| Size | Price | |
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| Other Sizes |
| Targets |
The compound reacts with nucleophilic centers in proteins. Primary targets are thiol groups (cysteine residues) and amino groups (lysine residues). It has two electrophilic centers: the C5 carbon and the sulfur atom. Attack at C5 by amines leads to vinylic substitution; attack at sulfur leads to ring opening.
Methylisothiazolinone targets cellular thiol groups, particularly glutathione (GSH), through its reactive isothiazolone ring. It acts as a biocide by disrupting essential cellular processes in microorganisms. The compound is a potent cytotoxic agent that affects bronchial epithelial cells. |
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| ln Vitro |
In vitro reactivity studies with model nucleophiles were performed. Methylisothiazolinone HCl reacted with sodium propanethiolate (PrSNa) at both the sulfur atom and C5, but attack at sulfur predominated (activation energy index 10.75 for S-attack vs 11.31 for C5-attack). With n-butylamine (BuNH2), it reacted at C5 (AE index 11.47) rather than at sulfur (AE index 11.67). The initial product from BuNH2 attack at C5 (chloride displacement product 2) underwent secondary reactions to yield ring-opened products 3, 4, and 5 (Figure 2). A proposed mechanism involves formation of N‑chloroamine (BuNHCl or BuNCl2) as a coproduct, which could contribute to sensitization. These reactivity patterns were consistent with the AE indices derived from molecular orbital calculations. [1]
Additionally, the compound can react with thiol groups to form protein‑S‑S‑CCl‑CH‑CONHMe, which can further react to produce disulfide‑bridged determinants. [1] In biochemical assays, methylisothiazolinone reacts covalently with GSH, depleting cellular glutathione levels. This reaction is the basis for its antimicrobial activity and also contributes to its sensitizing potential. The compound shows broad-spectrum antimicrobial activity against bacteria and fungi. |
| ln Vivo |
In vivo skin sensitization potency was quantified using the mouse local lymph node assay (LLNA). The EC3 value (concentration required to produce a stimulation index of 3) for Methylisothiazolinone HCl is 0.009%, which classifies it as an extreme sensitizer. No other in vivo pharmacological effects were reported. [1]
In cellular models, methylisothiazolinone has been used as a cytotoxic substance to investigate its effects on bronchial epithelial cells. It induces cell death through oxidative stress mechanisms involving GSH depletion. The compound is a moderate sensitizer that can cause contact dermatitis in susceptible individuals. |
| Enzyme Assay |
Cellular assays for methylisothiazolinone involve treating cultured cells (e.g., bronchial epithelial cells) with varying concentrations (typically 1-1000 µM) for 24-72 hours. Cell viability is assessed by MTT, LDH release, or other cytotoxicity assays. GSH levels are measured spectrophotometrically to assess the compound's effect on cellular thiol status.
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| Cell Assay |
In vitro enzyme assays evaluate the compound's reactivity with GSH by incubating MIT HCl with reduced glutathione and measuring the remaining free thiol groups using Ellman's reagent. The reaction kinetics are monitored spectrophotometrically at 412 nm. Antimicrobial activity is assessed by minimum inhibitory concentration (MIC) determination against bacterial and fungal strains.
|
| Animal Protocol |
The animal protocol referenced is the murine local lymph node assay (LLNA), which measures the proliferative response of lymph node cells following topical application of the test substance. The EC3 value is derived from the dose‑response curve. Specific details of the protocol (e.g., vehicle, application frequency, duration) were not provided in the cited literature. The EC3 for Methylisothiazolinone HCl is 0.009%. [1]
In vivo toxicity studies have focused on the sensitizing potential of methylisothiazolinone in animal models. The compound is a known skin sensitizer, and guinea pig maximization tests or local lymph node assays are used to assess its sensitization potential. Dermal exposure studies evaluate skin irritation and allergic contact dermatitis responses. |
| ADME/Pharmacokinetics |
Methylisothiazolinone HCl (C₄H₅NOS·HCl, MW 151.6) is a water-soluble compound. It is stable as a solid powder and is typically stored at room temperature. The compound is used as a preservative in various aqueous formulations at concentrations typically below 100 ppm.
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| Toxicity/Toxicokinetics |
The primary toxicity reported is skin sensitization. In the LLNA, the EC3 value is 0.009%, indicating extreme sensitization potential. The compound is electrophilic and can modify skin proteins, leading to allergic contact dermatitis. No other toxicity endpoints (e.g., LD50, organ toxicity) were described. [1]
Toxicological data indicate that methylisothiazolinone is a moderate skin sensitizer and can cause allergic contact dermatitis. It is cytotoxic to bronchial epithelial cells and reacts with GSH, which may contribute to its toxicity. The compound is regulated in cosmetic products due to its sensitizing potential. |
| References |
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| Additional Infomation |
The compound's mechanism of skin sensitization involves multiple pathways: (i) reaction with thiol groups of proteins to form disulfide‑linked determinants; (ii) reaction with amino groups to form vinylic substitution products that further rearrange; (iii) formation of N‑chloroamines (positive chlorine species) that may also react with proteins. The activation energy (AE) index was proposed to rationalize its reactivity; a lower AE index corresponds to higher reactivity. Methylisothiazolinone HCl has an AE index of 11.47 for BuNH2 attack at C5 and 10.75 for PrSNa attack at S, consistent with its observed reactivity. The compound is more reactive than MI (2‑methylisothiazol‑3‑one) and is a stronger sensitizer due to its wider range of protein modification pathways. [1]
Methylisothiazolinone HCl is extensively used as a preservative in the cosmetic industry and in industrial products such as paints, adhesives, and cooling water systems. It is one of the components of the biocide Kathon CG. The compound has been the subject of regulatory scrutiny due to its sensitizing potential, leading to restrictions on its use in leave-on cosmetic products. |
| Molecular Formula |
C4H6CLNOS
|
|---|---|
| Molecular Weight |
151.608
|
| Exact Mass |
150.986
|
| CAS # |
26172-54-3
|
| Related CAS # |
Methylisothiazolinone-d3 hydrochloride;1329509-49-0;Methylisothiazolinone;2682-20-4
|
| PubChem CID |
117746
|
| Appearance |
White to off-white solid powder
|
| LogP |
1.248
|
| Hydrogen Bond Donor Count |
1
|
| Hydrogen Bond Acceptor Count |
2
|
| Rotatable Bond Count |
0
|
| Heavy Atom Count |
8
|
| Complexity |
121
|
| Defined Atom Stereocenter Count |
0
|
| InChi Key |
SJXPQSRCFCPWQQ-UHFFFAOYSA-N
|
| InChi Code |
InChI=1S/C4H5NOS.ClH/c1-5-4(6)2-3-7-5;/h2-3H,1H3;1H
|
| Chemical Name |
2-methyl-1,2-thiazol-3-one;hydrochloride
|
| Synonyms |
KB-838 MI N-Methylisothiazolin-3-oneMethylisothiazolinone HCl
|
| 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)
|
| Solubility (In Vitro) |
DMSO : ~100 mg/mL (~659.59 mM)
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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 | 6.5959 mL | 32.9794 mL | 65.9587 mL | |
| 5 mM | 1.3192 mL | 6.5959 mL | 13.1917 mL | |
| 10 mM | 0.6596 mL | 3.2979 mL | 6.5959 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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