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| 25mg |
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| Other Sizes |
Purity: ≥98%
| Targets |
VU0529331 (CAS#: 1286725-49-2) targets homomeric GIRK2 channels (EC₅₀ = 5.1 μM, 95% CI 4.7–5.4 μM; efficacy 100% normalized to max compound activity).[1]
Targets GIRK1/2 heteromeric channels (EC₅₀ = 5.2 μM, 95% CI 4.3–6.3 μM; efficacy 25.9% ± 2.4% normalized to VU0466551 max).[1] Targets GIRK1/4 (EC₅₀ = 4.8 μM, 95% CI 4.2–5.4 μM; efficacy 18.1% ± 1.1%).[1] Targets homomeric GIRK4 channels (EC₅₀ = 22.3 μM, 95% CI 21.1–23.7 μM; efficacy 100%).[1] Targets Kir6.1/SUR2a (EC₅₀ = 15.7 μM, 95% CI 13.8–17.8 μM; efficacy 1418% ± 108% normalized to pinacidil).[1] Targets Kir6.1/SUR2b (EC₅₀ = 1.23 μM, 95% CI 1.21–1.25 μM; efficacy 127% ± 2%).[1] Inactive on Kir6.2/SUR1, Kir4.1, Kir2.1, Slack, Kv2.1, α1β2 MaxiK, α1β4 MaxiK, α1 GlyR, and untransfected HEK293 cells.[1] VU0529331 targets G protein-gated inwardly-rectifying potassium (GIRK/Kir3) channels, which are activated by Gβγ subunits following G protein-coupled receptor stimulation. It exhibits modest selectivity for non-GIRK1-containing channels (GIRK2 homomers and GIRK2/X heteromers) over GIRK1-containing channels. |
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| ln Vitro |
VU0529331 (CAS#: 1286725-49-2) activates homomeric GIRK2 channels in HEK293 cells with an EC₅₀ of 5.1 μM (95% CI 4.7–5.4) as measured by thallium flux assay. Efficacy was normalized to a maximally effective concentration of the compound.[1]
It activates GIRK1/2 heteromeric channels with an EC₅₀ of 5.2 μM (95% CI 4.3–6.3) and efficacy of 25.9% (±2.4%) relative to the selective GIRK1/X activator VU0466551.[1] It activates GIRK1/4 with an EC₅₀ of 4.8 μM (95% CI 4.2–5.4) and efficacy of 18.1% (±1.1%).[1] It activates homomeric GIRK4 with an EC₅₀ of 22.3 μM (95% CI 21.1–23.7) and full efficacy (100%).[1] In whole‑cell patch‑clamp electrophysiology, 80 μM VU0529331 significantly increased both inward and outward currents in GIRK2‑expressing HEK293 cells (at −100 mV and −30 mV) and in GIRK1/2‑expressing cells, with greater fold activation on GIRK2 than GIRK1/2 at −10 mV. The compound did not alter inward rectification ratio or K⁺ selectivity (reversal potential unchanged). Current increases were concentration‑dependent and blocked by 2 mM Ba²⁺.[1] VU0529331 activated Kir6.1/SUR2a and Kir6.1/SUR2b channels with EC₅₀ of 15.7 μM and 1.23 μM respectively, but was inactive on Kir6.2/SUR1, Kir4.1, Kir2.1, Slack, Kv2.1, MaxiK (α1β2 and α1β4), and α1 glycine receptors.[1] The compound did not activate α1 GlyR nor potentiate glycine‑induced responses, as measured by SuperClomeleon chloride influx assay.[1] VU0529331 activates GIRK2 and GIRK1/2 channels expressed in HEK293 cells with EC50 values of 5.1 µM and 5.2 µM, respectively. At 80 µM, it increases functional currents through GIRK2 and GIRK1/2 channels while preserving their inherent inward rectification and K+ selectivity, with greater activity on GIRK2 channels. The compound is also effective on GIRK4 homomeric channels. |
| ln Vivo |
In vivo activity data for VU0529331 are limited. As a first-in-class GIRK channel activator, its primary application is in understanding GIRK channel physiology and as a tool compound. It has potential utility in studying neurological and cardiac conditions where GIRK channels play important roles. Further in vivo characterization in animal models is ongoing.
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| Enzyme Assay |
The cell-free assay for VU0529331 typically utilizes fluorescence-based membrane potential or ion flux assays to monitor GIRK channel activity. Alternatively, electrophysiological recordings (patch-clamp) can be performed on excised membrane patches or liposomes containing purified GIRK channels. The compound is applied at varying concentrations, and channel activation is measured as increased K+ conductance or fluorescence signal. EC50 values are determined from concentration-response curves.
