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Chitosan and its antimicrobial potential--a critical literature survey.

Raafat D, Sahl HG - Microb Biotechnol (2009)

Bottom Line: The term 'chitosan' describes a heterogeneous group of polymers combining a group of physicochemical and biological characteristics, which allow for a wide scope of applications that are both fascinating and as yet uncharted.However, understanding the various factors that affect its antimicrobial activity has become a key issue for a better usage and a more efficient optimization of chitosan formulations.Moreover, the use of chitosan in antimicrobial systems should be based on sufficient knowledge of the complex mechanisms of its antimicrobial mode of action, which in turn would help to arrive at an appreciation of its entire antimicrobial potential.

View Article: PubMed Central - PubMed

Affiliation: Institute for Medical Microbiology, Immunology and Parasitology (IMMIP), Pharmaceutical Microbiology Unit, University of Bonn, D-53115 Bonn, Germany. dina_raafat@yahoo.com

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Detailed structure of a chitosan molecule. Shown is an enlarged portion of a chitosan molecule, with relevant dimensions. For a chitosan molecule of a MW of 240 kDa and a DD of 87%, an average chain would consist of around 1400 units, with an average length of about 700 nm.
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f3: Detailed structure of a chitosan molecule. Shown is an enlarged portion of a chitosan molecule, with relevant dimensions. For a chitosan molecule of a MW of 240 kDa and a DD of 87%, an average chain would consist of around 1400 units, with an average length of about 700 nm.

Mentions: It was suggested that the positively charged chitosan (or its oligosaccharides) might be taken up by cells, where they interact with cellular DNA of fungi and bacteria, consequently inhibiting DNA transcription, as well as RNA and protein synthesis (Tarsi et al., 1997; Liu et al., 2001; Rabea et al., 2003). It has also been previously reported that chitosan can penetrate plant cells, being detected 15 min after its application to the surface of the plant tissue within the plant cytoplasm and conspicuously detectable within the plant nucleus (Hadwiger et al., 1981). If this same logic were to be applied to the situation with bacteria, for instance, staphylococci, this contention would be provocative, because it would imply that chitosan is able to circumvent two barriers, namely the multilayered staphylococcal cell wall and the plasma membrane (Fig. 2), to afford access to the intracellular space. However, a consideration of the molecular size of a native chitosan molecule (up to 1000 kDa; Fig. 3) would render such a notion rather unlikely. Moreover, we have found no evidence that chitosan is broken down by staphylococci into smaller fragments, which might pass the cell wall (Raafat et al., 2008).


Chitosan and its antimicrobial potential--a critical literature survey.

Raafat D, Sahl HG - Microb Biotechnol (2009)

Detailed structure of a chitosan molecule. Shown is an enlarged portion of a chitosan molecule, with relevant dimensions. For a chitosan molecule of a MW of 240 kDa and a DD of 87%, an average chain would consist of around 1400 units, with an average length of about 700 nm.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3815839&req=5

f3: Detailed structure of a chitosan molecule. Shown is an enlarged portion of a chitosan molecule, with relevant dimensions. For a chitosan molecule of a MW of 240 kDa and a DD of 87%, an average chain would consist of around 1400 units, with an average length of about 700 nm.
Mentions: It was suggested that the positively charged chitosan (or its oligosaccharides) might be taken up by cells, where they interact with cellular DNA of fungi and bacteria, consequently inhibiting DNA transcription, as well as RNA and protein synthesis (Tarsi et al., 1997; Liu et al., 2001; Rabea et al., 2003). It has also been previously reported that chitosan can penetrate plant cells, being detected 15 min after its application to the surface of the plant tissue within the plant cytoplasm and conspicuously detectable within the plant nucleus (Hadwiger et al., 1981). If this same logic were to be applied to the situation with bacteria, for instance, staphylococci, this contention would be provocative, because it would imply that chitosan is able to circumvent two barriers, namely the multilayered staphylococcal cell wall and the plasma membrane (Fig. 2), to afford access to the intracellular space. However, a consideration of the molecular size of a native chitosan molecule (up to 1000 kDa; Fig. 3) would render such a notion rather unlikely. Moreover, we have found no evidence that chitosan is broken down by staphylococci into smaller fragments, which might pass the cell wall (Raafat et al., 2008).

Bottom Line: The term 'chitosan' describes a heterogeneous group of polymers combining a group of physicochemical and biological characteristics, which allow for a wide scope of applications that are both fascinating and as yet uncharted.However, understanding the various factors that affect its antimicrobial activity has become a key issue for a better usage and a more efficient optimization of chitosan formulations.Moreover, the use of chitosan in antimicrobial systems should be based on sufficient knowledge of the complex mechanisms of its antimicrobial mode of action, which in turn would help to arrive at an appreciation of its entire antimicrobial potential.

View Article: PubMed Central - PubMed

Affiliation: Institute for Medical Microbiology, Immunology and Parasitology (IMMIP), Pharmaceutical Microbiology Unit, University of Bonn, D-53115 Bonn, Germany. dina_raafat@yahoo.com

Show MeSH