title: Extent of shielding by counterions determines the bactericidal activity of N,N,N-trimethyl chitosan salts.
abstract: In this study, we show that the bactericidal activity of quaternized chitosans (TMCs) with sulfate, acetate, and halide counterions against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) correlates with the "availability" of N-quaternized groups [-(+)N(CH3)3] in the TMCs backbones. N,N,N-trimethyl chitosan sulfate (TMCS) and N,N,N-trimethyl chitosan acetate (TMCAc) displayed the highest activities, probably due to their delocalized π system. Among TMCs with halide counterions, activity was higher for N,N,N-trimethyl chitosan chloride (TMCCl), whereas N,N,N-trimethyl chitosan iodide (TMCI) and N,N,N-trimethyl chitosan bromide (TMCBr) exhibited lower, similar values to each other. This is consistent with the shielding of -(+)N(CH3)3 groups inferred from chemical shifts for halide counterions in (1)HNMR spectra. We also demonstrate that TMCs with distinct bactericidal activities can be classified according to their vibrational spectra using principal component analysis. Taken together, these physicochemical characterization approaches represent a predictive tool for the bactericidal activity of chitosan derivatives.
authors.affiliation: São Carlos Institute of Physics, University of São Paulo (USP), PO Box 369, CEP 13566-590 São Carlos, São Paulo, Brazil; Polymers and Composite Materials Group (GMPC), Department of Chemistry, State University of Maringá (UEM), Av. Colombo 5790, CEP 87020-900 Maringá, Paraná, Brazil.
authors.forename: Heveline D M
authors.initials: HDM
authors.lastname: Follmann
authors.affiliation: Technological University of Paraná (UTFPR), CEP 86812-460 Apucarana, Paraná, Brazil; Polymers and Composite Materials Group (GMPC), Department of Chemistry, State University of Maringá (UEM), Av. Colombo 5790, CEP 87020-900 Maringá, Paraná, Brazil.
authors.forename: Alessandro F
authors.initials: AF
authors.lastname: Martins
authors.affiliation: São Carlos Institute of Physics, University of São Paulo (USP), PO Box 369, CEP 13566-590 São Carlos, São Paulo, Brazil.
authors.forename: Thatyane M
authors.initials: TM
authors.lastname: Nobre
authors.affiliation: Embrapa Instrumentation, CEP 13560-970 São Carlos, São Paulo, Brazil.
authors.forename: Joana D
authors.initials: JD
authors.lastname: Bresolin
authors.affiliation: Polymers and Composite Materials Group (GMPC), Department of Chemistry, State University of Maringá (UEM), Av. Colombo 5790, CEP 87020-900 Maringá, Paraná, Brazil.
authors.forename: Thelma S P
authors.initials: TSP
authors.lastname: Cellet
authors.affiliation: Technological Federal University of Paraná (UTFPR), Via Rosalina Maria dos Santos, CEP 87301-899 Campo Mourão, Paraná, Brazil.
authors.forename: Patrícia
authors.initials: P
authors.lastname: Valderrama
authors.affiliation: Embrapa Instrumentation, CEP 13560-970 São Carlos, São Paulo, Brazil.
authors.forename: Daniel S
authors.initials: DS
authors.lastname: Correa
authors.affiliation: Polymers and Composite Materials Group (GMPC), Department of Chemistry, State University of Maringá (UEM), Av. Colombo 5790, CEP 87020-900 Maringá, Paraná, Brazil; The Graduate Program in Biotechnology Applied to Agriculture, Paranaense University (UNIPAR), CEP 87502-210 Umuarama, Paraná, Brazil.
authors.forename: Edvani C
authors.initials: EC
authors.lastname: Muniz
authors.affiliation: São Carlos Institute of Physics, University of São Paulo (USP), PO Box 369, CEP 13566-590 São Carlos, São Paulo, Brazil. Electronic address: chu@ifsc.usp.br.
authors.forename: Osvaldo N
authors.initials: ON
authors.lastname: Oliveira
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry* / Q000494:pharmacology; D001965:Bromides / Q000737:chemistry; D048271:Chitosan / Q000031:analogs & derivatives* / Q000494:pharmacology; D002712:Chlorides / Q000737:chemistry; D007454:Iodides / Q000737:chemistry; D013211:Staphylococcus aureus / Q000187:drug effects; D013329:Structure-Activity Relationship
chemical_list: D000900:Anti-Bacterial Agents; D001965:Bromides; D002712:Chlorides; D007454:Iodides; D048271:Chitosan
keywords: Bactericidal activity; Chitosan derivatives; Counterions; N,N,N-trimethyl chitosan salts; “Availability” of−(+)N(CH(3))(3) groups