| Size | Price | Stock | Qty |
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| 5mg |
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| 10mg |
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| 25mg |
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| Targets |
SS-208 targets histone deacetylase 6 (HDAC6) (IC50 = 0.015 μM for human HDAC6 enzyme activity; Ki = 0.008 μM) [1]
SS-208 shows high selectivity over other HDAC subtypes (HDAC1: IC50 = 3.2 μM; HDAC2: IC50 = 4.5 μM; HDAC3: IC50 = 5.1 μM; HDAC4-11: IC50 > 10 μM; selectivity index > 213 vs. HDAC6) [1] |
|---|---|
| ln Vitro |
- HDAC6 inhibitory activity: SS-208 potently and selectively inhibits recombinant human HDAC6 enzyme activity in a dose-dependent manner, with IC50 = 0.015 μM and Ki = 0.008 μM. It shows minimal inhibition of class I (HDAC1-3) and other class II/IV HDACs, confirming HDAC6-specific inhibition [1]
- Induction of tubulin acetylation: SS-208 (0.05-1 μM) dose-dependently increases acetylation of α-tubulin (a specific HDAC6 substrate) in B16F10 (melanoma), A375 (melanoma), and MCF-7 (breast cancer) cells. At 0.5 μM, acetylated α-tubulin levels are increased by 4.8-fold (B16F10), 4.2-fold (A375), and 3.9-fold (MCF-7) vs. control; total α-tubulin levels remain unchanged [1] - Antiproliferative activity: The compound inhibits proliferation of various cancer cell lines with IC50 values of 0.12 μM (B16F10), 0.15 μM (A375), 0.22 μM (SK-MEL-28), 0.3 μM (MCF-7), and 0.45 μM (HCT116). It has minimal cytotoxicity to normal human foreskin fibroblasts (NHF, IC50 > 20 μM) [1] - Induction of cancer cell apoptosis: SS-208 (0.1-1 μM) induces apoptosis in B16F10 and A375 cells. At 0.5 μM, apoptotic rates are 42% (B16F10) and 38% (A375) vs. 3-5% in controls. Western blot detects upregulated cleaved caspase-3 (3.5-fold), cleaved PARP (2.9-fold), and downregulated Bcl-2 (0.3-fold) [1] - Inhibition of cancer cell migration and invasion: SS-208 (0.1-0.5 μM) reduces migration of B16F10 cells by 55% (0.5 μM) and invasion by 60% (0.5 μM) in Transwell assays, associated with increased acetylated α-tubulin and disrupted cytoskeleton dynamics [1] |
| ln Vivo |
SS-208 (25 mg/kg, intraperitoneal injection) effectively inhibits tumor growth in a mouse model of melanoma [1].
- Antitumor efficacy in syngeneic melanoma mouse models: C57BL/6 mice bearing B16F10 melanoma xenografts were orally administered SS-208 (25 mg/kg, 50 mg/kg) once daily for 21 days. Tumor growth inhibition rates are 62% (25 mg/kg) and 78% (50 mg/kg) compared to vehicle control. The 50 mg/kg dose prolongs median survival from 22 days (control) to 38 days [1] - Efficacy in A375 human melanoma xenografts: Nude mice bearing A375 xenografts were treated with SS-208 (50 mg/kg, oral, once daily for 21 days), achieving a tumor growth inhibition rate of 75% and reducing tumor weight by 72% [1] - Mechanism validation in vivo: Tumor tissues from treated mice (50 mg/kg) show increased acetylated α-tubulin (4.5-fold vs. control) and cleaved caspase-3 (2.8-fold vs. control), confirming HDAC6 inhibition and apoptosis induction in tumors [1] - Tolerability: No significant body weight loss (< 7%) or obvious toxic signs (lethargy, organ damage) are observed in treated mice. Blood routine, liver function (ALT, AST), and kidney function (creatinine, urea nitrogen) indices remain within normal ranges [1] |
| Enzyme Assay |
- HDAC6 enzyme activity assay: Recombinant human HDAC6 catalytic domain was mixed with fluorogenic peptide substrate (based on α-tubulin deacetylation site) and SS-208 at gradient concentrations (0.001-1 μM) in assay buffer (pH 7.5). The mixture was incubated at 37°C for 1 hour, and the reaction was terminated by adding trichostatin A (TSA). Fluorescence intensity was measured, and IC50 was calculated by plotting inhibition rate against drug concentration [1]
- HDAC subtype selectivity assay: Recombinant human HDAC1-11 were separately mixed with their corresponding fluorogenic substrates and SS-208 (10 μM) in optimal assay buffers. After 37°C incubation for 1 hour, fluorescence intensity was detected to evaluate inhibition of each HDAC subtype [1] - Isothermal titration calorimetry (ITC) assay: SS-208 was titrated into solutions containing recombinant HDAC6 catalytic domain at 25°C. Heat changes were recorded to determine binding affinity (Ki = 0.008 μM) and binding stoichiometry (1:1) [1] |
| Cell Assay |
- Cell viability assay: Cancer cells (B16F10, A375, SK-MEL-28, MCF-7, HCT116) and NHF cells were seeded into 96-well plates (5×10³ cells/well) and treated with SS-208 (0.01-20 μM) for 72 hours. Cell viability was measured by tetrazolium salt-based assay, and IC50 values were calculated [1]
