Synthesis And Antibacterial Property Of Heterocycle-modified O-quaternized Chitosan

The heterocyclic modified O-quaternized chitosan and its antibacterial propertieswere studied. First the amino group of chitosan C-2was protected by benzaldehyde toform N-benzylidene chitosan schiff`s base [CS (BA)]. Then glycidyltrimethylammonium chloride was reacted with chitosan andO-quaternized-N-benzylidene chitosan schiff`s base [O-HTCC (BA)] was obtained.The benzaldehyde was hydrolyzed to deprived from O-HTCC(BA) to getO-quaternized chitosan (O-HTCC). Then O-HTCC was modified byfuran-2-formaldehyde (furfural) and thiophene-2-formaldehyde respectively toobtain two new products O-quaternized-N-furan methylene chitosan schiff`s base[O-HTCC (FF)] and O-quaternized-N-thiophene methylene chitosan schiff`s base [O-HTCC(ThP)]. And by reduction O-quaternized-N-furan methylene chitosan (O-FHTCC) and O-quaternized-N-thiophene methylene chitosan was formed. Due to theamino group on the chitosan had better activity, N-quaternized chitosan (N-HTCC)was easily to be obtained by the reaction of chitosan and glycidyltrimethylammonium chloride.By using FTIR,1H NMR and Elemental Analysis, above seven target productsO-ThPHTCC, O-HTCC (ThP), O-FHTCC, O-HTCC（FF）, O-HTCC (BA), N-HTCCand O-HTCC, were characterized and the experimental results showed that they weresynthesized successfully.The results of the experiments showed that the solubility of these sevenantibacterial materials were analogous. They could not be dissolved in acetone,ethanol, cyclohexane, ether, DMF, glacial acetic acid, and ethyl acetate. Except forO-HTCC (BA) dissolving in chloroform partially, other six materials could bedissolved in chloroform, THF and water. According to the thermal gravimetric analysis, the thermostability ofO-ThPHTCC and O-FHTCC were much better than O-HTCC (ThP) andO-HTCC(FF).Antibacterial experimental results showed that the materials had antibacterialeffect, and antibacterial activity for gram positive bacteria S. aureus was strongerthan for gram-negative bacteria E. coil, and antibacterial activity at pH5.5was betterthan at pH7.2. The order of antibacterial effect of the materials was as following,O-ThPHTCC> O-FHTCC> O-HTCC(ThP)>O-HTCC（FF）>O-HTCC (BA)>O-HTCC. The results indicated that the antibacterial activity of chitosan derivativescontaining heterocyclic were obviously better than that not containing heterocyclic.And the antibacterial activity of chitosan derivatives containing thiopheneheterocyclic(O-ThPHTCC) was stronger than that of chitosan derivatives containingfuran heterocyclic(O-FHTCC).