Grafting of p-Methoxy cinnamic acid on chitosan

Abstract

In this work, UV-filtering polymer was synthesized by grafting of UV- absorptive chromophore onto chitosan. The synthesis process involved 1) reacting chitosan with phthalic anhydride to give phthaloylchitosan that could be soluble in organic solvent such as DMF and 2) esterifying between 4-methoxycinnamic acid and/or 2,4,5-trimethoxycinnamic acid with the phthaloylchitosan. The three obtained polymeric chitosan derivatives, 4-methoxycinnamoyl-phthaloylchitosan, 2,4,5-trimethoxycinnamoyl-phthaloyl chitosan and 2,4,5-trimethoxycinnamoyl-4- methoxycinnamoyl-phthaloylchitosan showed UVB, UVA and both UVA and UVB absorption properties, respectively. Moreover, all three polymeric chitosan derivatives were photostable. Experiments using baby mice skin revealed that all three polymers could not penetrate the baby mice skin.