DRB Chemical Properties

Melting point:

222-224°C

Boiling point:

606.2±65.0 °C(Predicted)

Density 

1.5917 (rough estimate)

refractive index 

1.6200 (estimate)

storage temp. 

-20°C

solubility 

Soluble in DMSO (up to 20 mg/ml)

pka

13.23±0.70(Predicted)

form 

White solid

color 

White

Water Solubility 

Soluble in DMSO to 75mMSoluble in dimethyl sulfoxide, hot ethanol, dimethyl formamide, (1:2) dimethyl formamide:Phosphate buffer saline, water, methanol and pyridine. Slightly soluble in aqueous buffers.

λmax

296nm(lit.)

BRN 

39123

Stability:

Stable for 1 year from date of purchase as supplied. Solutions in DMSO may be stored at -20°C for up to 3 months.

InChIKey

XHSQDZXAVJRBMX-AYLPWXGPSA-N

CAS DataBase Reference

53-85-0

Safety Information

Safety Statements 

24/25

WGK Germany 

3

RTECS 

DD7310000

HS Code 

29349990

MSDS

• Language:English Provider:SigmaAldrich

DRB Usage And Synthesis

Description

DRB (53-85-0) is a classic inhibitor of transcription by RNA polymerase II.?A relatively selective inhibitor of Cdk9 (IC50=3 μM), the kinase of the positive transcription elongation factor b (P-TEF-b) required for processive transcription elongation by RNA polymerase II.1,2?Also inhibits casein kinase II, IC50=4-10 μM.?3?Suppresses the SIRT1/CK2α pathway and enhances the radiosensitivity of human cancer cells.4?Kinase-independent activities of Cdk9 such as glucocorticoid receptor modulation are not inhibited by DRB.5

Chemical Properties

White Solid

Uses

Inhibits casein kinase II and blocks RNA synthesis. An adenosine analog.5,6-Dichlorobenzimidazole riboside is used as an inhibitor of RNA Polymerase II. It is nucleoside analogue and used in research to study the mechanisms of cellular regulation. Further, it inhibits some protein kinases.

Uses

5,6-Dichlorobenzimidazole 1-β-D-ribofuranoside has been used:

• as an inhibitor of RNA polymerase II in mouse melanoma cells
• for the inhibition of cyclin D1 mRNA synthesis in human prostate epithelial cell lines
• in the inhibition of interleukin-2 gene transcription in Jurkat cells

Uses

DRB is an inhibitor of RNA synthesis (causes premature termination of transcription).

Biochem/physiol Actions

5,6-Dichlorobenzimidazole 1-β-D-ribofuranoside (DRB), a nucleoside analog that halts mRNA synthesis by phosphorylation of the C-terminal domain of RNA polymerase II, making it inactive. It also interferes with the DNA topoisomerase II, may modulate response to cytokines and blocks the human immunodeficiency virus (HIV) via RNA modification. It also inhibits cyclin-dependent kinases (CDKs) 7 and 9 and favors apoptosis in leukemic cells. It may serve as a therapeutic agent in treating cancer.

References

1) Baumli?et al.?(2010),?Halogen bonds form the basis for selective P-TEFb inhibition by DRB; Chem. Biol.,?17?931 2) Yamaguchi?et al.?(1998),?Interplay between positive and negative elongation factors: drawing a new view of DRB; Genes Cells,?3?9 3) Zandomeni (1989), Kinetics of inhibition by 5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole; Biochem.J., 262 469 4) Wang?et al.?(2014),?Inhibition of P-TEFb by DRB suppresses SIRT1/CK2α pathway and enhances radiosensitivity of human cancer cells; Anticancer Res.,?34?6981 5) Zhu?et al.?(2014),?A kinase-independent activity of Cdk9 modulates glucocorticoid receptor-mediated gene induction; Biochemistry,?53?1753

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