The drug is described to act via antioxidant activity, activation of the succinate dehydrogenase pathway of glucose oxidation, and inhibition of free radical oxidation of biomembrane lipids. It also increases superoxide dismutase activity and blocks leukotriene formation. No IC50, Ki, EC50, or binding affinity values are provided. [1]
The mechanism of action of Emoxypine Succinate involves multiple molecular targets and signaling pathways. Its primary actions include: functioning as an antioxidant that scavenges free radicals and inhibits lipid peroxidation ; modulating monoamine oxidase activity—in vitro studies show a 34-44% reduction in MAO-A activity and 9-10% reduction in MAO-B activity ; exerting iron-chelating properties that bind excess iron ions ; inhibiting NLRP3 inflammasome activation, thereby reducing expression of pro-inflammatory cytokines such as IL-1β and TNF-α ; modulating ion channels of the NMDA receptor complex to inhibit glutamatergic excitotoxicity ; while also enhancing binding interactions at the GABA-benzodiazepine receptor complex to exert anxiolytic effects .

Emoxypine succinate reduces transmembrane potential, which damages the inner mitochondrial membrane and produces an excessive amount of reactive oxygen species [1].

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In vitro studies demonstrate that Emoxypine Succinate exhibits multiple biological activities. In enzyme activity assays, the compound significantly inhibits MAO-A (by 34-44%) and MAO-B (by 9-10%) activities within the pharmacokinetic concentration range (10⁻⁹ to 10⁻⁶ M) . Additionally, emoxypine exhibits iron-chelating properties, binding free iron ions, which provides a theoretical basis for its potential application in neurodegenerative diseases (such as Alzheimer's disease) and hematological disorders (such as thalassemia and hemochromatosis) . In isolated heart perfusion experiments, emoxypine at a concentration of 5×10⁻⁴ M increases the outflow rate of perfusate from isolated rat hearts and reduces potassium-induced contraction in isolated coronary artery segments, demonstrating direct coronary vasodilatory effects .

- Effect on reactive oxygen species (ROS) production by leukocytes: In rats with combined trauma, ROS production increased 2.5-fold at 24 hours, 2.8-fold at 3 days, and peaked at 3.2-fold at 7 days compared to control. With emoxypine succinate treatment (40 mg/kg/day intraperitoneally for 14 days), ROS production began to decline after 3 days, with maximal effect at 7 days. By day 28, ROS production decreased by 39.8% compared to untreated trauma rats. [1]
- Effect on percentage of leukocytes with low mitochondrial transmembrane potential (Δψ): In untreated trauma rats, the percentage of leukocytes with low Δψ peaked at 7 days (2.6 times higher than control). With emoxypine succinate treatment, this percentage decreased by 34.6% by day 28 compared to untreated trauma rats. [1]
- Effect on apoptosis (FITC Annexin V-positive leukocytes): In untreated trauma rats, the percentage of apoptotic leukocytes increased progressively, with highest values at 7-14 days (44.4% higher than control). With emoxypine succinate treatment, the percentage of Annexin V-positive cells on day 28 decreased by 16.7% compared to untreated trauma rats. The drug’s effect on apoptosis appeared after 3 days of observation with maximum action at 7 days. [1]

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Emoxypine succinate (ip; 40 mg/kg; once daily for 14 days) decreases the percentage of FITC annexin V-positive cells in leukocyte suspensions, the percentage of leukocyte mitochondrial transmembrane potential, and the generation of reactive oxygen species [1].

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In vivo studies demonstrate that Emoxypine Succinate exhibits significant neuroprotective and anti-inflammatory activities in various animal models. In a zebrafish model of iron overload-induced neuroinflammation, emoxypine succinate treatment groups (4, 8, 12 mg/L for 14 days) showed significantly improved behavioral performance: in the novel tank test, treated groups exhibited significantly increased time in the upper zone (p < 0.001) and shorter latency to the top; in the Y-maze test, both time in the novel arm and total distance traveled were significantly increased (p < 0.001) . Biochemical analysis showed significant reductions in oxidative stress markers, as well as significant decreases in acetylcholinesterase (AChE) activity and brain iron levels (p < 0.001) in treated groups. Molecular analysis confirmed significant reductions in pro-inflammatory markers including IL-1β, TNF-α, CDK-5, GSK-3β, and NLRP3 (p < 0.001) . Furthermore, in a rat model of coronary artery administration, emoxypine dose-dependently increased mean coronary blood flow .

