Methylisothiazolinone (MI) is an isothiazolinone-derived biocide used for controlling microbial growth in industrial and household products, often in a mixture with 5-chloro-2-methyl-3-isothiazolone (MCI).1,2 MI is active against Gram-positive and Gram-negative bacteria, fungi, and yeast with MIC values of 0.0045, 0.0015, >0.01, and 0.0065% (w/w) for S. aureus, P. aeruginosa, A. niger, and C. albicans, respectively, when used alone.1 MIC values are 7 to 200-fold lower when MI is used in combination with MCI. MI decreases neurite outgrowth of rat cortical neurons when used at concentrations of 0.1-3 ?M and inhibits Src family kinases in cell-free assays.3 MI, alone and as a mixture with MCI, can elicit contact sensitization.2
1.Lundov, M.D., Johansen, J.D., Zachariae, C., et al.Low-level efficacy of cosmetic preservativesInt. J. Cosmet. Sci.33(2)190-196(2011) 2.Scherrer, M.A.R., and Rocha, V.B.Increasing trend of sensitization to methylchloroisothiazolinone/methylisothiazolinone (MCI/MI)An. Bras. Dermatol.89(3)527-528(2014) 3.He, K., Huang, J., Lagenaur, C.F., et al.Methylisothiazolinone, a neurotoxic biocide, disrupts the association of SRC family tyrosine kinases with focal adhesion kinase in developing cortical neuronsJ. Pharmacol. Exp. Ther.317(3)1320-1329(2006)