title: Chitosan-thioglycolic acid as a versatile antimicrobial agent.
abstract: As functionalized chitosans hold great potential for the development of effective and broad-spectrum antibiotics, representative chitosan derivatives were tested for antimicrobial activity in neutral media: trimethyl chitosan (TMC), carboxy-methyl chitosan (CMC), and chitosan-thioglycolic acid (TGA; medium molecular weight: MMW-TGA; low molecular weight: LMW-TGA). Colony forming assays indicated that LMW-TGA displayed superior antimicrobial activity over the other derivatives tested: a 30 min incubation killed 100% Streptococcus sobrinus (Gram-positive bacteria) and reduced colony counts by 99.99% in Neisseria subflava (Gram-negative bacteria) and 99.97% in Candida albicans (fungi). To elucidate LMW-TGA effects at the cellular level, microscopic studies were performed. Use of fluorescein isothiocyanate (FITC)-labeled chitosan derivates in confocal microscopy showed that LMW-TGA attaches to microbial cell walls, while transmission electron microscopy indicated that this derivative severely affects cell wall integrity and intracellular ultrastructure in all species tested. We therefore propose LMW-TGA as a promising and effective broad-band antimicrobial compound.
authors.affiliation: Institute of Inorganic Chemistry, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland.
authors.forename: Georg
authors.initials: G
authors.lastname: Geisberger
authors.forename: Emina Besic
authors.initials: EB
authors.lastname: Gyenge
authors.forename: Doris
authors.initials: D
authors.lastname: Hinger
authors.forename: Andres
authors.initials: A
authors.lastname: Käch
authors.forename: Caroline
authors.initials: C
authors.lastname: Maake
authors.forename: Greta R
authors.initials: GR
authors.lastname: Patzke
mesh_terms: D000890:Anti-Infective Agents / Q000737:chemistry / Q000494:pharmacology; D001672:Biocompatible Materials / Q000737:chemistry / Q000494:pharmacology; D002176:Candida albicans / Q000187:drug effects*; D002473:Cell Wall / Q000187:drug effects; D048271:Chitosan / Q000031:analogs & derivatives / Q000737:chemistry / Q000494:pharmacology*; D008826:Microbial Sensitivity Tests; D009343:Neisseria / Q000187:drug effects*; D016986:Streptococcus sobrinus / Q000187:drug effects*; D013864:Thioglycolates / Q000737:chemistry / Q000494:pharmacology*
chemical_list: D000890:Anti-Infective Agents; D001672:Biocompatible Materials; D013864:Thioglycolates; C017487:2-mercaptoacetate; D048271:Chitosan