Synthesis of Novel Cellulose Carbamates Possessing Terminal Amino Groups and Their Bioactivity

Abstract

Cellulose phenyl carbonates are an excellent platform to synthesize a broad variety of soluble and functional cellulose carbamates. In this study, the synthesis of cellulose carbamates with terminal amino groups, namely ω-aminoethylcellulose- and ω-aminoethyl-p-aminobenzyl-cellulose carbamate, is discussed. The products are well soluble and their structures can be clearly described by NMR spectroscopy. The cellulose carbamates exhibit a bactericide and fungicide activity in vitro. The ω-aminoethylcellulose carbamate possesses a strong activity against Candida albicans and Staphylococcus aureus (IC50 of 0.02 mg mL(-1) and 0.05 mg mL(-1)). The antimicrobial activity and cytotoxicity can be improved by p-amino-benzylamine (ABA) as an additional substituent. The mixed cellulose carbamate exhibits a high biocompatibility (LC50 of 3.18 mg mL(-1)) and forms films on cotton and PES, which exhibit a strong activity against S. aureus and Klebsiella pneumoniae.

Evaluation of the Synthesis of Soluble Aromatic Cellulose Carbonates of Low Degree of Substitution

“…The modification of the polysaccharide has to be carried out under nitrogen atmosphere at 0 °C to avoid side reactions like hydrolysis or decomposition of the reagent. Furthermore, acid chlorides may form with DMAc a Vilsmeyer‐adduct yielding side product . The DS values of the products could be adjusted by the molar ratio of AGU to reagent applying substituted chloroformates ( Figure ).…”

“…For the structure design of advanced polysaccharide derivatives, the activation of the polymer backbone by a leaving group is a promising path . Cellulose esters of p ‐toluensulfonic acid (tosylates) could be used to generate a broad variety of novel cellulose derivatives with extraordinary properties like monolayer formation on various substrates . For example, cellulose tosylates could be modified with several amines by a nucleophilic displacement (S N ) reaction to the corresponding 6‐deoxy‐6‐amino celluloses .…”

“…The conversion of polysaccharide phenyl carbonates homogeneously with amines may yield the corresponding polysaccharide carbamates with varying DS of even up to 3 . For example, cellulose carbamate with terminal reactive amino groups could be synthesized by aminolysis of cellulose phenyl carbonate with 1,2‐ethanediamine and p ‐aminobenzylamine that show controlled antimicrobial and cytotoxic properties depending on the variation of the nature of functional groups . However, the reaction of cellulose phenyl carbonates with DS values below 1.2 with amines yields cross‐linked, insoluble products .…”

“…[1,2] Cellulose esters of p-toluensulfonic acid (tosylates) could be used to generate a broad variety of novel cellulose derivatives with extraordinary properties like monolayer formation on various substrates. [3,4] For example, cellulose tosylates could be modified with several amines by a nucleophilic displacement (S N ) reaction to the corresponding 6-deoxy-6-amino celluloses. [5,6] The modification occurs selectively at position 6 of the anhydroglucose unit (AGU), thus, amino celluloses with a degree of substitution (DS) of maximal 1 are accessible.…”

“…[1,11,12] For example, cellulose carbamate with terminal reactive amino groups could be synthesized by aminolysis of cellulose phenyl carbonate with 1,2-ethanediamine and p-aminobenzylamine that show controlled antimicrobial and cytotoxic properties depending on the variation of the nature of functional groups. [3] However, the reaction of cellulose phenyl carbonates with DS values below 1.2 with amines yields crosslinked, insoluble products. [1,8,11] Thus, the question appeared if the synthesis of soluble cellulose phenyl carbonates with DS values below 1.2 and their subsequent modification to soluble products is possible.…”