Mode of action of hydrogen peroxide and other oxidizing agents: differences between liquid and gas forms.
OBJECTIVE
Antimicrobials such as chlorine dioxide, peracetic acid and hydrogen peroxide (H(2)O(2)) share a basic mechanism of action (chemical oxidation of cellular components), but profound differences arise in their efficacy against microorganisms. Optimization of activity requires an understanding of their interaction with microbial targets and a clear differentiation between the chemical efficacies of each oxidative biocide. This study aimed to elucidate the biochemical mechanisms of action of oxidizing biocides at a macromolecular level, using amino acids, protein and an enzyme as model substrates for the action of each biocide.


METHODS
The interactions of a number of oxidising agents (liquid and gaseous H(2)O(2), ClO(2), peracetic acid formulations) with amino acids, proteins (bovine serum albumin and aldolase) and enzymes were investigated by spectrophotometry, SDS-PAGE and alkaline phosphatase activity measurements.


RESULTS
Biocide reactions yielded different types of oxidative structural change and different degrees of oxidation to amino acids and proteins, and differences in activity against a microbial enzyme. In particular there was a marked difference in the interactions of liquid H(2)O(2) and gaseous H(2)O(2) with the macromolecules, the latter causing greater oxidation; these results explain the dramatic differences in antimicrobial efficacy between liquid and gas peroxide.


CONCLUSIONS
These results provide a comprehensive understanding of the differences in interactions between a number of oxidizing agents and macromolecules commonly found in microbial cells. Biochemical mechanistic differences between these oxidative biocides do exist and lead to differential effects on macromolecules. This in turn could provide an explanation as to their differences in biocidal activity, particularly between liquid and gas peroxide.
Finnegan
Michelle
M
Welsh School of Pharmacy, Cardiff University, Cardiff CF10 3NB, UK.
Linley
Ezra
E
Denyer
Stephen P
SP
McDonnell
Gerald
G
Simons
Claire
C
Maillard
Jean-Yves
JY
D000469:Alkaline Phosphatase / Q000378:metabolism; D000596:Amino Acids / Q000378:metabolism; D000900:Anti-Bacterial Agents / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D004798:Enzymes / Q000378:metabolism; D005740:Gases / Q000633:toxicity; D006861:Hydrogen Peroxide / Q000378:metabolism*; D016877:Oxidants / Q000378:metabolism*; D010084:Oxidation-Reduction; D011506:Proteins / Q000378:metabolism; D013053:Spectrophotometry
D000596:Amino Acids; D000900:Anti-Bacterial Agents; D004798:Enzymes; D005740:Gases; D016877:Oxidants; D011506:Proteins; D006861:Hydrogen Peroxide; D000469:Alkaline Phosphatase