Characterization of Potential Antibacterial Activity of High- Degree Polymerized Chitooligosaccharides

The potential antibacterial activity of high degree polymerized chitooligosaccharides designated as medium molecular weight chitosans (MMWCs) was evaluated as IC50 ranged from 150 to 490 μg/ml of the concentration toward gram-positive and gram-negative bacteria. The results of this study suggest that MMWCs derived from the high molecular weight chitosan (CTSN) can be a potent factor affecting on antimicrobial activity. For the determination of MW of high degree polymerized chitooligosaccharides having potent antibacterial activity, quantitative analysis of amine residue, high performance liquid chromatography (HPLC) and matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) in an effort to determine a more precise measurement of MW, respectively, for MMWCs were performed. Consequently, the MW of the MMWCs was subsequently determined by spectrophotometric method which showed the proportionality in the concentration of MMWCs, ranged from 0 to 10 mg/ml. Determination of the MW of several MMWCs obtained from the hydrolysis of CTSN showed good agreement with those values from HPLC and MALDI-TOF MS analyses. This is the first report demonstrating the relationship between the molecular weight of MMWCs determined in comparative methods and their potent antibacterial activity.