Preparation of chitosan-rosmarinic acid derivatives with enhanced antioxidant and anti-inflammatory activities

In present study, several chitosan derivatives grafted with rosmarinic acid，including chitosan-rosmarinic acid conjugate (CS-RA), chitosan rosmarinic acid salt (CSRA), N,N,N-trimethylated chitosan rosmarinic acid salt (TMCRA), and N-[(2-hydroxy-3-trimethylammonium)propyl]chitosan rosmarinic acid salt (HACRA), were prepared and the effects of different grafting methods on bioactivity of these derivatives were investigated. The structural characterization was identified by FTIR and 1H NMR spectroscopy. The chitosan derivatives were also evaluated biologically for antioxidant, cytotoxic, and anti-inflammatory activities. Derivatives CSRA, TMCRA, and HACRA prepared through ion exchange method exhibited significant antioxidant ability. All derivatives remarkably inhibited lipopolysaccharide-induced nitric oxide and TNF-α production in RAW 264.7 cells without cytotoxicity, especially derivative TMCRA, whose inhibition rate was >50 % at only 250 μg/mL. The results suggested that chitosan quaternary ammonium derivatives grafted with rosmarinic acid possessed better antioxidant and anti-inflammatory properties than chitosan, which could be used as drug materials against oxidative and inflammation-related pathological processes.