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 H-1 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-alpha production in RAW 264.7 cells without cytotoxicity, especially derivative TMCRA, whose inhibition rate was > 50 % at only 250 mu g/mL. The results suggested that chitosan quaternary ammonium derivatives grafted with rosmarinic acid possessed better anti-oxidant and anti-inflammatory properties than chitosan, which could be used as drug materials against oxidative and inflammation-related pathological processes.