4methylumbelliferone

4-Methylumbelliferone, also known as 4-MU, is a methylated derivative of the coumarin family and a hydroxylated analogue of umbelliferone (7-hydroxycoumarin). It is a yellowish crystalline solid used primarily for its fluorescent properties in biochemical assays.

Chemical properties: The molecule features a coumarin core with a methyl group at position 4 and a hydroxy group at position 7. It is soluble in many organic solvents and has limited water solubility. Upon excitation with near-UV light, 4-MU emits blue fluorescence, with emission typically in the 440–450 nm range, making it a convenient fluorophore for fluorescence-based detection.

Applications: In biochemistry and molecular biology, 4-MU is produced when 4-methylumbelliferyl glycosides (for example, 4-methylumbelliferyl β-D-glucuronide) are cleaved by specific hydrolases, releasing 4-methylumbelliferone that fluoresces under UV light. This property underpins many enzyme assays, including those for beta-glucuronidase and alkaline phosphatase, where fluorescence intensity correlates with enzymatic activity. It is also used as a fluorescent standard and in chromatography methods with fluorescence detection.

Safety and handling: 4-Methylumbelliferone is generally handled as a chemical reagent. It should be stored protected from light and moisture. It may cause irritation on contact with skin or eyes, and inhalation of dust should be avoided; standard laboratory precautions apply.