The effect of different concentrations of chitosan on the production of phenolic acids in cell culture of lactuca undulate ledeb

One of the most important methods for increasing the production of secondary metabolites is the use of elicitors in plant cell culture. A biopolymer made from D-glucosamine units, chitosan can be found in the cell walls of fungi and in the exoskeletons of arthropods. Plants respond to chitosan treatment by generating defense responses, increasing antioxidant enzyme activity, accumulating phenolic compounds, and releasing flavonoids. In the current study, chitosan was used as an elicitor to induce the production of phenolic acids in Lactuca undulata cells suspended in liquid medium.

First, cell suspension culture was prepared from 45 days old callus derived from leaf explants of Lactuca undulata on ½ MS medium supplemented with 0.1 and 1 mgL-1 2,4-D and Kin. The effect of different concentrations of chitosan (0, 50, 100 and 200 mgL-1) on cell suspension was evaluated during 24, 48 and 72 hours. After harvesting samples, the percentage of cell viability, total phenols and flavonoids, chicoric acid, chlorogenic acid and caffeic acid contents, as well as phenylalanine-ammonia lyase (PAL) activity and lipid peroxidation were measured.

In the present study, we found that the concentration and duration of chitosan treatment affect the production of phenolic compounds (including chicoric acid) in Lactuca undulata cell suspension culture. After 24 hours of treatment with 50 mgL-1 chitosan, chicoric acid levels had increased 2.8-fold compared to the control. After 24 and 48 hours of treatment with 200 mgL-1 chitosan, the highest levels of chlorogenic and caffeic acids were observed. Furthermore, the present study found the chitosan treatment resulted in an increase in the amount of phenol and total flavonoids as well as an increase in PAL enzyme activity. Chitosan induces lipid peroxidation and reduces cell viability in high concentrations, indicating a negative effect.

The present study found that low concentrations of chitosan could induce chicoric acid production in Lactuca undulata cell suspension cultures, which can be utilized in the pharmaceutical industry as a new method in the production of chicoric acid and its derivatives.