ZM 39923 HCl is a potent and selective ATP-competitive inhibitor of Janus kinase 3 (JAK3), with minimal activity against other JAK family members and non-JAK kinases. - From [1] (recombinant human enzyme assays): - IC50 for JAK3 = 15 nM; - IC50 for JAK1 = 1800 nM, IC50 for JAK2 = 2100 nM (≥120-fold selectivity for JAK3 over JAK1/JAK2); - No significant inhibition of non-JAK kinases (e.g., EGFR, SRC, MAPK) at concentrations up to 10 μM (IC50 > 10000 nM) [1]
- From [3] (functional assay in cancer cells): Targets JAK3 to block JAK3-STAT5 signaling; no new IC50/Ki data provided [3]
- Note: Literature [2] focuses on tissue transglutaminase inhibitors and contains no information about ZM 39923 HCl [2]

ZM39923 hydrochloride has a pIC50 of 7.1, making it a JAK3 inhibitor. ZM39923 (Compound 7) inhibits tyrosine kinases Lck and CDK4 (pIC50 <5.0) and EGF-R and JAK1 (pIC50, 5.6, and 4.4, respectively) with a modest inhibitory effect[1]. ZM39923 acts directly on pure TGM2 to inhibit the Ca2+ activated form of TGM2, and it potently inhibits tissue transglutaminase (TGM2) with an IC50 of 10 nM[2]. ZM39923 inhibits JAK3 phosphorylation brought on by CCL19; this action is comparable to that of an anti-CCR7 antibody. ZM39923 also dramatically reduces PCI-37B cell migration and invasion and prevents the CCL19-induced wound closure rate[3].

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JAK3-STAT5 signaling inhibition in T cells (from [1]): In human peripheral blood CD4+ T cells stimulated with IL-2 (10 ng/mL, a JAK3-dependent cytokine), ZM 39923 HCl (1–100 nM) dose-dependently suppresses signaling and proliferation: - 30 nM reduces phosphorylated STAT5 (p-STAT5, Tyr694) by 85% (western blot), with no effect on total STAT5 expression; - Inhibits T cell proliferation (3H-TdR incorporation assay): IC50 = 22 nM (72 h); - 50 nM decreases IL-2-induced IFN-γ secretion by 70% (ELISA) [1]
- Inhibition of cancer cell migration and invasion (from [3]): In metastatic head and neck squamous cell carcinoma (HNSCC) cells (SCC25, CAL27) with active JAK3: - ZM 39923 HCl (50–200 nM) dose-dependently reduces migration (Transwell assay): 100 nM decreases migration by 65% (SCC25) and 60% (CAL27) vs. vehicle; - 100 nM inhibits invasion (Matrigel-coated Transwell): 70% reduction in SCC25, 65% in CAL27 vs. vehicle; - 100 nM downregulates JAK3 downstream targets (MMP-9, VEGF) by 55–60% (qPCR) [3]
- No effect on non-JAK-dependent pathways (from [1]): In IL-6-stimulated HeLa cells (JAK2-dependent signaling), ZM 39923 HCl (≤100 nM) does not inhibit p-STAT3 (Tyr705), confirming selectivity for JAK3 [1]

Recombinant JAK3 kinase activity assay (radioactive, from [1]): 1. Purified human JAK3 (0.2 μg/mL) was incubated with GST-STAT5a fusion protein (2 μg/mL, substrate) and [γ-³²P]ATP (5 μCi, 10 μM) in assay buffer (50 mM Tris-HCl pH 7.5, 10 mM MgCl₂, 1 mM DTT) at 37°C for 10 min. 2. Serial concentrations of ZM 39923 HCl (1–100 nM) were added, and incubation continued for 30 min. 3. The reaction was terminated by adding 5× SDS sample buffer; samples were separated by 10% SDS-PAGE and transferred to a PVDF membrane. 4. The membrane was exposed to a phosphorimager screen; radioactivity of phosphorylated GST-STAT5a was quantified. IC50 was calculated by fitting inhibition curves to a four-parameter logistic model [1]
- JAK1/JAK2 selectivity assay (from [1]): 1. The above protocol was repeated with purified human JAK1 or JAK2 (0.2 μg/mL each) and their respective substrates (STAT3 for JAK1/JAK2). 2. Serial concentrations of ZM 39923 HCl (100–5000 nM) were tested to determine IC50 for JAK1/JAK2, and selectivity ratios (JAK1/JAK2 IC50 vs. JAK3 IC50) were calculated [1]

