Membrane-disrupting bactericidal activity

Imazato and co-workers [29,30] prepared a novel monomer, methacryloyloxydodecyl pyrimidinium bromide (MDPB). A water-soluble homopolymer of MDPB and copolymer of MDPB with acrylamide were also synthesised and the bactericidal activity against oral streptococci was studied. The mechanism of action of these quaternary compounds is assumed to be due to direct cationic binding to cell wall components, which results in disruption of the cell wall membrane, and subsequently results in leakage of critical cell contents and cell death. 

Aliphatic alcohols such as ethanol, n-propanol, n-butanol and isopentyl (isoamyl) alcohol exert disruptive effects upon bacterial membranes as shown by the lysis of protoplasts [76]. Of these, only ethanol displays any useful bactericidal activity it is used to cleanse the skin before injections and to sterilize instruments. Butanol is used to solubilize membrane-bound enzymes [22,91], its action being similar to that of the non-ionic detergents described below. 

A valuable approach for preventing surface-mediated Infection consists In coating the surface with an Intrinsically bactericidal polymer, Polycatlonic chains with long alkyl chain quaternary ammonium (octyl or dodecyl) constitutive units were found to be very efficient In eliminating bacteria as a result of Increased hydrophobicity and cldal activity,It Is now widely accepted that the target site of these cationic polymers Is the cytoplasmic membrane of bacterial cells and that the crucial step of their lethal action Is the disruption of the membrane - penetrated by the ammonium alkyl chain -followed by the rapid release of Ions and other cytoplasmic constituents. 

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