Methylchloroisothiazolinone 

Methylchloroisothiazolinone is a widely used fungicide and also an aquatic pollutant with pro-inflammatory activity and neurotoxicity. Methylchloroisothiazolinone induces the production of pro-inflammatory cytokines (such as IL-1β, TNF-α, IL-6) by activating the NF-κB signaling pathway and upregulating TLR4 expression, thereby triggering allergic contact dermatitis. Methylchloroisothiazolinone reduces cholinesterase activity and exacerbates oxidative stress by impairing catalase activity and disrupting redox balance. Methylchloroisothiazolinone poses significant harm to Mediterranean mussels, reducing the viability of hemocytes and digestive gland cells, inhibiting immune phagocytic function, and disrupting osmoregulatory capacity. Methylchloroisothiazolinone is used in studies on allergic contact dermatitis and related immunotoxicity mechanisms^[1][2].

Methylchloroisothiazolinone (0.01-0.1 mg/L; 14 d) induces concentration-dependent cytotoxicity in hemocytes of the Mediterranean mussel (Mytilus galloprovincialis): cell viability decreases significantly at 0.01 mg/L, partially recovers at 0.1 mg/L, and lysosomal membrane stability reduces at both concentrations^[2].
Methylchloroisothiazolinone (0.01-0.1 mg/L; 14 d) induces concentration-dependent cytotoxicity in isolated Mytilus galloprovincialis (Mediterranean mussel), with significant loss of cell viability and lysosomal stability at 0.01 mg/L, and partial recovery observed at 0.1 mg/L^[2].
Methylchloroisothiazolinone (0.01-0.1 mg/L; 14 d) impairs the osmoregulatory capacity of digestive gland cells isolated from the Mediterranean mussel (Mytilus galloprovincialis)^[2].
Methylchloroisothiazolinone (0.01-0.1 mg/L; 14 d) significantly reduces the phagocytic activity of hemocytes in Mediterranean mussels (Mytilus galloprovincialis)^[2].
Methylchloroisothiazolinone (0.01-0.1 mg L^-1; 14 days) induces concentration-dependent oxidative stress, biotransformation activation, and neurotoxicity in the digestive glands of Mediterranean mussels (Mytilus galloprovincialis)^[2].

MedChemExpress (MCE) has not independently confirmed the accuracy of these methods. They are for reference only.

149.60

C₄H₄ClNOS

26172-55-4

Liquid

O=C1N(C)SC(Cl)=C1

Room temperature in continental US; may vary elsewhere.

4°C, stored under nitrogen

*In solvent : -80°C, 6 months; -20°C, 1 month (stored under nitrogen)

• [1]. Goes H F O, et al. Proinflammatory and regulatory mechanisms in allergic contact dermatitis caused by methylchloroisothiazolinone and methylisothiazolinone[J]. Experimental dermatology, 2020, 29(5): 490-498.

  [2]. Multisanti C R, et al. From biocide to biohazard: influence of methylchloroisothiazolinone on physiological integrity of Mytilus galloprovincialis[J]. Emerging Contaminants, 2025: 100617.

  [3]. Park EJ, et al. Methylisothiazolinone induces apoptotic cell death via matrix metalloproteinase activation in human bronchial epithelial cells. Toxicol In Vitro. 2020;62:104661.  [Content Brief]

  [4]. Park EJ, et al. Methylisothiazolinone may induce cell death and inflammatory response through DNA damage in human liver epithelium cells. Environ Toxicol. 2018;33(2):156-166.