Effect of Low Molecular Weight Chitosan on Cells of Epidermis from Pea Leaves

The effect of low molecular weight chitosans with a molecular weight (MW) of 5, 6, 10, 25, and 45 kDa and a deacetylation degree (DD) of 85–99% obtained by chemical depolymerization and enzymatic hydrolysis on the cells of the epidermis of pea leaves was analyzed. Low molecular weight chitosans induced damage to guard cells' plasma membrane, which was estimated from the change in its permeability for the fluorescent dye propidium iodide, and programmed death of epidermal cells determined from the destruction of cell nuclei. These effects are similar to those of commercial high molecular weight chitosan with an MW of 290 kDa and a DD of 90%, which was manifested at higher concentrations than with low molecular weight chitosan. The destructive effect of chitosan on the cells was predominantly DD-dependent, and it was not produced at concentrations up to 10 μg/mL inclusive. Low molecular weight chitosan enhanced the generation of reactive oxygen species in the epidermis, which was detected by monitoring the fluorescence of 2′,7′-dichlorofluorescein. The antioxidants nitroblue tetrazolium and propyl gallate inhibited this process, while Н 2 О 2 accelerated it.