KH-CB20, an E/Z mixture, is a potent and specific inhibitor of CLK1 and the closely related isoform CLK4, with IC50 for CLK1 inhibition of 16.5 nM. KH-CB20 also inhibits DYRK1A (IC50=57.8 nM) and CLK3 (IC50=488 nM).

Physicochemical Properties

Molecular Formula	C15H13CL2N3O2
Molecular Weight	338.19
Exact Mass	337.038
CAS #	1354448-60-4
Related CAS #	KH-CB19;1354037-26-5
PubChem CID	44237094
Appearance	Off-white to light yellow solid powder
LogP	3.1
Hydrogen Bond Donor Count	1
Hydrogen Bond Acceptor Count	4
Rotatable Bond Count	4
Heavy Atom Count	22
Complexity	516
Defined Atom Stereocenter Count	0
SMILES	N1(C)C2=C(C=CC(Cl)=C2Cl)C(C(C#N)=CN)=C1C(OCC)=O
InChi Key	CXJCGSPAPOTTSF-VURMDHGXSA-N
InChi Code	InChI=1S/C15H13Cl2N3O2/c1-3-22-15(21)14-11(8(6-18)7-19)9-4-5-10(16)12(17)13(9)20(14)2/h4-6H,3,18H2,1-2H3/b8-6-
Chemical Name	ethyl 3-[(E)-2-amino-1-cyanoethenyl]-6,7-dichloro-1-methylindole-2-carboxylate
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

Targets	CLK1 16.5 nM (IC50) DYRK1A 57.8 nM (IC50) CLK3 488 nM (IC50)
ln Vitro	KH-CB20 is more selective than DYRK1A (IC50=57.8 nM) and CLK3 (IC50=488 nM) for CLK1 (IC50=16.5 nM) [1].
References	[1]. Specific CLK inhibitors from a novel chemotype for regulation of alternative splicing. Chem Biol. 2011 Jan 28;18(1):67-76.

Solubility Data

Solubility (In Vitro)

DMSO : 100 mg/mL (295.69 mM)

Solubility (In Vivo)

Solubility in Formulation 1: ≥ 2.5 mg/mL (7.39 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), suspension solution. For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 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: ≥ 2.5 mg/mL (7.39 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 25.0 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: ≥ 2.5 mg/mL (7.39 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 25.0 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	2.9569 mL	14.7846 mL	29.5692 mL
	5 mM	0.5914 mL	2.9569 mL	5.9138 mL
	10 mM	0.2957 mL	1.4785 mL	2.9569 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.