WARNING: This product is for research use only, not for human or veterinary use.

MedKoo CAT#: 200550

CAS#: 288628-05-7

Description: Irosustat, also known as STX64, BN83495 and 667 coumate, is a potent, irreversible inhibitor of steroid sulfatase. Inhibition of steroid sulfatase (STS), the enzyme responsible for the hydrolysis of steroid sulfates, represents a potential novel treatment for postmenopausal women with hormone-dependent breast cancer. Estrone and DHEA are formed by this sulfatase pathway and can be converted to steroids (estradiol and androstenediol, respectively), which have potent estrogenic properties. STX64 (667 coumate) is a potent tricylic coumarin-based sulfamate that irreversibly inhibits STS activity (IC50 = 8 nM in a placental microsomal assay system). Estrone sulfamate (EMATE) is also a potent STS inhibitor, but has estrogenic activity.

Chemical Structure

CAS# 288628-05-7

Theoretical Analysis

MedKoo Cat#: 200550
Name: Irosustat
CAS#: 288628-05-7
Chemical Formula: C14H15NO5S
Exact Mass: 309.07
Molecular Weight: 309.3376
Elemental Analysis: C, 54.36; H, 4.89; N, 4.53; O, 25.86; S, 10.37

Price and Availability

Size Price Availability Quantity
50.0mg USD 450.0 2 Weeks
100.0mg USD 750.0 2 Weeks
200.0mg USD 1250.0 2 Weeks
500.0mg USD 1950.0 2 Weeks
1.0g USD 2950.0 2 Weeks
2.0g USD 5250.0 2 Weeks
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Synonym: STX64; STX-64; STX 64; BN83495; BN-83495; BN 83495; STX 64667; STX64667; ST-64667; COUMATE. Irosustat.

IUPAC/Chemical Name: 6-oxo-6,7,8,9,10,11-hexahydrocyclohepta[c]chromen-3-yl sulfamate.


InChi Code: InChI=1S/C14H15NO5S/c15-21(17,18)20-9-6-7-11-10-4-2-1-3-5-12(10)14(16)19-13(11)8-9/h6-8H,1-5H2,(H2,15,17,18)

SMILES Code: O=S(OC1=CC(O2)=C(C=C1)C(CCCCC3)=C3C2=O)(N)=O

Appearance: Solid powder

Purity: >98%

Shipping Condition: Shipped under ambient temperature as non-hazardous chemical. This product is stable enough for a few weeks during ordinary shipping and time spent in Customs.

Storage Condition: Dry, dark and at 0 - 4 C for short term (days to weeks) or -20 C for long term (months to years).

Solubility: Soluble in DMSO, not in water

Shelf Life: >5 years if stored properly

Drug Formulation: This drug may be formulated in DMSO

Stock Solution Storage: 0 - 4 C for short term (days to weeks), or -20 C for long term (months).

HS Tariff Code: 2934.99.9001

Certificate of Analysis:

Safety Data Sheet (SDS):

Preparing Stock Solutions

The following data is based on the product molecular weight 309.3376 Batch specific molecular weights may vary from batch to batch due to the degree of hydration, which will affect the solvent volumes required to prepare stock solutions.

Recalculate based on batch purity %
Concentration / Solvent Volume / Mass 1 mg 5 mg 10 mg
1 mM 1.15 mL 5.76 mL 11.51 mL
5 mM 0.23 mL 1.15 mL 2.3 mL
10 mM 0.12 mL 0.58 mL 1.15 mL
50 mM 0.02 mL 0.12 mL 0.23 mL

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1: Lawrence Woo LW, Leblond B, Purohit A, Potter BV. Synthesis and evaluation of analogues of estrone-3-O-sulfamate as potent steroid sulfatase inhibitors. Bioorg Med Chem. 2012 Apr 15;20(8):2506-19. Epub 2012 Mar 8. PubMed PMID: 22455789.

2: Ventura V, Solà J, Peraire C, Brée F, Obach R. In vitro evaluation of the interaction potential of irosustat with drug-metabolizing enzymes. Drug Metab Dispos. 2012 Jul;40(7):1268-78. Epub 2012 Mar 26. PubMed PMID: 22451700.

3: Woo LW, Ganeshapillai D, Thomas MP, Sutcliffe OB, Malini B, Mahon MF, Purohit A, Potter BV. Structure-activity relationship for the first-in-class clinical steroid sulfatase inhibitor Irosustat (STX64, BN83495). ChemMedChem. 2011 Nov 4;6(11):2019-34. doi: 10.1002/cmdc.201100288. Epub 2011 Aug 25. PubMed PMID: 21990014; PubMed Central PMCID: PMC3262147.

4: Purohit A, Woo LW, Potter BV. Steroid sulfatase: a pivotal player in estrogen synthesis and metabolism. Mol Cell Endocrinol. 2011 Jul 4;340(2):154-60. Epub 2011 Jun 30. Review. PubMed PMID: 21693170.

5: Ventura V, Solà J, Celma C, Peraire C, Obach R. In vitro metabolism of irosustat, a novel steroid sulfatase inhibitor: interspecies comparison, metabolite identification, and metabolic enzyme identification. Drug Metab Dispos. 2011 Jul;39(7):1235-46. Epub 2011 Apr 4. PubMed PMID: 21464173.

6: Palmieri C, Januszewski A, Stanway S, Coombes RC. Irosustat: a first-generation steroid sulfatase inhibitor in breast cancer. Expert Rev Anticancer Ther. 2011 Feb;11(2):179-83. Review. Erratum in: Expert Rev Anticancer Ther. 2011 Sep;11(9):1472. PubMed PMID: 21342037.

7: Woo LW, Purohit A, Potter BV. Development of steroid sulfatase inhibitors. Mol Cell Endocrinol. 2011 Jul 4;340(2):175-85. Epub 2011 Jan 14. Review. PubMed PMID: 21238537.

8: Fusi L, Purohit A, Brosens J, Woo LW, Potter BV, Reed MJ. Inhibition of steroid sulfatase activity in endometriotic implants by STX64 (667Coumate): a potential new therapy. ScientificWorldJournal. 2008 Dec 25;8:1325-7. PubMed PMID: 19112542.

9: Purohit A, Chander SK, Woo LW, Parsons MF, Jhalli R, Potter BV, Reed MJ. Inhibition of steroid sulphatase activity via the percutaneous route: a new option for breast cancer therapy. Anticancer Res. 2008 May-Jun;28(3A):1517-23. PubMed PMID: 18630506.

10: Foster PA, Chander SK, Parsons MF, Newman SP, Woo LW, Potter BV, Reed MJ, Purohit A. Efficacy of three potent steroid sulfatase inhibitors: pre-clinical investigations for their use in the treatment of hormone-dependent breast cancer. Breast Cancer Res Treat. 2008 Sep;111(1):129-38. Epub 2007 Oct 4. PubMed PMID: 17914670.

11: Stanway SJ, Delavault P, Purohit A, Woo LW, Thurieau C, Potter BV, Reed MJ. Steroid sulfatase: a new target for the endocrine therapy of breast cancer. Oncologist. 2007 Apr;12(4):370-4. Review. PubMed PMID: 17470679.  


10.0mg / Not available

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