Thioacetamide targets the liver, specifically hepatocytes, through its reactive metabolites. The primary target is CYP2E1, the microsomal enzyme responsible for its metabolic activation. The reactive metabolite thioacetamide-S-dioxide covalently binds to cellular proteins and lipids, causing mitochondrial disruption, inhibition of lipid transport or metabolism, and nuclear receptor modulation. These events lead to cholestasis, steatosis, phospholipidosis, fibrosis, and cell death.

In WB-F344 cells, thioacetamide (TAA; 0–10,000 μM; 24 h) exhibits concentration-dependent cytotoxicity[4]. In the early stages, at low (1000 μM) and high (10000 μM) concentrations, thioacetamide (TAA; 1000 and 10000 μM; 0-24 h; WB-F344 cells) contains differentially-expressed genes[4].
In vitro, thioacetamide requires metabolic activation to exert its toxic effects. In cell culture systems containing CYP2E1-expressing cells, TAA induces cytotoxicity, oxidative stress, and apoptosis. Apoptosis induced by thioacetamide is mediated through the mitochondrial pathway, involving cytochrome C release, caspase-9 activation, and PARP cleavage. TAA exposure leads to increased reactive oxygen species (ROS) production and lipid peroxidation.

In male ICR mice, thioacetamide (TAA; 100 mg/kg; i.p., three times per week) can cause chronic liver fibrosis[2]. In C57BL/6 mice, thioacetamide (200–1200 mg/kg; intraperitoneal; once) causes a hepatic encephalopathy model [3].
In vivo, thioacetamide is administered to rodents (typically rats or mice) to induce liver injury models. Intraperitoneal injection is the most common route of administration, with doses ranging from 50 to 300 mg/kg given 2-3 times per week. Chronic administration (4-12 weeks) induces liver fibrosis, cirrhosis, and hepatic encephalopathy. Acute administration causes centrilobular necrosis, elevated serum transaminases (ALT, AST), and oxidative stress markers. TAA-induced liver fibrosis is characterized by collagen deposition, activated hepatic stellate cells, and impaired liver function.

For non-cellular assays, thioacetamide is studied for its metabolic activation by CYP2E1. Microsomal preparations (e.g., rat liver microsomes) are incubated with TAA and NADPH, and the formation of reactive metabolites is detected using HPLC or mass spectrometry. Covalent binding of reactive metabolites to proteins is assessed using radiolabeled TAA or immunodetection of protein adducts. Lipid peroxidation is measured by malondialdehyde (MDA) or 4-hydroxynonenal (4-HNE) levels.

Cell Viability Assay[4]
Cell Types: WB-F344 cells
Tested Concentrations: 0-10000 μM
Incubation Duration: 24 hrs (hours)
Experimental Results: Had 20% and 50% cell death at the 1000 and 10000 μM concentrations, respectively.
In vitro cell culture experiments utilize hepatocyte cell lines (e.g., HepG2, primary rat hepatocytes) or CYP2E1-transfected cells. Cells are treated with TAA at concentrations ranging from 1 to 50 mM for 6-48 hours. Endpoints include cell viability (MTT assay), ROS production (DCFH-DA staining), apoptosis (Annexin V/PI, caspase activity), mitochondrial membrane potential (JC-1 staining), and expression of fibrosis-related genes (TGF-β, collagen, α-SMA). Metabolic activation by CYP2E1 is a critical requirement for TAA cytotoxicity in vitro.

Animal/Disease Models: Male ICR mice[2]
Doses: 100 mg/kg
Route of Administration: intraperitoneal (ip)injection; three times weekly for eight weeks
Experimental Results: Induced chronic liver fibrosis in male ICR mice and resulted in lower body weight, serum cholesterol and triglycerides as well as increased liver size, ALT, AST and LDH values.

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Animal/Disease Models: Male C57BL/6 mice (20-25g, aged 8-12 weeks )[3]
Doses: 200, 600, and 1,200 mg/kg
Route of Administration: intraperitoneal (ip)injection; once
Experimental Results: Altered the neuropsychiatric state, motor behavior and reflex and sensory functions. Increased in the glutamate release in the cerebral cortex of Hepatic encephalopathy (HE ) mice.
In vivo animal models are the primary application of thioacetamide. Rodents (rats, mice) are administered TAA via intraperitoneal injection at doses of 50-300 mg/kg, 2-3 times per week for 4-12 weeks to induce chronic liver fibrosis. Acute liver injury models use single doses of 100-300 mg/kg. Endpoints include serum biochemistry (ALT, AST, bilirubin, albumin), liver histology (H&E, Masson's trichrome, Sirius Red staining), hydroxyproline content (collagen quantification), hepatic stellate cell activation markers, and assessment of hepatic encephalopathy (behavioral tests, ammonia levels).

Absorption, Distribution and Excretion
When 5 mg of (3)H-thioacetamide was added to the oral diet of male albino rats… radioactivity was detected in all examined organs (liver, kidney, and adrenal glands), with the highest radioactivity observed in the liver. Whole-body autoradiography showed that the antithyroid drug (35)S-thioacetamide was absorbed by the liver, kidneys (medulla), myocardium, Haver glands, spleen, lymph nodes, and gastrointestinal tract of rats after intravenous injection. Approximately 80% was excreted in the urine over 24 hours. The distribution of labeled thioacetamide in the liver, kidneys, plasma, and muscle of rats over time was investigated. Centrilobular necrosis was first observed 6 hours after the peak plasma concentration of thioacetamide-S-oxide (i.e., 9 hours after administration of thioacetamide).

