Chitosan-hydroxycinnamic acid conjugates: Synthesis, photostability and phytotoxicity to seed germination of barley

摘要

Chitosan-caffeic and chitosan-ferulic acid conjugates are synthesized by carbodiimide method and characterized by UV, FTIR, and NMR spectroscopy. There are two obtained forms of conjugates: freshly synthesized and reconstituted freeze-dried. A comparative study of the stability of various conjugate forms over time and under UV irradiation has been carried out. It has been shown that the absorption intensity of an aqueous solution of the freshly synthesized chitosan-caffeic acid conjugate decrease in similar to 2 times during 20 weeks of storage, while the maximum rate of intensity decrease is observed during the first 40 days. The absorption intensity of the chitosan-ferulic acid conjugate decrease by 6-7 during the entire storage period. It has been found that freeze-dried powders of chitosan-caffeic and chitosan-ferulic acid conjugates are stable for at least 1 year. It has been established that freeze-dried chitosan-caffeic and chitosan-ferulic acid conjugates are more stable under UV irradiation (in 4-8 and 1.4-1.9 times, respectively) compared to freshly synthesized ones. A comparative study of the influence of conjugates on barley seedlings (Hordeum vulgare L.) growth has been carried out.