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| 1mg |
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| Targets |
Oxalic acid-13C2 is a stable isotope-labeled version of oxalic acid. The unlabeled compound, oxalic acid, is not a drug with a specific pharmacological target, but rather a naturally occurring metabolite. It is an end product of the metabolism of glyoxylate and ascorbic acid. Its primary targets in human pathology are the kidneys, where it can bind with calcium to form calcium oxalate crystals. This process is the leading cause of kidney stones (nephrolithiasis). Oxalic acid is also a known inhibitor of certain enzymes, including lactate dehydrogenase (LDH) and pyruvate kinase, due to its structural similarity to pyruvate. It acts as a chelator of divalent metal ions like calcium and iron. The labeled version, Oxalic acid-13C2, is used as a tracer to study these metabolic pathways and pathological mechanisms without altering the biological targets.
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| ln Vitro |
Drug compounds have included stable heavy isotopes of carbon, hydrogen, and other elements, mostly as tracers that influence measurement during the drug development process. It's possible that the pharmacokinetics and functional range of medications contribute to the concern over mutagenesis [1].
Oxalic acid-13C2 is a stable isotope-labeled compound used primarily as an analytical internal standard, so its own in vitro biological activity is not the focus of study. However, the in vitro activity of its unlabeled counterpart, oxalic acid, has been characterized. In renal epithelial cell lines (e.g., HK-2 or MDCK cells), oxalic acid (0.5-5 mM) induces cellular injury, including loss of cell viability, disruption of cell membrane integrity, and increased production of reactive oxygen species (ROS). At lower concentrations (0.1-1 mM), oxalic acid has been shown to increase the expression of inflammatory markers such as MCP-1 and osteopontin. Furthermore, in enzymatic assays, oxalic acid is a potent competitive inhibitor of lactate dehydrogenase (LDH), with a Ki value in the low micromolar range. It is also used to induce calcium oxalate crystal formation in cultured cells to model nephrolithiasis in vitro. The ¹3C-labeled version serves as a tracer to track oxalate metabolism in these systems. |
| ln Vivo |
Oxalic acid-13C2 is a stable isotope-labeled internal standard, and its in vivo activity is the same as its unlabeled parent compound. Oxalic acid is not a pharmacologically active drug but a metabolic end product. In animal models, administration of a high-oxalate diet or intraperitoneal injection of sodium oxalate (50-100 mg/kg) leads to hyperoxaluria and the deposition of calcium oxalate crystals in the renal tubules, causing acute kidney injury (AKI). In rats, this results in increased serum creatinine and BUN levels, indicating impaired kidney function. Chronic oxalate feeding leads to the development of renal stones (urolithiasis). Furthermore, oxalic acid is acutely toxic when absorbed systemically; intravenous administration in rodents causes hypocalcemia, cardiac arrhythmias, and death due to calcium chelation. Oxalic acid-13C2 is used as a tracer to study the absorption, distribution, and elimination of oxalate in these models using mass spectrometry.
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| Enzyme Assay |
A generic non-cell-based assay for Oxalic acid-13C2 is used in an isotope dilution mass spectrometry method. First, prepare a stock solution of the unlabeled Oxalic acid in water (1 mg/mL). Prepare a separate stock of the internal standard (Oxalic acid-13C2) at the same concentration. Prepare calibration standards by serially diluting the unlabeled oxalic acid in a blank matrix (e.g., artificial urine) to achieve concentrations ranging from 0.1 to 100 ug/mL. To each calibration standard, add a fixed concentration of the internal standard (e.g., 10 ug/mL). Also prepare blank and double-blank samples. For sample preparation, mix 100 uL of the calibration standard with 300 uL of acetonitrile to precipitate proteins. Centrifuge at 10,000g for 5 minutes. Transfer the supernatant to an autosampler vial. Analyze the samples by LC-MS/MS in negative ion mode, monitoring the specific mass transitions for the analyte (m/z 89.0 → 61.0 for oxalic acid) and the internal standard (m/z 91.0 → 63.0 for oxalic acid-13C2). Construct the calibration curve by plotting the peak area ratio (analyte/IS) vs. the nominal concentration.
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| Cell Assay |
There are no established cell-based assays for Oxalic acid-13C2 itself, but a standard in vitro protocol for its unlabeled counterpart involves assessing calcium oxalate (CaOx) crystal adhesion to renal epithelial cells. Culture MDCK or HK-2 human kidney cells in DMEM/F12 media supplemented with 10% fetal bovine serum and 1% penicillin/streptomycin at 37degC in a 5% CO2 incubator. Seed the cells in 12-well plates at a density of 2×10⁵ cells per well and allow them to grow to confluence (typically 2-3 days). Remove the culture medium and wash the cells twice with PBS. Pre-incubate the cells with or without unlabeled oxalic acid (0.5-2 mM) for 4 hours. Then, add a suspension of pre-formed calcium oxalate monohydrate crystals (COM, 200 ug/mL) to each well. Incubate for 30-60 minutes at 37degC. Gently wash the cells with PBS to remove unattached crystals. Lyse the cells with 0.1 N NaOH. Quantify the amount of adherent crystals by measuring the oxalate content using a commercial assay kit or by LC-MS. Use Oxalic acid-13C2 as an internal standard for LC-MS analysis of oxalate to accurately measure crystal adhesion.
