N-acetylcysteine side-chain functionalization of poly(globalide-co-ε-caprolactone) through thiol-ene reaction.

ABSTRACT

N-Acetylcysteine (NAC) is a drug well known for its antimucolytic action, antioxidant activity and ability to protect cells from oxidative stress. Conjugation of NAC with double bonds in the main polymer chain of poly(globalide-co-ε-caprolactone) (PGlCL) through thiol-ene reaction is reported. Different globalide (Gl) (an unsaturated macrolactone) to ε-caprolactone (CL) ratios were employed for PGlCL synthesis. The polymeric materials (PGlCL-NAC) were evaluated in terms of the number of functionalized double bonds, thermal properties, affinity for water and antioxidant potential. PGlCL-NAC containing more globalide repeating units presented higher degree of functionalization, due to the higher number of double bonds available to react through thiol-ene coupling. For high globalide contents (Gl/CL ratios above 50/50), NAC coupling in PGlCL chains resulted in completely amorphous copolymers with a more hydrophilic character, which should enhance bioresorption and cell adhesion characteristics. Functionalization also gave rise to a thioether linkage, conferring to PGlCL-NAC an antioxidant character, important for biomedical applications, where the material could combat cellular oxidative-stress.