- Measurement of reactive oxygen species (ROS): Blood leukocyte samples were analyzed by flow laser cytometry using 2,7-dichlorodihydrofluorescein diacetate. The value was expressed as a percentage (intensity of luminescence per cell). [1]
- Measurement of mitochondrial transmembrane potential (Δψ): The number of leukocytes with low mitochondrial transmembrane potential was evaluated by flow laser cytometry using a MitoScreen reagent kit. [1]
- Measurement of apoptosis: The percentage of apoptotic leukocytes was evaluated by flow laser cytometry using an Annexin V FITC reagent kit. Leukocyte suspension was resuspended in binding buffer, adjusted to 1×10⁶ cells/mL, mixed with Annexin V-FITC solution and propidium iodide (PI), and incubated at room temperature. Cells were classified as: alive (Annexin V⁻/PI⁻), apoptotic (Annexin V⁺/PI⁻), and necrotic (Annexin V⁺/PI⁺). [1]

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In vitro enzyme activity studies of Emoxypine Succinate primarily focus on its modulation of monoamine oxidase. A typical protocol includes: 1) Prepare mitochondrial fractions from rat liver as a source of MAO enzyme; 2) Dissolve Emoxypine Succinate in appropriate buffer to prepare serial concentrations (10⁻⁹ to 10⁻⁶ M); 3) Pre-incubate the drug with the enzyme preparation for 10 minutes at 37°C; 4) Add specific substrates: serotonin for MAO-A or phenylethylamine for MAO-B; 5) Incubate for 30-60 minutes at 37°C; 6) Detect reaction product formation (e.g., aldehydes) using fluorometric or spectrophotometric methods; 7) Calculate the percentage inhibition of MAO-A and MAO-B activity to evaluate the modulatory effect of the drug. Studies show that emoxypine reduces MAO-A activity by 34-44% and MAO-B activity by 9-10% within the pharmacokinetic concentration range .

Since all experiments were conducted on whole blood leukocyte suspensions from rats, no isolated cell culture experiments are described. The following assays were performed on ex vivo leukocyte samples: ROS measurement via DCFH-DA staining and flow cytometry; mitochondrial transmembrane potential measurement via MitoScreen kit and flow cytometry; apoptosis measurement via Annexin V-FITC/PI staining and flow cytometry. [1]

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The in vitro cell assay protocol for Emoxypine Succinate is as follows: 1) Seed target cells (e.g., primary neurons, PC12 cells, or hepatocytes) in culture plates and culture to appropriate density at 37°C with 5% CO₂; 2) Pre-treat cells with various concentrations of Emoxypine Succinate (typically 1-100 μM) for 12-24 hours; 3) Expose to injury conditions, such as H₂O₂-induced oxidative stress, iron overload, or hypoxia/reoxygenation injury; 4) Assess cell viability using MTT or CCK-8 assays; 5) Measure intracellular reactive oxygen species levels using fluorescent probes; 6) Detect relevant protein expression (e.g., NLRP3, caspase-1, IL-1β, CDK-5, and GSK-3β) by Western blot; 7) Determine apoptosis rate by flow cytometry or TUNEL staining. Such experiments have demonstrated that Emoxypine Succinate significantly attenuates oxidative stress and inflammatory responses .

- Animals: Male, non-linear, white rats (200-210 g body weight) were housed at 25±3°C, 55±2% humidity, 12-hour light/dark cycle, with water ad libitum. [1]
- Combined trauma model: Right-sided closed pneumothorax with rib fracture combined with closed fractures of left and right femurs was modeled under sodium thiopental anesthesia (40 mg/kg). Skeletal injury was induced by a single dosed impact (0.375 J) on each thigh using a specially designed device, causing moderate-severity closed fractures. Combined injury was produced by sequential application of both injuries. Mortality: 11 rats. [1]
- Drug administration: Emoxypine succinate was injected intraperitoneally once per day for 14 days starting from the first day of the experiment at a dosage of 40 mg/kg. [1]
- Euthanasia: Rats were euthanized at 24 hours, 3 days, 7 days, 14 days, and 28 days after trauma by administration of sodium thiopental (90 mg/kg). [1]
- Control group: Control rats (n=10) received no trauma or drug treatment. [1]
- Experimental groups: Ten experimental groups (E1-E10) were defined based on time points (24h, 3d, 7d, 14d, 28d) with or without emoxypine succinate treatment. [1]
- Ethical compliance: All procedures followed the European Convention for the Protection of Vertebrate Animals used for Experimental and Other Scientific Purposes (Strasbourg, 1986). The study was approved by the Human Research Ethic Review Committee, I Danylo Halytskyi Lviv National Medical University, Ukraine. [1]

