| Size | Price | Stock | Qty |
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| 1mg |
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| Other Sizes |
| Targets |
RARα[1]
ER 50891 specifically targets the retinoic acid receptor alpha (RARalpha), a member of the nuclear receptor superfamily of transcription factors. RARalpha binds all-trans retinoic acid (ATRA) as its endogenous ligand and regulates gene expression involved in development, differentiation, and apoptosis. ER 50891 functions as a competitive antagonist at RARalpha, blocking ATRA binding and subsequent transcriptional activation. |
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| ln Vitro |
In vitro, ER 50891 quarterhydrate rescues ATRA-inhibited osteocalcin (OCN) expression and extracellular matrix mineralization in osteoblast cultures. It suppresses alkaline phosphatase (ALP) activity synergistically with other modulators and restores BMP2-induced osteoblast differentiation. It also reduces the inhibitory effect of ATRA and restores osteoblast differentiation induced by BMP2. These effects are mediated through RARalpha antagonism.
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| ln Vivo |
In vivo, ER 50891 quarterhydrate is studied in animal models of ATRA-induced inhibition of osteoblastogenesis, such as in models of osteoporosis or bone healing. By antagonizing RARalpha, it counteracts the suppressive effects of endogenous retinoids or exogenous ATRA on bone formation. The compound can be used for the study of osteoporosis related to ATRA-induced inhibition of osteoblastogenesis, potentially promoting bone formation and mineralization.
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| Enzyme Assay |
For receptor binding assays: coat 96-well plates with purified RARalpha ligand-binding domain protein (LBD) at 0.5-2 ug/well. Incubate with 1-10 nM [3H]-ATRA and varying concentrations of ER 50891 (1 pM-10 uM) in binding buffer (50 mM Tris-HCl, 150 mM KCl, 1 mM DTT, 0.1% CHAPS, pH 7.4) for 2-4 hours at 4degC. Separate bound from free by washing with cold buffer. Measure radioactivity by scintillation counting. For competitive binding assays, use fluorescence polarization with fluorescently labeled ATRA tracer. Determine IC50 and Ki values by nonlinear regression.
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| Cell Assay |
Culture primary osteoblasts isolated from neonatal rat calvariae or use MC3T3-E1 mouse preosteoblast cell line. Culture in alpha-MEM with 10% FBS and 1% penicillin/streptomycin. Treat cells with BMP2 (50-100 ng/mL) to induce osteoblast differentiation, with or without ATRA (1-10 uM) and ER 50891 quarterhydrate (0.1-10 uM) for 7-21 days. Assess osteoblast differentiation by measuring alkaline phosphatase (ALP) activity using p-nitrophenyl phosphate substrate at 405 nm. Quantify mineralization by Alizarin Red S staining and calcium deposition by o-cresolphthalein complexone assay. Measure osteocalcin (OCN) and osteopontin (OPN) expression by qPCR and Western blot. Perform von Kossa staining for mineralized nodules.
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| Animal Protocol |
For osteoporosis or bone healing models, use ATRA-treated rodents or ovariectomized (OVX) rats with ATRA treatment to simulate ATRA-induced bone loss. Administer ER 50891 quarterhydrate via intraperitoneal (IP) injection at 1-10 mg/kg daily for 2-8 weeks. For pharmacokinetic analysis, collect blood at multiple time points. At study endpoint, harvest femurs and tibiae. Perform micro-CT analysis to quantify bone mineral density (BMD), trabecular bone volume fraction (BV/TV), trabecular number, thickness, and separation. Process bones for histomorphometry and staining for osteoblasts (ALP) and osteoclasts (TRAP). Alternatively, use calvarial bone defect models to assess bone regeneration.
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| ADME/Pharmacokinetics |
Pharmacokinetic data are limited for ER 50891. As a small molecule (MW approximately 437 for quarterhydrate), it is expected to have good oral bioavailability and tissue distribution. DMSO solubility is 25 mg/mL (57.21 mM). For in vivo administration, dissolve in DMSO and dilute in appropriate vehicle (e.g., PBS containing 10% DMSO, 40% PEG300, 5% Tween 80, 45% saline). Storage conditions: powder at -20degC; in solvent at -80degC for 6 months or -20degC for 1 month in sealed containers away from moisture.
