Pifithrin-μ (NSC303580) is a novel and potent inhibitor of p53 binding and p53-mediated apoptosis with a Kd of 0.82 mM in vitro. It has neuroprotective and antitumor properties.

Physicochemical Properties

Molecular Formula	C8H7NO2S
Molecular Weight	181.21
Exact Mass	181.019
Elemental Analysis	C, 53.03; H, 3.89; N, 7.73; O, 17.66; S, 17.69
CAS #	64984-31-2
Related CAS #	64984-31-2
PubChem CID	327653
Appearance	White to light brown solid powder
Density	1.4±0.1 g/cm3
Boiling Point	351.7±25.0 °C at 760 mmHg
Melting Point	135.0 to 139.0 °C
Flash Point	166.5±23.2 °C
Vapour Pressure	0.0±0.8 mmHg at 25°C
Index of Refraction	1.634
LogP	2
Hydrogen Bond Donor Count	1
Hydrogen Bond Acceptor Count	3
Rotatable Bond Count	1
Heavy Atom Count	12
Complexity	295
Defined Atom Stereocenter Count	0
SMILES	S(C#CC1C([H])=C([H])C([H])=C([H])C=1[H])(N([H])[H])(=O)=O
InChi Key	ZZUZYEMRHCMVTB-UHFFFAOYSA-N
InChi Code	InChI=1S/C8H7NO2S/c9-12(10,11)7-6-8-4-2-1-3-5-8/h1-5H,(H2,9,10,11)
Chemical Name	2-phenylethynesulfonamide
Synonyms	Pifithrin-µ; Pifithrin µ; Pifithrinµ; 2-Phenylethynesulfonamide; PFT-µ; PFT µ; PFTµ; NSC303580; NSC-303580; NSC 303580
HS Tariff Code	2934.99.03.00
Storage	Powder-20°C 3 years 4°C 2 years In solvent -80°C 6 months -20°C 1 month Note: Please store this product in a sealed and protected environment (e.g. under nitrogen), avoid exposure to moisture.
Shipping Condition	Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

Biological Activity

Targets	MDM-2/p53; HSP70
ln Vitro	Pifithrin-μ interferes with p53 binding to mitochondria and inhibits rapid p53-dependent apoptosis of primary cell cultures of mouse thymocytes in response to gamma radiation.[1] In acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML) cell lines, as well as in primary AML blasts, Pifithrin-μ, an inhibitor of inducible HSP70, significantly reduced cell viability. The IC50 values ranged from 2.5 to 12.7 μM. Apoptosis and cell cycle arrest are induced by Pifithrin-μ in primary AML blasts in a dose-dependent manner, with a median IC50 of 8.9 μM (range 5.7-37.2 μM). Additionally, Pifithrin-μ decreases AKT and ERK1/2 in NALM-6 cells while increasing caspase-3's active form. [2] Pifithrin-μ promotes TRAIL-induced apoptosis and arrests the growth of cancer cells. It also increases Annexin V(+) cells in both caspase-dependent and caspase-independent ways. [3]
ln Vivo	Pifithrin-μ (40 mg/kg, ip) protects C57B1/6J mice exposed to 8 or 9 Gy of total body gamma radiation from p53-dependent apoptosis. [1] Pifithrin-μ significantly improves TRAIL's ability to inhibit the growth of the MiaPaca-2 tumor in a xenograft mouse model. [3]
Cell Assay	By staining with 0.5% methylene blue and calculating optical density with a Multiscan Ascent microplate reader, the number of attached cells is inferred. Using 0.1% trypan blue2 staining or FACScan analysis of annexin- or propidium iodide (PI)-positive cells, cell viability in suspension of short-term culture of primary thymocytes is assessed.
Animal Protocol	40 mg/kg DMSO C57B1/6J mice.
References	[1]. Nat Chem Biol . 2006 Sep;2(9):474-9. [2]. Blood Cancer J . 2011 Jul;1(7):e28. [3]. Mol Cancer Ther . 2013 Apr;12(4):341-51.
Additional Infomation	2-phenylethynesulfonamide is a member of benzenes.

Solubility Data

Solubility (In Vitro)

DMSO: ~36 mg/mL (~198.7 mM) Water: <1 mg/mL (slightly soluble or insoluble) Ethanol: N/A

Solubility (In Vivo)

Solubility in Formulation 1: ≥ 2.08 mg/mL (11.48 mM) (saturation unknown) in 10% DMSO + 40% PEG300 + 5% Tween80 + 45% Saline (add these co-solvents sequentially from left to right, and one by one), clear solution. For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 20.8 mg/mL clear DMSO stock solution to 400 μL PEG300 and mix evenly; then add 50 μL Tween-80 to the above solution and mix evenly; then add 450 μL normal saline to adjust the volume to 1 mL. Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution. Solubility in Formulation 2: ≥ 2.08 mg/mL (11.48 mM) (saturation unknown) in 10% DMSO + 90% (20% SBE-β-CD in Saline) (add these co-solvents sequentially from left to right, and one by one), clear solution. For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 20.8 mg/mL clear DMSO stock solution to 900 μL of 20% SBE-β-CD physiological saline solution and mix evenly. Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution. Solubility in Formulation 3: ≥ 2.08 mg/mL (11.48 mM) (saturation unknown) in 10% DMSO + 90% Corn Oil (add these co-solvents sequentially from left to right, and one by one), clear solution. For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 20.8 mg/mL clear DMSO stock solution to 900 μL of corn oil and mix evenly. Solubility in Formulation 4: 1% DMSO +30% polyethylene glycol+1% Tween 80 : 10 mg/mL  (Please use freshly prepared in vivo formulations for optimal results.)

Preparing Stock Solutions		1 mg	5 mg	10 mg
	1 mM	5.5185 mL	27.5923 mL	55.1846 mL
	5 mM	1.1037 mL	5.5185 mL	11.0369 mL
	10 mM	0.5518 mL	2.7592 mL	5.5185 mL

*Note: Please select an appropriate solvent for the preparation of stock solution based on your experiment needs. For most products, DMSO can be used for preparing stock solutions (e.g. 5 mM, 10 mM, or 20 mM concentration); some products with high aqueous solubility may be dissolved in water directly. Solubility information is available at the above Solubility Data section. Once the stock solution is prepared, aliquot it to routine usage volumes and store at -20°C or -80°C. Avoid repeated freeze and thaw cycles.