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Metabolism/Metabolites
…Thioacetamide is metabolized in the body to acetamide, which itself is carcinogenic…Acetamide is then hydrolyzed to acetate…
Thioacetamide is a procarcinogen or original carcinogen and must be activated by the host's biochemical metabolism. /Excerpt from table/
The hepatotoxicity of thioacetamide may be related to its metabolism to thioacetamide sulfoxide, which is then further metabolized into the final toxic metabolite.
Thioacetamide is oxidized to thioacetamide S-oxide in rat liver microsomes and mixed-function oxidase systems.
For more complete metabolite/metabolite data on thioacetamide (9 metabolites in total), please visit the HSDB record page.
Thioacetamide is a small molecule with a molecular weight of 75.13 g/mol and the formula C2H5NS. It is metabolically activated by CYP2E1 in the liver, and its reactive metabolites have short half-lives. The compound is typically administered intraperitoneally in animal studies. It is soluble in water and organic solvents. Pharmacokinetic studies are limited due to its use as a toxicological tool rather than a therapeutic agent. The compound is stable under recommended storage conditions.

Thioacetamide is classified as a hepatotoxin and carcinogen. It causes liver necrosis, fibrosis, and cirrhosis in animal models. Chronic exposure is associated with an increased risk of liver tumors. It is toxic by ingestion, inhalation, and skin absorption. Safety precautions include handling in a fume hood, wearing protective gloves and clothing. The compound is for research use only and is not intended for human therapeutic applications.

[1]. Standard operating procedures in experimental liver research: thioacetamide model in mice and rats. Lab Anim. 2015 Apr;49(1 Suppl):21-9.

[2]. Hepatoprotection of silymarin against thioacetamide-induced chronic liver fibrosis. J Sci Food Agric. 2012 May;92(7):1441-7.

[3]. A thioacetamide-induced hepatic encephalopathy model in C57BL/6 mice: a behavioral and neurochemical study. Arq Neuropsiquiatr. 2010 Aug;68(4):597-602.

[4]. Expression analysis of early response-related genes in rat liver epithelial cells exposed to thioacetamide in vitro. J Vet Med Sci. 2009 Jun;71(6):719-27.

According to an independent committee of scientific and health experts, thioacetamide may be carcinogenic. Thioacetamide is a white crystalline solid with a thiol odor. It is a thiocarboxamide formed by replacing the oxygen atom in acetamide with a sulfur atom. It is a hepatotoxic substance with similar functions to acetamide. Thioacetamide is a synthetic, colorless crystalline solid, soluble in water and ethanol. Currently, thioacetamide is only used as a substitute for hydrogen sulfide in qualitative analysis. When heated, it decomposes, releasing toxic nitrogen oxides and sulfur oxide fumes. The main routes of human exposure to thioacetamide are inhalation and skin contact. It is likely a human carcinogen. (NCI05) A crystalline compound used as a laboratory reagent to replace hydrogen sulfide. It is a potent hepatocarcinogen. Mechanism of Action: Repeated injections of thioacetamide…reduce the synthesis of cytochrome P450b and the amount of its translatable mRNA.
A factor was isolated from the liver of rats with thioacetamide-induced fibrosis that stimulated collagen synthesis in cultured fibroblasts without affecting their proliferation rate.
Alterations in nuclear RNA sequence transport are an early response to carcinogens. Based on the hypothesis that nucleoside triphosphatases (NTPases) are involved in RNA transport, the nuclear membrane was isolated and its NTPase activity was detected. A common feature of low-dose thioacetamide (without obvious toxicity) effects was increased nuclear membrane NTPase activity and increased RNA transport, which could be assessed by the appearance of rapidly labeled RNA in the cytoplasm and in vitro assays. The increase in NTPase activity specifically occurred in nuclear membrane components, and this increase was masked by early toxic effects at high doses. The induced increase in nuclear membrane NTPase activity was long-lasting. In contrast, the increase in nuclear membrane NTPase activity was observed only during the regeneration phase of carbon tetrachloride poisoning; the increase induced by carbon tetrachloride was transient and rapidly returned to control levels. These changes in NTPase activity were independent of parallel changes in the phosphorylation/dephosphorylation levels of nuclear membrane proteins. Increased nuclear membrane NTPase activity and altered RNA transport (without nuclear replication) may be associated with changes in nuclear RNA restriction. These alterations in regulation may make these cells more susceptible to further modification and could potentially play a role in the initiation of oncogenic effects.
TAA is used as a model compound to study liver fibrosis, cirrhosis, hepatic encephalopathy, and hepatocellular carcinoma. It is also used to investigate the mechanisms of drug-induced liver injury, oxidative stress, and mitochondrial dysfunction. Thioacetamide-induced liver fibrosis models are widely used to evaluate potential anti-fibrotic and hepatoprotective agents. The compound has also been used as a model system to study apoptosis. It is not approved for clinical use and is strictly a research chemical.

C2H5NS

75.13

75.014

62-55-5

2723949

White to off-white solid powder

1.1±0.1 g/cm3

45.3±23.0 °C at 760 mmHg

108-112 °C(lit.)

-18.8±22.6 °C

363.9±0.1 mmHg at 25°C

1.522

0.12

1

1

0

4

33

0

YUKQRDCYNOVPGJ-UHFFFAOYSA-N

InChI=1S/C2H5NS/c1-2(3)4/h1H3,(H2,3,4)

ethanethioamide

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 (e.g. under nitrogen), 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)

DMSO : 100 mg/mL (1331.03 mM)
H2O : 50 mg/mL (665.51 mM)

Solubility in Formulation 1: ≥ 2.5 mg/mL (33.28 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 25.0 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.

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Solubility in Formulation 2: ≥ 2.5 mg/mL (33.28 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 25.0 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.

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Solubility in Formulation 3: ≥ 2.5 mg/mL (33.28 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 25.0 mg/mL clear DMSO stock solution to 900 μL of corn oil and mix evenly.

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