Chemical Agent(s)

Mechanism(s) of Action


Denaturation of proteins. Ethyl and isopropyl alcohols are most used; methyl alcohol has the weakest bactericidal action of the alcohols, so is seldom used for this application.

Chlorine and chlorine compounds

Unknown, but might involve oxidation of sulfhydryl groups in amino acids (enzymes) ® oxidation of respiratory components, depressed DNA synthesis, decreased ATP production, etc.


Alkylation of amino acid sulfhydryl groups of proteins and ring N atoms of purine bases.


Alkylation of sulfhydryl, hydroxyl, carboxyl, and amino groups ® alteration of DNA, RNA, and protein synthesis.

Hydrogen peroxide (H2O2)

Production of hydroxyl free radicals ® attack membrane lipids, DNA, and other essential cell components.

Iodine and iodophors

Iodine penetrates cell walls quickly ® disruption of protein and nucleic acid structure and synthesis.

OPA (ortho-phthalaldehyde)

Mechanisms similar to glutaraldehyde; less potent, but greater uptake through outer layers of myco- and gram-negative bacteria.

Peracetic acid

Unknown, but believed to be an oxidizer ® denatures proteins, disrupts cell wall permeability, and oxidizes sulfhydryl and sulfur bonds in structural proteins, enzymes, etc.


Low concentration: inactivation of essential enzyme systems and leakage of essential substances from the cell wall. High concentration: protoplasmic poison (penetration and disruption of cell wall, and precipitation of cell proteins).

Quaternary ammonium compounds

Inactivation of energy-producing enzymes, denaturation of essential cell proteins, and disruption of the cell membrane.