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Animal/Disease Models: Rat[1]
Doses: 40 mg/kg
Route of Administration: intraperitoneal (ip) injection, one time/day, 14 days
Experimental Results: Dramatically increased the percentage of Annexin V-positive cells, diminished the percentage of leukocyte apoptosis, and diminished the production of leukocytes Reactive oxygen species.

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An in vivo animal assay protocol for Emoxypine Succinate, using a zebrafish neuroinflammation model as an example: 1) Use adult zebrafish and induce iron overload-induced neurodegeneration by adding iron ions (e.g., FeSO₄) to the tank water for 28 consecutive days; 2) Randomly divide zebrafish into model control, vehicle control, and emoxypine succinate treatment groups (concentrations of 4, 8, and 12 mg/L); 3) Add corresponding drug concentrations to the tank water of treatment groups for 14 consecutive days; 4) Behavioral testing: perform novel tank test to assess anxiety-like behavior and exploratory behavior, and Y-maze test to assess spatial memory; 5) Biochemical assays: measure malondialdehyde, catalase, superoxide dismutase, and glutathione levels in brain tissue; 6) Molecular analysis: detect expression levels of AChE, iron content, IL-1β, TNF-α, CDK-5, GSK-3β, and NLRP3 by qPCR or Western blot . In rat models, the compound can also be administered via intracoronary injection or intraperitoneal injection (25 mg/kg) .

Pharmacokinetic studies of Emoxypine Succinate demonstrate favorable absorption and tissue distribution properties. Due to its low molecular weight (255.26 Da) and moderate lipophilicity, the compound effectively penetrates the blood-brain barrier to reach the central nervous system . The elimination half-life in vivo is 2-2.5 hours, indicating moderate rates of metabolism and clearance . The compound is rapidly absorbed and widely distributed throughout various tissues. As a succinic acid derivative, Emoxypine Succinate exhibits "energotropic" properties: the succinate moiety undergoes oxidation by mitochondrial succinate dehydrogenase, providing an energy-rich substrate that helps maintain ATP synthesis under hypoxic or ischemic conditions . It is primarily metabolized in the liver, with metabolites excreted via the kidneys.

Based on available research data, Emoxypine Succinate demonstrates a favorable safety and tolerability profile. In preclinical studies, the compound exhibits a wide therapeutic index with no significant toxicity observed at conventional therapeutic doses. Zebrafish model studies show no obvious developmental toxicity or lethal effects during 14 days of continuous administration at concentrations ranging from 4-12 mg/L . As a drug that has been used clinically in Russia for many years, the safety of Mexidol in humans has been extensively validated, with common adverse reactions being rare and mild, primarily including occasional drowsiness, dry mouth, or mild gastrointestinal discomfort in some patients. The compound is not classified as a carcinogen by NTP, IARC, or OSHA. It is worth noting that Emoxypine Succinate has not yet received FDA approval for marketing and is primarily used for scientific research purposes in the United States and Europe .

[1]. Features of leukocytes’ apoptosis and emoxypine succinate efficacy in case of combined trauma of the chest and both thighs in rats. Bangladesh Journal of Medical Science, (2019). 18(2), 244-251.