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| Animal Protocol |
A standard in vivo protocol for Oxalic acid-13C2 uses a rat model of hyperoxaluria. Use male Wistar rats (150-200 g). Induce hyperoxaluria by administering 0.5% ethylene glycol in drinking water for 4 weeks (a standard method for inducing calcium oxalate stones). Divide the rats into groups (n=6-8 per group): control (regular water) and treatment (0.5% ethylene glycol). On day 28, anesthetize the animals and collect 24-hour urine samples using metabolic cages before sacrifice. Euthanize the animals and collect blood via cardiac puncture, and harvest both kidneys. Prepare plasma and urine samples for analysis. Homogenize one kidney from each animal. For LC-MS analysis, extract oxalic acid from the plasma, urine, and kidney homogenates. Add a fixed amount of Oxalic acid-13C2 as the internal standard to each sample. Analyze by LC-MS/MS to quantify the concentration of endogenous oxalic acid. Perform histological analysis of the second kidney (H&E staining) to assess calcium oxalate crystal deposition and tissue damage.
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| ADME/Pharmacokinetics |
The pharmacokinetic profile of Oxalic acid-13C2 is identical to that of its non-labeled analog, oxalic acid. Oxalic acid is a small, water-soluble molecule. Following oral administration, it is poorly absorbed from the gastrointestinal tract (bioavailability approx. 2-10% in humans), as unabsorbed oxalate binds to calcium in the gut and is excreted in feces. Absorbed oxalate is rapidly distributed in total body water with a volume of distribution approximating 0.5 L/kg. It is not metabolized in the body to a significant extent. The primary route of elimination is renal excretion via glomerular filtration and tubular secretion. The plasma elimination half-life is short, ranging from 1.5 to 3.5 hours in humans. In chronic kidney disease, the half-life can be prolonged. Oxalic acid-13C2 is used as an internal standard to accurately quantify these parameters in metabolic studies, providing a precise measure of oxalate handling.
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| Toxicity/Toxicokinetics |
The toxicity of Oxalic acid-13C2 itself is not characterized, but it is expected to be the same as its non-labeled analog, oxalic acid. Oxalic acid is corrosive and toxic. The oral LD₅0 for oxalic acid is approximately 375 mg/kg in rats. In humans, ingestion of as little as 5-15 grams can be fatal. The primary mechanism of acute toxicity is the chelation of calcium in the blood, leading to acute hypocalcemia, which can cause cardiac arrhythmias, tetany, and central nervous system depression. It also causes direct corrosive injury to the gastrointestinal tract. Long-term, lower-level exposure to oxalic acid leads to the formation of calcium oxalate kidney stones (nephrolithiasis), which can cause hematuria, obstruction, and renal failure. In the workplace, inhalation of oxalic acid dust can cause respiratory tract irritation. Researchers handling this compound should wear appropriate PPE (gloves, goggles, lab coat) and avoid generating dust.
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| References | |
| Additional Infomation |
Oxalic acid-13C2 is a stable isotope-labeled version of oxalic acid, in which both carbon atoms have been replaced with carbon-13 (¹3C). It is intended for research use only, serving as an internal standard for the quantitative analysis of oxalic acid in various matrices by GC-MS or LC-MS. The unlabeled compound, oxalic acid (H2C2O4), is a strong dicarboxylic acid found naturally in many foods, including spinach, rhubarb, and nuts. It is an end-product of metabolism, and excessive intake or reduced renal clearance leads to kidney stone formation (nephrolithiasis). It is also used as an analytical reagent and general reducing agent. This labeled compound is essential for method development, toxicokinetic studies, and clinical chemistry applications, allowing for high-precision quantitative analysis of oxalate in biological samples.
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| Molecular Formula |
13C2H2O4
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| Molecular Weight |
92.02
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| Exact Mass |
92.002
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| CAS # |
62654-02-8
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| Related CAS # |
Oxalic acid, 99%;144-62-7
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| PubChem CID |
16213468
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| Appearance |
White to off-white solid powder
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| LogP |
-0.3
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| Hydrogen Bond Donor Count |
2
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| Hydrogen Bond Acceptor Count |
4
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| Rotatable Bond Count |
1
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| Heavy Atom Count |
6
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| Complexity |
71.5
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| Defined Atom Stereocenter Count |
0
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| SMILES |
[13C](=O)([13C](=O)O)O
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| InChi Key |
MUBZPKHOEPUJKR-ZDOIIHCHSA-N
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| InChi Code |
InChI=1S/C2H2O4/c3-1(4)2(5)6/h(H,3,4)(H,5,6)/i1+1,2+1
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| Chemical Name |
oxalic acid
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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 | 10.8672 mL | 54.3360 mL | 108.6720 mL | |
| 5 mM | 2.1734 mL | 10.8672 mL | 21.7344 mL | |
| 10 mM | 1.0867 mL | 5.4336 mL | 10.8672 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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