While many cleaning products accomplish the same goal, most are made up of a unique blend of active ingredients responsible for their potency. These bacteria killing chemicals can be broken down in to a number of more general categories: phenolics, quarternary ammonium centers, alcohols, and halogen based compounds. In this first segment, we'll discuss phenolics.
Phenolics are molecules which contain a phenol group (an aromatic six carbon ring with a hydroxyl (OH)). This anti-bacterial, first used as an antiseptic in the 1860s, acts by damaging cell membranes and denaturing enzymes within bacterial cells. On a molecular level, phenolics work by inserting into the phospholipid bilayer of cells, acidifying the cell membrane, and denaturing proteins within the cell.
The hydrogen atom of the hydroxyl group in phenol is weakly acidic, but can lose it's proton around biological pH (~7). At the surface of the plasma membrane, phenols can exchange protons with molecules and proteins, changing the relative distribution of charge across the cell membrane. While this may seem minor, even small changes in the charge surrounding the cell membrane can cause charge sensitive membranes, responsible for the transport of compounds across the cell membrane to shut down: nothing in and nothing out.
While phenol compounds contain a polar alcohol (R-OH) group, the phenyl ring make them largely nonpolar. This characteristic allows phenols to insert themselves into the phospholipid bilayer of the cell membrane. As these molecules begin to build up within the cell membrane, they can begin to displace phospholipids, compromising the integrity of the cell membrane. Once within the membrane, phenolics which have lost their hydrogen atom also have the ability to shuttle cations across the cell membrane, leading to further membrane permeability and loss of the cell's content.
Lastly, once within the cell, phenolics can denature (inactivate) proteins. The cell's cytoplasm is mostly made up of water, a polar substance. Normally, proteins fold in such a way to expose a maximum number of its polar side chains to the surrounding polar environments while hiding its nonpolar side chains internally. When nonpolar phenolic molecules begin to interact with a protein it will change its shape to expose some of its nonpolar portions. This change in conformation leads to inactivation of the protein (denaturation), due to the fact that protein form and function are interdependent.
In terms of disinfectants, phenolics are only one component that makes up the laundry list of ingredients in household cleaners. As you can see, however, the way these molecules interact with bacteria, viruses, and fungi can be quite complicated! Tune in soon for the next antiseptic in the series!
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References:
- http://www.madsci.org/posts/archives/mar99/921165350.Mi.r.html
- http://www.cliffsnotes.com/study_guide/Chemical-Methods-of-Control.topicArticleId-8524,articleId-8429.html
- http://books.google.com/books?id=iwiJwnrq6a8C&pg=SA10-PA13&lpg=SA10-PA13&dq=phenolics+inactivate+proteins&source=bl&ots=Agoq5Kp9a4&sig=0WUHpss8Mp2Q6FsWzpQq4Y5oHXU&hl=en&sa=X&ei=BbgOUdD7O_SB0QGq1IHwDw&ved=0CHwQ6AEwCA#v=onepage&q=phenolics%20inactivate%20proteins&f=false
- http://books.google.com/books?id=y5-VzA5CxvsC&pg=PA170&lpg=PA170&dq=mechanism+of+phenolic+membrane+disruption&source=bl&ots=ZY93r4K4X5&sig=OzUFOL1Mvbz5NrW3Oqr9siOiVvY&hl=en&sa=X&ei=HrwOUYjYGMqw0AG1woHYAg&ved=0CEwQ6AEwAw#v=onepage&q=mechanism%20of%20phenolic%20membrane%20disruption&f=false
- http://ecosystems.wcp.muohio.edu/studentresearch/ns1fall02/cummins/morning/resistance/articles/Mechanisms%20of%20Action%20of%20Disinfectants.pdf
- https://facultystaff.richmond.edu/~lrunyenj/bio384/lecturenotes/ch7.pdf
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