- Chemical structure: 2-ethyl-6-methyl-3-hydroxypyridine succinate. The structure resembles that of pyridoxine (vitamin B6). It contains succinate as a component which functions as a substrate for increasing intracellular energy metabolism. [1]
- Mechanism of action (as described in the manuscript): Emoxypine succinate effectively inhibits free radical oxidation of biomembrane lipids, reacts with peroxide radicals of lipids, primary and hydroxyl radicals of peptides. It increases the activity of antioxidant enzymes, specifically superoxide dismutase, which is responsible for the formation and consumption of lipid peroxides and active oxygen forms. It inhibits free radicals during prostaglandin synthesis catalyzed by cyclooxygenase and lipoxygenase, increases the prostacyclin/thromboxane A2 ratio, and blocks leukotriene formation. It also activates the succinate dehydrogenase pathway of glucose oxidation, shifting cellular metabolism to a more oxygen-saving direction of energy exchange. The drug enters the cell cytosol and dissociates into two components, each acting independently. [1]
- Pharmacological effects: Emoxypine succinate has anxiolytic, antistress, anti-alcohol, anticonvulsant, neuroprotective, and vegetotropic actions. It improves cerebral blood circulation, inhibits platelet aggregation, lowers cholesterol levels, and has cardioprotective and antiatherosclerotic effects. [1]
- Advantage over other cytoprotectants: The ability to directly increase mitochondrial energy production by improving the delivery and consumption of succinate under hypoxic conditions, activating the mitochondrial respiratory chain and leading to ATP resynthesis. [1]
- Efficacy in combined trauma: The study concludes that emoxypine succinate has a positive effect in reducing ROS production, reducing the percentage of leukocytes with low mitochondrial transmembrane potential, and reducing the percentage of apoptotic leukocytes in rats with combined chest and thigh trauma. The effect appears after 3 days of observation with maximum action at 7 days. However, the incomplete reduction of Annexin V-positive cells suggests that other non-mitochondrial mechanisms of apoptosis initiation also exist. [1]

C12H17NO5

255.27

255.11

C, 56.46; H, 6.71; N, 5.49; O, 31.34

127464-43-1

2364-75-2

122298

White to off-white solid powder

280.6ºC at 760 mmHg

113 °C

123.5ºC

0.0022mmHg at 25°C

1.593

3

6

4

18

198

0

CCC1=C(C=CC(=N1)C)O.C(CC(=O)O)C(=O)O

IKMNOGHPKNFPTK-UHFFFAOYSA-N

InChI=1S/C8H11NO.C4H6O4/c1-3-7-8(10)5-4-6(2)9-7;5-3(6)1-2-4(7)8/h4-5,10H,3H2,1-2H3;1-2H2,(H,5,6)(H,7,8)

butanedioic acid;2-ethyl-6-methylpyridin-3-ol

Mexidol; mexidol; Emoxypine succinate; methylethylpiridinol succinate; 2R985002CT; Emoxypine Succinate

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)

H2O : ~250 mg/mL (~979.36 mM)

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.

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Injection Formulation 1: DMSO : Tween 80： Saline = 10 : 5 : 85 (i.e. 100 μL DMSO stock solution → 50 μL Tween 80 → 850 μL Saline)
*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).

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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)]
*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.
Injection Formulation 5: 2-Hydroxypropyl-β-cyclodextrin : Saline = 50 : 50 (i.e. 500 μL 2-Hydroxypropyl-β-cyclodextrin → 500 μL Saline)
Injection Formulation 6: DMSO : PEG300 : castor oil : Saline = 5 : 10 : 20 : 65 (i.e. 50 μL DMSO → 100 μLPEG300 → 200 μL castor oil → 650 μL Saline)
Injection Formulation 7: Ethanol : Cremophor : Saline = 10： 10 : 80 (i.e. 100 μL Ethanol → 100 μL Cremophor → 800 μL Saline)
Injection Formulation 8: Dissolve in Cremophor/Ethanol (50 : 50), then diluted by Saline
Injection Formulation 9: EtOH : Corn oil = 10 : 90 (i.e. 100 μL EtOH → 900 μL Corn oil)
Injection Formulation 10: EtOH : PEG300：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL EtOH → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)

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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).

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Oral Formulation 3: Dissolved in PEG400
Oral Formulation 4: Suspend in 0.2% Carboxymethyl cellulose
Oral Formulation 5: Dissolve in 0.25% Tween 80 and 0.5% Carboxymethyl cellulose
Oral Formulation 6: Mixing with food powders

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Note: Please be aware that the above formulations are for reference only. InvivoChem strongly recommends customers to read literature methods/protocols carefully before determining which formulation you should use for in vivo studies, as different compounds have different solubility properties and have to be formulated differently.

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