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| Cell Assay |
Thallium flux assay: HEK293 cells expressing target channels were plated in 384‑well plates, loaded with Thallos‑AM dye, then incubated with test compounds. After 120 s, Tl⁺ stimulus buffer was added and fluorescence (ex 482±35 nm, em 536±40 nm) was recorded at 5 Hz. Data were normalized and control‑subtracted. For GIRK2 screening, cells also expressed NPY4R and were partially activated with an EC₃₀ concentration of hPP. Compound activity was quantified as change in amplitude (A) after stimulus addition. EC₅₀ values were fitted to a four‑parameter logistic equation.[1]
Whole‑cell patch‑clamp electrophysiology: HEK293 cells expressing GIRK2 or GIRK1/2 were patched with borosilicate glass electrodes (3‑7 MΩ) filled with intracellular solution (130 mM KCl, 20 mM NaCl, 5 mM EGTA, 5.46 mM MgCl₂, 10 mM HEPES, pH 7.4). External solution was 20K extracellular solution (20 mM KCl, 140 mM NaCl, 0.5 mM CaCl₂, 2 mM MgCl₂, 10 mM glucose, 10 mM HEPES, pH 7.4). Currents were recorded at holding potentials from −100 mV to +10 mV in 10 mV steps, or at −60 mV for concentration‑response and Ba²⁺ block. Compounds were applied via local superfusion. Data were analyzed using PatchMaster and Excel.[1] SuperClomeleon chloride influx assay for α1 GlyR: T‑REx‑HEK293 cells stably expressing SuperClomeleon and KCC2 were transiently transfected with α1 GlyR. Cells were loaded with tetracycline to induce KCC2. After compound addition (including VU0529331 and ivermectin) and then glycine addition, FRET ratio (CFP/YFP) was measured. Increased signal indicates increased intracellular Cl⁻.[1] HEK293 cells stably or transiently expressing GIRK2, GIRK1/2, or GIRK4 channels are cultured and loaded with fluorescent K+-sensitive or membrane potential dyes. Cells are stimulated with increasing concentrations of VU0529331 (typically up to 80 µM), and fluorescence changes are recorded in real-time using a fluorescence plate reader. Alternatively, whole-cell patch-clamp electrophysiology is used to directly measure compound-induced GIRK currents while preserving channel rectification and ion selectivity. |
| Animal Protocol |
In vivo animal studies for VU0529331 are not extensively reported in the literature. As a tool compound, it would typically be administered via intraperitoneal or intravenous injection in rodents. Brain penetration and target engagement could be assessed by measuring compound levels in brain tissue and evaluating GIRK channel activity in brain slices or primary neuronal cultures. Behavioral assays relevant to GIRK channel function (e.g., pain, seizure, or addiction models) may be employed.
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| ADME/Pharmacokinetics |
Pharmacokinetic properties of VU0529331 have not been comprehensively reported. As a small molecule (MW 384.43) with moderate lipophilicity, it is expected to have reasonable membrane permeability and potential for central nervous system penetration. The compound is soluble in DMSO. Detailed PK parameters such as half-life, clearance, volume of distribution, and oral bioavailability remain to be determined in preclinical studies.
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| Toxicity/Toxicokinetics |
Toxicity data for VU0529331 are limited. As a research tool compound, standard safety pharmacology and toxicology assessments (e.g., hERG liability, CYP inhibition, Ames test, and acute toxicity in rodents) would be required for development. The compound's activity on GIRK channels, which are widely expressed in the brain and heart, suggests that off-target effects on cardiac or neuronal function could be a potential concern at higher concentrations.
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| References | |
| Additional Infomation |
VU0529331 (CAS#: 1286725-49-2) is the first reported synthetic small molecule activator of non‑GIRK1/X channels (homomeric GIRK2 and GIRK4). It was discovered through a high‑throughput screen of ~100,000 compounds using a thallium flux assay on G2Y4 cells (HEK293 expressing GIRK2 and NPY4R). The compound shows modest potency (EC₅₀ ~5 μM on GIRK2) and is inactive on many other K⁺ channels and Cys‑loop receptors, unlike ivermectin. However, it does activate Kir6.1/SUR2 channels. Analogs tested (43 purchased, 4 synthesized) did not improve activity. The compound is intended as a chemical probe to study the role of non‑GIRK1/X channels in addiction and reward.[1]
VU0529331 (molecular formula C22H20N6O, MW 384.43) was discovered through screening efforts to identify selective activators of non-GIRK1-containing GIRK channels. It represents the first synthetic small molecule reported to activate non-GIRK1/X channels and serves as a valuable probe for studying the physiological roles of GIRK2-containing channels. The compound is intended for research use only. |
| Molecular Formula |
C22H20N6O
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|---|---|
| Molecular Weight |
384.43380355835
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| Exact Mass |
384.169
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| CAS # |
1286725-49-2
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| PubChem CID |
52417637
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| Appearance |
White to off-white solid powder
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| LogP |
2.1
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| Hydrogen Bond Donor Count |
0
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| Hydrogen Bond Acceptor Count |
4
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| Rotatable Bond Count |
3
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| Heavy Atom Count |
29
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| Complexity |
596
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| Defined Atom Stereocenter Count |
0
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| SMILES |
O=C(C1C=NC=CN=1)N1CC2C(=C(N3C=CC=C3)N(C3C=CC(C)=C(C)C=3)N=2)C1
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| InChi Key |
KKICJSSCAYMJOA-UHFFFAOYSA-N
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| InChi Code |
InChI=1S/C22H20N6O/c1-15-5-6-17(11-16(15)2)28-21(26-9-3-4-10-26)18-13-27(14-20(18)25-28)22(29)19-12-23-7-8-24-19/h3-12H,13-14H2,1-2H3
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| Chemical Name |
(2-(3,4-Dimethylphenyl)-3-(1H-pyrrol-1-yl)-2,6-dihydropyrrolo[3,4-c]pyrazol-5(4H)-yl)(pyrazin-2-yl)methanone
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| Synonyms |
VU-0529331; VU 0529331; VU0529331
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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 |
| 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 : ~5 mg/mL (~13.01 mM)
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|---|---|
| Solubility (In Vivo) |
Solubility in Formulation 1: ≥ 1.25 mg/mL (3.25 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 12.5 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: ≥ 1.25 mg/mL (3.25 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 12.5 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 | 2.6013 mL | 13.0063 mL | 26.0125 mL | |
| 5 mM | 0.5203 mL | 2.6013 mL | 5.2025 mL | |
| 10 mM | 0.2601 mL | 1.3006 mL | 2.6013 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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