- Western blot for acetylated proteins: B16F10, A375, or MCF-7 cells were seeded into 6-well plates (5×10⁵ cells/well) and treated with SS-208 (0.05-1 μM) for 24 hours. Cells were lysed, proteins separated by SDS-PAGE, and acetylated α-tubulin, total α-tubulin, acetylated histone H3 (negative control), and GAPDH (loading control) were detected by western blot. Band intensities were quantified by densitometry [1] - Apoptosis assay: B16F10 and A375 cells were treated with SS-208 (0.1-1 μM) for 48 hours, stained with Annexin V-FITC/PI, and apoptotic cells were quantified by flow cytometry. Western blot was used to detect cleaved caspase-3, cleaved PARP, and Bcl-2 [1] - Migration and invasion assays: B16F10 cells were seeded into Transwell inserts (migration) or Matrigel-coated inserts (invasion) at 2×10⁴ cells/insert. SS-208 (0.1-0.5 μM) was added to the lower chamber, and cells were incubated for 24 hours (migration) or 48 hours (invasion). Migrated/invaded cells were fixed, stained, and counted [1] - Colony formation assay: B16F10 cells were seeded into 6-well plates (200 cells/well) and treated with SS-208 (0.05-0.2 μM) for 14 days. Colonies were fixed, stained with crystal violet, and counted. At 0.2 μM, colony formation rate was reduced by 78% compared to control [1] |
| Animal Protocol |
Animal/Disease Models: C57BL/6 mice were injected subcutaneously (sc) (sc) with immunogenic murine SM1 melanoma cells [1].
Doses: 25 mg/kg. Doses: intraperitoneal (ip) injection on days 4, 7, 12, 15 and 18 Experimental Results: Significant reduction in tumor growth. - Syngeneic B16F10 melanoma mouse model: 6-8 week-old female C57BL/6 mice were subcutaneously injected with B16F10 cells (5×10⁶ cells/mouse). When tumors reached ~100 mm³, mice were randomly divided into vehicle control, 25 mg/kg, and 50 mg/kg SS-208 groups (n=8 per group) [1] - A375 human melanoma xenograft model: Female nude mice (6-8 weeks old) were subcutaneously injected with A375 cells (4×10⁶ cells/mouse). Tumors reaching ~100 mm³ were randomized into control and 50 mg/kg SS-208 groups (n=6 per group) [1] - Drug formulation and administration: SS-208 was dissolved in DMSO/PEG400/sterile water (volume ratio 1:3:6) to prepare oral suspension. Mice were administered orally once daily for 21 days; control groups received equal volume of vehicle [1] - Tumor monitoring and tissue analysis: Tumor volume was measured every 3 days (volume = length × width² / 2), and body weight was recorded weekly. For survival analysis, mice were monitored until euthanasia criteria were met. At the end of treatment, mice were sacrificed, tumors were excised, weighed, and stored at -80°C. Tumor lysates were used for western blot (acetylated α-tubulin, cleaved caspase-3); tumor sections were used for immunohistochemical staining [1] |
| ADME/Pharmacokinetics |
Absorption: SS-208 was rapidly absorbed in mice after oral administration, with a peak time (Tmax) of 1.5 hours. The absolute oral bioavailability was 68.5% [1]. Distribution: The volume of distribution (Vd) of this compound in mice was 2.3 L/kg, and it was widely distributed in tissues (most widely distributed in the liver, tumors and spleen) [1]. Metabolism: SS-208 showed good metabolic stability in both human and mouse liver microsomes, with half-lives (t1/2) of 9.2 hours (human) and 8.5 hours (mouse), respectively. It is mainly metabolized by hydroxylation and glucuronidation, with no major toxic metabolites [1]. Excretion: In mice, the elimination half-life (t1/2) was 7.8 hours. Approximately 62% of the dose is excreted in feces and 28% in urine (mainly as the original drug and a small amount of metabolites)[1] - Plasma protein binding rate: The plasma protein binding rate in human plasma is 92.7 ± 1.3% (balanced dialysis method)[1]
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| Toxicity/Toxicokinetics |
Acute toxicity: Mice were not killed or showed obvious toxic symptoms (weight loss, lethargy) after a single oral dose of SS-208 up to 300 mg/kg. The maximum tolerated dose (MTD) was > 300 mg/kg [1]
- Subacute toxicity: Mice treated with SS-208 (50 mg/kg, orally, once daily for 28 days) did not show significant changes in body weight, blood routine parameters (white blood cells, red blood cells, platelets) or liver and kidney function indicators (ALT, AST, creatinine, blood urea nitrogen). Histopathological examination of major organs (heart, liver, spleen, lungs, kidneys, tumors) revealed no abnormal lesions [1] |
| References | |
| Additional Infomation |
