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Biocides General
DEFINITION
Biocide is a general term used to denote a chemical that
possesses antiseptic, disinfectant or preservative activity.
CLASSIFICATION
Biocides are classified as 1) sanitizers, 2) disinfectants and
3) sterilants.
Sanitizers are defined as agents added to inanimate objects
(food contact or non-food contact products) to reduce, but not
necessarily to eliminate, the number of microbial contaminants
to levels that are considered safe by public health codes or
regulations. Disinfectants are chemical or physical agents
applied to inanimate objects to destroy or irreversibly
inactivate disease causing microorganisms, but not necessarily
their spores. Sterilizing agents, on the other hand, are
chemical or physical agents used to destroy or eliminate all
forms of microbial life, including bacterial spores (Bacillus
anthracis)
MODE OF ACTION
Biocides vary in their chemical structures and in their mode
of action. However, the final damage, when lethal
concentrations are used, may show similarities. Biocides must
reach and interact with their microbial target site(s) to be
effective. Biocide target sites may include but are not
limited to outer cellular components, the cytoplasmic
membrane, cytoplasmic constituents and/or metabolic processes.
CHEMICAL OXIDANTS
In all chemical processes, when one substance is oxidized
another one must be reduced. Oxidation is an increase in the
positive valance state of a substance, such as by the removal
of one or more electrons from an atom or ion. Conversely,
reduction is the addition of one or more electrons to a
molecule, resulting in a less positive or more negative
valance state. Ozone, hydrogen peroxide, hypochlorites,
chlorine and chlorine dioxide are the oxidizing agents most
commonly used for the chemical treatment of organic
contaminants. Antimicrobial agents such as sodium hypochlorite
and hydrogen peroxide work directly via radical-mediated
reactions to oxidize organic material.
OxB BIOCIDE
This strong oxidant results from the precise ratio of peroxide
and hypochlorite. Singlet oxygen and reactive oxygen species (ROS)
such as hydroxyl radicals, superoxide anion radicals and
chlorine radicals result from the above reaction. Singlet
oxygen and ROS react with organic biomolecules (e.g.,
carbohydrates, proteins, lipids, nucleic acids) resulting in
the modification of both their chemical structures and
chemical properties. Singlet oxygen reacts directly with
moieties of high electron density such as carbon double bonds
which are found in most biomolecules, leading to protein
oxidation, non-enzymatic lipid peroxidation and nucleic acid
(RNA and DNA) damage. Overall, direct and indirect (by the
release of reactive compounds) damage to biological systems by
singlet oxygen and ROS can result in the loss of cell membrane
fluidity, leakage of cell enzymes and enzyme inactivation,
disruption of cell homeostasis and interference with RNA, DNA
and protein synthesis. Ultimately, the accumulation of damage
as a result of oxidative stress will lead to cell death. |