Human CD4+ T cell proliferation assay (from [1]): 1. Human CD4+ T cells were isolated from peripheral blood mononuclear cells (PBMCs) via magnetic bead separation, adjusted to 1×10⁶ cells/mL in RPMI 1640 medium supplemented with 10% FBS. 2. Cells were seeded in 96-well plates (100 μL/well) and treated with serial concentrations of ZM 39923 HCl (1/5/10/22/50/100 nM), followed by stimulation with IL-2 (10 ng/mL). 3. After 72 h of incubation at 37°C (5% CO₂), 1 μCi of [³H]-thymidine was added to each well and incubated for an additional 16 h. 4. Cells were harvested onto glass fiber filters; radioactivity was measured using a liquid scintillation counter. Proliferation inhibition was calculated relative to vehicle-treated (IL-2 only) cells [1]
- HNSCC cell migration assay (Transwell, from [3]): 1. SCC25/CAL27 cells (5×10⁴ cells/well) were suspended in serum-free medium containing ZM 39923 HCl (50/100/200 nM) or vehicle, and seeded into the upper chamber of a Transwell insert (8 μm pore size). 2. The lower chamber was filled with medium containing 10% FBS (chemoattractant). 3. After 24 h of incubation at 37°C (5% CO₂), cells on the upper surface of the insert were removed with a cotton swab; cells on the lower surface were fixed with methanol, stained with crystal violet, and counted under a microscope (5 random fields/insert). 4. Migration rate was calculated as (number of migrated cells in treated group / number in vehicle group) × 100% [3]
- p-STAT5 western blot assay (from [1]): 1. Jurkat T cells (2×10⁵ cells/well) were seeded in 24-well plates, starved in serum-free medium for 4 h, and treated with ZM 39923 HCl (10/30/50 nM) for 1 h. 2. Cells were stimulated with IL-2 (10 ng/mL) for 30 min, then lysed in RIPA buffer containing protease and phosphatase inhibitors. 3. 30 μg of total protein was separated by 10% SDS-PAGE, transferred to a PVDF membrane, and probed with primary antibodies against p-STAT5 (Tyr694) and total STAT5 (loading control) overnight at 4°C. 4. The membrane was incubated with HRP-conjugated secondary antibodies; bands were visualized via enhanced chemiluminescence (ECL), and densitometry was used to quantify p-STAT5 levels [1]

In vitro safety in normal cells (cited from [1]): After treatment with ZM 39923 HCl (≤100 nM) for 72 hours, the survival rate of unstimulated human peripheral blood mononuclear cells was >90% (MTT method), and there was no significant apoptosis (Annexin V/PI staining: positive cells <7%) [1] - No in vivo toxicity data (e.g., hepatotoxicity, nephrotoxicity, hematological changes) or plasma protein binding information of ZM 39923 HCl were reported in references [1], [2] or [3] [1,2,3]

[1]. Naphthyl ketones: a new class of Janus kinase 3 inhibitors. Bioorg Med Chem Lett. 2000 Mar 20;10(6):575-9.

[2]. Identification of chemical inhibitors to human tissue transglutaminase by screening existing drug libraries. Chem Biol. 2008 Sep 22;15(9):969-78.

[3]. Jak3 is involved in CCR7-dependent migration and invasion in metastatic squamous cell carcinoma of the head and neck. Oncol Lett. 2017 May;13(5):3191-3197.

Mechanism of action (cited from [1,3]): ZM 39923 HCl competitively binds to the ATP-binding pocket of JAK3, inhibiting its kinase activity. This blocks JAK3-mediated STAT5 phosphorylation, thereby inhibiting JAK3-dependent biological processes: T cell activation/proliferation (immune response) and head and neck squamous cell carcinoma (HNSCC) cell migration/invasion (tumor metastasis) [1,3].
- Drug class and application (cited from [1]): ZM 39923 HCl belongs to the naphthone class of compounds and is the first reported selective JAK3 inhibitor. It is mainly used as a research tool to study the role of the JAK3 signaling pathway in immune response and cancer [1]
- Application in cancer research (cited from [3]): ZM 39923 HCl was used to verify the role of JAK3 in the metastasis of CCR7-dependent head and neck squamous cell carcinoma (HNSCC): its ability to inhibit migration/invasion confirms that JAK3 is a potential therapeutic target for metastatic HNSCC [3]

C23H25NO.HCL

367.91

367.17

1021868-92-7

ZM39923;273727-89-2

176406

White to off-white solid powder

6.955

1

2

7

26

412

0

NJTUORMLOPXPBY-UHFFFAOYSA-N

InChI=1S/C23H25NO.ClH/c1-18(2)24(17-19-8-4-3-5-9-19)15-14-23(25)22-13-12-20-10-6-7-11-21(20)16-22;/h3-13,16,18H,14-15,17H2,1-2H3;1H

3-[benzyl(propan-2-yl)amino]-1-naphthalen-2-ylpropan-1-one;hydrochloride

2934.99.9001

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, avoid exposure to moisture.

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

Solubility in Formulation 1: ≥ 2.5 mg/mL (6.80 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 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.

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Solubility in Formulation 2: ≥ 2.5 mg/mL (6.80 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.

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Solubility in Formulation 3: ≥ 2.5 mg/mL (6.80 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.

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 (Please use freshly prepared in vivo formulations for optimal results.)