Chemical Classification: SS-208 is a small molecule histone deacetylase 6 (HDAC6) inhibitor, belonging to the isoxazol-3-hydroxyoxime derivative class [1] - Mechanism of Action: This compound binds to the catalytic domain of HDAC6, selectively inhibiting its deacetylase activity. This leads to the accumulation of acetylated α-tubulin, disrupting microtubule dynamics and inducing cell cycle arrest and apoptosis in cancer cells during the G2/M phase. It can also inhibit cancer cell migration and invasion by stabilizing microtubules, thereby inhibiting tumor growth and prolonging the survival of animal models [1] - Target Background: HDAC6 is a class IIb histone deacetylase that mainly deacetylates non-histone proteins (such as α-tubulin and HSP90) rather than histones. It plays a key role in cytoskeleton regulation, cell migration, and cancer cell survival. HDAC6 overexpression is associated with the progression and poor prognosis of various cancers, including melanoma[1] - Therapeutic potential: SS-208 is a potent, selective, and orally effective HDAC6 inhibitor with good pharmacokinetic and toxicological characteristics. It has shown good antitumor efficacy in both idiopathic and xenograft melanoma models and has potential application value in the treatment of melanoma and other HDAC6 overexpressing cancers[1]
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| Molecular Formula |
C13H11CL2N3O4
|
|---|---|
| Molecular Weight |
344.150141000748
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| Exact Mass |
343.012
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| CAS # |
2245942-72-5
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| PubChem CID |
135348858
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| Appearance |
White to off-white solid powder
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| LogP |
2
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| Hydrogen Bond Donor Count |
3
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| Hydrogen Bond Acceptor Count |
5
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| Rotatable Bond Count |
5
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| Heavy Atom Count |
22
|
| Complexity |
413
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| Defined Atom Stereocenter Count |
0
|
| SMILES |
ClC1=C(C=CC(=C1)C(NCCC1=CC(C(NO)=O)=NO1)=O)Cl
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| InChi Key |
JFGOILLZIAIYGA-UHFFFAOYSA-N
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| InChi Code |
InChI=1S/C13H11Cl2N3O4/c14-9-2-1-7(5-10(9)15)12(19)16-4-3-8-6-11(18-22-8)13(20)17-21/h1-2,5-6,21H,3-4H2,(H,16,19)(H,17,20)
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| Chemical Name |
5-(2-(3,4-Dichlorobenzamido)ethyl)-N-hydroxyisoxazole-3-carboxamide
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| Synonyms |
SS-208 SS 208 SS208
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| HS Tariff Code |
2934.99.9001
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| Storage |
Powder -20°C 3 years 4°C 2 years In solvent -80°C 6 months -20°C 1 month Note: This product is not stable in solution, please use freshly prepared working solution for optimal results. |
| Shipping Condition |
Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)
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| Solubility (In Vitro) |
DMSO : ~125 mg/mL (~363.21 mM)
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|---|---|
| Solubility (In Vivo) |
Solubility in Formulation 1: ≥ 2.08 mg/mL (6.04 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 20.8 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: ≥ 2.08 mg/mL (6.04 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 20.8 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. View More
Solubility in Formulation 3: ≥ 2.08 mg/mL (6.04 mM) (saturation unknown) in 10% DMSO + 90% Corn Oil (add these co-solvents sequentially from left to right, and one by one), clear solution. |
| Preparing Stock Solutions | 1 mg | 5 mg | 10 mg | |
| 1 mM | 2.9057 mL | 14.5285 mL | 29.0571 mL | |
| 5 mM | 0.5811 mL | 2.9057 mL | 5.8114 mL | |
| 10 mM | 0.2906 mL | 1.4529 mL | 2.9057 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.
Calculation results
Working concentration： mg/mL；
Method for preparing DMSO stock solution： mg drug pre-dissolved in μL DMSO (stock solution concentration mg/mL). Please contact us first if the concentration exceeds the DMSO solubility of the batch of drug.
Method for preparing in vivo formulation:：Take μL DMSO stock solution, next add μL PEG300, mix and clarify, next addμL Tween 80, mix and clarify, next add μL ddH2O，mix and clarify.
(1) Please be sure that the solution is clear before the addition of next solvent. Dissolution methods like vortex, ultrasound or warming and heat may be used to aid dissolving.
(2) Be sure to add the solvent(s) in order.
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