Technical Information

The Antimicrobial Active (Chloroxylenol or PCMX) and its Mechanism of Action

Parachlorometaxylenol (more commonly known as chloroxylenol or PCMX and also known as 4-chloro-3,5-dimethyl-hydroxybenzene, para chloro meta xylenol, 4 chloro 3,5-dimethyl phenol, 4 chloro 3,5 xylenol, and 4 chloro meta xylenol) is a substituted phenol with a molecular formula of C₈H₉ClO and molecular weight of 156.5 with CAS No. 88-04-0. Its mechanism of antimicrobial action is by the denaturation of proteins and inactivation of enzymes in the microorganisms. Also likely, this agent, as for other phenolic compounds, alters the permeability of the cell membrane that could result in the uncoupling of oxidative phosphorylation, inhibition of active transport, and loss of pool metabolites due to cytoplasmic membrane damage (1). It was first registered in the United States in 1959 for use as a fungicide and has been used in Europe for over six decades. Compared to phenols, xylenols exhibit increased microbiocidal activity, on the order of 30 times more (1). The chlorine substitution intensifies the microbiocidal potency. PCMX has been widely used as a broad spectrum antimicrobial in disinfectants, antiseptics, and soaps, as a topical antiseptic for skin and mucous membranes, an antimicrobial in cosmetic formulations, and as a fungicide for adhesives, paints, textiles, paper products, and polishes. It has FDA clearance for use as a preservative in food packaging adhesives.