STA-21 (NSC628869; Ochromycinone; STA21; Rac-STA-21) is a potent STAT3 inhibitor and natural antibiotic with anticancer and antimicrobial activity. It inhibits STAT3 with IC50 of 12.2 μM in DU145 cells. In cells, STA-21 inhibits Stat3 DNA binding activity, Stat3 dimerization, and Stat3-dependent luciferase activity. STA-21 remarkably inhibits the growth and the survival of the breast carcinoma cells MDA-MB-231, MDA-MB-435s, and MDA-MB-468 that express persistently activated Stat3. In RH30 and RD2 cells, STA-21 also inhibits cell viability and growth and induced apoptosis through caspases 3, 8 and 9 pathways

Physicochemical Properties

Molecular Formula	C19H14O4
Molecular Weight	306.31
Exact Mass	306.089
CAS #	111540-00-2
Related CAS #	(+)-Ochromycinone;28882-53-3
PubChem CID	363709
Appearance	Light yellow to yellow solid powder
LogP	2.932
Hydrogen Bond Donor Count	1
Hydrogen Bond Acceptor Count	4
Rotatable Bond Count	0
Heavy Atom Count	23
Complexity	554
Defined Atom Stereocenter Count	0
InChi Key	ZAWXOCUFQSQDJS-UHFFFAOYSA-N
InChi Code	InChI=1S/C19H14O4/c1-9-7-10-5-6-12-17(15(10)14(21)8-9)19(23)11-3-2-4-13(20)16(11)18(12)22/h2-6,9,20H,7-8H2,1H3
Chemical Name	8-hydroxy-3-methyl-3,4-dihydrotetraphene-1,7,12(2H)-trione
Synonyms	NSC-628869; STA21;NSC 628869; STA21;NSC628869; STA 21; Ochromycinone.
HS Tariff Code	2934.99.9001
Storage	Powder-20°C 3 years 4°C 2 years In solvent -80°C 6 months -20°C 1 month
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

ln Vitro	STAT3 dimerization, STAT3-dependent luciferase activity, and STAT3 DNA binding activity are all inhibited by STA-21. Moreover, STA-21 decreased the survival of breast cancer cells that expressed constitutive STAT3 signaling, while it had no effect on those that did not [2].
ln Vivo	In previous animal study, IL-1Ra-KO mice were treated with i.p. injections of STA-21 at 0.5 mg/kg 3 times per week for 3 weeks. Results showed that STA-21 could suppress inflammatory arthritis in IL-1Ra-KO mice. The Th17 cell proportion decreased and the proportion of Treg cells expressing FoxP3 was increased in the spleens of STA-21-treated mice markedly. Moreover, the adoptive transfer of CD4+CD25+ T cells from STA-21-treated IL-1Ra-KO mice suppressed inflammatory arthritis markedly.
Animal Protocol	Dissolved in saline; 0.5 mg/kg; i.p. injection IL-1Ra–KO mice
References	[1]. A low-molecular-weight compound discovered through virtual database screening inhibits Stat3 function in breast cancer cells. Proc Natl Acad Sci U S A. 2005 Mar 29;102(13):4700-5. [2]. New Angucyclinones from the Marine Mollusk Associated Actinomycete Saccharothrix espanaensis An 113. Natural product communications. 2008, 3(10):1611-1616.
Additional Infomation	See also: Ochromycinone (annotation moved to).

Solubility Data

Solubility (In Vitro)

DMSO:10mg/mL Water:<1 mg/mL Ethanol: N/A

Solubility (In Vivo)

Solubility in Formulation 1: ≥ 1.67 mg/mL (5.45 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 16.7 mg/mL clear DMSO stock solution to 900 μL of corn oil and mix evenly.  (Please use freshly prepared in vivo formulations for optimal results.)

Preparing Stock Solutions		1 mg	5 mg	10 mg
	1 mM	3.2647 mL	16.3233 mL	32.6467 mL
	5 mM	0.6529 mL	3.2647 mL	6.5293 mL
	10 mM	0.3265 mL	1.6323 mL	3.2647 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.