications. However, because DMSO itself can influence cell membrane integrity, gene expression, and other cellular processes, its concentration is typically kept below 0.1–1% in biological assays to minimize confounding effects.
- Moreover, DMSO’s ability to penetrate biological membranes has led to its use not only as a solvent but also as a carrier in drug delivery applications, although this property requires caution due to the risk of carrying unwanted contaminants into systemic circulation. Its utility in cryopreservation as a cryoprotectant further exemplifies its solvent strength—allowing the distribution of solutes within and around cells during freezing to prevent ice crystal formation and ensure cell viability.
- Despite its broad utility, the use of DMSO must be carefully managed due to some of its limitations. It is hygroscopic and readily absorbs water from the air, which can affect reactions sensitive to moisture. It can also react with strong oxidizers and acids, and under certain conditions (e.g., high temperatures or in the presence of reactive species), it may degrade to release dimethyl sulfide or other volatile compounds. Additionally, while DMSO is relatively non-toxic at low levels, high concentrations can cause skin irritation, systemic toxicity, or interfere with experimental outcomes.