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| Toxicity/Toxicokinetics |
Specific toxicity data for ER 50891 quarterhydrate are not widely available. As an experimental RARalpha antagonist, it is not approved for human use. In vitro studies show that the compound is well tolerated in osteoblast cultures at concentrations up to 10 uM. In animal models, no severe acute toxicity has been reported at doses of 1-10 mg/kg. Standard laboratory safety precautions should be followed. The compound should be handled as a potential irritant to eyes, skin, and respiratory tract.
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| References | |
| Additional Infomation |
The quarterhydrate designation indicates the compound contains 1/4 equivalent of water per molecule of ER 50891. This crystalline form provides improved stability during storage and handling compared to the anhydrous form. The compound has CAS number 187400-85-7 (anhydrous). ER 50891 is also known as ER-50891. It is a valuable research tool for studying RARalpha-mediated signaling in bone biology, osteoporosis, and developmental biology. For research use only.
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| Molecular Formula |
C29H24N2O2.1/4H2O
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|---|---|
| Molecular Weight |
437.02
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| Related CAS # |
ER 50891;187400-85-7
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| Appearance |
Light yellow to yellow solid powder
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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: Please store this product in a sealed and protected environment, avoid exposure to moisture. |
| 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) |
May dissolve in DMSO (in most cases), if not, try other solvents such as H2O, Ethanol, or DMF with a minute amount of products to avoid loss of samples
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| Solubility (In Vivo) |
Note: Listed below are some common formulations that may be used to formulate products with low water solubility (e.g. < 1 mg/mL), you may test these formulations using a minute amount of products to avoid loss of samples.
Injection Formulations
Injection Formulation 1: DMSO : Tween 80： Saline = 10 : 5 : 85 (i.e. 100 μL DMSO stock solution → 50 μL Tween 80 → 850 μL Saline)(e.g. IP/IV/IM/SC) *Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH ₂ O to obtain a clear solution. Injection Formulation 2: DMSO : PEG300 ：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL DMSO → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline) Injection Formulation 3: DMSO : Corn oil = 10 : 90 (i.e. 100 μL DMSO → 900 μL Corn oil) Example: Take the Injection Formulation 3 (DMSO : Corn oil = 10 : 90) as an example, if 1 mL of 2.5 mg/mL working solution is to be prepared, you can take 100 μL 25 mg/mL DMSO stock solution and add to 900 μL corn oil, mix well to obtain a clear or suspension solution (2.5 mg/mL, ready for use in animals). View More
Injection Formulation 4: DMSO : 20% SBE-β-CD in saline = 10 : 90 [i.e. 100 μL DMSO → 900 μL (20% SBE-β-CD in saline)] Oral Formulations
Oral Formulation 1: Suspend in 0.5% CMC Na (carboxymethylcellulose sodium) Oral Formulation 2: Suspend in 0.5% Carboxymethyl cellulose Example: Take the Oral Formulation 1 (Suspend in 0.5% CMC Na) as an example, if 100 mL of 2.5 mg/mL working solution is to be prepared, you can first prepare 0.5% CMC Na solution by measuring 0.5 g CMC Na and dissolve it in 100 mL ddH2O to obtain a clear solution; then add 250 mg of the product to 100 mL 0.5% CMC Na solution, to make the suspension solution (2.5 mg/mL, ready for use in animals). View More
Oral Formulation 3: Dissolved in PEG400 (Please use freshly prepared in vivo formulations for optimal results.) |
| Preparing Stock Solutions | 1 mg | 5 mg | 10 mg | |
| 1 mM | 2.2882 mL | 11.4411 mL | 22.8822 mL | |
| 5 mM | 0.4576 mL | 2.2882 mL | 4.5764 mL | |
| 10 mM | 0.2288 mL | 1.1441 mL | 2.2882 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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