Maleic Anhydride-Derived Copolymers Conjugated with Beta-Lactam Antibiotics: Synthesis, Characterization, In Vitro Activity/Stability Tests with Antibacterial Studies

Abstract

The synthesis and characterization of biocompatible three different maleic anhydride co-polymer conjugated with two different beta-lactam antibiotics at in vitro conditions were conducted. The polymer–drug conjugates were synthesized by coupling β-lactam antibiotics via amide bonds to the copolymer. In this work, six different drug-functionalized maleic anhydride copolymers (DFMACs) were synthesized by the chemical conjugation method. This method is based on the ring-opening reaction of the anhydride ring of the copolymer to form an amide bond linking the drug. The synthesized DFMACs were characterized by 1H NMR and FTIR/ATR spectroscopies and analyses were carried out by UV/VIS spectroscopy and Zeta-sizer instrument in detail with consecutive antibacterial tests. The existence of a newly formed amide covalent bond between the drug and the copolymer chains was confirmed by 1H NMR and FTIR/ATR studies. This is the first report on the application of the selected branched biodegradable polymeric matrices for the covalent conjugation of ampicillin and cefalexin. Optimum stability and activity conditions for the synthesized DFMACs were determined. Analyses were conducted under in vitro conditions including varying pH values and simulated body fluids as a function of time to obtain new drug delivery system candidates for the two different antibiotics.