The antibacterial structure-activity relationship for common chitosan derivatives

Antimicrobial Properties of Chitosan and Chitosan Derivatives in the Treatment of Enteric Infections

“…Chitosan is only active in the acidic medium; however, it was reported that the limited activity above pH 6 may originate from the poor solubility above pH 6. Chitosan was observed to be equally active against S. aureus at pH 5.5 and 7.2 (MIC = 256 μg/mL) [ 39 ]. Further investigations are required to fully understand the importance of the polycationic charge of chitosan.…”

“…In the study on the relationship between the degree of substitution (DS) and antibacterial activity, Professor Másson and his coworkers have reported that HTC was more active than chitosan against S. aureus , but this activity is independent of DS, whereas the antibacterial activity of HTC decreases with an increase in DS in other cases. Additionally, a surprising result shows that only the lowest DS structure possessed more antibacterial activity than chitosan [ 39 ]. HTCC was also reported to block subsequent interaction between the S protein of coronavirus and the cellular receptor [ 75 ].…”

“…HPC exhibits no inhibitory effect on E. coli or S. aureus , whereas it shows inhibitory effectiveness against the four fruit pathogenic fungi ( A. mali , C. diplodiella , F. oxysporum , and P. piricola ) [ 77 ]. In the study on the relationship between the degree of substitution (DS) and antibacterial activity, the antibacterial activity of HPC decreases with DS [ 39 ]. HPC was used to formulate nail lacquers containing antifungal agents such as ciclopirox for onychomycosis, a fungal infection of the nails [ 78 ].…”

“…Thioglycolic chitosan is a thiolated chitosan derivative with antimicrobial properties. It is synthesized by the reacting chitosan, 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide and thioglycolic acid [ 39 ]. Recently, low molecular weight TGC has displayed excellent antimicrobial activity over the other derivatives (CMC and TMC): a 30 min treatment killed 100% Streptococcus sobrinus (Gram-positive bacteria) and reduced bacteria by 99.99% in Neisseria subflava (Gram-negative bacteria) and 99.97% in Candida albicans (fungi) [ 49 ].…”

“…Good mucoadhesive properties of TGC can serve as a promising tool for the mucoadhesive drug delivery systems [ 50 ]. In the study on the relationship between the degree of substitution (DS) and antibacterial activity, the degree of substitution for the TGC is very low and the antibacterial activity is similar to unmodified chitosan [ 39 ].…”