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The Effect of Substituent, Degree of Acetylation and Positioning of the Cationic Charge on the Antibacterial Activity of Quaternary Chitosan Derivatives

Authors :
Priyanka Sahariah
Vivek S. Gaware
Ramona Lieder
Sigríður Jónsdóttir
Martha Á. Hjálmarsdóttir
Olafur E. Sigurjonsson
Már Másson
Source :
Marine Drugs, Vol 12, Iss 8, Pp 4635-4658 (2014)
Publication Year :
2014
Publisher :
MDPI AG, 2014.

Abstract

A series of water-soluble cationic chitosan derivatives were prepared by chemoselective functionalization at the amino group of five different parent chitosans having varying degrees of acetylation and molecular weight. The quaternary moieties were introduced at different alkyl spacer lengths from the polymer backbone (C-0, C-2 and C-6) with the aid of 3,6-di-O-tert-butyldimethylsilyl protection of the chitosan backbone, thus allowing full (100%) substitution of the free amino groups. All of the derivatives were characterized using 1H-NMR, 1H-1H COSY and FT-IR spectroscopy, while molecular weight was determined by GPC. Antibacterial activity was investigated against Gram positive S. aureus and Gram negative E. coli. The relationship between structure and activity/toxicity was defined, considering the effect of the cationic group’s structure and its distance from the polymer backbone, as well as the degree of acetylation within a molecular weight range of 7–23 kDa for the final compounds. The N,N,N-trimethyl chitosan with 100% quaternization showed the highest antibacterial activity with moderate cytotoxicity, while increasing the spacer length reduced the activity. Trimethylammoniumyl quaternary ammonium moieties contributed more to activity than 1-pyridiniumyl moieties. In general, no trend in the antibacterial activity of the compounds with increasing molecular weight or degree of acetylation up to 34% was observed.

Details

Language :
English
ISSN :
16603397
Volume :
12
Issue :
8
Database :
Directory of Open Access Journals
Journal :
Marine Drugs
Publication Type :
Academic Journal
Accession number :
edsdoj.3ee500f6e8b46a0bc7c4f9d2d71959d
Document Type :
article
Full Text :
https://doi.org/10.3390/md12084635