Coumarins are small molecular weight, water soluble, UV-excitable, blue fluorescent dyes (emission range ~410 to 470 nm). They can be either cell permeable or cell impermeant depending on their structure; the more charged moieties that are on the dye he less cell permeable the molecule is. 7-hydroxycoumarin and derivatives are also referred in the literature as umbelliferones or umbelliferyls.

Coumarin dyes are often used to provide contrast in multicolor applications, but because coumarin fluorescence may not be as bright as that of other dyes or may be obscured by autofluorescence, they are only recommended for use with highly abundant targets or in cell tracking applications.

Coumarin derivatives (e.g., MUG, MUP, DiFMUP) are extensively used as substrates for detecting enzymatic activity in cells, homogenates, and solution.

We offer a range of coumarin-based reagents as well as high-performance fluorophores with improved characteristics for labeling and detection.

Coumarin and coumarin derivatives dashboard

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Coumarin and its derivatives are traditional blue-fluorescent labels and are most commonly used as fluorogenic enzyme substrates.


Photostability in buffer


Photostability in antifade


Rat basophilic leukemia (RBL) cells labeled in suspension with various CellTracker™ dyes. Rat basophilic leukemia (RBL) cells labeled in suspension with CellTracker™ Blue CMAC, CellTracker™ Green CMFDA or CellTracker™ Orange CMTMR prior to plating. The image was acquired using optical filter sets appropriate for DAPI, fluorescein and the Texas Red® dye.

High-performance alternatives to coumarins

You have a choice when it comes to labeling with blue-fluorescent dye conjugates.

Imaging applications

For imaging applications, the Alexa Fluor® 350 dye is spectrally identical to coumarin with improved characteristics for labeling and detection.

Alexa Fluor® dyes

Alexa Fluor® dyes are among the most trusted fluorescent dyes available today. In addition to superior performance, you’ll get an experienced, problem-solving technical support team, >50,000 published references, application and experimental tips, as well as protocols to help with experiment planning. For an outstanding research experience, choose Alexa Fluor® dyes.

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Bovine pulmonary endothelial cells. MitoTracker® Red CMXRos, SYTO® 16 nucleic acid stain, anti–bovine α-tubulin (mouse monoclonal) and Alexa Fluor® 350 goat anti–mouse IgG. Bovine pulmonary endothelial cells incubated with the fixable, mitochondrion-selective MitoTracker® Red CMXRos. The cells were then formaldehyde-fixed, acetone-permeabilized and counterstained using SYTO® 16 green-fluorescent nucleic acid stain. Microtubules were labeled with mouse monoclonal anti–α-tubulin antibody and visualized with blue-fluorescent Alexa Fluor® 350 goat anti–mouse IgG. The multiple-exposure image was acquired using filter sets appropriate for Texas Red® dye, fluorescein and DAPI.

Flow cytometry applications

For flow cytometry, Pacific Blue™ dye is a high-performance blue label that is ideally suited to the 405 nm violet laser.

Violet laser–compatible antibody conjugates

We offer Pacific Blue™, Pacific Green™ and Pacific Orange™ dyes as well as Qdot® labels for use with the violet laser. In addition to primary and secondary antibody conjugates of these dyes, we’ve developed kits for cell proliferation, immunophenotyping, dead-cell discrimination, apoptosis, and cell cycle analysis—all aimed at helping you maximize the data you can get from your violet laser–equipped flow cytometer.


Molecular Probes® Handbook

Molecular Probes HandbookThe significantly revised 11th Edition is the most complete fluorescence labeling and detection reference available. The Molecular Probes® Handbook can help you achieve the best experimental results for your fluorescence labeling and detection experiments. View the handbook online or order your own copy.


Antifade reagents

Antifade reagentsAntifade reagents suppress photobleaching and preserve the signals of your fluorescently labeled target molecules. They offer excellent compatibility with Coumarin and a multitude of dyes across the spectrum, making them especially valuable tools for multicolor applications.

Cell stain tool

Cell stain toolStain your own cell by using our simulation tool to develop reproducible results with many of our signature fluorescent dyes. Develop your multiplexing strategy for antibody probes, reactive dyes, and counterstains to create your perfectly labeled fluorescent cell.


Fluorescence SpectraViewer

Fluorescence SpectraviewerPlot and compare spectra and check the spectral compatibility for common fluorophores including all the Molecular Probes® fluorescent probes. The Fluorescence SpectraViewer tool is formatted for both microscope imaging and flow cytometry applications.

For Research Use Only. Not for use in diagnostic procedures.