Stemolecule™ Pifithrin-μ

This product has been discontinued.

04 0039 Figure 1

Product Overview

Stemolecule Pifithrin-µ (also known as PES or 2-phenylethynesulfonamide) inhibits p53 binding to mitochondria by reducing its affinity for antiapoptotic proteins Bcl-2 and Bcl-XL. The mechanism of action of Pifithrin-µ is different from Pifithrin-α since Pifithrin-µ inhibits the p53 mitochondrial pathway but does not affect any additional transcriptional functions of p53. Pifithrin-µ rescues cells from lethal γ-irradiation induced cell death and protects mice from doses of radiation that cause lethal hematopoietic syndrome1. The reduction of p53 activity has also been shown to enhance reprogramming efficiency of human and mouse somatic cells2.

Product Specifications


5 mg

Alternate Name


Chemical Formula


Molecular Weight


CAS Number



Greater than 99% by HPLC analysis


White to off-white solid


For a 10 mM concentrated stock solution of Pifithrin-µ, reconstitute the compound by adding 2.76 ml of DMSO to the entire contents of the vial. If precipitate is observed, warm the solution to 37°C for 2 to 5 minutes. For cell culture, the media should be prewarmed prior to adding the reconstituted compound. Note: for most cells, the maximum tolerance to DMSO is less than 0.5%. This molecule is soluble in DMSO at 100 mM.

Storage and Stability

Store powder at 4°C protected from light. Following reconstitution, store aliquots at -20°C. Stock solutions are stable for 6 months when stored as directed.

Quality Control

The purity of Pifithrin-µ was determined by HPLC analysis. The accurate mass was determined by mass spectrometry. Cellular toxicity of Pifithrin-µ was tested on mouse embryonic stem cells.

Specification Sheets

Safety Data Sheets

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