Synthesis And Antibacterial Research Of Hydantoin Modified Chitosan Derivatives

In this study, two series of water-soluble chitosan derivatives were synthesized,which were N-hydroxypropyl chitosan derivatives and N-(2-hydroxy)propyl trimethylammonium chloride chitosan derivatives. The antibacterial activities against thegram-positive bacterium E. coli and gram-positive bacterium S. aureus were tested todiscuss the relationship of structure and antibacterial activity, and to explainedantibacterial mechanism. Furthermore, the effect of pH, metal ions and EDTA on theantibacterial activities of the products was investigated. The study hopes to expandthe application of chitosan in the antibacterial area.Hydroxypropyl chitosan (HPCS) was synthesized by reacting with propyleneepoxide and chitosan, N-(2-hydroxy)propyl chitosan (HTCC) was synthesized byepoxypropyl trimethyl ammonium chloride and chitosan. And3-glycidyl-5,5-dimethyl hydantoin (made in our lab) and epoxy propane wererespectively used to synthesize O-hydroxy-propyl (5,5-dimethyl hydantoin)-N-(2-hydroxy)propyl trimethyl ammonium chloride chitosan (GH-HTCC),O-hydroxy-propyl (5,5-dimethyl hydantoin)-N-(2-hydroxypropyl) chitosan(GH-HPCS) and O-hydroxy-propyl-N-(2-hydroxy)propyl trimethyl ammoniumchloride chitosan (HP-HTCC). The structures of products were characterized throughproton nuclear magnetic resonance spectroscopy (1H NMR), fourier transforminfrared spectroscopy (FTIR), elemental analysis(EA) and ultraviolet-visibleanalysis(UV-Vis) and results indicated that the products were successfully prepared.The thermal staibilty and crystallization properties were tested throughthermogravimetric analysis (TGA) and X-ray diffraction (XRD).The antibacterial data exhibited that the antibacterial activity of products againstS. aureus was better than the activity against E. coli. The antibacterial activities offive kinds of products decreased progressively in this order: GH-HTCC>GH-HPCS>HP-HTCC>HTCC>HPCS. The antibacterial activities of final products wereincreased as the degree of substitution of O-substitute groups increased. Thus, the difference of products’ antibacterial activities was greatly affected by the structure ofproducts.The result of effect of pH (3.5,5.0,7.2,8.0and9.0) on all of chitosanderivatives showed the antibacterial activity was reduced as pH was increased.Whenthe value of pH was7.2, the action was weakest. Then the value of pH was added, theaction was increased. And the activity against S. aureus was stronger than one againstE. coli under the basic condition.The result of effect of metal ions(50mmol/L Na+, Mg2+, Al3+, Ca2+and Ba2+) onthe antibacterial activities of N-hydroxypropyl chitosan derivatives showed Na+andMg2+reduced their property, but the other three kinds of ions improved theirs to someextent, especially for Al3+.The experimental results showed the effect of EDTA concentration on theantibacterial activities of HTCC, HP-HTCC and GH-HTCC. When EDTA was aloneused in test, the antibacterial activities against S. aureus and E. coli. were enhancedwith its concentration increasing. EDTA could improve their antibacterial activitiesof chitosan derivatives. But in the rang of1~6mmol/L, the antibacterial activitywould be declined with EDTA concentration raising. In a word, the EDTAconcentration was an important control factor in antimicrobial application system.The usage of EDTA was better no more than1mmol/L.