Inhibition of acetylcholinesterase by gallic acid-grafted-chitosans

This paper discusses acetylcholinesterase inhibitory properties of gallic acid-grafted-chitosans (GA-g-chitosans) with different grafting ratios. The GA-g-chitosans exhibited potent acetylcholinesterase inhibitory effects in a dose-dependent manner, and their IC50 values ranged from 138.5 ± 0.25 to 397.6 ± 5.2 μg/mL. The acetylcholinesterase inhibition kinetics of the GA-g-chitosan (I) by Lineweaver-Burk plots showed a decrease in Vmax, whereas Km was not altered, thus suggesting a non-competitive mode of inhibition. The inhibition constant, Ki, was found to be 64.85 μg/mL by the secondary plot of the Lineweaver-Burk plots. In addition, the GA-g-chitosan (I) did not exert any significant cytotoxicity against PC12 cells, and the cellular acetylcholinesterase activity in PC12 cells was significantly inhibited by the GA-g-chitosan (I). This is the first report on acetylcholinesterase inhibition by the grafting of GA onto chitosan, and this compound might be helpful in preventing Alzheimer's disease by elevating cholinergic transmission.